/*
 * Copyright 2022 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package androidx.build.dackka

import com.google.gson.Gson
import com.google.gson.GsonBuilder
import java.io.File
import java.io.FileWriter
import java.util.zip.ZipFile
import org.gradle.api.DefaultTask
import org.gradle.api.artifacts.component.ComponentArtifactIdentifier
import org.gradle.api.artifacts.component.ModuleComponentIdentifier
import org.gradle.api.file.RegularFileProperty
import org.gradle.api.provider.ListProperty
import org.gradle.api.tasks.CacheableTask
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.InputFiles
import org.gradle.api.tasks.OutputFile
import org.gradle.api.tasks.PathSensitive
import org.gradle.api.tasks.PathSensitivity
import org.gradle.api.tasks.TaskAction
import org.gradle.internal.component.external.model.DefaultModuleComponentIdentifier

@CacheableTask
abstract class GenerateMetadataTask : DefaultTask() {

    /** List of artifacts to convert to JSON */
    @Input abstract fun getArtifactIds(): ListProperty<ComponentArtifactIdentifier>

    /** List of files corresponding to artifacts in [getArtifactIds] */
    @InputFiles
    @PathSensitive(PathSensitivity.NONE)
    abstract fun getArtifactFiles(): ListProperty<File>

    /** List of multiplatform artifacts to convert to JSON */
    @Input abstract fun getMultiplatformArtifactIds(): ListProperty<ComponentArtifactIdentifier>

    /** List of files corresponding to artifacts in [getMultiplatformArtifactIds] */
    @InputFiles
    @PathSensitive(PathSensitivity.NONE)
    abstract fun getMultiplatformArtifactFiles(): ListProperty<File>

    /** Location of the generated JSON file */
    @get:OutputFile abstract val destinationFile: RegularFileProperty

    @TaskAction
    fun generate() {
        val entries =
            createEntries(getArtifactIds().get(), getArtifactFiles().get(), multiplatform = false) +
                createEntries(
                    getMultiplatformArtifactIds().get(),
                    getMultiplatformArtifactFiles().get(),
                    multiplatform = true
                )

        val gson =
            if (DEBUG) {
                GsonBuilder().setPrettyPrinting().create()
            } else {
                Gson()
            }
        val writer = FileWriter(destinationFile.get().toString())
        gson.toJson(entries, writer)
        writer.close()
    }

    private fun createEntries(
        ids: List<ComponentArtifactIdentifier>,
        artifacts: List<File>,
        multiplatform: Boolean
    ): List<MetadataEntry> =
        ids.indices.mapNotNull { i ->
            val id = ids[i]
            val file = artifacts[i]
            // Only process artifact if it can be cast to ModuleComponentIdentifier.
            //
            // In practice, metadata is generated only for docs-public and not docs-tip-of-tree
            // (where id.componentIdentifier is DefaultProjectComponentIdentifier).
            if (id.componentIdentifier !is DefaultModuleComponentIdentifier) return@mapNotNull null

            // Created https://github.com/gradle/gradle/issues/21415 to track surfacing
            // group / module / version in ComponentIdentifier
            val componentId = (id.componentIdentifier as ModuleComponentIdentifier)

            // Fetch the list of files contained in the .jar file
            val fileList =
                ZipFile(file).entries().toList().map {
                    if (multiplatform) {
                        // Paths for multiplatform will start with a directory for the platform
                        // (e.g.
                        // "commonMain"), while Dackka only sees the part of the path after this.
                        it.name.substringAfter("/")
                    } else {
                        it.name
                    }
                }

            MetadataEntry(
                groupId = componentId.group,
                artifactId = componentId.module,
                releaseNotesUrl = generateReleaseNotesUrl(componentId.group),
                jarContents = fileList
            )
        }

    private fun generateReleaseNotesUrl(groupId: String): String {
        val library = groupId.removePrefix("androidx.").replace(".", "-")
        return "/jetpack/androidx/releases/$library"
    }

    companion object {
        private const val DEBUG = false
    }
}