import Foundation

final class Importer {

    var posts: [String : PostFile] = [:]

    var pages: [String : PageOnDisk] = [:]

    var tags: [String : TagFile] = [:]

    var files: [String : FileOnDisk] = [:]

    var ignoredFiles: [URL] = []

    var foldersToSearch: [(path: String, tag: String)] = [
        ("/Users/ch/Downloads/Website/projects/electronics", "electronics"),
        ("/Users/ch/Downloads/Website/projects/endeavor", "endeavor"),
        ("/Users/ch/Downloads/Website/projects/furniture", "furniture"),
        ("/Users/ch/Downloads/Website/projects/lighting", "lighting"),
        ("/Users/ch/Downloads/Website/projects/other", "other"),
        ("/Users/ch/Downloads/Website/projects/sewing", "sewing"),
        ("/Users/ch/Downloads/Website/projects/software", "software"),
        ("/Users/ch/Downloads/Website/articles", "articles"),
        ("/Users/ch/Downloads/Website/photography", "photography"),
        ("/Users/ch/Downloads/Website/travel", "travel")
    ]

    func importContent() throws {
        for (path, name) in foldersToSearch {
            let folder = URL(filePath: path)
            let pageFolders = try findPageFolders(in: folder)

            let tag = try importTag(name: name, folder: folder)

            for pageFolder in pageFolders {
                try importEntry(at: pageFolder, tag: tag)
            }
        }
    }

    private func importTag(name: String, folder: URL) throws -> String {
        let metadataUrl = folder.appending(path: "metadata.json", directoryHint: .notDirectory)
        let data = try Data(contentsOf: metadataUrl)
        let meta = try JSONDecoder().decode(ImportableTag.self, from: data)

        let thumbnailUrl = folder.appending(path: "thumbnail.jpg", directoryHint: .notDirectory)
        var thumbnail: FileOnDisk? = nil
        if FileManager.default.fileExists(atPath: thumbnailUrl.path()) {
            thumbnail = FileOnDisk(type: .image, url: thumbnailUrl, name: "\(name)-thumbnail.jpg")
            add(resource: thumbnail!)
        }

        func makeTag(metadata: TagLanguage) throws -> LocalizedTagFile {
            let language = ContentLanguage(rawValue: metadata.language)!
            let originalUrl = folder
                .appendingPathComponent("\(language.rawValue).html", isDirectory: false)
                .path()
                .replacingOccurrences(of: "/Users/ch/Downloads/Website", with: "")

            return LocalizedTagFile(
                urlComponent: metadata.title.lowercased().replacingOccurrences(of: " ", with: "-"),
                name: metadata.title,
                subtitle: metadata.subtitle,
                description: metadata.description,
                thumbnail: thumbnail?.name,
                originalURL: originalUrl)
        }

        let en = meta.info(for: .english)!
        let de = meta.info(for: .german)!

        let tagId = en.title.lowercased().replacingOccurrences(of: " ", with: "-")

        let enTag = try makeTag(metadata: en)
        let deTag = try makeTag(metadata: de)

        let tag = TagFile(
            id: enTag.urlComponent,
            isVisible: true,
            german: deTag,
            english: enTag)
        tags[tagId] = tag
        return tagId
    }

    private func findPageFolders(in folder: URL) throws -> [URL] {
        try FileManager.default
            .contentsOfDirectory(at: folder, includingPropertiesForKeys: [.isDirectoryKey])
            .filter { $0.hasDirectoryPath }
    }

    private func findResources(in folder: URL, pageId: String) throws -> [FileOnDisk] {
        try FileManager.default
            .contentsOfDirectory(at: folder, includingPropertiesForKeys: [.isDirectoryKey])
            .filter { !$0.hasDirectoryPath }
            .compactMap { url in
                let fileName = url.lastPathComponent
                let fileExtension = url.pathExtension

                guard fileName != "metadata.json",
                      fileName != "de.md",
                      fileName != "en.md" else {
                    return nil
                }

                let type = FileType(fileExtension: fileExtension)
                guard type != .resource else {
                    self.ignoredFiles.append(url)
                    return nil
                }

                let name = pageId + "-" + fileName

                return FileOnDisk(type: type, url: url, name: name)
            }
    }

    private func importEntry(at url: URL, tag: String) throws {
        let metadataUrl = url.appending(path: "metadata.json", directoryHint: .notDirectory)
        guard FileManager.default.fileExists(atPath: metadataUrl.path()) else {
            print("No entry at \(url.path())")
            return
        }
        let data = try Data(contentsOf: metadataUrl)
        let meta = try JSONDecoder().decode(GenericMetadata.self, from: data)

        let pageId = meta.customId ?? url.lastPathComponent

        let resources = try findResources(in: url, pageId: pageId)

        guard let languages = meta.languages else {
            print("No languages for \(url.path())")
            return
        }

        let externalFiles = meta.externalFiles ?? []
        let requiredFiles = meta.requiredFiles ?? []

        let date = meta.date!.toDate()
        let endDate = meta.endDate?.toDate()

        let de = languages.first { $0.language == "de" }!
        let en = languages.first { $0.language == "en" }!

