import Foundation

final class Page: Item {

    /**
     The unique id of the entry
     */
    @Published
    var id: String

    /**
     The external link this page points to.

     If this value is not `nil`, then the page has no content
     and many other features are disabled.
     */
    @Published
    var externalLink: String?

    @Published
    var isDraft: Bool

    @Published
    var createdDate: Date

    @Published
    var startDate: Date

    @Published
    var hasEndDate: Bool

    @Published
    var endDate: Date

    @Published
    var german: LocalizedPage

    @Published
    var english: LocalizedPage

    @Published
    var tags: [Tag]

    /**
     Additional images required by the element.

     These images are specified as: `source_name destination_name width (height)`.
     */
    @Published
    var images: Set<String> = []

    init(content: Content,
         id: String,
         externalLink: String?,
         isDraft: Bool,
         createdDate: Date,
         startDate: Date,
         endDate: Date?,
         german: LocalizedPage,
         english: LocalizedPage,
         tags: [Tag]) {
        self.id = id
        self.externalLink = externalLink
        self.isDraft = isDraft
        self.createdDate = createdDate
        self.startDate = startDate
        self.hasEndDate = endDate != nil
        self.endDate = endDate ?? startDate
        self.german = german
        self.english = english
        self.tags = tags

        super.init(content: content)
    }

    func localized(in language: ContentLanguage) -> LocalizedPage {
        switch language {
        case .german: return german
        case .english: return english
        }
    }

    func update(id newId: String) -> Bool {
        guard content.storage.move(page: id, to: newId) else {
            print("Failed to move file of page \(id)")
            return false
        }
        id = newId
        return true
    }

    var isExternalUrl: Bool {
        externalLink != nil
    }

    // MARK: Paths

    func absoluteUrl(for language: ContentLanguage) -> String {
        if let url = externalLink {
            return url
        }
        // TODO: Record link to trace connections between pages
        return makeCleanAbsolutePath(internalPath(for: language))
    }

    func filePathRelativeToOutputFolder(for language: ContentLanguage) -> String {
        makeCleanRelativePath(internalPath(for: language))
    }

    private func internalPath(for language: ContentLanguage) -> String {
        content.settings.pages.pageUrlPrefix + "/" + localized(in: language).urlString
    }
}

extension Page: Identifiable {
    
}

extension Page: Equatable {

    static func == (lhs: Page, rhs: Page) -> Bool {
        lhs.id == rhs.id
    }
}

extension Page: Hashable {

    func hash(into hasher: inout Hasher) {
        hasher.combine(id)
    }
}

extension Page: Comparable {

    static func < (lhs: Page, rhs: Page) -> Bool {
        lhs.id < rhs.id
    }
}

extension Page: DateItem {

}