From 605760c75afe27e154177b939b4a1cd289e3a2b2 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Mon, 19 Aug 2024 00:12:59 +0530
Subject: [PATCH 1/9] APIs for email communication

---
 azure-email/Azure/Email.hs    |  2 ++
 azure-email/CHANGELOG.md      |  5 +++
 azure-email/LICENSE           | 21 ++++++++++++
 azure-email/azure-email.cabal | 60 +++++++++++++++++++++++++++++++++++
 cabal.project                 |  1 +
 5 files changed, 89 insertions(+)
 create mode 100644 azure-email/Azure/Email.hs
 create mode 100644 azure-email/CHANGELOG.md
 create mode 100644 azure-email/LICENSE
 create mode 100644 azure-email/azure-email.cabal

diff --git a/azure-email/Azure/Email.hs b/azure-email/Azure/Email.hs
new file mode 100644
index 0000000..4bc78fa
--- /dev/null
+++ b/azure-email/Azure/Email.hs
@@ -0,0 +1,2 @@
+module Azure.Email
+    ( ) where
diff --git a/azure-email/CHANGELOG.md b/azure-email/CHANGELOG.md
new file mode 100644
index 0000000..18f52d5
--- /dev/null
+++ b/azure-email/CHANGELOG.md
@@ -0,0 +1,5 @@
+# Revision history for azure-auth
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.
diff --git a/azure-email/LICENSE b/azure-email/LICENSE
new file mode 100644
index 0000000..1f229d7
--- /dev/null
+++ b/azure-email/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2024 Holmusk
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/azure-email/azure-email.cabal b/azure-email/azure-email.cabal
new file mode 100644
index 0000000..57b36d1
--- /dev/null
+++ b/azure-email/azure-email.cabal
@@ -0,0 +1,60 @@
+cabal-version:      3.0
+name:               azure-email
+version:            0.1.0.0
+synopsis:           Boilerplace/startkit for azure in Haskell (using servant)
+description:        This provides from useful functionalities for starting out with Azure in Haskell.
+                    This includes authentication, Key vault, Blob storage and email communication related APIs.
+license:            MIT
+author:             Holmusk
+maintainer:         tech@holmusk.com
+category:           Azure
+build-type:         Simple
+extra-doc-files:    CHANGELOG.md
+tested-with:        GHC == 9.2.8
+                    GHC == 9.4.8
+                    GHC == 9.6.3
+                    GHC == 9.8.2
+
+common common-options
+    ghc-options:    -Wall
+                    -Wincomplete-uni-patterns
+                    -Wincomplete-record-updates
+                    -Wcompat
+                    -Widentities
+                    -Wredundant-constraints
+                    -fhide-source-paths
+                    -Wpartial-fields
+                    -Wunrecognised-pragmas
+                    -Wmissing-deriving-strategies
+                    -Wunticked-promoted-constructors
+                    -Winvalid-haddock
+                    -Woperator-whitespace
+                    -Wredundant-bang-patterns
+                    -Wunused-packages
+    build-depends:  base >= 4.7 && <5
+    default-language:   GHC2021
+    default-extensions: DataKinds
+                        DerivingStrategies
+                        DerivingVia
+                        LambdaCase
+                        NoImportQualifiedPost
+                        NoGeneralisedNewtypeDeriving
+                        OverloadedStrings
+                        OverloadedLabels
+                        RecordWildCards
+                        TypeFamilies
+                        ViewPatterns
+    if os(linux)
+        ghc-options: -optl-fuse-ld=gold
+        ld-options:  -fuse-ld=gold
+
+library
+    import:           common-options
+    exposed-modules:  Azure.Email
+    build-depends:    aeson
+                    , http-client
+                    , servant
+                    , servant-client
+                    , text
+                    , unliftio
+    default-language: Haskell2010
diff --git a/cabal.project b/cabal.project
index 3ac2529..910676f 100644
--- a/cabal.project
+++ b/cabal.project
@@ -1,4 +1,5 @@
 packages:
   ./azure-auth
+  ./azure-email
   ./azure-key-vault
   ./azure-blob-storage

From 27fa80e92aade64640771c1f3ce2e58340fb6fd9 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Thu, 22 Aug 2024 14:01:49 +0530
Subject: [PATCH 2/9] core types

---
 Makefile                   |  2 +-
 azure-email/Azure/Email.hs | 76 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 75 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index ff41316..8d188a2 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-SRC=$(shell find azure-auth/ azure-key-vault/ azure-blob-storage/ -type f -name '*.hs')
+SRC=$(shell find azure-auth/ azure-key-vault/ azure-blob-storage/ azure-email/ -type f -name '*.hs')
 
