error.rs

use crate::constants::*;
use crate::datastructures::{
    Status, r#box, font_id_text, mag
};
use crate::io::term_input_string;
use crate::math::fam;
use crate::{
    Global, HalfWord, Integer, QuarterWord, Scaled, StrNum, update_terminal
};

use std::io::Write;

// Part 6: Reporting errors

pub enum TeXError {
    Arith,
    Overflow(&'static str, Integer),
    Confusion(&'static str),
    IO(&'static str),
    Fatal(&'static str),
    
    // Other errors that do no stop original TeX,
    // but will stop this implementation.
    // Section 288
    IncompatibleMag,
    IllegalMag(Integer),
    // Section 336
    IncompleteIf,
    // Section 338
    FileEndedOrForbiddenCSFound,
    // Section 346
    InvalidCharacter,
    // Section 370
    UndefinedControlSequence,
    // Section 373
    MissingEncCSName,
    // Section 395
    ArgumentExtraRightBrace,
    // Section 396
    ParagraphEndedBefore,
    // Section 398
    DoesNotMatchDefinition,
    // Section 403
    MissingLeftBrace,
    // Section 408
    IncompatibleGlueUnits,
    // Section 415, 446
    MissingNumber,
    // Section 418
    ImproperMode(Integer),
    // Section 428
    CantUseAfterThe,
    // Section 433
    BadRegisterCode,
    // Section 434
    BadCharacterCode,
    // Section 435
    BadNumber,
    // Section 436
    BadMathChar,
    // Section 437
    BadDelimiterCode,
    // Section 442
    ImproperAlphabeticConstant,
    // Section 445
    NumberTooBig,
    // Section 454
    IllegalUnitOfMeasureFilll,
    // Section 456
    IllegalUnitOfMeasureMu,
    // Section 459
    IllegalUnitOfMeasurePt,
    // Section 460
    DimensionTooLarge,
    // Section 475
    MissingLeftBrace2,
    // Section 476
    AlreadyNineParameters,
    ParametersNumberedConsecutively,
    // Section 479
    IllegalParameterNumber,
    // Section 486
    FileEndedWithin,
    // Section 500
    ExtraOr,
    // Section 503
    MissingEqual(HalfWord),
    // Section 510
    ExtraFiOrElse,
    // Section 530
    CantFindFile,
    CantWriteFile,
    // Section 561
    TfmNotLoadable(bool, HalfWord, Scaled),
    // Section 567
    TfmNotLoaded(HalfWord, Scaled),
    // Section 577
    MissingFontIdentifier,
    // Section 579
    FontHasOnly(QuarterWord),
    // Section 641
    HugePage,
    // Section 723
    UndefinedCharacter(HalfWord),
    // Section 776
    ImproperHalignDisplay,
    // Section 783
    MissingCroisillonAlign,
    // Section 784
    OnlyOneCroisillonAllowed,
    // Section 792
    ExtraAlignmentTab,
    // Section 826
    InfiniteGlueShrinkageInParagraph,
    // Section 936
    ImproperHyphenation,
    // Section 937
    NotALetter,
    // Section 960
    TooLateForPatterns,
    // Section 961
    BadPatterns,
    // Section 962
    Nonletter,
    // Section 963
    DuplicatePattern,
    // Section 976
    InfiniteGlueShrinkageInBoxBeingSplit,
    // Section 978
    VsplitNeedsAVbox,
    // Section 993
    InsertionCanOnlyBeAddedToVbox(HalfWord),
    // Section 1004
    InfiniteGlueShrinkageOnCurrentPage,
    // Section 1009
    InfiniteGlueShrinkageInsertedFrom(Integer),
    // Section 1015
    Box255IsNotVoid,
    // Section 1024
    OutputLoop,
    // Section 1027
    UnbalancedOutputRoutine,
    // Section 1028
    OutputRoutineDidntUseAllOfBox255,
    // Section 1049, 1050
    ReportIllegalCase,
    // Section 1047
    MissingDollar,
    // Section 1064, 1065
    MissingEndGroup,
    MissingMathRight,
    MissingRightBrace,
    // Section 1066
    Extra,
    // Section 1068
    TooManyRightBraces,
    // Section 1069
    ExtraRightBraceOrForgotten,
    // Section 1078
    LeadersNotFollowedByProperGlue,
    // Section 1080
    CantUseIn,
    CantUseIn2,
    // Section 1082
    MissingTo,
    // Section 1084
    BoxWasSupposedToBeHere,
    // Section 1095
    CantUseHrule,
    // Section 1099
    CantInsert255,
    // Section 1106
    CantTakeThings,
    // Section 1110
    IncompatibleListCantBeUnboxed,
    // Section 1120
    IllegalMathDisc,
    DiscListTooLong,
    // Section 1121
    ImproperDiscList,
    // Section 1127
    MissingLeftBrace3,
    MissingRightBrace2,
    // Section 1128
    MisplacedTabMark,
    // Section 1129
    MisplacedNoalign,
    MisplacedOmit,
    // Section 1132
    MissingCr,
    // Section 1135
    ExtraEndcsname,
    // Section 1159
    LimitControlsMustFollowMathOp,
    // Section 1161
    MissingDelimiterLeftParen,
    // Section 1166
    UseMathAccentInMathMode,
    // Section 1177
    DoubleSuperscript,
    DoubleSubscript,
    // Section 1183
    AmbiguousFraction,
    // Section 1192
    ExtraMathRight,
    // Section 1195
    InsufficientSymbolFonts,
    InsufficientExtensionFonts,
    // Section 1197
    DisplayMathEndsWithDollars,
    // Section 1207
    MissingDollarDollar,
    // Section 1212
    CantUsePrefix,
    // Section 1213
    CantUseLongOuter,
    // Section 1215
    MissingControlSequence,
    // Section 1225
    MissingTo2,
    // Section 1232
    InvalidCode(Integer, HalfWord),
    // Section 1237
    CantUseAfterCmd(QuarterWord),
    // Section 1241
    ImproperSetbox,
    // Section 1243
    BadSpaceFactor,
    // Section 1244
    BadPrevGraf,
    // Section 1252
    PatternsOnlyIniTeX,
    // Section 1259
    ImproperAt(Integer),
    // Section 1283
    ErrMessage(StrNum),
    // Section 1304
    CantDumpInGroup,
    // Section 1372
    UnbalancedWriteCmd,

