import Foundation

enum MediaToolLocator {
    static func executable(named name: String) -> URL? {
        guard let bundled = Bundle.main.resourceURL?.appendingPathComponent(name),
              FileManager.default.isExecutableFile(atPath: bundled.path) else {
            return nil
        }
        return bundled
    }

    static func javascriptRuntimeArguments() -> [String] {
        guard let runtime = executable(named: "deno") else { return [] }
        return ["--js-runtimes", "deno:\(runtime.path)"]
    }
}

enum MediaToolError: LocalizedError {
    case missing(String)
    case failed(String, String)

    var errorDescription: String? {
        switch self {
        case .missing(let tool): "\(tool) fehlt im App-Paket. Installiere eine App-Version mit gebündelten Werkzeugen."
        case .failed(let tool, let detail): "\(tool) ist fehlgeschlagen: \(detail)"
        }
    }
}

enum MediaProcess {
    static func run(_ executable: URL, arguments: [String]) throws -> Data {
        let id = UUID().uuidString
        let outputURL = FileManager.default.temporaryDirectory.appendingPathComponent("tonuino-tool-\(id).out")
        let errorURL = FileManager.default.temporaryDirectory.appendingPathComponent("tonuino-tool-\(id).err")
        FileManager.default.createFile(atPath: outputURL.path, contents: nil)
        FileManager.default.createFile(atPath: errorURL.path, contents: nil)
        defer {
            try? FileManager.default.removeItem(at: outputURL)
            try? FileManager.default.removeItem(at: errorURL)
        }

        let outputHandle = try FileHandle(forWritingTo: outputURL)
        let errorHandle = try FileHandle(forWritingTo: errorURL)
        defer { try? outputHandle.close(); try? errorHandle.close() }

        let process = Process()
        process.executableURL = executable
        process.arguments = arguments
        process.standardOutput = outputHandle
        process.standardError = errorHandle
        do { try process.run() }
        catch { throw MediaToolError.failed(executable.lastPathComponent, error.localizedDescription) }
        process.waitUntilExit()

        let output = try Data(contentsOf: outputURL)
        let errorOutput = String(data: try Data(contentsOf: errorURL), encoding: .utf8)?.trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
        guard process.terminationStatus == 0 else {
            let detail = errorOutput.isEmpty ? "Prozesscode \(process.terminationStatus)" : String(errorOutput.suffix(1800))
            throw MediaToolError.failed(executable.lastPathComponent, detail)
        }
        return output
    }
}