import Foundation

struct OverviewSectionGenerator {

    private let multipleSectionsTemplate: OverviewSectionTemplate

    private let singleSectionsTemplate: OverviewSectionCleanTemplate

    let files: FileProcessor

    private let generator: ThumbnailListGenerator

    init(factory: TemplateFactory, files: FileProcessor) {
        self.multipleSectionsTemplate = factory.overviewSection
        self.singleSectionsTemplate = factory.overviewSectionClean
        self.files = files
        self.generator = ThumbnailListGenerator(factory: factory, files: files)
    }

    func generate(sections: [Section], in parent: SiteElement, language: String, sectionItemCount: Int) throws -> String {
        try sections.map { section in
            let metadata = section.localized(for: language)
            let fullUrl = section.fullPageUrl(for: language)
            let relativeUrl = parent.relativePathToFileWithPath(fullUrl)

            var content = [OverviewSectionTemplate.Key : String]()
            content[.url] = relativeUrl
            content[.title] = metadata.title
            content[.items] = try sectionContent(section: section, in: parent, language: language, shownItemCount: sectionItemCount)
            content[.more] = metadata.moreLinkTitle

            return multipleSectionsTemplate.generate(content)
        }
        .joined(separator: "\n")
    }

    func generate(section: Section, language: String) throws -> String {
        var content = [OverviewSectionCleanTemplate.Key : String]()
        content[.items] = try sectionContent(section: section, in: section, language: language, shownItemCount: nil)
        return singleSectionsTemplate.generate(content)
    }

    private func sectionContent(section: Section, in parent: SiteElement, language: String, shownItemCount: Int?) throws -> String {
        let sectionItems: [SiteElement]
        if let shownItemCount = shownItemCount {
            sectionItems = Array(section.sortedItems.prefix(shownItemCount))
        } else {
            sectionItems = section.sortedItems
        }

        let items: [ThumbnailInfo] = sectionItems.map { item in
            #warning("Check if page exists for the language")
            let fullPageUrl = item.fullPageUrl(for: language)
            let relativePageUrl = parent.relativePathToFileWithPath(fullPageUrl)
            let fullThumbnailPath = item.thumbnailFilePath(for: language)
            let relativeImageUrl = parent.relativePathToFileWithPath(fullThumbnailPath)

            return ThumbnailInfo(
                url: relativePageUrl,
                imageFilePath: fullThumbnailPath,
                imageHtmlUrl: relativeImageUrl,
                title: item.title(for: language),
                cornerText: item.cornerText(for: language))
        }
        return try generator.generateContent(
            items: items,
            style: section.metadata.thumbnailStyle)
    }
}