    // Format
    CantFindFormat,
}

pub(crate) type TeXResult<T> = Result<T, TeXError>;

macro_rules! help_lines {
    ($($lines:expr),*) => {
        vec![$($lines),*]
    };
}

impl Global {
    // Section 92
    pub(crate) fn normalize_selector(&mut self) -> TeXResult<()> {
        self.selector = if self.log_opened {
            TERM_AND_LOG
        }
        else {
            TERM_ONLY
        };

        if self.job_name == 0 {
            self.open_log_file()?;
        }
        if self.interaction == BATCH_MODE {
            self.selector -= 1;
        }
        Ok(())
    }

    // Section 96
    pub(crate) fn check_interrupt(&mut self) -> TeXResult<()> {
        if !self.interrupt || !self.ok_to_interrupt {
            return Ok(());
        }

        // Section 98
        self.interaction = ERROR_STOP_MODE;
        if self.selector == LOG_ONLY || self.selector == NO_PRINT {
            self.selector += 1;
        }
        println!();
        println!("! Interruption.");
        println!("You rang?");
        println!("Not supported at the moment.");
        println!("Type <return> to continue or X to quit.");
        print!("? ");
        update_terminal!();
        if term_input_string()?.trim() == "X" {
            Err(TeXError::Fatal("interrupted by the user"))
        }
        else {
            Ok(())
        }
    }

    // Section 992
    fn box_error(&mut self, n: HalfWord) {
        self.begin_diagnostic();
        self.print_nl("Content of \\box255:");
        self.show_box(r#box(n));
        self.end_diagnostic(true);
    }

    // Section 82
    pub fn error(&mut self, texerror: TeXError) -> TeXResult<()> {
        // Section 73
        macro_rules! print_err {
            ($s:expr) => {
                {
                    self.print_nl("! ");
                    self.print($s);
                }
            };
        }
        
        // Section 1049
        macro_rules! you_cant {
            () => {
                print_err!("You can't use '");
                self.print_cmd_chr(self.cur_cmd, self.cur_chr);
                self.print(" in ");
                self.print_mode(self.mode());
                self.print_char(b'.');
            };
        }

        let help_message = match texerror {
            TeXError::IO(s) => {
                self.selector = TERM_ONLY;
                print_err!("Input/output error(");
                self.print(s);
                self.print_char(b')');
                help_lines!(
                    "Something wrong manipulating file happened.",
                    "By precaution, this message is only printed in terminal."
                )
            },

            // Section 93
            TeXError::Fatal(s) => {
                self.normalize_selector()?;
                print_err!("Emergency stop.");
                help_lines!(s)
            },

            // Section 94
            TeXError::Overflow(s, n) => {
                self.normalize_selector()?;
                print_err!("TeX capacity exceeded, sorry [");
                self.print(s);
                self.print_char(b'=');
                self.print_int(n);
                self.print_char(b']');
                help_lines!(
                    "If you really absolutely need more capacity",
                    "you can ask a wizard to enlarge me."
                )
            },

            // Section 95
            TeXError::Confusion(s) => {
                self.normalize_selector()?;
                print_err!("This can't happen (");
                self.print(s);
                self.print_char(b')');
                help_lines!("I'm broken. Please show this to someone who can fix can fix.")
            },

            // Section 288
            TeXError::IncompatibleMag => {
                print_err!("Incompatible magnification (");
                self.print_int(mag());
                self.print(").");
                help_lines!("I can handle only one magnification ratio per job.")
            },

            TeXError::IllegalMag(mag) => {
                print_err!("Illegal magnification (");
                self.print_int(mag);
                self.print(").");
                help_lines!("The magnification ratio must be between 1 and 32768.")
            },

            // Section 336
            TeXError::IncompleteIf => {
                print_err!("Incomplete ");
                self.print_cmd_chr(IF_TEST, self.cur_if as HalfWord);
                self.print_char(b'.');
                if self.cur_cs == 0 {
                    help_lines!(
                        "The file ended while I was skipping conditional text.",
                        "This kind of error happens when you say '\\if...' and forget\nthe matching '\\fi'."
                    )
                }
                else {
                    help_lines!(
                        "A forbidden control sequence occurred in skipped text.",
                        "This kind of error happens when you say '\\if...' and forget\nthe matching '\\fi'."
                    )
                }
            },

