import Foundation
import SwiftGtkGenCore

/// Command-line interface for the GIR-to-Swift binding generator.
///
/// Parses command-line arguments, invokes the GIR parser, analyzer, and code
/// generator, then writes the resulting Swift source to a file. Designed as
/// the subprocess entry point invoked by both the build tool plugin and the
/// command plugin.
@main
struct SwiftGtkGenCLI {
    /// Program entry point. Parses arguments, generates code, and writes output.
    static func main() {
        let args = parseArguments()
        if args.showHelp {
            printHelp()
            return
        }

        do {
            let parser = GIRParser()
            let primaryGIR = try parser.parse(fileURL: URL(fileURLWithPath: args.girFile))

            let generateList = args.generateAll ? [] : args.generate
            let config = GenerationConfig(
                library: args.library,
                version: args.version,
                girsDirectories: args.girsDirs,
                targetDirectory: args.output,
                externalLibraries: args.externalLibs,
                generate: generateList,
                manual: args.manual,
                ignore: args.ignore,
                objects: []
            )

            let analyzer = Analyzer(config: config)
            let analysis = analyzer.analyze(repository: primaryGIR)

            let generator = CodeGenerator(config: config)

            let outputDir = URL(fileURLWithPath: args.output)

            if args.emitSingleFile {
                let output = try generator.generate(repository: primaryGIR, analysis: analysis)
                try FileManager.default.createDirectory(at: outputDir, withIntermediateDirectories: true)
                let outputFile = outputDir.appendingPathComponent("\(config.library).swift")
                try output.write(to: outputFile, atomically: true, encoding: .utf8)
                print("Generated \(outputFile.path)")
            } else {
                let files = try generator.generateFiles(repository: primaryGIR, analysis: analysis)
                let sourcesDir = outputDir.appendingPathComponent("Sources/\(config.library)")
                try FileManager.default.createDirectory(at: sourcesDir, withIntermediateDirectories: true)

                for (fileName, content) in files.sorted(by: { $0.key < $1.key }) {
                    let fileURL = sourcesDir.appendingPathComponent(fileName)
                    try content.write(to: fileURL, atomically: true, encoding: .utf8)
                    print("Generated \(fileURL.path)")
                }
            }

            let scaffolding = CodeGenerator.generatePackageScaffolding(config: config, repository: primaryGIR)
            for (relativePath, content) in scaffolding.sorted(by: { $0.key < $1.key }) {
                let fileURL = outputDir.appendingPathComponent(relativePath)
                try FileManager.default.createDirectory(at: fileURL.deletingLastPathComponent(), withIntermediateDirectories: true)
                try content.write(to: fileURL, atomically: true, encoding: .utf8)
                print("Generated \(fileURL.path)")
            }
        } catch {
            print("Error: \(error)")
            exit(1)
        }
    }

    /// Parsed command-line arguments for the GIR generator CLI.
    struct CLIArgs {
        var showHelp: Bool = false
        var emitSingleFile: Bool = false
        var girFile: String = ""
        var library: String = ""
        var version: String = ""
        var output: String = "."
        var girsDirs: [String] = []
        var externalLibs: [String] = []
        var generate: [String] = []
        var generateAll: Bool = false
        var manual: [String] = []
        var ignore: [String] = []
    }

    /// Parses command-line arguments into a ``CLIArgs`` value.
    ///
    /// Supports the flags `--help`, `--gir-file`, `--library`, `--version`,
    /// `--output`, `--girs-dirs`, `--external-libs`, `--generate`, `--manual`,
    /// and `--ignore`. Multi-value flags (`--girs-dirs`, etc.) accept
    /// comma-separated lists.
    ///
    /// - Returns: A populated ``CLIArgs`` extracted from `CommandLine.arguments`.
    static func parseArguments() -> CLIArgs {
        var args = Array(CommandLine.arguments.dropFirst())
        var cli = CLIArgs()

        while let flag = args.first {
            args.removeFirst()
            switch flag {
            case "--emit-single-file":
                cli.emitSingleFile = true
            case "--help", "-h":
                cli.showHelp = true
            case "--gir-file":
                cli.girFile = args.removeFirst()
            case "--library":
                cli.library = args.removeFirst()
            case "--version":
                cli.version = args.removeFirst()
            case "--output":
                cli.output = args.removeFirst()
            case "--girs-dirs":
                cli.girsDirs = args.removeFirst().components(separatedBy: ",")
            case "--external-libs":
                cli.externalLibs = args.removeFirst().components(separatedBy: ",")
            case "--generate-all":
                cli.generateAll = true
            case "--generate":
                cli.generate = args.removeFirst().components(separatedBy: ",")
            case "--manual":
                cli.manual = args.removeFirst().components(separatedBy: ",")
            case "--ignore":
                cli.ignore = args.removeFirst().components(separatedBy: ",")
            default:
                break
            }
        }

        return cli
    }

    /// Prints usage information and the list of accepted flags to stdout.
    static func printHelp() {
        print("Usage: swift-gtk-gen [options]")
        print("  --gir-file PATH     Path to the .gir file")
        print("  --library NAME      GIR library namespace (e.g., GLib)")
        print("  --version VER       GIR version (e.g., 2.0)")
        print("  --output DIR        Output directory (default: .)")
        print("  --girs-dirs DIRS    Comma-separated GIR directories")
        print("  --external-libs LIBS Comma-separated external libraries")
        print("  --generate TYPES    Comma-separated types to generate")
        print("  --generate-all      Generate all types in the namespace")
        print("  --manual TYPES      Comma-separated types to mark manual")
        print("  --ignore TYPES      Comma-separated types to ignore")
        print("  --emit-single-file  Emit a single file instead of per-type files")
        print("  --help, -h          Show this help")
    }
}