 .PHONY: format
 format: $(SRC)
diff --git a/azure-email/Azure/Email.hs b/azure-email/Azure/Email.hs
index 4bc78fa..abf5092 100644
--- a/azure-email/Azure/Email.hs
+++ b/azure-email/Azure/Email.hs
@@ -1,2 +1,74 @@
-module Azure.Email
-    ( ) where
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DerivingVia #-}
+
+module Azure.Email () where
+
+import Data.Aeson (ToJSON (..), object, (.=))
+import Data.Text (Text)
+import GHC.Generics (Generic)
+
+data EmailAddress = EmailAddress
+    { eaEmail :: !Text
+    , eaDisplayName :: !Text
+    }
+    deriving stock (Eq, Show, Generic)
+
+instance ToJSON EmailAddress where
+    toJSON EmailAddress{..} =
+        object
+            [ "address" .= eaEmail
+            , "displayName" .= eaDisplayName
+            ]
+
+-- | Fields to represent @cc@, @bcc@ and @to@ in an email
+data EmailRecipients = EmailRecipients
+    { ccRecipients :: ![EmailAddress]
+    , bccRecipients :: ![EmailAddress]
+    , toRecipients :: ![EmailAddress]
+    }
+    deriving stock (Generic)
+
+instance ToJSON EmailRecipients where
+    toJSON EmailRecipients{..} =
+        object
+            [ "to" .= toRecipients
+            , "cc" .= ccRecipients
+            , "bcc" .= bccRecipients
+            ]
+
+-- | Azure email requires both HTML and plain text format email content
+data EmailContent = EmailContent
+    { ecHtml :: !Text
+    -- ^ Html version of the email message.
+    , ecPlainText :: !Text
+    -- ^ Plain text version of the email message.
+    , ecSubject :: !Text
+    -- ^ Subject of the email message.
+    }
+    deriving stock (Eq, Show, Generic)
+
+instance ToJSON EmailContent where
+    toJSON EmailContent{..} =
+        object
+            [ "plainText" .= ecPlainText
+            , "html" .= ecHtml
+            , "subject" .= ecSubject
+            ]
+
+{- | Source:
+https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP
+-}
+data AzureEmailRequest = AzureEmailRequest
+    { aerContent :: !EmailContent
+    , aerRecipients :: !EmailRecipients
+    , aerSenderAddress :: !Text -- TODO: This should probably be it's own newtype
+    }
+    deriving stock (Generic)
+
+instance ToJSON AzureEmailRequest where
+    toJSON AzureEmailRequest{..} =
+        object
+            [ "content" .= aerContent
+            , "recipients" .= aerRecipients
+            , "senderAddress" .= aerSenderAddress
+            ]

From 953c93c47d574678dd82be772422126fbfe748e4 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Thu, 22 Aug 2024 14:04:40 +0530
Subject: [PATCH 3/9] Regenerate CI

---
 .github/workflows/haskell-ci.yml | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
index 31b6797..dba0cdb 100644
--- a/.github/workflows/haskell-ci.yml
+++ b/.github/workflows/haskell-ci.yml
@@ -140,6 +140,7 @@ jobs:
         run: |
           touch cabal.project
           echo "packages: $GITHUB_WORKSPACE/source/./azure-auth" >> cabal.project
+          echo "packages: $GITHUB_WORKSPACE/source/./azure-email" >> cabal.project
           echo "packages: $GITHUB_WORKSPACE/source/./azure-key-vault" >> cabal.project
           echo "packages: $GITHUB_WORKSPACE/source/./azure-blob-storage" >> cabal.project
           cat cabal.project
@@ -155,6 +156,8 @@ jobs:
         run: |
           PKGDIR_azure_auth="$(find "$GITHUB_WORKSPACE/unpacked" -maxdepth 1 -type d -regex '.*/azure-auth-[0-9.]*')"
           echo "PKGDIR_azure_auth=${PKGDIR_azure_auth}" >> "$GITHUB_ENV"
+          PKGDIR_azure_email="$(find "$GITHUB_WORKSPACE/unpacked" -maxdepth 1 -type d -regex '.*/azure-email-[0-9.]*')"
+          echo "PKGDIR_azure_email=${PKGDIR_azure_email}" >> "$GITHUB_ENV"
           PKGDIR_azure_key_vault="$(find "$GITHUB_WORKSPACE/unpacked" -maxdepth 1 -type d -regex '.*/azure-key-vault-[0-9.]*')"
           echo "PKGDIR_azure_key_vault=${PKGDIR_azure_key_vault}" >> "$GITHUB_ENV"
           PKGDIR_azure_blob_storage="$(find "$GITHUB_WORKSPACE/unpacked" -maxdepth 1 -type d -regex '.*/azure-blob-storage-[0-9.]*')"
@@ -163,17 +166,20 @@ jobs:
           touch cabal.project
           touch cabal.project.local
           echo "packages: ${PKGDIR_azure_auth}" >> cabal.project
+          echo "packages: ${PKGDIR_azure_email}" >> cabal.project
           echo "packages: ${PKGDIR_azure_key_vault}" >> cabal.project
           echo "packages: ${PKGDIR_azure_blob_storage}" >> cabal.project
           echo "package azure-auth" >> cabal.project
           echo "    ghc-options: -Werror=missing-methods" >> cabal.project
+          echo "package azure-email" >> cabal.project
+          echo "    ghc-options: -Werror=missing-methods" >> cabal.project
           echo "package azure-key-vault" >> cabal.project
           echo "    ghc-options: -Werror=missing-methods" >> cabal.project
           echo "package azure-blob-storage" >> cabal.project
           echo "    ghc-options: -Werror=missing-methods" >> cabal.project
           cat >> cabal.project <<EOF
           EOF
-          $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: $_ installed\n" unless /^(azure-auth|azure-blob-storage|azure-key-vault)$/; }' >> cabal.project.local
+          $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: $_ installed\n" unless /^(azure-auth|azure-blob-storage|azure-email|azure-key-vault)$/; }' >> cabal.project.local
           cat cabal.project
           cat cabal.project.local
       - name: dump install plan
@@ -200,6 +206,8 @@ jobs:
         run: |
           cd ${PKGDIR_azure_auth} || false
           ${CABAL} -vnormal check
+          cd ${PKGDIR_azure_email} || false
+          ${CABAL} -vnormal check
           cd ${PKGDIR_azure_key_vault} || false
           ${CABAL} -vnormal check
           cd ${PKGDIR_azure_blob_storage} || false