            // Section 338
            TeXError::FileEndedOrForbiddenCSFound => {
                self.runaway();
                match self.cur_cs {
                    0 => print_err!("File ended"),
                    _ => print_err!("Forbidden control sequence found"),
                }
                self.print(" while scanning ");
                // Section 339
                match self.scanner_status {
                    Status::Defining => self.print("definition"),
                    Status::Matching => self.print("use"),
                    Status::Aligning => self.print("preamble"),
                    Status::Absorbing => self.print("text"),
                    _ => (), // There are no other cases
                }
                // End section 339
                self.print(" of ");
                self.sprint_cs(self.warning_index);
                self.print_char(b'.');
                help_lines!(
                    "I suspect you have forgotten a '}', causing me",
                    "to read past where you wanted me to stop."
                )
            },

            // Section 346
            TeXError::InvalidCharacter => {
                print_err!("Text line contains an invalid character.");
                help_lines!("A funny symbol that I can't read has just been input.")
            },

            // Section 370
            TeXError::UndefinedControlSequence => {
                print_err!("Undefined control sequence.");
                help_lines!(
                    "The control sequence at the end of the top line",
                    "of your error message was never \\def'ed."
                )
            },

            // Section 373
            TeXError::MissingEncCSName => {
                print_err!("Missing ");
                self.print_esc("endcsname.");
                help_lines!(
                    "The control sequence marked <to be read again> should",
                    "not appear between \\csname and \\endcsname."
                )
            },

            // Section 395
            TeXError::ArgumentExtraRightBrace => {
                print_err!("Argument of ");
                self.sprint_cs(self.warning_index);
                self.print(" has an extra }.");
                help_lines!(
                    "I've run accros a '}' that doesn't seem to match anything.",
                    "For example, '\\def\\a#1{...}' and '\\a}' should produce",
                    "this error."
                )
            },

            // Section 396
            TeXError::ParagraphEndedBefore => {
                print_err!("Paragraph ended before ");
                self.sprint_cs(self.warning_index);
                self.print(" was complete.");
                help_lines!(
                    "I suspect you've forgotten a '}', causing me to apply this",
                    "control sequence to too much text. How can we recover?"
                )
            },

            // Section 398
            TeXError::DoesNotMatchDefinition => {
                print_err!("Use of ");
                self.sprint_cs(self.warning_index);
                self.print(" doesn't match its definition.");
                help_lines!(
                    "If you say, e.g., '\\def\\a1{...}', then you must always",
                    "put '1' after '\\a', since control sequence names are",
                    "made up of letters only. The macro here has not been",
                    "followed by the required stuff."
                )
            },

            // Section 403
            TeXError::MissingLeftBrace => {
                print_err!("Missing {.");
                help_lines!("A left brace was mandatory here.")
            },

            // Section 408
            TeXError::IncompatibleGlueUnits => {
                print_err!("Incompatible glue units.");
                help_lines!("I'm not going to assume that 1mu=1pt, you must choose.")
            },

            // Section 415, 446
            TeXError::MissingNumber => {
                print_err!("Missing number.");
                help_lines!(
                    "A number should have been here.",
                    "(If you can't figure out why I needed to see a number,",
                    "look up 'weird error' in the index of the TeXbook.)"
                )
            },

            // Section 418
            TeXError::ImproperMode(m) => {
                print_err!("Improper ");
                self.print_cmd_chr(SET_AUX, m);
                self.print_char(b'.');
                help_lines!(
                    "You can refer to \\spacefactor only in horizontal mode;",
                    "you can refer to \\prevdepth only in vertical mode, and",
                    "neither of these is meaningful inside \\write."
                )
            },

            // Section 428
            TeXError::CantUseAfterThe => {
                print_err!("You can't use '");
                self.print_cmd_chr(self.cur_cmd, self.cur_chr);
                self.print("' after ");
                self.print_esc("the.");
                help_lines!("I'm not forgetting what you said, fix that.")
            },

            // Section 433
            TeXError::BadRegisterCode => {
                print_err!("Bad register code.");
                help_lines!("A register must be between 0 and 255.")
            },

            // Section 434
            TeXError::BadCharacterCode => {
                print_err!("Bad character code.");
                help_lines!("A character number must be between 0 and 255.")
            },

            // Section 435
            TeXError::BadNumber => {
                print_err!("Bad number.");
                help_lines!("I expected to read a number between 0 and 15.")
            },

            // Section 436
            TeXError::BadMathChar => {
                print_err!("Bad mathchar.");
                help_lines!("A mathchar number must be between 0 and 32767.")
            },

            // Section 437
            TeXError::BadDelimiterCode => {
                print_err!("Bad delimiter code.");
                help_lines!("A numeric delimiter code must be between 0 and 2^{27}-1.")
            },

            // Section 442
            TeXError::ImproperAlphabeticConstant => {
                print_err!("Improper alphabetic constant.");
                help_lines!("A one-character control sequence belongs after a ` mark.")
            },

            // Section 445
            TeXError::NumberTooBig => {
                print_err!("Number too big.");
                help_lines!("I can only go up to 2 147 483 647 = \"7FFFFFFF.")
            },

            // Section 454
            TeXError::IllegalUnitOfMeasureFilll => {
                print_err!("Illegal unit of measure.");
                help_lines!("I dddon't go any higher than filll.")
            },

