import PackagePlugin
import Foundation

/// SwiftPM command plugin for manual GIR binding regeneration.
///
/// Invoked via `swift package generate-gir-bindings`. Forwards all
/// user-provided arguments directly to the `swift-gtk-gen` monorepo CLI,
/// defaulting `--output` to the package directory when the caller omits it.
/// The generator itself decides what to plan, render, and write from the
/// monorepo TOML config passed via `--monorepo-config`.
@main
struct SwiftGtkGenCommandPlugin: CommandPlugin {
    /// Runs `swift-gtk-gen` as a subprocess with the caller's arguments.
    ///
    /// Stdout and stderr are piped through to the caller. Throws if the
    /// subprocess exits non-zero.
    ///
    /// - Parameters:
    ///   - context: The plugin context providing access to tools and the package directory.
    ///   - arguments: User-provided arguments forwarded to the generator, e.g.
    ///     `--monorepo-config configs/tier1.toml --format-config .swift-format`.
    func performCommand(context: PluginContext, arguments: [String]) async throws {
        guard !arguments.isEmpty else {
            print("Usage: swift package generate-gir-bindings --monorepo-config <cfg> [--skip-report] [--smoke-target] [--format-config <path>]")
            return
        }

        let executable = try context.tool(named: "swift-gtk-gen")

        var procArgs = arguments
        if !procArgs.contains("--output") {
            procArgs.append(contentsOf: ["--output", context.package.directoryURL.path()])
        }

        let process = Process()
        process.executableURL = executable.url
        process.arguments = procArgs

        let stdoutPipe = Pipe()
        let stderrPipe = Pipe()
        process.standardOutput = stdoutPipe
        process.standardError = stderrPipe

        try process.run()
        process.waitUntilExit()

        let stdoutData = stdoutPipe.fileHandleForReading.readDataToEndOfFile()
        let stderrData = stderrPipe.fileHandleForReading.readDataToEndOfFile()
        if let stdoutStr = String(data: stdoutData, encoding: .utf8), !stdoutStr.isEmpty {
            print(stdoutStr, terminator: "")
        }
        if let stderrStr = String(data: stderrData, encoding: .utf8), !stderrStr.isEmpty {
            FileHandle.standardError.write(Data(stderrStr.utf8))
        }

        guard process.terminationStatus == 0 else {
            throw SwiftGtkGenPluginError.generationFailed
        }
    }
}

/// Errors that can occur during command-plugin GIR generation.
enum SwiftGtkGenPluginError: Error {
    /// The `swift-gtk-gen` subprocess exited non-zero.
    case generationFailed
}

extension SwiftGtkGenPluginError: CustomStringConvertible {
    /// A human-readable description of the error.
    var description: String {
        switch self {
        case .generationFailed:
            return "swift-gtk-gen generation failed; see output above for details."
        }
    }
}