Swiftgram/submodules/TelegramCore/Sources/WebpagePreview.swift

import Foundation
import Postbox
import SwiftSignalKit
import TelegramApi
import MtProtoKit

import SyncCore

public func webpagePreview(account: Account, url: String, webpageId: MediaId? = nil) -> Signal<TelegramMediaWebpage?, NoError> {
    return webpagePreviewWithProgress(account: account, url: url)
    |> mapToSignal { next -> Signal<TelegramMediaWebpage?, NoError> in
        if case let .result(result) = next {
            return .single(result)
        } else {
            return .complete()
        }
    }
}

public enum WebpagePreviewWithProgressResult {
    case result(TelegramMediaWebpage?)
    case progress(Float)
}

public func webpagePreviewWithProgress(account: Account, url: String, webpageId: MediaId? = nil) -> Signal<WebpagePreviewWithProgressResult, NoError> {
    return account.postbox.transaction { transaction -> Signal<WebpagePreviewWithProgressResult, NoError> in
        if let webpageId = webpageId, let webpage = transaction.getMedia(webpageId) as? TelegramMediaWebpage {
            return .single(.result(webpage))
        } else {
            return account.network.requestWithAdditionalInfo(Api.functions.messages.getWebPagePreview(flags: 0, message: url, entities: nil), info: .progress)
            |> `catch` { _ -> Signal<NetworkRequestResult<Api.MessageMedia>, NoError> in
                return .single(.result(.messageMediaEmpty))
            }
            |> mapToSignal { result -> Signal<WebpagePreviewWithProgressResult, NoError> in
                switch result {
                    case .acknowledged:
                        return .complete()
                    case let .progress(progress, packetSize):
                        if packetSize > 1024 {
                            return .single(.progress(progress))
                        } else {
                            return .complete()
                        }
                    case let .result(result):
                        if let preCachedResources = result.preCachedResources {
                            for (resource, data) in preCachedResources {
                                account.postbox.mediaBox.storeResourceData(resource.id, data: data)
                            }
                        }
                        switch result {
                            case let .messageMediaWebPage(webpage):
                                if let media = telegramMediaWebpageFromApiWebpage(webpage, url: url) {
                                    if case .Loaded = media.content {
                                        return .single(.result(media))
                                    } else {
                                        return .single(.result(media))
                                        |> then(
                                            account.stateManager.updatedWebpage(media.webpageId)
                                            |> take(1)
                                            |> map { next -> WebpagePreviewWithProgressResult in
                                                return .result(next)
                                            }
                                        )
                                    }
                                } else {
                                    return .single(.result(nil))
                                }
                            default:
                                return .single(.result(nil))
                        }
                }
            }
        }
    }
    |> switchToLatest
}

public func actualizedWebpage(postbox: Postbox, network: Network, webpage: TelegramMediaWebpage) -> Signal<TelegramMediaWebpage, NoError> {
    if case let .Loaded(content) = webpage.content {
        return network.request(Api.functions.messages.getWebPage(url: content.url, hash: content.hash))
            |> `catch` { _ -> Signal<Api.WebPage, NoError> in
                return .single(.webPageNotModified(flags: 0, cachedPageViews: nil))
            }
            |> mapToSignal { result -> Signal<TelegramMediaWebpage, NoError> in
                if let updatedWebpage = telegramMediaWebpageFromApiWebpage(result, url: nil), case .Loaded = updatedWebpage.content, updatedWebpage.webpageId == webpage.webpageId {
                    return postbox.transaction { transaction -> TelegramMediaWebpage in
                        updateMessageMedia(transaction: transaction, id: webpage.webpageId, media: updatedWebpage)
                        return updatedWebpage
                    }
                } else if case let .webPageNotModified(_, viewsValue) = result, let views = viewsValue, case let .Loaded(content) = webpage.content {
                    let updatedContent: TelegramMediaWebpageContent = .Loaded(TelegramMediaWebpageLoadedContent(url: content.url, displayUrl: content.displayUrl, hash: content.hash, type: content.type, websiteName: content.websiteName, title: content.title, text: content.text, embedUrl: content.embedUrl, embedType: content.embedType, embedSize: content.embedSize, duration: content.duration, author: content.author, image: content.image, file: content.file, attributes: content.attributes, instantPage: content.instantPage.flatMap({ InstantPage(blocks: $0.blocks, media: $0.media, isComplete: $0.isComplete, rtl: $0.rtl, url: $0.url, views: views) })))
                    let updatedWebpage = TelegramMediaWebpage(webpageId: webpage.webpageId, content: updatedContent)
                    return postbox.transaction { transaction -> TelegramMediaWebpage in
                        updateMessageMedia(transaction: transaction, id: webpage.webpageId, media: updatedWebpage)
                        return updatedWebpage
                    }
                } else {
                    return .complete()
                }
            }
    } else {
        return .complete()
    }
}

func updatedRemoteWebpage(postbox: Postbox, network: Network, webPage: WebpageReference) -> Signal<TelegramMediaWebpage?, NoError> {
    if case let .webPage(id, url) = webPage.content {
        return network.request(Api.functions.messages.getWebPage(url: url, hash: 0))
        |> `catch` { _ -> Signal<Api.WebPage, NoError> in
            return .single(.webPageNotModified(flags: 0, cachedPageViews: nil))
        }
        |> mapToSignal { result -> Signal<TelegramMediaWebpage?, NoError> in
            if let updatedWebpage = telegramMediaWebpageFromApiWebpage(result, url: nil), case .Loaded = updatedWebpage.content, updatedWebpage.webpageId.id == id {
                return postbox.transaction { transaction -> TelegramMediaWebpage? in
                    if transaction.getMedia(updatedWebpage.webpageId) != nil {
                        updateMessageMedia(transaction: transaction, id: updatedWebpage.webpageId, media: updatedWebpage)
                    }
                    return updatedWebpage
                }
            } else {
                return .single(nil)
            }
        }
    } else {
        return .single(nil)
    }
}