amethyst/app/src/main/java/com/vitorpamplona/amethyst/service/previews/UrlPreviewUtils.kt

/**
 * Copyright (c) 2024 Vitor Pamplona
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
 * Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package com.vitorpamplona.amethyst.service.previews

import com.vitorpamplona.amethyst.service.HttpClientManager
import com.vitorpamplona.amethyst.service.checkNotInMainThread
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
import okhttp3.MediaType
import okhttp3.MediaType.Companion.toMediaType
import okhttp3.Request
import org.jsoup.Jsoup
import org.jsoup.nodes.Document

private const val ELEMENT_TAG_META = "meta"
private const val ATTRIBUTE_VALUE_PROPERTY = "property"
private const val ATTRIBUTE_VALUE_NAME = "name"
private const val ATTRIBUTE_VALUE_ITEMPROP = "itemprop"

// for <meta itemprop=... to get title
private val META_X_TITLE =
    arrayOf(
        "og:title",
        "\"og:title\"",
        "'og:title'",
        "name",
        "\"name\"",
        "'name'",
        "twitter:title",
        "\"twitter:title\"",
        "'twitter:title'",
        "title",
        "\"title\"",
        "'title'",
    )

// for <meta itemprop=... to get description
private val META_X_DESCRIPTION =
    arrayOf(
        "og:description",
        "\"og:description\"",
        "'og:description'",
        "description",
        "\"description\"",
        "'description'",
        "twitter:description",
        "\"twitter:description\"",
        "'twitter:description'",
        "description",
        "\"description\"",
        "'description'",
    )

// for <meta itemprop=... to get image
private val META_X_IMAGE =
    arrayOf(
        "og:image",
        "\"og:image\"",
        "'og:image'",
        "image",
        "\"image\"",
        "'image'",
        "twitter:image",
        "\"twitter:image\"",
        "'twitter:image'",
    )

private const val CONTENT = "content"

suspend fun getDocument(
    url: String,
    timeOut: Int = 30000,
): UrlInfoItem =
    withContext(Dispatchers.IO) {
        val request: Request = Request.Builder().url(url).get().build()
        HttpClientManager.getHttpClient().newCall(request).execute().use {
            checkNotInMainThread()
            if (it.isSuccessful) {
                val mimeType =
                    it.headers.get("Content-Type")?.toMediaType()
                        ?: throw IllegalArgumentException(
                            "Website returned unknown mimetype: ${it.headers.get("Content-Type")}",
                        )

                if (mimeType.type == "text" && mimeType.subtype == "html") {
                    val document = Jsoup.parse(it.body.string())
                    parseHtml(url, document, mimeType)
                } else if (mimeType.type == "image") {
                    UrlInfoItem(url, image = url, mimeType = mimeType)
                } else if (mimeType.type == "video") {
                    UrlInfoItem(url, image = url, mimeType = mimeType)
                } else {
                    throw IllegalArgumentException(
                        "Website returned unknown encoding for previews: $mimeType",
                    )
                }
            } else {
                throw IllegalArgumentException("Website returned: " + it.code)
            }
        }
    }

suspend fun parseHtml(
    url: String,
    document: Document,
    type: MediaType,
): UrlInfoItem =
    withContext(Dispatchers.IO) {
        val metaTags = document.getElementsByTag(ELEMENT_TAG_META)

        var title: String = ""
        var description: String = ""
        var image: String = ""

        metaTags.forEach {
            when (it.attr(ATTRIBUTE_VALUE_PROPERTY)) {
                in META_X_TITLE ->
                    if (title.isEmpty()) {
                        title = it.attr(CONTENT)
                    }
                in META_X_DESCRIPTION ->
                    if (description.isEmpty()) {
                        description = it.attr(CONTENT)
                    }
                in META_X_IMAGE ->
                    if (image.isEmpty()) {
                        image = it.attr(CONTENT)
                    }
            }

            when (it.attr(ATTRIBUTE_VALUE_NAME)) {
                in META_X_TITLE ->
                    if (title.isEmpty()) {
                        title = it.attr(CONTENT)
                    }
                in META_X_DESCRIPTION ->
                    if (description.isEmpty()) {
                        description = it.attr(CONTENT)
                    }
                in META_X_IMAGE ->
                    if (image.isEmpty()) {
                        image = it.attr(CONTENT)
                    }
            }

            when (it.attr(ATTRIBUTE_VALUE_ITEMPROP)) {
                in META_X_TITLE ->
                    if (title.isEmpty()) {
                        title = it.attr(CONTENT)
                    }
                in META_X_DESCRIPTION ->
                    if (description.isEmpty()) {
                        description = it.attr(CONTENT)
                    }
                in META_X_IMAGE ->
                    if (image.isEmpty()) {
                        image = it.attr(CONTENT)
                    }
            }

            if (title.isNotEmpty() && description.isNotEmpty() && image.isNotEmpty()) {
                return@withContext UrlInfoItem(url, title, description, image, type)
            }
        }
        return@withContext UrlInfoItem(url, title, description, image, type)
    }