/
RedditSkraper.kt
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/
RedditSkraper.kt
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/*
* Copyright (c) 2019-present Mikhael Sokolov
*
* 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.
*/
@file:Suppress("MemberVisibilityCanBePrivate")
package ru.sokomishalov.skraper.provider.reddit
import com.fasterxml.jackson.databind.JsonNode
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.firstOrNull
import kotlinx.coroutines.flow.flow
import ru.sokomishalov.skraper.Skraper
import ru.sokomishalov.skraper.Skrapers
import ru.sokomishalov.skraper.client.HttpRequest
import ru.sokomishalov.skraper.client.SkraperClient
import ru.sokomishalov.skraper.client.fetchJson
import ru.sokomishalov.skraper.client.fetchOpenGraphMedia
import ru.sokomishalov.skraper.internal.consts.DEFAULT_POSTS_BATCH
import ru.sokomishalov.skraper.internal.iterable.emitBatch
import ru.sokomishalov.skraper.internal.net.host
import ru.sokomishalov.skraper.internal.net.path
import ru.sokomishalov.skraper.internal.number.div
import ru.sokomishalov.skraper.internal.serialization.*
import ru.sokomishalov.skraper.model.*
import java.time.Instant
open class RedditSkraper @JvmOverloads constructor(
override val client: SkraperClient = Skrapers.client
) : Skraper {
override fun getPosts(path: String): Flow<Post> = flow {
var nextPage: String? = null
while (true) {
val response = client.fetchJson(
HttpRequest(
url = BASE_URL.buildFullURL(
path = "${path.removeSuffix("/")}.json",
queryParams = mapOf("limit" to DEFAULT_POSTS_BATCH, "after" to nextPage)
)
)
)
val rawPosts = response
?.getFirstByPath("data.children", "0.data.children")
?.mapNotNull { it["data"] }
if (rawPosts.isNullOrEmpty()) break
emitBatch(rawPosts) {
Post(
id = getString("id").orEmpty(),
text = extractText(),
publishedAt = getLong("created_utc")?.let { Instant.ofEpochSecond(it) },
statistics = PostStatistics(
likes = getInt("score"),
comments = getInt("num_comments"),
),
media = extractPostMediaItems()
)
}
nextPage = response.getString("data.after")
}
}
override suspend fun getPageInfo(path: String): PageInfo? {
val response = client.fetchJson(
HttpRequest(url = BASE_URL.buildFullURL(path = "${path.removeSuffix("/")}/about.json"))
)
val isUser = path.removePrefix("/").startsWith("u")
return response?.get("data")?.run {
when {
isUser -> PageInfo(
nick = getString("subreddit.display_name_prefixed"),
name = getString("subreddit.display_name"),
description = getString("subreddit.public_description"),
avatar = getString("subreddit.icon_img")?.toImage(),
cover = getString("subreddit.banner_img")?.toImage()
)
else -> PageInfo(
nick = getString("display_name_prefixed"),
name = getString("display_name"),
description = getString("public_description"),
avatar = getString("icon_img")?.toImage(),
cover = getString("banner_background_image")?.toImage()
)
}
}
}
override fun supports(url: String): Boolean {
return "reddit.com" in url.host
}
override suspend fun resolve(media: Media): Media {
return when (media) {
is Image -> client.fetchOpenGraphMedia(media)
is Video -> {
getPosts(path = media.url.path)
.firstOrNull()
?.media
?.firstOrNull()
?: media
}
else -> media
}
}
private fun JsonNode.extractText(): String {
return listOf(getString("title"), getString("selftext"))
.filterNot { s -> s.isNullOrEmpty() }
.joinToString("\n")
}
private fun JsonNode.extractPostMediaItems(): List<Media> {
val previewMedia = getByPath("preview.images")
?.toList()
.orEmpty()
.mapNotNull {
it.get("source")?.let { source ->
Image(
url = source.getString("url").orEmpty().replace("&", "&"),
aspectRatio = source.getDouble("width") / source.getDouble("height")
)
}
}
val isVideo = this["media"].isEmpty.not()
return when {
isVideo -> listOf(
Video(
url = getString("url").orEmpty(),
aspectRatio = previewMedia.firstOrNull()?.aspectRatio,
thumbnail = previewMedia.firstOrNull()
)
)
else -> previewMedia
}
}
companion object {
const val BASE_URL: String = "https://reddit.com"
}
}