extension Content {

    private func makeCleanAbsolutePath(_ path: String) -> String {
        ("/" + path).replacingOccurrences(of: "//", with: "/")
    }

    private func pathPrefix(for file: FileResource) -> String {
        switch file.type {
        case .image: return settings.paths.imagesOutputFolderPath
        case .video: return settings.paths.videosOutputFolderPath
        default: return settings.paths.filesOutputFolderPath
        }
    }

    // MARK: Paths to items

    func absoluteUrlPrefixForTag(_ tag: Tag, language: ContentLanguage) -> String {
        makeCleanAbsolutePath(settings.paths.tagsOutputFolderPath + "/" + tag.localized(in: language).urlComponent)
    }

    func absoluteUrlToTag(_ tag: Tag, language: ContentLanguage) -> String {
        absoluteUrlPrefixForTag(tag, language: language) + ".html"
    }

    func absoluteUrlToPage(_ page: Page, language: ContentLanguage) -> String {
        // TODO: Record link to trace connections between pages
        makeCleanAbsolutePath(settings.pages.pageUrlPrefix + "/" + page.localized(in: language).urlString)
    }

    /**
     Get the url path to a file in the output folder.
     The result is an absolute path from the output folder for use in HTML.
     */
    func absoluteUrlToFile(_ file: FileResource) -> String {
        let path = pathPrefix(for: file) + "/" + file.id
        return makeCleanAbsolutePath(path)
    }

    // MARK: Find items by id

    func page(_ pageId: String) -> Page? {
        pages.first { $0.id == pageId }
    }

    func image(_ imageId: String) -> FileResource? {
        files.first { $0.id == imageId && $0.type.isImage }
    }

    func video(_ videoId: String) -> FileResource? {
        files.first { $0.id == videoId && $0.type.isVideo }
    }

    func file(id: String) -> FileResource? {
        files.first { $0.id == id }
    }

    func tag(_ tagId: String) -> Tag? {
        tags.first { $0.id == tagId }
    }
}