From 6c6586b41a7f0baad0da0b21d107ed2b5a707f68 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Thu, 22 Aug 2024 16:17:42 +0530
Subject: [PATCH 4/9] missing fields in email request type

---
 azure-email/Azure/Email.hs    | 35 +++++++++++++++++++++++++++++++++++
 azure-email/azure-email.cabal |  1 +
 2 files changed, 36 insertions(+)

diff --git a/azure-email/Azure/Email.hs b/azure-email/Azure/Email.hs
index abf5092..7d8e23e 100644
--- a/azure-email/Azure/Email.hs
+++ b/azure-email/Azure/Email.hs
@@ -55,6 +55,24 @@ instance ToJSON EmailContent where
             , "subject" .= ecSubject
             ]
 
+data EmailAttachment = EmailAttachment
+    { eaContentInBase64 :: !Text
+    -- ^ Base64 encoded contents of the attachment
+    , eaContentType :: !Text
+    -- ^ MIME type of the attachment
+    , eaName :: !Text
+    -- ^ Name of the attachment
+    }
+    deriving stock (Generic)
+
+instance ToJSON EmailAttachment where
+    toJSON EmailAttachment{..} =
+        object
+            [ "name" .= eaName
+            , "contentType" .= eaContentType
+            , "contentInBase64" .= eaContentInBase64
+            ]
+
 {- | Source:
 https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP
 -}
@@ -62,6 +80,9 @@ data AzureEmailRequest = AzureEmailRequest
     { aerContent :: !EmailContent
     , aerRecipients :: !EmailRecipients
     , aerSenderAddress :: !Text -- TODO: This should probably be it's own newtype
+    , aerReplyTo :: ![EmailAddress] -- TODO: Should this be NonEmpty instead?
+    , aerAttachments :: ![EmailAttachment]
+    , aerUserEngagementTrackingDisabled :: !Bool
     }
     deriving stock (Generic)
 
@@ -71,4 +92,18 @@ instance ToJSON AzureEmailRequest where
             [ "content" .= aerContent
             , "recipients" .= aerRecipients
             , "senderAddress" .= aerSenderAddress
+            , "replyTo" .= aerReplyTo
+            , "attachments" .= aerAttachments
+            , "userEngagementTrackingDisabled" .= aerUserEngagementTrackingDisabled
             ]
+
+{- | Possible states once a send email action is triggered.
+Source: https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP#emailsendstatus
+-}
+data EmailSendStatus
+    = Canceled
+    | Failed
+    | NotStarted
+    | Running
+    | Succeeded
+    deriving stock (Eq, Show, Generic, Enum, Bounded)
diff --git a/azure-email/azure-email.cabal b/azure-email/azure-email.cabal
index 57b36d1..e470590 100644
--- a/azure-email/azure-email.cabal
+++ b/azure-email/azure-email.cabal
@@ -52,6 +52,7 @@ library
     import:           common-options
     exposed-modules:  Azure.Email
     build-depends:    aeson
+                    , bytestring
                     , http-client
                     , servant
                     , servant-client

From 732b0781acc75fbf682916517e760f0bd5387fe6 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Sun, 25 Aug 2024 10:54:06 +0530
Subject: [PATCH 5/9] client for sending emails

---
 azure-email/Azure/Email.hs    | 178 +++++++++++++++-------------------
 azure-email/Azure/Types.hs    | 131 +++++++++++++++++++++++++
 azure-email/azure-email.cabal |   5 +
 3 files changed, 215 insertions(+), 99 deletions(-)
 create mode 100644 azure-email/Azure/Types.hs

diff --git a/azure-email/Azure/Email.hs b/azure-email/Azure/Email.hs
index 7d8e23e..bf5a206 100644
--- a/azure-email/Azure/Email.hs
+++ b/azure-email/Azure/Email.hs
@@ -1,109 +1,89 @@
-{-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE DerivingVia #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeOperators #-}
 
-module Azure.Email () where
+module Azure.Email where
 
-import Data.Aeson (ToJSON (..), object, (.=))
+import Azure.Types (AzureEmailRequest (..))
+import Crypto.Hash.SHA256 (hash, hmac)
+import Data.Aeson (encode)
+import Data.Proxy (Proxy (..))
 import Data.Text (Text)
-import GHC.Generics (Generic)
+import Data.Text.Encoding (decodeUtf8)
+import Data.Time (UTCTime, defaultTimeLocale, formatTime, getCurrentTime)
+import Network.HTTP.Client.TLS (newTlsManager)
+import Servant.API
+import Servant.Client (BaseUrl (..), ClientM, Scheme (..), client, mkClientEnv, runClientM)
+import UnliftIO (MonadIO (..))
 
