/*

 * AboutOss is an utility library to retrieve and display

 * opensource licenses in Android applications.

 *

 * Copyright (C) 2023 by Frederic-Charles Barthelery.

 *

 * This file is part of AboutOss.

 *

 * AboutOss is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * AboutOss is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with AboutOss.  If not, see <http://www.gnu.org/licenses/>.

 */

package com.geekorum.aboutoss.core.licensee

import kotlinx.coroutines.CoroutineDispatcher

import kotlinx.coroutines.withContext

import kotlinx.serialization.ExperimentalSerializationApi

import kotlinx.serialization.Serializable

import kotlinx.serialization.json.Json

import okio.Source

import okio.buffer

class LicenseeLicenseInfoRepository(

    private val produceInput: suspend () -> Source,

    private val mainCoroutineDispatcher: CoroutineDispatcher,

    private val ioCoroutineDispatcher: CoroutineDispatcher,

) {

    private var licensesInfo: Map<String, String>? = null

    suspend fun getLicensesInfo(): Map<String, String> = withContext(mainCoroutineDispatcher) {

        parseLicenses()

        checkNotNull(licensesInfo)

    }

    suspend fun getLicenseFor(dependency: String): String = withContext(mainCoroutineDispatcher) {

        parseLicenses()

        checkNotNull(licensesInfo).let {

            return@withContext it[dependency] ?: error("Dependency not found")

        }

    }

    @OptIn(ExperimentalSerializationApi::class)

    private suspend fun parseLicenses() = withContext(mainCoroutineDispatcher) {

        if (licensesInfo == null) {

            val licenses = withContext(ioCoroutineDispatcher) {

                LicenseeParser(produceInput()).use {

                    it.readLicensee()

                }

            }

            licensesInfo = licenses

        }

    }

}

private class LicenseeParser(

    input: Source

): AutoCloseable {

    private val buffered = input.buffer()

    fun readLicensee(): Map<String, String> {

        val json = Json {

            ignoreUnknownKeys = true

        }

        val items: List<LicenseItem> = json.decodeFromString(buffered.readUtf8())

        return items.associate {

            val name = it.name ?: "${it.groupId}:${it.artifactId}"

            val license = it.spdxLicenses.firstNotNullOfOrNull {

                "${it.name}\n\n${it.url}"

            } ?: it.unknownLicenses.firstNotNullOf {

                "${it.name}\n\n${it.url}"

            }

            name to license

        }

    }

    override fun close() {

        buffered.close()

    }

}

@Serializable

private data class LicenseItem(

    val groupId: String,

    val artifactId: String,

    val version: String,

    val spdxLicenses: List<SpdxLicense> = emptyList(),

    val unknownLicenses: List<UnknownLicense> = emptyList(),

    val name: String? = null,

    val scm: Scm? = null,

)

@Serializable

private data class SpdxLicense(

    val identifier: String,

    val name: String,

    val url: String,

)

@Serializable

private data class UnknownLicense(

    val name: String,

    val url: String

)

@Serializable

private data class Scm(

    val url: String,

)