/*
 * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
 * SPDX-License-Identifier: GPL-3.0-only
 */

import de.undercouch.gradle.tasks.download.Download
import java.io.File
import javax.xml.parsers.DocumentBuilderFactory
import org.gradle.api.GradleException
import org.gradle.api.Plugin
import org.gradle.api.Project
import org.gradle.api.tasks.Copy
import org.gradle.kotlin.dsl.create
import org.gradle.kotlin.dsl.register
import org.w3c.dom.Document

private const val EXCEPTION_MESSAGE =
  """Applying `crowdin-plugin` requires a projectName to be configured via the "crowdin" extension."""

class CrowdinDownloadPlugin : Plugin<Project> {

  override fun apply(project: Project) {
    with(project) {
      val extension = extensions.create<CrowdinExtension>("crowdin")
      afterEvaluate {
        val projectName = extension.projectName
        if (projectName.isEmpty()) {
          throw GradleException(EXCEPTION_MESSAGE)
        }
        tasks.register<Download>("downloadCrowdin") {
          src("https://crowdin.com/backend/download/project/$projectName.zip")
          dest("$buildDir/translations.zip")
          overwrite(true)
        }
        tasks.register<Copy>("extractCrowdin") {
          setDependsOn(setOf("downloadCrowdin"))
          doFirst { File(buildDir, "translations").deleteRecursively() }
          from(zipTree("$buildDir/translations.zip"))
          into("$buildDir/translations")
        }
        tasks.register<Copy>("extractStrings") {
          setDependsOn(setOf("extractCrowdin"))
          from("$buildDir/translations/")
          into("${projectDir}/src/")
          setFinalizedBy(setOf("removeIncompleteStrings"))
        }
        tasks.register("removeIncompleteStrings") {
          doLast {
            val sourceSets = arrayOf("main", "nonFree")
            for (sourceSet in sourceSets) {
              val stringFiles = File("${projectDir}/src/$sourceSet").walkTopDown().filter { it.name == "strings.xml" }
              val sourceFile =
                stringFiles.firstOrNull { it.path.endsWith("values/strings.xml") }
                  ?: throw GradleException("No root strings.xml found in '$sourceSet' sourceSet")
              val sourceDoc = parseDocument(sourceFile)
              val baselineStringCount = countStrings(sourceDoc)
              val threshold = 0.80 * baselineStringCount
              stringFiles.forEach { file ->
                if (file != sourceFile) {
                  val doc = parseDocument(file)
                  val stringCount = countStrings(doc)
                  if (stringCount < threshold) {
                    file.delete()
                  }
                }
              }
            }
          }
        }
        tasks.register("crowdin") {
          setDependsOn(setOf("extractStrings"))
          if (!extension.skipCleanup) {
            doLast {
              File("$buildDir/translations").deleteRecursively()
              File("$buildDir/nonFree-translations").deleteRecursively()
              File("$buildDir/translations.zip").delete()
            }
          }
        }
      }
    }
  }

  private fun parseDocument(file: File): Document {
    val dbFactory = DocumentBuilderFactory.newInstance()
    val documentBuilder = dbFactory.newDocumentBuilder()
    return documentBuilder.parse(file)
  }

  private fun countStrings(document: Document): Int {
    // Normalization is beneficial for us
    // https://stackoverflow.com/questions/13786607/normalization-in-dom-parsing-with-java-how-does-it-work
    document.documentElement.normalize()
    return document.getElementsByTagName("string").length
  }
}