/*

 * Geekttrss is a RSS feed reader application on the Android Platform.

 *

 *

 * This file is part of Geekttrss.

 *

 * Geekttrss 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.

 *

 * Geekttrss 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 Geekttrss.  If not, see <http://www.gnu.org/licenses/>.

 */

package com.geekorum.favikonsnoop.snoopers

import com.fleeksoft.ksoup.Ksoup

import com.geekorum.favikonsnoop.FaviconInfo

import com.geekorum.favikonsnoop.Snooper

import com.geekorum.favikonsnoop.await

import kotlinx.coroutines.CoroutineDispatcher

import kotlinx.coroutines.Dispatchers

import kotlinx.coroutines.withContext

import kotlinx.serialization.ExperimentalSerializationApi

import kotlinx.serialization.Serializable

import kotlinx.serialization.SerializationException

import kotlinx.serialization.json.Json

import kotlinx.serialization.json.JsonElement

import kotlinx.serialization.json.okio.decodeFromBufferedSource

import okhttp3.HttpUrl

import okhttp3.HttpUrl.Companion.toHttpUrl

import okhttp3.Request

import okio.BufferedSource

import okio.buffer

import okio.source

/**

 * https://www.w3.org/TR/appmanifest/

 */

class AppManifestSnooper internal constructor(

    private val webAppManifestParser: WebAppManifestParser,

    private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO

) : Snooper() {

    constructor(ioDispatcher: CoroutineDispatcher = Dispatchers.IO) : this(WebAppManifestParser(), ioDispatcher)

    override suspend fun snoop(baseUrl: HttpUrl, content: BufferedSource): Collection<FaviconInfo> = withContext(ioDispatcher) {

        val document = runCatching { Ksoup.parse(content.inputStream().bufferedReader(), baseUri = baseUrl.toString()) }

        val manifestUrl = document.getOrNull()?.head()?.let { head ->

            val manifestLinkElem = head.getElementsByTag("link").firstOrNull {

                "manifest" in it.attr("rel").split("\\s".toRegex())

            }

            manifestLinkElem?.attr("abs:href")?.toHttpUrl()

        }

        val appManifest = manifestUrl?.let {

            getAppManifest(it)

        }

        appManifest?.icons?.flatMap {

            val url = manifestUrl.resolve(it.src) ?: return@flatMap emptyList<FaviconInfo>()

            val sizes = parseSizes(it.sizes ?: "")

            if (sizes.isEmpty()) {

                listOf(FaviconInfo(url.toString(),

                    mimeType = it.type)

                )

            } else {

                sizes.map { dimension ->

                    FaviconInfo(url.toString(),

                        mimeType = it.type,

                        dimension = dimension

                    )

                }

            }

        } ?: emptyList()

    }

    private suspend fun getAppManifest(url: HttpUrl): WebAppManifest? = withContext(ioDispatcher) {

        val request = Request.Builder()

            .url(url)

            .get()

            .build()

        val response = okHttpClient.newCall(request).await()

        response.use {

            if (response.isSuccessful) {

                response.body?.source()?.let {

                    webAppManifestParser.parseManifest(it)

                }

            } else null

        }

    }

}

/**

 * Only encode the fields that we care about

 */

@Serializable

data class WebAppManifest(

    val dir: JsonElement? = null,

    val lang: JsonElement? = null,

    // name is required

    val name: JsonElement,

    val short_name: JsonElement? = null,

    val description: JsonElement? = null,

    val scope: JsonElement? = null,

    // icons is required

    val icons: Collection<ImageResource>,

    val display: JsonElement? = null,

    val orientation: JsonElement? = null,

    val start_url: JsonElement? = null,

    val serviceworker: JsonElement? = null,

    val theme_color: JsonElement? = null,

    val related_applications: JsonElement? = null,

    val prefer_related_applications: JsonElement? = null,

    val background_color: JsonElement? = null,

    val categories: JsonElement? = null,

    val screenshots: JsonElement? = null,

    val iarc_rating_id: JsonElement? = null

)

@Serializable

data class ImageResource(

    val src: String,

    val sizes: String? = null,

    val type: String? = null,

    val purpose: String? = null,

    val platform: String? = null

)

internal class WebAppManifestParser(

    private val  json: Json = Json.Default

) {

    @OptIn(ExperimentalSerializationApi::class)

    fun parseManifest(source: BufferedSource): WebAppManifest? {

        return try {

            json.decodeFromBufferedSource<WebAppManifest>(source)

        } catch (e: SerializationException) {

            null

        }

    }

    fun parseManifest(content: String): WebAppManifest? =

        parseManifest(content.byteInputStream().source().buffer())

}