            // Section 456
            TeXError::IllegalUnitOfMeasureMu => {
                print_err!("Illegal unit of measure.");
                help_lines!("The unit of measurement in math glue must be mu.")
            },

            // Section 459
            TeXError::IllegalUnitOfMeasurePt => {
                print_err!("Illegal unit of measure.");
                help_lines!(
                    "Dimensions can be in units of em, ex, in, pt, pc,",
                    "cm, mm, dd, cc, bp, or sp; but yours is a new one!"
                )
            },

            // Section 460
            TeXError::DimensionTooLarge => {
                print_err!("Dimension too large.");
                help_lines!("I can't work with sizes bigger than about 576 cm.")
            },

            // Section 475
            TeXError::MissingLeftBrace2 => {
                print_err!("Missing {.");
                help_lines!("Where was the left brace? You said saomething like `\\def\\a}'.")
            },

            // Section 476
            TeXError::AlreadyNineParameters => {
                print_err!("You already have nine parameters.");
                help_lines!("Remove the extra #.")
            },
            TeXError::ParametersNumberedConsecutively => {
                print_err!("Parameters must be numbered consecutively.");
                help_lines!("Check your parameters numbering.")
            },

            // Section 479
            TeXError::IllegalParameterNumber => {
                print_err!("Illegal parameter number in definition of ");
                self.sprint_cs(self.warning_index);
                self.print_char(b'.');
                help_lines!(
                    "You meant to type ## instead of #, right?",
                    "Or maybe a } was forgotten somewhere earlier, and things",
                    "are all screwed up?"
                )
            },

            // Section 486
            TeXError::FileEndedWithin => {
                print_err!("File ended within ");
                self.print_esc("read.");
                help_lines!("This \\read has unbalanced braces.")
            },

            // Section 500
            TeXError::ExtraOr => {
                print_err!("Extra ");
                self.print_esc("or.");
                help_lines!("It doesn't match any \\if.")
            },

            // Section 503
            TeXError::MissingEqual(this_if) => {
                print_err!("Missing = for ");
                self.print_cmd_chr(IF_TEST, this_if);
                self.print_char(b'.');
                help_lines!("I was expecting to see '<', '=' or '>'. Didn't.")
            },

            // Section 510
            TeXError::ExtraFiOrElse => {
                print_err!("Extra ");
                self.print_cmd_chr(FI_OR_ELSE, self.cur_chr);
                self.print_char(b'.');
                help_lines!("It doesn't match any \\if.")
            },

            // Section 530
            TeXError::CantFindFile => {
                print_err!("I can't find file '");
                self.print_file_name(self.cur_name, self.cur_area, self.cur_ext);
                self.print("'.");
                help_lines!("Maybe you have mispelled the name.")
            },

            TeXError::CantWriteFile => {
                print_err!("I can't write on file '");
                self.print_file_name(self.cur_name, self.cur_area, self.cur_ext);
                help_lines!("Is this file already busy?")
            },

            // Section 561
            TeXError::TfmNotLoadable(file_opened, u, s) => {
                print_err!("Font ");
                self.sprint_cs(u);
                self.print_char(b'=');
                self.print_strnumber(self.cur_area);
                self.print_strnumber(self.cur_name);
                if s >= 0 {
                    self.print(" at ");
                    self.print_scaled(s);
                    self.print("pt");
                }
                else if s != -1000 {
                    self.print(" scaled ");
                    self.print_int(-s);
                }
                self.print(
                    match file_opened {
                        true => " not loadable: Bad metric (TFM) file.",
                        false => " not loadable: Metric (TFM) file not found."
                    }
                );
                help_lines!("I wasn't able to read the size data for this font.")
            },

            // Section 567
            TeXError::TfmNotLoaded(u, s) => {
                print_err!("Font ");
                self.sprint_cs(u);
                self.print_char(b'=');
                self.print_strnumber(self.cur_area);
                self.print_strnumber(self.cur_name);
                if s >= 0 {
                    self.print(" at ");
                    self.print_scaled(s);
                    self.print("pt");
                }
                else if s != -1000 {
                    self.print(" scaled ");
                    self.print_int(-s);
                }
                print_err!(" not loaded: Not enough room left.");
                help_lines!(
                    "I'am afraid I won't be able to make use of this font,",
                    "because my memory for character-size data is too small.",
                    "If you're really stuck, ask a wizard to enlarge me."
                )
            },

            // Section 577
            TeXError::MissingFontIdentifier => {
                print_err!("Missing font identifier.");
                help_lines!(
                    "I was looking for a control sequence whose",
                    "whose current meaning has been defined by \\font."
                )
            },

            // Section 579
            TeXError::FontHasOnly(f) => {
                print_err!("Font ");
                self.print_esc_strnumber(font_id_text(f) as StrNum);
                self.print(" has only ");
                self.print_int(self.font_params[f as usize] as Integer);
                self.print(" fontdimen parameters.");
                help_lines!(
                    "To increase the number of font parameters, you must",
                    "use \\fontdimen immediately after the \\font is loaded."
                )
            },

            // Section 641
            TeXError::HugePage => {
                print_err!("Huge page cannot be shipped out.");
                help_lines!(
                    "The page created is more than 548 cm tall or",
                    "more than 548 cm wide, so I suspect something went wrong."
                )
            },

