import Foundation

struct SiteGenerator {

    let templates: TemplateFactory

    init() throws {
        let templatesFolder = files.urlInContentFolder("templates")
        self.templates = try TemplateFactory(templateFolder: templatesFolder)
    }

    func generate(site: Element) throws {
        site.requiredFiles.forEach(files.require)
        site.externalFiles.forEach(files.exclude)
        try site.languages.forEach { metadata in
            let language = metadata.language
            let template = try LocalizedSiteTemplate(
                factory: templates,
                language: language,
                site: site)

            // Generate sections
            let overviewGenerator = OverviewPageGenerator(factory: template)
            let pageGenerator = PageGenerator(factory: template)
            var elementsToProcess: [Element] = site.elements
            while let element = elementsToProcess.popLast() {
                // Move recursively down to all pages
                elementsToProcess.append(contentsOf: element.elements)

                element.requiredFiles.forEach(files.require)
                element.externalFiles.forEach(files.exclude)

                if !element.elements.isEmpty {
                    overviewGenerator.generate(
                        section: element,
                        language: language)
                } else {
                    #warning("Determine previous and next pages (with relative links)")
                    pageGenerator.generate(
                        page: element,
                        language: language,
                        nextPage: nil,
                        previousPage: nil)
                }
            }

            let generator = IndexPageGenerator(factory: template)

            // Generate front page
            let relativeUrl = site.localizedPath(for: language)
            let indexPageUrl = files.urlInOutputFolder(relativeUrl)
            let button = site.nextLanguage(for: language)
            generator.generate(
                site: site,
                language: language,
                languageButton: button,
                sectionItemCount: 6,
                to: indexPageUrl)
        }
    }
}