mjdev-desktop/buildSrc/src/main/kotlin/GenerateChangelogTask.kt

import org.gradle.api.DefaultTask
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.TaskAction
import java.io.ByteArrayOutputStream

open class GenerateChangelogTask : DefaultTask() {
    @Input
    var appName: String = ""
    @Input
    var versionName: String = ""
    @Input
    var tagPrefix: String = ""
        get() = field.lowercase()

    private val buildType: String
        get() = if (tagPrefix == "development") "debug" else "release"
  
    @TaskAction
    fun generate() {
        // Retrieve all tags sorted by date, latest first
        val tagsCommand = listOf("git", "tag", "--sort=-committerdate")
        val tagsOutput = execAndGetOutput(tagsCommand)
        val tags = tagsOutput.split("\n")
        // Extracting the two most recent tags
        val currentVersion = tags.first()
        val previousVersion = tags.last()
        // Getting changes between the latest and previous version tags
        val changes = execAndGetOutput(listOf(
            "git",
            "log",
            "--pretty=format:%s <%an>",
            "$previousVersion..$currentVersion"
        ))
        println("Changes between $previousVersion and $currentVersion:\n$changes")
        var features = "Features:\n"
        var fixes = "Fixes:\n"
        var improvements = "Improvements:\n"
        changes.lineSequence().forEach { line ->
            val parts = line.split(":", limit = 2)
            val prefix = parts.getOrNull(0) ?: ""
            val rest = parts.getOrNull(1) ?: ""
            when {
                prefix.startsWith("ft") -> features += "$rest\n"
                prefix.startsWith("fi") -> fixes += "$rest\n"
                prefix.startsWith("im") -> improvements += "$rest\n"
            }
        }
        val header = "Changelog from $previousVersion to $currentVersion\n\n"
        val changelog = header + features + "\n" + fixes + "\n" + improvements
        val fileName = "${appName}-${versionName}-$tagPrefix"
        val changelogDir = project.file("./build/outputs/apk/$buildType")
        val changelogFilePath = "$changelogDir/CHANGELOG-$fileName.md"
        println("Changelog file path: $changelogFilePath")
        // Ensure the directory exists
        changelogDir.mkdirs()
        // Create and write to the changelog file
        val changelogFile = project.file(changelogFilePath)
        changelogFile.createNewFile()
        changelogFile.writeText(changelog)
        println(changelog)
    }

    private fun execAndGetOutput(command: List<String>): String {
        val outputStream = ByteArrayOutputStream()
        project.providers.exec {
            commandLine(command)
            standardOutput = outputStream
        }
        return String(outputStream.toByteArray(), Charsets.UTF_8).trim()
    }
}