            // Section 723
            TeXError::UndefinedCharacter(a) => {
                print_err!("");
                self.print_size(self.cur_size as Integer);
                self.print_char(b' ');
                self.print_int(fam(a) as Integer);
                self.print(" is undefined (character ");
                self.print_strnumber(self.cur_c as StrNum);
                self.print(").");
                help_lines!(
                    "Somewhere in the math formula just ended, you used the",
                    "stated character from an undefined font family. For example,",
                    "plain TeX doesn't allow \\it or \\sl in subscripts."
                )
            },

            // Section 776
            TeXError::ImproperHalignDisplay => {
                print_err!("Improper ");
                self.print_esc("halign inside $$'s.");
                help_lines!(
                    "Displays can use special alignments (like \\eqalignno)",
                    "only if nothing but the alignment itself is between $$'s."
                )
            },

            // Section 783
            TeXError::MissingCroisillonAlign => {
                print_err!("Missing # in alignment preamble.");
                help_lines!(
                    "There should be exactly one # between &'s, when an \\halign",
                    "or \\valign is being set up. In this case you had none."
                )
            },

            // Section 784
            TeXError::OnlyOneCroisillonAllowed => {
                print_err!("Only one # is allowed per tab.");
                help_lines!(
                    "There should be exactly one # between &'s, when an",
                    "\\halign or \\valign is being set up.",
                    "In this case, you had more than one."
                )
            },

            // Section 792
            TeXError::ExtraAlignmentTab => {
                print_err!("Extra alignment tab.");
                help_lines!(
                    "You have given more \\span or & marks than there were",
                    "in the preamble to the \\halign or \\valign now in progress."
                )
            },

            // Section 826
            TeXError::InfiniteGlueShrinkageInParagraph => {
                print_err!("Infinite glue shrinkage found in a paragraph.");
                help_lines!(
                    "The paragraph just ended includes some glue that has",
                    "infinite shrinkability, e.g., '\\hskip 0pt minus 1fil'.",
                    "Such glue doesn't belong there---it allows a paragraph",
                    "of any length to fit on one line."
                )
            },

            // Section 936
            TeXError::ImproperHyphenation => {
                print_err!("Improper ");
                self.print_esc("hyphenation will be flushed.");
                help_lines!(
                    "Hyphenation exceptions must contain only letters",
                    "and hyphens."
                )
            },

            // Section 937
            TeXError::NotALetter => {
                print_err!("Not a letter.");
                help_lines!("Letters in \\hyphenation words must have \\lccode>0.")
            },

            // Section 960
            TeXError::TooLateForPatterns => {
                print_err!("Too late for ");
                self.print_esc("patterns.");
                help_lines!("All patterns my be given before typesetting begings.")
            },

            // Section 961
            TeXError::BadPatterns => {
                print_err!("Bad ");
                self.print_esc("patterns.");
                help_lines!("(See Appendix H.)")
            },

            // Section 962
            TeXError::Nonletter => {
                print_err!("Nonletter. ");
                help_lines!("(See Appendix H.)")
            },

            // Section 963
            TeXError::DuplicatePattern => {
                print_err!("Duplicate pattern. ");
                help_lines!("(See Appendix H.)")
            },

            // Section 976
            TeXError::InfiniteGlueShrinkageInBoxBeingSplit => {
                print_err!("Infnite glue shrinkage found in box beging split.");
                help_lines!(
                    "The box you are \\vsplitting contains some infinitely",
                    "shrinkable glue, e.g., '\\vss' or '\\vskip 0pt minus 1fil'.",
                    "Such glue doesn't belong there."
                )
            },

            // Section 978
            TeXError::VsplitNeedsAVbox => {
                print_err!("");
                self.print_esc("vsplit needs a ");
                self.print_esc("vbox.");
                help_lines!(
                    "The box you are trying to split is an \\hbox.",
                    "I can't slit such a box."
                )
            },

            // Section 993
            TeXError::InsertionCanOnlyBeAddedToVbox(_) => {
                print_err!("Insertions can only be added to a vbox.");
                help_lines!(
                    "Tut tut: You're trying to \\insert into a",
                    "\\box register that now contains an \\hbox."
                )
            },

            // Section 1004
            TeXError::InfiniteGlueShrinkageOnCurrentPage => {
                print_err!("Infnite glue shrinkage found on current page.");
                help_lines!(
                    "The page about to be output contains some infinitely",
                    "shrinkable glue, e.g., '\\vss' or '\\vskip 0pt minus 1fil'.",
                    "Such glue doesn't belong there."
                )
            },

            // Section 1009
            TeXError::InfiniteGlueShrinkageInsertedFrom(n) => {
                print_err!("Infnite glue shrinkage inserted from ");
                self.print_esc("skip");
                self.print_int(n);
                self.print_char(b'.');
                help_lines!(
                    "The correction glue for page breaking with insertions",
                    "must have finite shrinkability."
                )
            },

            // Section 1015
            TeXError::Box255IsNotVoid => {
                print_err!("");
                self.print_esc("box255 is not void.");
                help_lines!("You shouldn't use \\box255 except in \\output routines.")
            },

            // Section 1024
            TeXError::OutputLoop => {
                print_err!("Output loop---");
                self.print_int(self.dead_cycles);
                self.print(" consecutive dead cycles.");
                help_lines!(
                    "I've concluded that your \\output is awry; it never does a",
                    "\\shipout. Next time increase \\maxdeadcycles if you want me",
                    "to be more patient!"
                )
            },

