Add email service

build.gradle.kts

@@ -38,6 +38,10 @@ dependencies {
     implementation("com.cloudinary:cloudinary:1.0.14")
     annotationProcessor("org.springframework.boot:spring-boot-configuration-processor")
     implementation("org.springframework.boot:spring-boot-starter-validation:3.1.1")
+    implementation("org.springframework.boot:spring-boot-starter-mail:3.0.2")
+    implementation("org.springframework.boot:spring-boot-starter-mustache:3.0.2")
+    implementation("org.commonmark:commonmark:0.21.0")
+    implementation("org.commonmark:commonmark-ext-yaml-front-matter:0.21.0")
     developmentOnly("org.springframework.boot:spring-boot-devtools")
     runtimeOnly("com.h2database:h2")
     testImplementation("org.springframework.boot:spring-boot-starter-test")

src/main/kotlin/pt/up/fe/ni/website/backend/BackendApplication.kt

@@ -5,10 +5,11 @@ import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.boot.runApplication
 import org.springframework.data.jpa.repository.config.EnableJpaAuditing
 import pt.up.fe.ni.website.backend.config.auth.AuthConfigProperties
+import pt.up.fe.ni.website.backend.config.email.EmailConfigProperties
 import pt.up.fe.ni.website.backend.config.upload.UploadConfigProperties
 
 @SpringBootApplication
-@EnableConfigurationProperties(AuthConfigProperties::class, UploadConfigProperties::class)
+@EnableConfigurationProperties(AuthConfigProperties::class, UploadConfigProperties::class, EmailConfigProperties::class)
 @EnableJpaAuditing
 class BackendApplication
 

src/main/kotlin/pt/up/fe/ni/website/backend/config/email/EmailConfig.kt

@@ -0,0 +1,33 @@
+package pt.up.fe.ni.website.backend.config.email
+
+import com.samskivert.mustache.Mustache
+import org.commonmark.ext.front.matter.YamlFrontMatterExtension
+import org.commonmark.parser.Parser
+import org.commonmark.renderer.html.HtmlRenderer
+import org.commonmark.renderer.text.TextContentRenderer
+import org.springframework.boot.autoconfigure.mustache.MustacheResourceTemplateLoader
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+
+@Configuration
+class EmailConfig(
+    private val emailConfigProperties: EmailConfigProperties
+) {
+    @Bean
+    fun mustacheCompiler() = Mustache.compiler().withLoader(
+        MustacheResourceTemplateLoader(emailConfigProperties.templatePrefix, emailConfigProperties.templateSuffix)
+    )
+
+    @Bean
+    fun commonmarkParser() = Parser.builder().extensions(
+        listOf(
+            YamlFrontMatterExtension.create()
+        )
+    ).build()
+
+    @Bean
+    fun commonmarkHtmlRenderer() = HtmlRenderer.builder().build()
+
+    @Bean
+    fun commonmarkTextRenderer() = TextContentRenderer.builder().build()
+}

src/main/kotlin/pt/up/fe/ni/website/backend/config/email/EmailConfigProperties.kt

@@ -0,0 +1,13 @@
+package pt.up.fe.ni.website.backend.config.email
+
+import org.springframework.boot.context.properties.ConfigurationProperties
+
+@ConfigurationProperties(prefix = "email")
+data class EmailConfigProperties(
+    val from: String,
+    val fromPersonal: String = from,
+    val templatePrefix: String = "classpath:templates/email/",
+    val templateSuffix: String = ".mustache",
+    val defaultHtmlLayout: String = "layout.html",
+    val defaultStyle: String = "classpath:email/style.css"
+)