        @discardableResult
        func makePage(_ content: GenericMetadata.LocalizedMetadata) throws -> (LocalizedPageFile, URL, LocalizedPostFile) {
            let language = ContentLanguage(rawValue: content.language!)!

            let id: String
            if language == .english {
                id = pageId
            } else {
                id = pageId + "-" + language.rawValue
            }

            let originalUrl = url
                .appendingPathComponent("\(language.rawValue).html", isDirectory: false)
                .path()
                .replacingOccurrences(of: "/Users/ch/Downloads/Website", with: "")

            var pageFiles = Set(resources.map { $0.name })
            let thumbnail = try determineThumbnail(in: resources, folder: url, customPath: meta.thumbnailPath, pageId: id, language: language.rawValue)
            if let thumbnail {
                pageFiles.insert(thumbnail.name)
            }
            let page = LocalizedPageFile(
                url: id,
                files: pageFiles.sorted(),
                externalFiles: externalFiles.sorted(),
                requiredFiles: requiredFiles.sorted(),
                title: content.title!,
                linkPreviewImage: thumbnail?.name,
                linkPreviewTitle: content.linkPreviewTitle,
                linkPreviewDescription: content.linkPreviewDescription,
                lastModifiedDate: nil,
                originalURL: originalUrl)
            let contentUrl = url.appendingPathComponent("\(content.language!).md", isDirectory: false)

            let postContent = content.linkPreviewDescription ?? content.description ?? ""

            let post = createPost(page: page, content: postContent)

            return (page, contentUrl, post)
        }
        let (dePage, deUrl, dePost) = try makePage(de)
        let (enPage, enUrl, enPost) = try makePage(en)

        let page = PageFile(
            isDraft: meta.state == "draft",
            tags: [tag],
            createdDate: date,
            startDate: date,
            endDate: endDate,
            german: dePage,
            english: enPage)

        if pages[pageId] != nil {
            print("Conflicting page id \(pageId)")
        }

        pages[pageId] = .init(page: page, deContentUrl: deUrl, enContentUrl: enUrl)


        for resource in resources {
            add(resource: resource)
        }

        let post = PostFile(
            isDraft: page.isDraft || meta.state == "hidden",
            createdDate: page.createdDate,
            startDate: page.startDate,
            endDate: page.endDate,
            tags: page.tags,
            german: dePost,
            english: enPost,
            linkedPageId: pageId)

        posts[pageId] = post
    }

    private func add(resource: FileOnDisk) {
        guard let existingFile = files[resource.name] else {
            files[resource.name] = resource
            return
        }

        guard existingFile.url != resource.url else {
            return
        }
        print("Conflicting name for file \(resource.name)")
    }

    private func determineThumbnail(in resources: [FileOnDisk], folder: URL, customPath: String?, pageId: String, language: String) throws -> FileOnDisk? {
        guard let thumbnailUrl = findThumbnailUrl(in: folder, customPath: customPath, language: language) else {
            return nil
        }
        return resources.first { $0.url == thumbnailUrl }
    }

    private func determineThumbnail(in folder: URL, customPath: String?, pageId: String, language: String) throws -> FileOnDisk? {
        guard let thumbnailUrl = findThumbnailUrl(in: folder, customPath: customPath, language: language) else {
            return nil
        }
        let id = pageId + "-" + thumbnailUrl.lastPathComponent
        return FileOnDisk(image: id, url: thumbnailUrl)
    }

    private func findThumbnailUrl(in folder: URL, customPath: String?, language: String) -> URL? {
        if let customPath {
            return folder.appending(path: customPath, directoryHint: .notDirectory)
        }
        let thumbnailImageUrl = folder.appending(path: "thumbnail.jpg", directoryHint: .notDirectory)
        if FileManager.default.fileExists(atPath: thumbnailImageUrl.path()) {
            return thumbnailImageUrl
        }

        let localizedThumbnail = folder.appending(path: "thumbnail-\(language).jpg", directoryHint: .notDirectory)
        if FileManager.default.fileExists(atPath: localizedThumbnail.path()) {
            return localizedThumbnail
        }
        print("No thumbnail found in \(folder.path())")
        return nil
    }

    private func createPost(page: LocalizedPageFile, content: String) -> LocalizedPostFile {
        let images = page.linkPreviewImage.map { [$0] } ?? []

        return LocalizedPostFile(
            images: images.sorted(),
            title: page.linkPreviewTitle ?? page.title,
            content: content,
            lastModifiedDate: nil,
            linkPreviewImage: nil,
            linkPreviewTitle: nil,
            linkPreviewDescription: nil)
    }
}

private extension String {

    private static let metadataDate: DateFormatter = {
        let df = DateFormatter()
        df.dateFormat = "dd.MM.yy"
        return df
    }()

    func toDate() -> Date {
        String.metadataDate.date(from: self)!
    }
}