-data EmailAddress = EmailAddress
-    { eaEmail :: !Text
-    , eaDisplayName :: !Text
-    }
-    deriving stock (Eq, Show, Generic)
+import qualified Data.ByteString as BS
+import qualified Data.ByteString.Base64 as B64
+import qualified Data.ByteString.Char8 as C8
+import qualified Data.Text as Text
 
-instance ToJSON EmailAddress where
-    toJSON EmailAddress{..} =
-        object
-            [ "address" .= eaEmail
-            , "displayName" .= eaDisplayName
-            ]
+type SendEmailApi =
+    "emails:send"
+        :> QueryParam' '[Required, Strict] "api-version" Text
+        :> Header' '[Required, Strict] "x-ms-date" Text
+        :> Header' '[Required, Strict] "Host" Text
+        :> Header' '[Required, Strict] "x-ms-content-sha256" Text
+        :> Header' '[Required, Strict] "Authorization" Text
+        :> ReqBody '[JSON] AzureEmailRequest
+        :> PostNoContent
 
--- | Fields to represent @cc@, @bcc@ and @to@ in an email
-data EmailRecipients = EmailRecipients
-    { ccRecipients :: ![EmailAddress]
-    , bccRecipients :: ![EmailAddress]
-    , toRecipients :: ![EmailAddress]
-    }
-    deriving stock (Generic)
+sendEmailApi :: Text -> Text -> Text -> Text -> Text -> AzureEmailRequest -> ClientM NoContent
+sendEmailApi = client (Proxy @SendEmailApi)
 
-instance ToJSON EmailRecipients where
-    toJSON EmailRecipients{..} =
-        object
-            [ "to" .= toRecipients
-            , "cc" .= ccRecipients
-            , "bcc" .= bccRecipients
-            ]
+callSendEmailClient ::
+    (Text -> Text -> Text -> Text -> Text -> AzureEmailRequest -> ClientM NoContent) ->
+    AzureEmailRequest ->
+    Text ->
+    Text ->
+    IO (Either Text ())
+callSendEmailClient action req azureEmailHost secret = do
+    manager <- liftIO newTlsManager
+    (formatToAzureTime -> now) <- getCurrentTime
+    encodedPayload <- encodePayload
+    let stringToSign =
+            "POST\n"
+                <> "/emails:send?api-version="
+                <> apiVersion
+                <> "\n"
+                <> now
+                <> ";"
+                <> azureEmailHost
+                <> ";"
+                <> encodedPayload
+    let sign = buildSignature stringToSign secret
+    res <-
+        liftIO $
+            runClientM
+                (action apiVersion now azureEmailHost encodedPayload ("HMAC-SHA256 SignedHeaders=x-ms-date;host;x-ms-content-sha256&Signature=" <> sign) req)
+                (mkClientEnv manager $ BaseUrl Https (Text.unpack azureEmailHost) 443 "")
+    pure $ case res of
+        Left err -> do
+            Left . Text.pack $ show err
+        Right _ -> do
+            Right ()
+  where
+    apiVersion :: Text
+    apiVersion = "2023-03-31"
 
--- | Azure email requires both HTML and plain text format email content
-data EmailContent = EmailContent
-    { ecHtml :: !Text
-    -- ^ Html version of the email message.
-    , ecPlainText :: !Text
-    -- ^ Plain text version of the email message.
-    , ecSubject :: !Text
-    -- ^ Subject of the email message.
-    }
-    deriving stock (Eq, Show, Generic)
+    encodePayload :: IO Text
+    encodePayload = do
+        let contentBytes = encode req
+            hashedBytes = hash (BS.toStrict contentBytes)
+            encodedHash = B64.encode hashedBytes
+        pure $ decodeUtf8 encodedHash
 
-instance ToJSON EmailContent where
-    toJSON EmailContent{..} =
-        object
-            [ "plainText" .= ecPlainText
-            , "html" .= ecHtml
-            , "subject" .= ecSubject
-            ]
+    -- TODO: formatToAzureTime and buildSignature are borrowed from azure-blob-storage.
+    -- We should not be duplicating these utility functions
+    formatToAzureTime :: UTCTime -> Text
+    formatToAzureTime time = Text.pack $ formatTime defaultTimeLocale "%FT%TZ" time
 