src/main/kotlin/pt/up/fe/ni/website/backend/email/BaseEmailBuilder.kt

@@ -0,0 +1,55 @@
+package pt.up.fe.ni.website.backend.email
+
+import jakarta.validation.Valid
+import jakarta.validation.constraints.Email
+import org.springframework.mail.javamail.MimeMessageHelper
+import pt.up.fe.ni.website.backend.config.ApplicationContextUtils
+import pt.up.fe.ni.website.backend.config.email.EmailConfigProperties
+import pt.up.fe.ni.website.backend.model.Account
+
+abstract class BaseEmailBuilder : EmailBuilder {
+    protected open val emailConfigProperties = ApplicationContextUtils.getBean(EmailConfigProperties::class.java)
+
+    var from: String? = null
+    var fromPersonal: String? = null
+    var to: MutableSet<String> = mutableSetOf()
+    var cc: MutableSet<String> = mutableSetOf()
+    var bcc: MutableSet<String> = mutableSetOf()
+
+    fun from(@Email email: String, personal: String = email) = apply {
+        from = email
+        fromPersonal = personal
+    }
+
+    fun to(@Email vararg emails: String) = apply {
+        to.addAll(emails)
+    }
+
+    fun to(@Valid vararg users: Account) = apply {
+        to.addAll(users.map { it.email })
+    }
+
+    fun cc(@Email vararg emails: String) = apply {
+        cc.addAll(emails)
+    }
+
+    fun cc(@Valid vararg users: Account) = apply {
+        cc.addAll(users.map { it.email })
+    }
+
+    fun bcc(@Email vararg emails: String) = apply {
+        bcc.addAll(emails)
+    }
+
+    fun bcc(@Valid vararg users: Account) = apply {
+        bcc.addAll(users.map { it.email })
+    }
+
+    override fun build(helper: MimeMessageHelper) {
+        helper.setFrom(from ?: emailConfigProperties.from, fromPersonal ?: emailConfigProperties.fromPersonal)
+
+        to.forEach(helper::setTo)
+        cc.forEach(helper::setCc)
+        bcc.forEach(helper::setBcc)
+    }
+}

src/main/kotlin/pt/up/fe/ni/website/backend/email/EmailBuilder.kt

@@ -0,0 +1,7 @@
+package pt.up.fe.ni.website.backend.email
+
+import org.springframework.mail.javamail.MimeMessageHelper
+
+interface EmailBuilder {
+    fun build(helper: MimeMessageHelper)
+}

src/main/kotlin/pt/up/fe/ni/website/backend/email/SimpleEmailBuilder.kt

@@ -0,0 +1,74 @@
+package pt.up.fe.ni.website.backend.email
+
+import jakarta.activation.DataSource
+import jakarta.activation.FileDataSource
+import jakarta.activation.URLDataSource
+import java.io.File
+import java.net.URL
+import org.springframework.mail.javamail.MimeMessageHelper
+
+class SimpleEmailBuilder : BaseEmailBuilder() {
+    private var text: String? = null
+    private var html: String? = null
+    private var subject: String? = null
+    private var attachments: MutableList<EmailFile> = mutableListOf()
+
+    // Inlines - similar to attachments, not shown as downloadable but can be inserted in an email. For example, inline images.
+    private var inlines: MutableList<EmailFile> = mutableListOf()
+
+    fun text(text: String) = apply {
+        this.text = text
+    }
+
+    fun html(html: String) = apply {
+        this.html = html
+    }
+
+    fun subject(subject: String) = apply {
+        this.subject = subject
+    }
+
+    fun attach(name: String, content: DataSource) = apply {
+        attachments.add(EmailFile(name, content))
+    }
+
+    fun attach(name: String, content: File) = apply {
+        attachments.add(EmailFile(name, FileDataSource(content)))
+    }
+
+    fun attach(name: String, path: String) = apply {
+        attachments.add(EmailFile(name, URLDataSource(URL(path))))
+    }
+
+    fun inline(name: String, content: DataSource) = apply {
+        inlines.add(EmailFile(name, content))
+    }
+
+    fun inline(name: String, content: File) = apply {
+        inlines.add(EmailFile(name, FileDataSource(content)))
+    }
+
+    fun inline(name: String, path: String) = apply {
+        inlines.add(EmailFile(name, URLDataSource(URL(path))))
+    }
+
+    override fun build(helper: MimeMessageHelper) {
+        super.build(helper)
+
+        when {
+            text != null && html != null -> helper.setText(text!!, html!!)
+            html != null -> helper.setText(html!!, true)
+            text != null -> helper.setText(text!!)
+        }
+
+        subject?.let { helper.setSubject(it) }
+
+        attachments.forEach { helper.addAttachment(it.name, it.content) }
+        inlines.forEach { helper.addInline(it.name, it.content) }
+    }
+
+    private data class EmailFile(
+        val name: String,
+        val content: DataSource
+    )
+}

