Created schema for flexible and extensible forms (#11)

* created basic user and form struct

* edited and expanded schema for flexibility

* Removed unused HashMap and created module for models

* resolved issues raised in pull request

* created doc comments and added the example to the doc comment

* fixed non-public test issue

* fixed _id problems

* finally fixed id issues and tested

src/app/mod.rs

@@ -1,3 +1,6 @@
+pub mod models;
+
+use std::sync::Arc;
 use std::time::Duration;
 
 use anyhow::Context;

src/app/models/mod.rs

@@ -0,0 +1,205 @@
+use mongodb::bson::{oid::ObjectId, DateTime};
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct User {
+    #[serde(rename = "_id", skip_serializing_if = "Option::is_none")]
+    id: Option<ObjectId>,
+    first_name: String,
+    last_name: String,
+    national_health_identifer: String,
+    email_address: String,
+    hashed_password: String,
+    is_patient: bool,
+    caregivers: Vec<ObjectId>,
+    form_templates: Vec<Form>,
+}
+
+/// A form that clients fill in is represented here
+///
+///
+/// # Examples
+/// ```
+/// use parkinsons_pulse_service::app::models::*;
+/// use mongodb::bson::{oid::ObjectId, DateTime};
+///
+/// Form {
+///     id: Some(ObjectId::new()),
+///     title: String::from("Tremors"),
+///     created_by: ObjectId::new(),
+///     created_at: DateTime::now(),
+///     questions: vec![
+///         Question::Multichoice(MultichoiceQuestion {
+///             id: Some(ObjectId::new()),
+///             title: String::from("How many times have you experienced this in the last week?"),
+///             options: vec![MultichoiceQuestionOption {
+///                 name: String::from("Once"),
+///                 id: ObjectId::new(),
+///             }],
+///             min_selected: 1,
+///             max_selected: 2,
+///         }),
+///         Question::FreeForm(FreeFormQuestion {
+///             id: Some(ObjectId::new()),
+///             title: String::from("Is there anything else you would like to add?"),
+///             max_length: 200,
+///             min_length: 0,
+///         }),
+///     ],
+///     events: vec![
+///         Event::QuestionEdited(QuestionEdited {
+///             question_id: ObjectId::new(),
+///             former_question: Question::FreeForm(FreeFormQuestion {
+///                 id: Some(ObjectId::new()),
+///                 title: String::from("How are you feeling this week?"),
+///                 max_length: 100,
+///                 min_length: 10,
+///             }),
+///             new_question: Question::FreeForm(FreeFormQuestion {
+///                 id: Some(ObjectId::new()),
+///                 title: String::from("Is there anything else you would like to add?"),
+///                 max_length: 200,
+///                 min_length: 0,
+///             }),
+///             edited_at: DateTime::now(),
+///             edited_by: ObjectId::new(),
+///         }),
+///         Event::FormSubmitted(FormSubmitted {
+///             answers: vec![
+///                 QuestionAndAnswer::Multichoice(
+///                     MultichoiceQuestion {
+///                         id: Some(ObjectId::new()),
+///                         title: String::from(
+///                             "How many times have you experienced this in the last week?",
+///                         ),
+///                         options: vec![MultichoiceQuestionOption {
+///                             name: String::from("Once"),
+///                             id: ObjectId::new(),
+///                         }],
+///                         min_selected: 1,
+///                         max_selected: 2,
+///                     },
+///                     ObjectId::new(),
+///                 ),
+///                 QuestionAndAnswer::FreeForm(
+///                     FreeFormQuestion {
+///                         id: Some(ObjectId::new()),
+///                         title: String::from("Is there anything else you would like to add?"),
+///                         max_length: 200,
+///                         min_length: 0,
+///                     },
+///                     String::from("I wasn't able to press the elevator buttons this morning"),
+///                 ),
+///             ],
+///             submitted_at: DateTime::now(),
+///             submitted_by: ObjectId::new(),
+///         }),
+///     ],
+/// };
+/// ```
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct Form {
+    #[serde(rename = "_id", skip_serializing_if = "Option::is_none")]
+    pub id: Option<ObjectId>,
+    /// Title of the form for clients
+    pub title: String,
+    pub created_by: ObjectId,
+    pub created_at: DateTime,
+    /// List of questions in the form
+    pub questions: Vec<Question>,
+    /// List of events such as a user filling in a form or a moderator updating the form
+    pub events: Vec<Event>,
+}
+
+/// This represents a form event, either filling in the form and submitting it, or changing a question
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub enum Event {
+    FormSubmitted(FormSubmitted),
+    QuestionEdited(QuestionEdited),
+}
+
+/// This represents how a question may change
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct QuestionEdited {
+    /// This is the ID of the question in the form being changed
+    pub question_id: ObjectId,
+    pub former_question: Question,
+    pub new_question: Question,
+    pub edited_by: ObjectId,
+    pub edited_at: DateTime,
+}
+
+/// This is how we represent a form being filled
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct FormSubmitted {
+    /// This is a list of all of the questions and the answers that were selected or entered
+    pub answers: Vec<QuestionAndAnswer>,
+    /// This is the ID of the user that submitted the form
+    pub submitted_by: ObjectId,
+    /// This is the time that they submitted it
+    pub submitted_at: DateTime,
+}
+
+/// This represents a form question for clients to answer
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub enum Question {
+    /// This is a list of multiple choices for a question
+    Multichoice(MultichoiceQuestion),
+    /// This is a numeric slider
+    Slider(SliderQuestion),
+    /// This is for free form questions where the client may type whatever
+    FreeForm(FreeFormQuestion),
+}
+
+/// ID of choice in the questions that is selected
+pub type MultichoiceAnswer = ObjectId;
+/// Numerical value that the user selects
+pub type SliderAnswer = f64;
+/// String for the answer that the client types
+pub type FreeFormAnswer = String;
+
+/// Combination of both the question and answer
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub enum QuestionAndAnswer {
+    Multichoice(MultichoiceQuestion, MultichoiceAnswer),
+    Slider(SliderQuestion, SliderAnswer),
+    FreeForm(FreeFormQuestion, FreeFormAnswer),
+}
+
+/// Free form question with some validation rules you could apply
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
+pub struct FreeFormQuestion {
+    #[serde(rename = "_id", skip_serializing_if = "Option::is_none")]
+    pub id: Option<ObjectId>,
+    pub title: String,
+    pub max_length: u64,
+    pub min_length: u64,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
+pub struct SliderQuestion {
+    #[serde(rename = "_id", skip_serializing_if = "Option::is_none")]
+    pub id: Option<ObjectId>,
+    pub title: String,
+    pub units: Option<String>,
+    pub low: f64,
+    pub high: f64,
+    pub step: f64,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
+pub struct MultichoiceQuestion {
+    #[serde(rename = "_id", skip_serializing_if = "Option::is_none")]
+    pub id: Option<ObjectId>,
+    pub title: String,
+    pub options: Vec<MultichoiceQuestionOption>,
+    pub min_selected: u64,
+    pub max_selected: u64,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
+pub struct MultichoiceQuestionOption {
+    pub name: String,
+    #[serde(rename = "_id")]
+    pub id: ObjectId,
+}