-data EmailAttachment = EmailAttachment
-    { eaContentInBase64 :: !Text
-    -- ^ Base64 encoded contents of the attachment
-    , eaContentType :: !Text
-    -- ^ MIME type of the attachment
-    , eaName :: !Text
-    -- ^ Name of the attachment
-    }
-    deriving stock (Generic)
-
-instance ToJSON EmailAttachment where
-    toJSON EmailAttachment{..} =
-        object
-            [ "name" .= eaName
-            , "contentType" .= eaContentType
-            , "contentInBase64" .= eaContentInBase64
-            ]
-
-{- | Source:
-https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP
--}
-data AzureEmailRequest = AzureEmailRequest
-    { aerContent :: !EmailContent
-    , aerRecipients :: !EmailRecipients
-    , aerSenderAddress :: !Text -- TODO: This should probably be it's own newtype
-    , aerReplyTo :: ![EmailAddress] -- TODO: Should this be NonEmpty instead?
-    , aerAttachments :: ![EmailAttachment]
-    , aerUserEngagementTrackingDisabled :: !Bool
-    }
-    deriving stock (Generic)
-
-instance ToJSON AzureEmailRequest where
-    toJSON AzureEmailRequest{..} =
-        object
-            [ "content" .= aerContent
-            , "recipients" .= aerRecipients
-            , "senderAddress" .= aerSenderAddress
-            , "replyTo" .= aerReplyTo
-            , "attachments" .= aerAttachments
-            , "userEngagementTrackingDisabled" .= aerUserEngagementTrackingDisabled
-            ]
-
-{- | Possible states once a send email action is triggered.
-Source: https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP#emailsendstatus
--}
-data EmailSendStatus
-    = Canceled
-    | Failed
-    | NotStarted
-    | Running
-    | Succeeded
-    deriving stock (Eq, Show, Generic, Enum, Bounded)
+    buildSignature :: Text -> Text -> Text
+    buildSignature stringToSign sec =
+        let decodedSecret = B64.decodeLenient (C8.pack (Text.unpack sec))
+            encodedStringToSign = C8.pack (Text.unpack stringToSign)
+            hashedBytes = hmac decodedSecret encodedStringToSign
+            encodedSignature = B64.encode hashedBytes
+         in decodeUtf8 encodedSignature
diff --git a/azure-email/Azure/Types.hs b/azure-email/Azure/Types.hs
new file mode 100644
index 0000000..8f01256
--- /dev/null
+++ b/azure-email/Azure/Types.hs
@@ -0,0 +1,131 @@
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DerivingVia #-}
+
+module Azure.Types (AzureEmailRequest (..), AzureEmailResponse (..)) where
+
+import Data.Aeson (FromJSON (..), ToJSON (..), object, withObject, withText, (.:), (.=))
+import Data.Aeson.Types (parseFail)
+import Data.Text (Text)
+import GHC.Generics (Generic)
+
+data EmailAddress = EmailAddress
+    { eaEmail :: !Text
+    , eaDisplayName :: !Text
+    }
+    deriving stock (Eq, Show, Generic)
+
+instance ToJSON EmailAddress where
+    toJSON EmailAddress{..} =
+        object
+            [ "address" .= eaEmail
+            , "displayName" .= eaDisplayName
+            ]
+
+-- | Fields to represent @cc@, @bcc@ and @to@ in an email
+data EmailRecipients = EmailRecipients
+    { ccRecipients :: ![EmailAddress]
+    , bccRecipients :: ![EmailAddress]
+    , toRecipients :: ![EmailAddress]
+    }
+    deriving stock (Generic)
+
+instance ToJSON EmailRecipients where
+    toJSON EmailRecipients{..} =
+        object
+            [ "to" .= toRecipients
+            , "cc" .= ccRecipients
+            , "bcc" .= bccRecipients
+            ]
+
+-- | Azure email requires both HTML and plain text format email content
+data EmailContent = EmailContent
+    { ecHtml :: !Text
+    -- ^ Html version of the email message.
+    , ecPlainText :: !Text
+    -- ^ Plain text version of the email message.
+    , ecSubject :: !Text
+    -- ^ Subject of the email message.
+    }
+    deriving stock (Eq, Show, Generic)
+
+instance ToJSON EmailContent where
+    toJSON EmailContent{..} =
+        object
+            [ "plainText" .= ecPlainText
+            , "html" .= ecHtml
+            , "subject" .= ecSubject
+            ]
+
+data EmailAttachment = EmailAttachment
+    { eaContentInBase64 :: !Text
+    -- ^ Base64 encoded contents of the attachment
+    , eaContentType :: !Text
+    -- ^ MIME type of the attachment
+    , eaName :: !Text
+    -- ^ Name of the attachment
+    }
+    deriving stock (Generic)
+
+instance ToJSON EmailAttachment where
+    toJSON EmailAttachment{..} =
+        object
+            [ "name" .= eaName
+            , "contentType" .= eaContentType
+            , "contentInBase64" .= eaContentInBase64
+            ]
+
+{- | Source:
+https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP
+-}
+data AzureEmailRequest = AzureEmailRequest
+    { aerContent :: !EmailContent
+    , aerRecipients :: !EmailRecipients
+    , aerSenderAddress :: !Text -- TODO: This should probably be it's own newtype
+    , aerReplyTo :: ![EmailAddress] -- TODO: Should this be NonEmpty instead?
+    , aerAttachments :: ![EmailAttachment]
+    , aerUserEngagementTrackingDisabled :: !Bool
+    }
+    deriving stock (Generic)
+
+instance ToJSON AzureEmailRequest where
+    toJSON AzureEmailRequest{..} =
+        object
+            [ "content" .= aerContent
+            , "recipients" .= aerRecipients
+            , "senderAddress" .= aerSenderAddress
+            , "replyTo" .= aerReplyTo
+            , "attachments" .= aerAttachments
+            , "userEngagementTrackingDisabled" .= aerUserEngagementTrackingDisabled
+            ]
+
+{- | Possible states once a send email action is triggered.
+Source: https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP#emailsendstatus
+-}
+data EmailSendStatus
+    = Canceled
+    | Failed
+    | NotStarted
+    | Running
+    | Succeeded
+    deriving stock (Eq, Show, Generic, Enum, Bounded)
+
+instance FromJSON EmailSendStatus where
+    parseJSON = withText "EmailSendStatus" $ \case
+        "Canceled" -> pure Canceled
+        "Failed" -> pure Failed
+        "NotStarted" -> pure NotStarted
+        "Running" -> pure Running
+        "Succeeded" -> pure Succeeded
+        invalidStatus -> parseFail $ "Unexpected EmailSendStatus: " <> show invalidStatus
+
+data AzureEmailResponse = AzureEmailResponse
+    { aerId :: !Text
+    , aerStatus :: !EmailSendStatus
+    }
+    deriving stock (Eq, Show, Generic)
+
+instance FromJSON AzureEmailResponse where
+    parseJSON = withObject "AzureEmailResponse" $ \o -> do
+        aerId <- o .: "id"
+        aerStatus <- o .: "status"
+        pure AzureEmailResponse{..}
diff --git a/azure-email/azure-email.cabal b/azure-email/azure-email.cabal
index e470590..1e974f9 100644
--- a/azure-email/azure-email.cabal
+++ b/azure-email/azure-email.cabal
@@ -51,11 +51,16 @@ common common-options
 library
     import:           common-options
     exposed-modules:  Azure.Email
+                      Azure.Types
     build-depends:    aeson
+                    , base64-bytestring
                     , bytestring
+                    , cryptohash-sha256
                     , http-client
+                    , http-client-tls
                     , servant
                     , servant-client
+                    , time
                     , text
                     , unliftio
     default-language: Haskell2010