            // Section 1027
            TeXError::UnbalancedOutputRoutine => {
                print_err!("Unbalanced output routine.");
                help_lines!(
                    "Your sneaky output routine has problematic {'s and/or }'s.",
                    "I can't handle that very well; good luck."
                )
            },

            // Section 1028
            TeXError::OutputRoutineDidntUseAllOfBox255 => {
                print_err!("Output routine didn't use all of ");
                self.print_esc("box");
                self.print_int(255);
                self.print_char(b'.');
                help_lines!(
                    "Your \\output commands should empty \\box255,",
                    "e.g., by saying '\\shipout\\box255'."
                )
            },

            // Section 1050
            TeXError::ReportIllegalCase => {
                you_cant!();
                help_lines!("Sorry, but I'm not programmed to handle this case.")
            },

            // Section 1047
            TeXError::MissingDollar => {
                print_err!("Missing $.");
                help_lines!(
                    "Either you forgot opening or closing math mode with $,",
                    "or a math character/control sequence is used outside",
                    "of math mode (or vice versa)."
                )
            },

            // Section 1064, 1065
            TeXError::MissingEndGroup => {
                print_err!("Missing ");
                self.print_esc("endgroup.");
                help_lines!("Groups not properly nested (did you forget to close one?)")
            },

            TeXError::MissingMathRight => {
                print_err!("Missing ");
                self.print_esc("right.");
                help_lines!("Groups not properly nested (did you forget a \"\\right.\"?")
            },

            TeXError::MissingRightBrace => {
                print_err!("Missing }.");
                help_lines!("Groups not properly nested (did you forget a right brace?)")
            },

            // Section 1066
            TeXError::Extra => {
                print_err!("Extra ");
                self.print_cmd_chr(self.cur_cmd, self.cur_chr);
                self.print_char(b'.');
                help_lines!("Things are pretty mixed up.")
            },

            // Section 1068
            TeXError::TooManyRightBraces => {
                print_err!("Too many }'s.");
                help_lines!("You've closed more groups than you opened.")
            },

            // Section 1069
            TeXError::ExtraRightBraceOrForgotten => {
                print_err!("Extra }, or forgotten ");
                match self.cur_group {
                    SEMI_SIMPLE_GROUP => self.print_esc("endgroup."),
                    MATH_SHIFT_GROUP => self.print("$."),
                    MATH_LEFT_GROUP => self.print_esc("right."),
                    _ => (), // Cannot happen
                }
                help_lines!(
                    "Perhaps the } is legitimate and you forgot",
                    "something else, as in '\\hbox{$x}'."
                )
            },

            // Section 1078
            TeXError::LeadersNotFollowedByProperGlue => {
                print_err!("Leaders not followed by proper glue.");
                help_lines!(
                    "You should say '\\leaders <box or rule><hskip or vskip>'.",
                    "I found the <box or rule>, but there's not suitable",
                    "<hskip or vskip>."
                )
            },

            // Section 1080
            TeXError::CantUseIn => {
                you_cant!();
                help_lines!("Sorry.")
            },

            TeXError::CantUseIn2 => {
                you_cant!();
                help_lines!("Sorry... I usually can't take things from the current page.")
            },

            // Section 1082
            TeXError::MissingTo => {
                print_err!("Missing 'to'.");
                help_lines!(
                    "I'm working on '\\vskip<box number> to <dimen>',",
                    "and didn't found 'to'."
                )
            },

            // Section 1084
            TeXError::BoxWasSupposedToBeHere => {
                print_err!("A <box> was supposed to be here.");
                help_lines!(
                    "I was expecting to see \\hbox or \\vbox or \\copy or \\box or",
                    "something like that."
                )
            },

            // Section 1084
            TeXError::CantUseHrule => {
                print_err!("You can't use '");
                self.print_esc("hrule here except with leaders.");
                help_lines!(
                    "To put a horizontal rule in an hbox or an alignment,",
                    "you should use \\leaders or \\hrulefill (see the TeXbook)."
                )
            },

            // Section 1099
            TeXError::CantInsert255 => {
                print_err!("You can't ");
                self.print_esc("insert");
                self.print_int(255);
                self.print_char(b'.');
                help_lines!("Box 255 is special.")
            },

            // Section 1106
            TeXError::CantTakeThings => {
                you_cant!();
                if self.cur_chr == KERN_NODE as HalfWord {
                    help_lines!(
                        "Sorry... I usually can't take things from the current page.",
                        "Last node is a kern."
                    )
                }
                else if self.cur_chr != GLUE_NODE as HalfWord {
                    help_lines!(
                        "Sorry... I usually can't take things from the current page.",
                        "Perhaps you can make the output routine do it."
                    )
                }
                else {
                    help_lines!(
                        "Sorry... I usually can't take things from the current page.",
                        "Last node is a skip."
                    )
                }
            },

            // Section 1110
            TeXError::IncompatibleListCantBeUnboxed => {
                print_err!("Incompatible list can't be unboxed.");
                help_lines!(
                    "Sorry, Pandora. (You sneaky devil.)",
                    "I refuse to unbox an \\hbox in vertical mode or vice versa.",
                    "And I can't open any boxes in math mode."
                )
            },

            // Section 1120
            TeXError::IllegalMathDisc => {
                print_err!("Illegal math ");
                self.print_esc("discretionary.");
                help_lines!(
                    "Sorry: The third part of a discretionary break must be",
                    "empty, in math formulas."
                )
            },

