import Foundation
import SwiftUI
import Combine

final class Content: ObservableObject {

    @Published
    var posts: [Post] = []

    @Published
    var pages: [Page] = []

    @Published
    var tags: [Tag] = []

    @Published
    var images: [ImageResource] = []

    @Published
    var files: [FileResource] = []

    @AppStorage("contentPath")
    private var storedContentPath: String = ""

    @Published
    var contentPath: String = "" {
        didSet {
            storedContentPath = contentPath
        }
    }

    let storage: Storage

    private var cancellables = Set<AnyCancellable>()

    init(posts: [Post] = [],
         pages: [Page] = [],
         tags: [Tag] = [],
         images: [ImageResource] = [],
         files: [FileResource] = [],
         storedContentPath: String) {
        self.posts = posts
        self.pages = pages
        self.tags = tags
        self.images = images
        self.files = files
        self.storedContentPath = storedContentPath
        self.contentPath = storedContentPath
        self.storage = Storage(baseFolder: URL(filePath: storedContentPath))
        do {
            try storage.createFolderStructure()
        } catch {
            print(error)
            return
        }
        observeContentPath()
    }

    init() {
        self.storage = Storage(baseFolder: URL(filePath: ""))

        contentPath = storedContentPath
        do {
            try storage.createFolderStructure()
        } catch {
            print(error)
            return
        }

        try? storage.update(baseFolder: URL(filePath: contentPath), moveContent: false)
        observeContentPath()
    }

    private func observeContentPath() {
        $contentPath.sink { newValue in
            let url = URL(filePath: newValue)
            try? self.storage.update(baseFolder: url, moveContent: true)
        }
        .store(in: &cancellables)
    }

    private func convert(_ tag: LocalizedTagFile) -> LocalizedTag {
        LocalizedTag(
            urlComponent: tag.urlComponent,
            name: tag.name,
            subtitle: tag.subtitle,
            description: tag.description,
            thumbnail: tag.thumbnail,
            originalUrl: tag.originalURL)
    }

    private func convert(_ post: LocalizedPostFile, images: [String : ImageResource]) -> LocalizedPost {
        LocalizedPost(
            title: post.title,
            content: post.content,
            lastModified: post.lastModifiedDate,
            images: post.images.compactMap { images[$0] },
            linkPreviewImage: post.linkPreviewImage.map { images[$0] },
            linkPreviewTitle: post.linkPreviewTitle,
            linkPreviewDescription: post.linkPreviewDescription)
    }

    private func convert(_ page: LocalizedPageFile) -> LocalizedPage {
        LocalizedPage(
            urlString: page.url,
            title: page.title,
            lastModified: page.lastModifiedDate,
            originalUrl: page.originalURL,
            files: Set(page.files),
            externalFiles: Set(page.externalFiles),
            requiredFiles: Set(page.requiredFiles),
            linkPreviewImage: page.linkPreviewImage,
            linkPreviewTitle: page.linkPreviewTitle,
            linkPreviewDescription: page.linkPreviewDescription)
    }

    func loadFromDisk() throws {
        let storage = Storage(baseFolder: URL(filePath: contentPath))

        let tagData = try storage.loadAllTags()
        let pagesData = try storage.loadAllPages()
        let postsData = try storage.loadAllPosts()
        let filesData = try storage.loadAllFiles()

        let tags = tagData.reduce(into: [:]) { (tags, data) in
            tags[data.key] = Tag(german: convert(data.value.german),
                                 english: convert(data.value.english))
        }

        let pages: [String : Page] = loadPages(pagesData, tags: tags)

        let images: [String : ImageResource] = filesData.reduce(into: [:]) { dict, item in
            let (file, url) = item
            let ext = file.components(separatedBy: ".").last!.lowercased()
            let type = FileType(fileExtension: ext)
            guard type == .image else { return }
            dict[file] = ImageResource(uniqueId: file, altText: .init(en: "", de: ""), fileUrl: url)
        }

        let files: [FileResource] = filesData.compactMap { file, url in
            let ext = file.components(separatedBy: ".").last!.lowercased()
            let type = FileType(fileExtension: ext)
            guard type == .file else {
                return nil
            }
            return FileResource(uniqueId: file, description: "")
        }
        
        let posts = postsData.map { postId, post in
            let linkedPage = post.linkedPageId.map { pages[$0] }
            let german = convert(post.german, images: images)
            let english = convert(post.english, images: images)

            return Post(
                id: postId,
                isDraft: post.isDraft,
                createdDate: post.createdDate,
                startDate: post.startDate,
                endDate: post.endDate,
                tags: post.tags.map { tags[$0]! },
                german: german,
                english: english,
                linkedPage: linkedPage)
        }

        self.tags = tags.values.sorted()
        self.pages = pages.values.sorted(ascending: false) { $0.startDate }
        self.files = files.sorted { $0.uniqueId }
        self.images = images.values.sorted { $0.id }
        self.posts = posts.sorted(ascending: false) { $0.startDate }
    }

    private func loadPages(_ pagesData: [String : PageFile], tags: [String : Tag]) -> [String : Page] {
        pagesData.reduce(into: [:]) { pages, data in
            let (pageId, page) = data
            pages[pageId] = Page(
                id: pageId,
                isDraft: page.isDraft,
                createdDate: page.createdDate,
                startDate: page.startDate,
                endDate: page.endDate,
                german: convert(page.german),
                english: convert(page.english),
                tags: page.tags.map { tags[$0]! })
        }
    }

    // MARK: Saving

    func saveToDisk() {
        //print("Starting save")
        for page in pages {
            storage.save(pageMetadata: page.pageFile, for: page.id)
        }

        for post in posts {
            storage.save(post: post.postFile, for: post.id)
        }

        for tag in tags {
            storage.save(tagMetadata: tag.tagFile, for: tag.id)
        }
        // TODO: Remove all files that are no longer in use (they belong to deleted items)
        //print("Finished save")
    }

    // MARK: Folder access

    static func accessFolderFromBookmark(key: String, operation: (URL) -> Void) {
        guard let bookmarkData = UserDefaults.standard.data(forKey: key) else {
            print("No bookmark data to access folder")
            return
        }
        var isStale = false
        let folderURL: URL
        do {
            // Resolve the bookmark to get the folder URL
            folderURL = try URL(resolvingBookmarkData: bookmarkData, options: .withSecurityScope, relativeTo: nil, bookmarkDataIsStale: &isStale)
        } catch {
            print("Failed to resolve bookmark: \(error)")
            return
        }

        if isStale {
            print("Bookmark is stale, consider saving a new bookmark.")
        }

        // Start accessing the security-scoped resource
        if folderURL.startAccessingSecurityScopedResource() {
            print("Accessing folder: \(folderURL.path)")

            operation(folderURL)
            folderURL.stopAccessingSecurityScopedResource()
        } else {
            print("Failed to access folder: \(folderURL.path)")
        }
    }
}