From fc38c4da4435ecda8d6ab1f5928c5b967e201b65 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Sun, 25 Aug 2024 11:02:02 +0530
Subject: [PATCH 6/9] exports

---
 azure-email/Azure/Email.hs    | 14 +++++++++++++-
 azure-email/azure-email.cabal |  1 -
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/azure-email/Azure/Email.hs b/azure-email/Azure/Email.hs
index bf5a206..795be82 100644
--- a/azure-email/Azure/Email.hs
+++ b/azure-email/Azure/Email.hs
@@ -1,7 +1,7 @@
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeOperators #-}
 
-module Azure.Email where
+module Azure.Email (sendEmail, sendEmailEither) where
 
 import Azure.Types (AzureEmailRequest (..))
 import Crypto.Hash.SHA256 (hash, hmac)
@@ -20,6 +20,18 @@ import qualified Data.ByteString.Base64 as B64
 import qualified Data.ByteString.Char8 as C8
 import qualified Data.Text as Text
 
+sendEmail ::
+    MonadIO m =>
+    Text ->
+    m ()
+sendEmail apiSecret = undefined
+
+sendEmailEither ::
+    MonadIO m =>
+    Text ->
+    m (Either Text ())
+sendEmailEither apiSecret = undefined
+
 type SendEmailApi =
     "emails:send"
         :> QueryParam' '[Required, Strict] "api-version" Text
diff --git a/azure-email/azure-email.cabal b/azure-email/azure-email.cabal
index 1e974f9..dccf94a 100644
--- a/azure-email/azure-email.cabal
+++ b/azure-email/azure-email.cabal
@@ -56,7 +56,6 @@ library
                     , base64-bytestring
                     , bytestring
                     , cryptohash-sha256
-                    , http-client
                     , http-client-tls
                     , servant
                     , servant-client

From 84a9b7796d03e2eddaf2d11709c61daaa3d832c6 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Mon, 7 Oct 2024 16:31:42 +0530
Subject: [PATCH 7/9] remove redundant derivingVia

---
 azure-email/Azure/Email.hs | 17 +++++++++++------
 azure-email/Azure/Types.hs | 39 +++++++++++++++++++++++++++-----------
 2 files changed, 39 insertions(+), 17 deletions(-)

diff --git a/azure-email/Azure/Email.hs b/azure-email/Azure/Email.hs
index 795be82..1b57852 100644
--- a/azure-email/Azure/Email.hs
+++ b/azure-email/Azure/Email.hs
@@ -1,9 +1,12 @@
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeOperators #-}
 
-module Azure.Email (sendEmail, sendEmailEither) where
+module Azure.Email
+    ( sendEmail
+    , sendEmailEither
+    ) where
 
-import Azure.Types (AzureEmailRequest (..))
+import Azure.Types (AzureEmailRequest (..), AzureEmailResponse (..))
 import Crypto.Hash.SHA256 (hash, hmac)
 import Data.Aeson (encode)
 import Data.Proxy (Proxy (..))
@@ -23,14 +26,16 @@ import qualified Data.Text as Text
 sendEmail ::
     MonadIO m =>
     Text ->
-    m ()
-sendEmail apiSecret = undefined
+    AzureEmailRequest ->
+    m AzureEmailResponse
+sendEmail apiSecret payload = undefined
 
 sendEmailEither ::
     MonadIO m =>
     Text ->
-    m (Either Text ())
-sendEmailEither apiSecret = undefined
+    AzureEmailRequest ->
+    m (Either Text AzureEmailResponse)
+sendEmailEither apiSecret payload = undefined
 
 type SendEmailApi =
     "emails:send"
diff --git a/azure-email/Azure/Types.hs b/azure-email/Azure/Types.hs
index 8f01256..dab3b3c 100644
--- a/azure-email/Azure/Types.hs
+++ b/azure-email/Azure/Types.hs
@@ -1,18 +1,34 @@
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE DerivingVia #-}
 
-module Azure.Types (AzureEmailRequest (..), AzureEmailResponse (..)) where
+module Azure.Types
+    ( AzureEmailRequest (..)
+    , AzureEmailResponse (..)
+
+      -- * Types to work with email addresses.
+
+    -- These types merely represent the address and
+    -- are not responsible for validating them whatsoever.
+    , EmailAddress (..)
+    , EmailRecipients (..)
+    , EmailContent (..)
+    , EmailAttachment (..)
+    ) where
 
 import Data.Aeson (FromJSON (..), ToJSON (..), object, withObject, withText, (.:), (.=))
 import Data.Aeson.Types (parseFail)
 import Data.Text (Text)
-import GHC.Generics (Generic)
 
