import Foundation

/// LibreOffice bridge for formats Apple's frameworks cannot render (PPT/PPTX,
/// XLS/XLSX/ODS when they need layout, PAGES, Keynote).
enum Office {
    /// LibreOffice cannot run two headless conversions at once in the same
    /// profile, so every call is serialised.
    private static let lock = NSLock()

    static func convert(
        _ source: URL,
        to format: Format,
        at destination: URL,
        cancellation: Cancellation? = nil
    ) throws {
        guard let soffice = Toolchain.soffice, Settings.shared.useExternalTools else {
            throw ConversionError.missingTool(
                "\(format.displayName) needs LibreOffice. Install it with: brew install --cask libreoffice"
            )
        }
        let filter = filterName(for: format)
        let staging = FileManager.default.temporaryDirectory
            .appendingPathComponent("konverter-office-\(UUID().uuidString)", isDirectory: true)
        defer { try? FileManager.default.removeItem(at: staging) }
        try FileManager.default.createDirectory(at: staging, withIntermediateDirectories: true)

        lock.lock()
        defer { lock.unlock() }
        try cancellation?.check()

        try Shell.run(
            soffice,
            [
                "--headless", "--norestore", "--nolockcheck", "--nodefault",
                "-env:UserInstallation=file://" + staging.path + "/profile",
                "--convert-to", filter,
                "--outdir", staging.path,
                source.path
            ],
            cancellation: cancellation
        )

        let produced = try FileManager.default
            .contentsOfDirectory(at: staging, includingPropertiesForKeys: nil)
            .first { $0.pathExtension.lowercased() == destination.pathExtension.lowercased() }
        guard let produced else {
            throw ConversionError.failed("LibreOffice did not produce a \(format.displayName) file.")
        }
        try? FileManager.default.removeItem(at: destination)
        try FileManager.default.moveItem(at: produced, to: destination)
    }

    static func filterName(for format: Format) -> String {
        switch format {
        case .pdf: return "pdf"
        case .docx: return "docx"
        case .odt: return "odt"
        case .rtf: return "rtf"
        case .txt: return "txt"
        case .html: return "html"
        case .csv: return "csv"
        case .xlsx: return "xlsx"
        case .ods: return "ods"
        case .pptx: return "pptx"
        case .epub: return "epub"
        case .png: return "png"
        case .jpg: return "jpg"
        default: return format.ext
        }
    }
}

/// PPT/PPTX/KEY → PDF or images. Everything funnels through a PDF so multi
/// slide decks come out with one image per slide.
enum SlidesConverter {
    static func convert(
        source: URL,
        to format: Format,
        at destination: URL,
        cancellation: Cancellation? = nil,
        progress: ((Double) -> Void)? = nil
    ) throws {
        switch format {
        case .pdf:
            try Office.convert(source, to: .pdf, at: destination, cancellation: cancellation)
        case .png, .jpg:
            let staging = FileManager.default.temporaryDirectory
                .appendingPathComponent("konverter-slides-\(UUID().uuidString)", isDirectory: true)
            defer { try? FileManager.default.removeItem(at: staging) }
            try FileManager.default.createDirectory(at: staging, withIntermediateDirectories: true)
            let pdf = staging.appendingPathComponent("deck.pdf")
            try Office.convert(source, to: .pdf, at: pdf, cancellation: cancellation)
            let directory = OutputNaming.artifactDirectory(
                for: destination,
                suffix: ""
            )
            try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
            _ = try PDFConverter.renderPages(
                pdf,
                to: format,
                into: directory,
                dpi: 200,
                cancellation: cancellation,
                progress: progress
            )
        default:
            throw ConversionError.unsupported("Slides become PDF or images.")
        }
    }
}