            TeXError::DiscListTooLong => {
                print_err!("Discretionary list is too long.");
                help_lines!(
                    "Wow---I never thought anybody would tweak me here.",
                    "You can't seriously need such a huge discretionary list?"
                )
            },

            // Section 1121
            TeXError::ImproperDiscList => {
                print_err!("Improper discretionary list.");
                help_lines!("Discretionary lists must contain only boxes and kerns.")
            },

            // Section 1127
            TeXError::MissingLeftBrace3 => {
                print_err!("Missing {.");
                help_lines!(
                    "Something needs to be done to fix the current column",
                    "of the current alignment."
                )
            },
            TeXError::MissingRightBrace2 => {
                print_err!("Missing }.");
                help_lines!(
                    "Something needs to be done to fix the current column",
                    "of the current alignment."
                )
            },

            // Section 1128
            TeXError::MisplacedTabMark => {
                print_err!("Misplaced ");
                self.print_cmd_chr(self.cur_cmd, self.cur_chr);
                if self.cur_tok == TAB_TOKEN + b'&' as HalfWord {
                    help_lines!(
                        "I can't figure out why you would wantt to use a tab mark",
                        "here. If you want an ampersand, you need to write \\&.",
                        "Or maybe some right brace up above has ended a previous",
                        "alignment prematurely?"
                    )
                }
                else {
                    help_lines!(
                        "I can't figure out why you would wantt to use a tab mark",
                        "or \\cr or \\span just now. Or maybe some right brace up",
                        "above has ended a previous alignment prematurely?"
                    )
                }
            },

            // Section 1129
            TeXError::MisplacedNoalign => {
                print_err!("Misplaced ");
                self.print_esc("noalign.");
                help_lines!("I expect to see \\noalign only after the \\cr of an alignment.")
            },

            TeXError::MisplacedOmit => {
                print_err!("Misplaced ");
                self.print_esc("omit.");
                help_lines!(
                    "I expect to see \\omit only after tab marks or the \\cr",
                    "of an alignment."
                )
            },

            // Section 1132
            TeXError::MissingCr => {
                print_err!("Missing ");
                self.print_esc("cr.");
                help_lines!("I'm guessing that you meant to end an alignment here.")
            },

            // Section 1135
            TeXError::ExtraEndcsname => {
                print_err!("Extra ");
                self.print_esc("endcsname.");
                help_lines!("I wasn't doing a \\csname.")
            },

            // Section 1159
            TeXError::LimitControlsMustFollowMathOp => {
                print_err!("Limit controls must follow a math operator.");
                help_lines!("Misplaced \\limits or \\nolimits command.")
            },

            // Section 1161
            TeXError::MissingDelimiterLeftParen => {
                print_err!("Missing delimiter (.");
                help_lines!(
                    "I was expecting to see something like '(' or '\\{' or",
                    "'\\}' here. Maybe you typed, e.g., '{' instead of '\\{',",
                    "and now braces are unbalanced.",
                    "Acceptable delimiters are characters whose \\delcode is",
                    "nonnegative, or you can use '\\delimiter <delimiter code>'."
                )
            },

            // Section 1166
            TeXError::UseMathAccentInMathMode => {
                print_err!("Please use ");
                self.print_esc("mathaccent for accents in math mode.");
                help_lines!("Accents are not the same in formulas as they are in text.")
            },

            // Section 1177
            TeXError::DoubleSuperscript => {
                print_err!("Double superscript.");
                help_lines!(
                    "You wrote something like x^1^2 which is confusing:",
                    "did you mean {x^1}^2 or x^{1^2} (or something else)?"
                )
            },

            TeXError::DoubleSubscript => {
                print_err!("Double subscript.");
                help_lines!(
                    "You wrote something like x_1_2 which is confusing:",
                    "did you mean {x_1}_2 or x_{1_2} (or something else)?"
                )
            },

            // Section 1183
            TeXError::AmbiguousFraction => {
                print_err!("Ambiguous; you need another { and }.");
                help_lines!(
                    "This fraction specification is bad, since I don't",
                    "know whether a construction like 'x \\over y \\over z'",
                    "means {x \\over y} \\over z' or 'x \\over {y \\over z}'."
                )
            },

            // Section 1192
            TeXError::ExtraMathRight => {
                print_err!("Extra ");
                self.print_esc("right.");
                help_lines!("This \\right has no matching \\left.")
            },

            // Section 1195
            TeXError::InsufficientSymbolFonts => {
                print_err!("Insufficient symbol fonts for math formula.");
                help_lines!(
                    "Sorry, but I can't typeset math unless \\textfont 2",
                    "and \\scriptfont 2 and \\scriptscriptfont 2 have all",
                    "the \\fontdimen values needed in math symbol fonts."
                )
            },

            TeXError::InsufficientExtensionFonts => {
                print_err!("Insufficient extension fonts for math formula.");
                help_lines!(
                    "Sorry, but I can't typeset math unless \\textfont 3",
                    "and \\scriptfont 3 and \\scriptscriptfont 3 have all",
                    "the \\fontdimen values needed in math extension fonts."
                )
            },

            // Section 1197
            TeXError::DisplayMathEndsWithDollars => {
                print_err!("Display math should end with $$.");
                help_lines!("The '$' that I just saw supposedly matches a previous '$$'.")
            },