+{- | Each email is represented as an object with @displayName@
+and an associated @address@.
+
+Source: https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP#emailaddress
+-}
 data EmailAddress = EmailAddress
     { eaEmail :: !Text
     , eaDisplayName :: !Text
     }
-    deriving stock (Eq, Show, Generic)
+    deriving stock (Eq, Show)
 
 instance ToJSON EmailAddress where
     toJSON EmailAddress{..} =
@@ -27,7 +43,7 @@ data EmailRecipients = EmailRecipients
     , bccRecipients :: ![EmailAddress]
     , toRecipients :: ![EmailAddress]
     }
-    deriving stock (Generic)
+    deriving stock (Show)
 
 instance ToJSON EmailRecipients where
     toJSON EmailRecipients{..} =
@@ -46,7 +62,7 @@ data EmailContent = EmailContent
     , ecSubject :: !Text
     -- ^ Subject of the email message.
     }
-    deriving stock (Eq, Show, Generic)
+    deriving stock (Eq, Show)
 
 instance ToJSON EmailContent where
     toJSON EmailContent{..} =
@@ -64,7 +80,7 @@ data EmailAttachment = EmailAttachment
     , eaName :: !Text
     -- ^ Name of the attachment
     }
-    deriving stock (Generic)
+    deriving stock (Show)
 
 instance ToJSON EmailAttachment where
     toJSON EmailAttachment{..} =
@@ -74,8 +90,9 @@ instance ToJSON EmailAttachment where
             , "contentInBase64" .= eaContentInBase64
             ]
 
-{- | Source:
-https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP
+{- | Represents the payload for sending an email message.
+
+Source: https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP#emailmessage
 -}
 data AzureEmailRequest = AzureEmailRequest
     { aerContent :: !EmailContent
@@ -85,7 +102,7 @@ data AzureEmailRequest = AzureEmailRequest
     , aerAttachments :: ![EmailAttachment]
     , aerUserEngagementTrackingDisabled :: !Bool
     }
-    deriving stock (Generic)
+    deriving stock (Show)
 
 instance ToJSON AzureEmailRequest where
     toJSON AzureEmailRequest{..} =
@@ -107,7 +124,7 @@ data EmailSendStatus
     | NotStarted
     | Running
     | Succeeded
-    deriving stock (Eq, Show, Generic, Enum, Bounded)
+    deriving stock (Eq, Show, Enum, Bounded)
 
 instance FromJSON EmailSendStatus where
     parseJSON = withText "EmailSendStatus" $ \case
@@ -122,7 +139,7 @@ data AzureEmailResponse = AzureEmailResponse
     { aerId :: !Text
     , aerStatus :: !EmailSendStatus
     }
-    deriving stock (Eq, Show, Generic)
+    deriving stock (Eq, Show)
 
 instance FromJSON AzureEmailResponse where
     parseJSON = withObject "AzureEmailResponse" $ \o -> do

From eb79866e8b4e4da955d37c7006d6db8cc376dcb3 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Sun, 27 Oct 2024 20:52:46 +0530
Subject: [PATCH 8/9] smart constructor + top level send function

---
 azure-email/Azure/Email.hs | 31 ++++++++++++++++++++++---------
 azure-email/Azure/Types.hs | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 54 insertions(+), 10 deletions(-)

diff --git a/azure-email/Azure/Email.hs b/azure-email/Azure/Email.hs
index 1b57852..1a9db38 100644
--- a/azure-email/Azure/Email.hs
+++ b/azure-email/Azure/Email.hs
@@ -16,26 +16,39 @@ import Data.Time (UTCTime, defaultTimeLocale, formatTime, getCurrentTime)
 import Network.HTTP.Client.TLS (newTlsManager)
 import Servant.API
 import Servant.Client (BaseUrl (..), ClientM, Scheme (..), client, mkClientEnv, runClientM)
-import UnliftIO (MonadIO (..))
+import UnliftIO (MonadIO (..), throwString)
 
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.Base64 as B64
 import qualified Data.ByteString.Char8 as C8
 import qualified Data.Text as Text
 
+{- | Send an email provided a request payload
+
+Errors are thrown in IO. For a variant where error is captured
+in an @Left@ branch, see @sendEmailEither@
+-}
 sendEmail ::
     MonadIO m =>
     Text ->
+    Text ->
     AzureEmailRequest ->
     m AzureEmailResponse
-sendEmail apiSecret payload = undefined
+sendEmail apiSecret emailHost payload = do
+    resp <- sendEmailEither apiSecret emailHost payload
+    case resp of
+        Left err -> throwString $ show err
+        Right r -> pure r
 
+-- | Send an email provided a request payload
 sendEmailEither ::
     MonadIO m =>
     Text ->
+    Text ->
     AzureEmailRequest ->
     m (Either Text AzureEmailResponse)
-sendEmailEither apiSecret payload = undefined
+sendEmailEither apiSecret emailHost payload =
+    liftIO $ callSendEmailClient sendEmailApi payload emailHost apiSecret
 
 type SendEmailApi =
     "emails:send"
@@ -45,17 +58,17 @@ type SendEmailApi =
         :> Header' '[Required, Strict] "x-ms-content-sha256" Text
         :> Header' '[Required, Strict] "Authorization" Text
         :> ReqBody '[JSON] AzureEmailRequest
-        :> PostNoContent
+        :> Post '[JSON] AzureEmailResponse
 