src/main/kotlin/pt/up/fe/ni/website/backend/email/TemplateEmailBuilder.kt

@@ -0,0 +1,78 @@
+package pt.up.fe.ni.website.backend.email
+
+import com.samskivert.mustache.Mustache
+import org.commonmark.ext.front.matter.YamlFrontMatterVisitor
+import org.commonmark.parser.Parser
+import org.commonmark.renderer.html.HtmlRenderer
+import org.commonmark.renderer.text.TextContentRenderer
+import org.springframework.core.io.Resource
+import org.springframework.core.io.UrlResource
+import org.springframework.mail.javamail.MimeMessageHelper
+import org.springframework.util.ResourceUtils
+import pt.up.fe.ni.website.backend.config.ApplicationContextUtils
+
+abstract class TemplateEmailBuilder<T>(
+    private val template: String
+) : BaseEmailBuilder() {
+    private val commonmarkParser = ApplicationContextUtils.getBean(Parser::class.java)
+    private val commonmarkHtmlRenderer = ApplicationContextUtils.getBean(HtmlRenderer::class.java)
+    private val commonmarkTextRenderer = ApplicationContextUtils.getBean(TextContentRenderer::class.java)
+    private val mustache = ApplicationContextUtils.getBean(Mustache.Compiler::class.java)
+
+    private var data: T? = null
+
+    fun data(data: T) = apply {
+        this.data = data
+    }
+
+    override fun build(helper: MimeMessageHelper) {
+        super.build(helper)
+
+        if (data == null) return
+
+        val markdown = mustache.loadTemplate(template).execute(data)
+
+        val doc = commonmarkParser.parse(markdown)
+        val htmlContent = commonmarkHtmlRenderer.render(doc)
+        val text = commonmarkTextRenderer.render(doc)
+
+        val yamlVisitor = YamlFrontMatterVisitor()
+        doc.accept(yamlVisitor)
+
+        val subject = yamlVisitor.data["subject"]?.firstOrNull()
+        subject?.let { helper.setSubject(it) }
+
+        val styles = yamlVisitor.data.getOrDefault("styles", mutableListOf()).apply {
+            if (yamlVisitor.data["no_default_style"].isNullOrEmpty()) {
+                this.add(emailConfigProperties.defaultStyle)
+            }
+        }.map {
+            ResourceUtils.getFile(it).readText()
+        }
+
+        val htmlTemplate = yamlVisitor.data["layout"]?.firstOrNull() ?: emailConfigProperties.defaultHtmlLayout
+        val html = mustache.loadTemplate(htmlTemplate).execute(
+            mapOf(
+                "subject" to subject,
+                "content" to htmlContent,
+                "styles" to styles
+            )
+        )
+
+        helper.setText(text, html)
+
+        yamlVisitor.data.getOrDefault("attachments", emptyList()).forEach { addFile(helper::addAttachment, it) }
+        yamlVisitor.data.getOrDefault("inline", emptyList()).forEach { addFile(helper::addInline, it) }
+    }
+
+    private fun addFile(fn: (String, Resource) -> Any, file: String) {
+        val split = file.split("\\s*::\\s*".toRegex(), 2)
+
+        if (split.isEmpty()) return
+
+        val name = split[0]
+        val path = split.getOrElse(1) { split[0] }
+
+        fn(name, UrlResource(path))
+    }
+}

src/main/kotlin/pt/up/fe/ni/website/backend/service/EmailService.kt

@@ -0,0 +1,20 @@
+package pt.up.fe.ni.website.backend.service
+
+import org.springframework.mail.javamail.JavaMailSender
+import org.springframework.mail.javamail.MimeMessageHelper
+import org.springframework.stereotype.Service
+import pt.up.fe.ni.website.backend.email.EmailBuilder
+
+@Service
+class EmailService(
+    private val mailSender: JavaMailSender
+) {
+    fun send(email: EmailBuilder) {
+        val message = mailSender.createMimeMessage()
+
+        val helper = MimeMessageHelper(message, true)
+        email.build(helper)
+
+        mailSender.send(message)
+    }
+}

src/main/resources/application.properties

@@ -43,3 +43,17 @@ spring.mvc.throw-exception-if-no-handler-found=true
 
 # Cors Origin
 cors.allow-origin = http://localhost:3000
+
+# Email config
+spring.mail.host=
+spring.mail.port=
+spring.mail.username=
+spring.mail.password=
+spring.mail.properties[mail.smtp.auth]=true
+spring.mail.properties[mail.smtp.starttls.enable]=true
+spring.mail.properties[mail.smtp.connectiontimeout]=5000
+spring.mail.properties[mail.smtp.timeout]=3000
+spring.mail.properties[mail.smtp.writetimeout]=5000
+
+email.from=ni@aefeup.pt
+email.from-personal=NIAEFEUP

src/main/resources/email/style.css

@@ -0,0 +1,3 @@
+/*
+TODO
+*/

src/main/resources/templates/email/layout.html.mustache

@@ -0,0 +1,20 @@
+<!doctype html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport"
+          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
+    <meta http-equiv="X-UA-Compatible" content="ie=edge">
+    <title>{{{subject}}}</title>
+
+    {{#styles}}
+    <style>
+        {{.}}
+    </style>
+    {{/styles}}
+</head>
+<body>
+    <!-- TODO -->
+    {{{content}}}
+</body>
+</html>