            // Section 1207
            TeXError::MissingDollarDollar => {
                print_err!("Missing $$.");
                help_lines!(
                    "Displays can use special alignments (like \\eqalignno)",
                    "only if nothing but the alignment itself is between $$'s."
                )
            },

            // Section 1212
            TeXError::CantUsePrefix => {
                print_err!("You can't use a prefix with '");
                self.print_cmd_chr(self.cur_cmd, self.cur_chr);
                self.print("'.");
                help_lines!(
                    "I could ignore you said \\long or \\outer or \\global here,",
                    "but I don't."
                )
            },

            // Section 1213
            TeXError::CantUseLongOuter => {
                print_err!("You can't use '");
                self.print_esc("long' or '");
                self.print_esc("outer' with '");
                self.print_cmd_chr(self.cur_cmd, self.cur_chr);
                self.print("'.");
                help_lines!("I could ignore you said \\long or \\outer here, but I don't.")
            },

            // Section 1215
            TeXError::MissingControlSequence => {
                print_err!("Missing control sequence.");
                help_lines!("Please don't say '\\def cs{...}', say '\\def\\cs{...}'.")
            },

            // Section 1225
            TeXError::MissingTo2 => {
                print_err!("Missing 'to'.");
                help_lines!("You should have said '\\read<number> to \\cs'.")
            },

            // Section 1232
            TeXError::InvalidCode(n, p) => {
                print_err!("Invalid code (");
                self.print_int(self.cur_val);
                self.print(
                    if p < DEL_CODE_BASE {
                        "), should be in the range 0.."
                    }
                    else {
                        "), should be at most "
                    }
                );
                self.print_int(n);
                self.print_char(b'.');
                help_lines!("You used an illegal code value.")
            },

            // Section 1236
            TeXError::Arith => {
                print_err!("Arithmetic overflow.");
                help_lines!(
                    "I can't carry out that multiplication or division,",
                    "since the result is out of range."
                )
            },

            // Section 1237
            TeXError::CantUseAfterCmd(q) => {
                print_err!("You can't use '");
                self.print_cmd_chr(self.cur_cmd, self.cur_chr);
                self.print("' after ");
                self.print_cmd_chr(q, 0);
                self.print_char(b'.');
                help_lines!("Try to fix that.")
            },

            // Section 1241
            TeXError::ImproperSetbox => {
                print_err!("Improper ");
                self.print_esc("setbox.");
                help_lines!(
                    "Sorry, \\setbox is not allowed after \\halign in a display,",
                    "or between \\accent and an accented character."
                )
            },

            // Section 1243
            TeXError::BadSpaceFactor => {
                print_err!("Bad space factor");
                self.print(" (");
                self.print_int(self.cur_val);
                self.print(").");
                help_lines!("I allow only values in the range 1..32767 here.")
            },

            // Section 1244
            TeXError::BadPrevGraf => {
                print_err!("Bad ");
                self.print_esc("prevgraf (");
                self.print_int(self.cur_val);
                self.print(").");
                help_lines!("I allow only nonnegative values here.")
            },

            // Section 1252
            TeXError::PatternsOnlyIniTeX => {
                print_err!("Patterns can be loaded only by INITEX.");
                help_lines!("")
            },

            // Section 1259
            TeXError::ImproperAt(s) => {
                print_err!("Improper 'at' size (");
                self.print_scaled(s);
                self.print("pt).");
                help_lines!(
                    "I can only handle fonts at positive sizes that are",
                    "less than 2048pt."
                )
            },

            // Section 1283
            TeXError::ErrMessage(s) => {
                print_err!("");
                self.slow_print(s);
                self.print_char(b'.');
                help_lines!(
                    "This error message was generated by an \\errmessage",
                    "command, so I can't give any explicit help.",
                    "Pretend that you're Hercule Poirot: Examine all clues,",
                    "and deduce the truth by order and method."
                )
            },

            // Section 1304
            TeXError::CantDumpInGroup => {
                print_err!("You can't dump inside a group.");
                help_lines!("'{...\\dump}' is a no-no.")
            },

            // Section 1372
            TeXError::UnbalancedWriteCmd => {
                print_err!("Unbalanced write command.");
                help_lines!(
                    "On this page there's a \\write with fewer real {'s than }'s.",
                    "I can't handle that very well; good luck."
                )
            }

            // Format
            TeXError::CantFindFormat => {
                print_err!("Sorry, I can't find that format.");
                help_lines!(
                    "Either you got the name wrong (e.g., 'plaine.fmt'",
                    "instead of 'plain.fmt') or the format is not present",
                    "in the format directory or the current one."
                )
            }
        };

        self.show_context();
        for help_line in help_message {
            self.print_nl(help_line);
        }
        self.print_ln();

        // Supplementary messages
        match texerror {
            TeXError::InsertionCanOnlyBeAddedToVbox(n) => self.box_error(n),
            TeXError::Box255IsNotVoid => self.box_error(255),
            _ => (),
        }

        // Interactive debugging
        #[cfg(feature = "debug")]
        if self.interaction == ERROR_STOP_MODE {
            println!("Type \"D\" to debug or <return> to quit.");
            print!("? ");
            update_terminal!();
            if term_input_string()?.trim() == "D" {
                self.debug_help()?;
            }
        }

        Ok(())
    }
}