-sendEmailApi :: Text -> Text -> Text -> Text -> Text -> AzureEmailRequest -> ClientM NoContent
+sendEmailApi :: Text -> Text -> Text -> Text -> Text -> AzureEmailRequest -> ClientM AzureEmailResponse
 sendEmailApi = client (Proxy @SendEmailApi)
 
 callSendEmailClient ::
-    (Text -> Text -> Text -> Text -> Text -> AzureEmailRequest -> ClientM NoContent) ->
+    (Text -> Text -> Text -> Text -> Text -> AzureEmailRequest -> ClientM AzureEmailResponse) ->
     AzureEmailRequest ->
     Text ->
     Text ->
-    IO (Either Text ())
+    IO (Either Text AzureEmailResponse)
 callSendEmailClient action req azureEmailHost secret = do
     manager <- liftIO newTlsManager
     (formatToAzureTime -> now) <- getCurrentTime
@@ -79,8 +92,8 @@ callSendEmailClient action req azureEmailHost secret = do
     pure $ case res of
         Left err -> do
             Left . Text.pack $ show err
-        Right _ -> do
-            Right ()
+        Right r -> do
+            Right r
   where
     apiVersion :: Text
     apiVersion = "2023-03-31"
diff --git a/azure-email/Azure/Types.hs b/azure-email/Azure/Types.hs
index dab3b3c..32e20a5 100644
--- a/azure-email/Azure/Types.hs
+++ b/azure-email/Azure/Types.hs
@@ -13,12 +13,17 @@ module Azure.Types
     , EmailRecipients (..)
     , EmailContent (..)
     , EmailAttachment (..)
+
+      -- * Smart constructors
+    , newAzureEmailRequest
     ) where
 
 import Data.Aeson (FromJSON (..), ToJSON (..), object, withObject, withText, (.:), (.=))
 import Data.Aeson.Types (parseFail)
 import Data.Text (Text)
 
+import qualified Data.Text as Text
+
 {- | Each email is represented as an object with @displayName@
 and an associated @address@.
 
@@ -37,6 +42,14 @@ instance ToJSON EmailAddress where
             , "displayName" .= eaDisplayName
             ]
 
+{- | Why text type instead of represting it as @EmailAddress@?
+
+Well, Azure API dictates that sender address should only be the email
+instead of a combination of email and display name (EmailAddress in our case).
+Therefore, we fallback to use text as a type alias for this one case.
+-}
+type SenderEmailAddress = Text
+
 -- | Fields to represent @cc@, @bcc@ and @to@ in an email
 data EmailRecipients = EmailRecipients
     { ccRecipients :: ![EmailAddress]
@@ -97,7 +110,7 @@ Source: https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email
 data AzureEmailRequest = AzureEmailRequest
     { aerContent :: !EmailContent
     , aerRecipients :: !EmailRecipients
-    , aerSenderAddress :: !Text -- TODO: This should probably be it's own newtype
+    , aerSenderAddress :: !SenderEmailAddress
     , aerReplyTo :: ![EmailAddress] -- TODO: Should this be NonEmpty instead?
     , aerAttachments :: ![EmailAttachment]
     , aerUserEngagementTrackingDisabled :: !Bool
@@ -115,6 +128,24 @@ instance ToJSON AzureEmailRequest where
             , "userEngagementTrackingDisabled" .= aerUserEngagementTrackingDisabled
             ]
 
+{- | Smart constructor to build a send email request.
+
+There are few default settings that the caller needs to be aware of:
+1. @replyTo@ for recipient is the sender's email address. In case there needs to be multiple
+   email addresses in @replyTo@ field, it is advised to build a custom request based on the
+   exposed data types instead.
+2. Attachements are not included, yet.
+3. Enagagement tracking is disabled.
+-}
+newAzureEmailRequest ::
+    SenderEmailAddress ->
+    EmailRecipients ->
+    EmailContent ->
+    AzureEmailRequest
+newAzureEmailRequest senderAddress recipients content =
+    let senderEmailAddress = EmailAddress senderAddress Text.empty
+     in AzureEmailRequest content recipients senderAddress [senderEmailAddress] [] True
+
 {- | Possible states once a send email action is triggered.
 Source: https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP#emailsendstatus
 -}

From 85bfd17ef106037a02d124208d09133959be4a82 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Tue, 29 Oct 2024 09:12:22 +0530
Subject: [PATCH 9/9] haddocks

---
 azure-email/Azure/Types.hs | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/azure-email/Azure/Types.hs b/azure-email/Azure/Types.hs
index 32e20a5..961a6b7 100644
--- a/azure-email/Azure/Types.hs
+++ b/azure-email/Azure/Types.hs
@@ -130,21 +130,23 @@ instance ToJSON AzureEmailRequest where
 
 {- | Smart constructor to build a send email request.
 
+This is very priliminary in nature and facilitates quickly building an email request
+with 1 recipient and sender with the content.
 There are few default settings that the caller needs to be aware of:
 1. @replyTo@ for recipient is the sender's email address. In case there needs to be multiple
    email addresses in @replyTo@ field, it is advised to build a custom request based on the
    exposed data types instead.
-2. Attachements are not included, yet.
+2. Attachements are not included.
 3. Enagagement tracking is disabled.
 -}
 newAzureEmailRequest ::
     SenderEmailAddress ->
-    EmailRecipients ->
+    EmailAddress ->
     EmailContent ->
     AzureEmailRequest
-newAzureEmailRequest senderAddress recipients content =
+newAzureEmailRequest senderAddress recipient content =
     let senderEmailAddress = EmailAddress senderAddress Text.empty
-     in AzureEmailRequest content recipients senderAddress [senderEmailAddress] [] True
+     in AzureEmailRequest content (EmailRecipients [] [] [recipient]) senderAddress [senderEmailAddress] [] True
 
 {- | Possible states once a send email action is triggered.
 Source: https://learn.microsoft.com/en-us/rest/api/communication/dataplane/email/send?view=rest-communication-dataplane-2023-03-31&tabs=HTTP#emailsendstatus