/*
 * Copyright 2020 the original author or authors.
 *
 * 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 org.gradle.configurationcache.problems

import org.gradle.BuildAdapter
import org.gradle.BuildResult
import org.gradle.api.internal.GradleInternal
import org.gradle.api.logging.Logging
import org.gradle.configurationcache.ConfigurationCacheAction
import org.gradle.configurationcache.ConfigurationCacheAction.LOAD
import org.gradle.configurationcache.ConfigurationCacheAction.STORE
import org.gradle.configurationcache.ConfigurationCacheKey
import org.gradle.configurationcache.ConfigurationCacheProblemsException
import org.gradle.configurationcache.ConfigurationCacheReport
import org.gradle.configurationcache.TooManyConfigurationCacheProblemsException
import org.gradle.configurationcache.initialization.ConfigurationCacheStartParameter
import org.gradle.initialization.RootBuildLifecycleListener
import org.gradle.internal.event.ListenerManager
import org.gradle.internal.service.scopes.Scopes
import org.gradle.internal.service.scopes.ServiceScope
import java.io.File
import java.util.concurrent.CopyOnWriteArrayList


private
const val maxCauses = 5


@ServiceScope(Scopes.BuildTree::class)
class ConfigurationCacheProblems(

    private
    val startParameter: ConfigurationCacheStartParameter,

    private
    val report: ConfigurationCacheReport,

    private
    val cacheKey: ConfigurationCacheKey,

    private
    val listenerManager: ListenerManager

) : ProblemsListener, AutoCloseable {

    private
    val buildFinishedHandler = BuildFinishedProblemsHandler()

    private
    val postBuildHandler = PostBuildProblemsHandler()

    private
    val problems = CopyOnWriteArrayList<PropertyProblem>()

    private
    var isFailOnProblems = startParameter.failOnProblems

    private
    var isFailingBuildDueToSerializationError = false

    private
    var cacheAction: ConfigurationCacheAction? = null

    private
    var invalidateStoredState: (() -> Unit)? = null

    init {
        listenerManager.addListener(buildFinishedHandler)
        listenerManager.addListener(postBuildHandler)
    }

    override fun close() {
        listenerManager.removeListener(buildFinishedHandler)
        listenerManager.removeListener(postBuildHandler)
    }

    fun storing(invalidateState: () -> Unit) {
        cacheAction = STORE
        invalidateStoredState = invalidateState
    }

    fun loading() {
        cacheAction = LOAD
    }

    fun failingBuildDueToSerializationError() {
        isFailingBuildDueToSerializationError = true
        isFailOnProblems = false
    }

    private
    fun List<PropertyProblem>.causes() = mapNotNull { it.exception }.take(maxCauses)

    override fun onProblem(problem: PropertyProblem) {
        problems.add(problem)
    }

    private
    inner class BuildFinishedProblemsHandler : BuildAdapter() {

        override fun buildFinished(result: BuildResult) {
            if (result.gradle?.parent != null || cacheAction == null || problems.isEmpty()) {
                return
            }
            val tooManyProblems = problems.size > startParameter.maxProblems
            if (cacheAction == STORE && (isFailOnProblems || tooManyProblems)) {
                // Invalidate stored state if problems fail the build
                requireNotNull(invalidateStoredState).invoke()
            }
            val cacheActionText = requireNotNull(cacheAction).summaryText()
            val outputDirectory = outputDirectoryFor(result.gradle?.rootProject?.buildDir ?: startParameter.rootDirectory)
            val htmlReportFile = report.writeReportFileTo(outputDirectory, cacheActionText, problems)
            when {
                isFailOnProblems -> {
                    // TODO - always include this as a build failure; currently it is disabled when a serialization problem happens
                    throw newProblemsException(cacheActionText, htmlReportFile)
                }
                tooManyProblems -> {
                    throw newTooManyProblemsException(cacheActionText, htmlReportFile)
                }
                else -> {
                    logger.warn(report.consoleSummaryFor(cacheActionText, problems, htmlReportFile))
                }
            }
        }

        private
        fun ConfigurationCacheAction.summaryText() =
            when (this) {
                LOAD -> "reusing"
                STORE -> "storing"
            }

        private
        fun newProblemsException(cacheActionText: String, htmlReportFile: File) =
            ConfigurationCacheProblemsException(
                problems.causes(),
                cacheActionText,
                problems,
                htmlReportFile
            )

        private
        fun newTooManyProblemsException(cacheActionText: String, htmlReportFile: File) =
            TooManyConfigurationCacheProblemsException(
                problems.causes(),
                cacheActionText,
                problems,
                htmlReportFile
            )

        private
        fun outputDirectoryFor(buildDir: File): File =
            buildDir.resolve("reports/configuration-cache/$cacheKey").let { base ->
                if (!base.exists()) base
                else generateSequence(1) { it + 1 }
                    .map { base.resolveSibling("${base.name}-$it") }
                    .first { !it.exists() }
            }
    }

    private
    inner class PostBuildProblemsHandler : RootBuildLifecycleListener {

        override fun afterStart(gradle: GradleInternal) = Unit

        override fun beforeComplete(gradle: GradleInternal) {
            if (cacheAction == null) return
            val hasProblems = problems.isNotEmpty()
            val hasTooManyProblems = problems.size > startParameter.maxProblems
            when {
                isFailingBuildDueToSerializationError && !hasProblems -> log("Configuration cache entry discarded.")
                isFailingBuildDueToSerializationError -> log("Configuration cache entry discarded with {}.", problemCount)
                cacheAction == STORE && isFailOnProblems && hasProblems -> log("Configuration cache entry discarded with {}.", problemCount)
                cacheAction == STORE && hasTooManyProblems -> log("Configuration cache entry discarded with too many problems ({}).", problemCount)
                cacheAction == LOAD && !hasProblems -> log("Configuration cache entry reused.")
                cacheAction == LOAD -> log("Configuration cache entry reused with {}.", problemCount)
                !hasProblems -> log("Configuration cache entry stored.")
                else -> log("Configuration cache entry stored with {}.", problemCount)
            }
        }

        private
        val problemCount: String
            get() = if (problems.size == 1) "1 problem"
            else "${problems.size} problems"
    }

    private
    fun log(msg: String, vararg args: Any = emptyArray()) {
        logger.warn(msg, *args)
    }

    private
    val logger = Logging.getLogger(ConfigurationCacheProblems::class.java)
}
