import Foundation

struct Page {

    let metadata: Metadata

    /// The input folder where the page data is stored
    let inputFolder: URL

    let path: String

    init?(folder: URL, path: String) throws {
        self.path = path
        guard let metadata = try Metadata(in: folder) else {
            return nil
        }
        self.inputFolder = folder
        self.metadata = metadata
    }
}

extension Page {

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

extension Page: SiteElement {

    var sortIndex: Int? {
        metadata.sortIndex
    }

    var sortDate: Date? {
        metadata.date
    }

    var elements: [SiteElement] { [] }

    func cornerText(for language: String) -> String? {
        localized(for: language).cornerText
    }

    var isExternalPage: Bool {
        metadata.languages.contains { $0.externalUrl != nil }
    }

    func fullPageUrl(for language: String) -> String {
        localized(for: language).externalUrl ?? "\(path)/\(language).html"
    }
}

extension Page: LocalizedMetadataContainer {

    /**
     Get the url of the content markdown file for a language.

     To check if the file also exists, use `existingContentUrl(for:)`
     */
    func contentUrl(for language: String) -> URL {
        inputFolder.appendingPathComponent("\(language).md")
    }

    /**
     Get the url of existing markdown content for a language.
     */
    func existingContentUrl(for language: String) -> URL? {
        let url = contentUrl(for: language)
        guard url.exists else {
            return nil
        }
        return url
    }
    
    func hasContent(for language: String) -> Bool {
        existingContentUrl(for: language) != nil
    }


}