import Foundation

private struct AboveRootDummy: SiteElement {
    var sortIndex: Int? { nil }

    var sortDate: Date? { nil }

    var path: String { "" }

    let inputFolder: URL

    func title(for language: String) -> String { "" }

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

    var elements: [SiteElement] { [] }
}

struct IndexPageGenerator {

    private let factory: LocalizedSiteTemplate

    init(factory: LocalizedSiteTemplate) {
        self.factory = factory
    }

    func generate(
        site: Site,
        language: String,
        languageButton: String?,
        sectionItemCount: Int,
        to url: URL) throws {
            let localized = site.localized(for: language)

            var content = [PageTemplate.Key : String]()
            content[.head] = try makeHead(site: site, language: language)
            content[.topBar] = factory.topBar.generate(section: nil, languageButton: languageButton)
            content[.contentClass] = "overview"
            content[.header] = makeHeader(localized: localized)
            let sections = site.elements.compactMap { $0 as? Section }
            content[.content] = try factory.overviewSection.generate(
                sections: sections,
                in: site,
                language: language,
                sectionItemCount: sectionItemCount)
            content[.footer] = try site.customFooterContent()
            try factory.page.generate(content, to: url)
    }

    private func makeHead(site: Site, language: String) throws -> String {
        let localized = site.localized(for: language)
        return try factory.pageHead.generate(page: PageHeadInfo(
            author: site.metadata.author,
            linkPreviewTitle: localized.linkPreviewTitle,
            linkPreviewDescription: localized.linkPreviewDescription,
            linkPreviewImage: site.linkPreviewImage(for: language),
            customHeadContent: try site.customHeadContent()))
    }

    private func makeHeader(localized: Site.LocalizedMetadata) -> String {
        var content = [HeaderKey : String]()
        content[.title] = localized.title
        content[.subtitle] = localized.subtitle
        content[.titleText] = localized.description
        return factory.factory.centeredHeader.generate(content)
    }
}