/*
 * Copyright 2018 Allan Wang
 *
 * This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.pitchedapps.frost.facebook.parsers

import com.pitchedapps.frost.db.CookieEntity
import com.pitchedapps.frost.facebook.FB_EPOCH_MATCHER
import com.pitchedapps.frost.facebook.FB_MESSAGE_NOTIF_ID_MATCHER
import com.pitchedapps.frost.facebook.FbItem
import com.pitchedapps.frost.facebook.formattedFbUrl
import com.pitchedapps.frost.facebook.get
import com.pitchedapps.frost.services.NotificationContent
import com.pitchedapps.frost.utils.L
import com.pitchedapps.frost.utils.urlEncode
import org.apache.commons.text.StringEscapeUtils
import org.jsoup.Jsoup
import org.jsoup.nodes.Document
import org.jsoup.nodes.Element

/**
 * Created by Allan Wang on 2017-10-06.
 *
 * In Facebook, messages are passed through scripts and loaded into view via react afterwards
 * We can parse out the content we want directly and load it ourselves
 *
 */
object MessageParser : FrostParser<FrostMessages> by MessageParserImpl() {

    fun queryUser(cookie: String?, name: String) =
        parseFromUrl(cookie, "${FbItem.MESSAGES.url}/?q=${name.urlEncode()}")
}

data class FrostMessages(
    val threads: List<FrostThread>,
    val seeMore: FrostLink?,
    val extraLinks: List<FrostLink>
) : ParseNotification {

    override val isEmpty: Boolean
        get() = threads.isEmpty()

    override fun toString() = StringBuilder().apply {
        append("FrostMessages {\n")
        append(threads.toJsonString("threads", 1))
        append("\tsee more: $seeMore\n")
        append(extraLinks.toJsonString("extra links", 1))
        append("}")
    }.toString()

    override fun getUnreadNotifications(data: CookieEntity) =
        threads.asSequence().filter(FrostThread::unread).map {
            with(it) {
                NotificationContent(
                    data = data,
                    id = id,
                    href = url,
                    title = title,
                    text = content ?: "",
                    timestamp = time,
                    profileUrl = img,
                    unread = unread
                )
            }
        }.toList()
}

/**
 * [id] user/thread id, or current time fallback
 * [img] parsed url for profile img
 * [time] time of message
 * [url] link to thread
 * [unread] true if image is unread, false otherwise
 * [content] optional string for thread
 */
data class FrostThread(
    val id: Long,
    val img: String?,
    val title: String,
    val time: Long,
    val url: String,
    val unread: Boolean,
    val content: String?,
    val contentImgUrl: String?
)

private class MessageParserImpl : FrostParserBase<FrostMessages>(true) {

    override var nameRes = FbItem.MESSAGES.titleId

    override val url = FbItem.MESSAGES.url

    override fun textToDoc(text: String): Document? {
        var content = StringEscapeUtils.unescapeEcmaScript(text)
        val begin = content.indexOf("id=\"threadlist_rows\"")
        if (begin <= 0) {
            L.d { "Threadlist not found" }
            return null
        }
        content = content.substring(begin)
        val end = content.indexOf("</script>")
        if (end <= 0) {
            L.d { "Script tail not found" }
            return null
        }
        content = content.substring(0, end).substringBeforeLast("</div>")
        return Jsoup.parseBodyFragment("<div $content")
    }

    override fun parseImpl(doc: Document): FrostMessages? {
        val threadList = doc.getElementById("threadlist_rows") ?: return null
        val threads: List<FrostThread> =
            threadList.getElementsByAttributeValueMatching(
                "id",
                ".*${FB_MESSAGE_NOTIF_ID_MATCHER.pattern}.*"
            )
                .mapNotNull(this::parseMessage)
        val seeMore = parseLink(doc.getElementById("see_older_threads"))
        val extraLinks = threadList.nextElementSibling().select("a")
            .mapNotNull(this::parseLink)
        return FrostMessages(threads, seeMore, extraLinks)
    }

    private fun parseMessage(element: Element): FrostThread? {
        val a = element.getElementsByTag("a").first() ?: return null
        val abbr = element.getElementsByTag("abbr")
        val epoch = FB_EPOCH_MATCHER.find(abbr.attr("data-store"))[1]?.toLongOrNull() ?: -1L
        // fetch id
        val id = FB_MESSAGE_NOTIF_ID_MATCHER.find(element.id())[1]?.toLongOrNull()
            ?: System.currentTimeMillis() % FALLBACK_TIME_MOD
        val snippet = element.select("span.snippet").firstOrNull()
        val content = snippet?.text()?.trim()
        val contentImg = snippet?.select("i[style*=url]")?.getStyleUrl()
        val img = element.getInnerImgStyle()
        return FrostThread(
            id = id,
            img = img,
            title = a.text(),
            time = epoch,
            url = a.attr("href").formattedFbUrl,
            unread = !element.hasClass("acw"),
            content = content,
            contentImgUrl = contentImg
        )
    }
}