using GLib;

namespace Spry.Cli {

    /**
     * Maintains a `compile_commands.json` in the application root for the
     * Vala language server: meson emits the database as a build artifact in
     * `builddir/`, and it is copied out to the root whenever a build
     * happens (the initial build on `spry new`, and every `spry dev`
     * build/rebuild). The copied file is generated state — gitignored and
     * excluded from packaging.
     */
    public class CompileCommands : Object {

        /**
         * Runs the initial meson setup + build of a freshly scaffolded
         * application (so the compile database exists) and copies the
         * database to the project root. Failures are reported but do not
         * fail scaffolding itself.
         */
        public static void build_initial(string app_dir, string? libdir) {
            var launcher = new SubprocessLauncher(SubprocessFlags.NONE);
            Tools.apply_env(launcher, libdir);
            stdout.printf("[spry] Running initial build (for compile_commands.json)…\n");
            if (!run_step(launcher, app_dir, { "meson", "setup", ".", "builddir" })
                    || !run_step(launcher, app_dir, { "ninja", "-C", "builddir" })) {
                return;
            }
            copy_from_builddir(app_dir);
        }

        private static bool run_step(SubprocessLauncher launcher, string app_dir, string[] argv) {
            try {
                var previous = Environment.get_current_dir();
                Environment.set_current_dir(app_dir);
                var process = launcher.spawnv(argv);
                Environment.set_current_dir(previous);
                if (!process.wait_check()) {
                    stderr.printf("[spry] Initial build failed — compile_commands.json not generated\n");
                    return false;
                }
            }
            catch (Error e) {
                stderr.printf("[spry] Initial build could not run: %s\n", e.message);
                return false;
            }
            return true;
        }

        /**
         * Copies `builddir/compile_commands.json` to the project root when
         * it exists; a no-op otherwise (e.g. the build failed or produced
         * none).
         */
        public static void copy_from_builddir(string app_dir) {
            try {
                var source = File.new_for_path(Path.build_filename(app_dir, "builddir", "compile_commands.json"));
                if (!source.query_exists()) {
                    return;
                }
                var destination = File.new_for_path(Path.build_filename(app_dir, "compile_commands.json"));
                if (!destination.query_exists()
                        || source.query_info("time::modified", FileQueryInfoFlags.NONE).get_modification_date_time()
                            .difference(destination.query_info("time::modified", FileQueryInfoFlags.NONE).get_modification_date_time()) > 0) {
                    source.copy(destination, FileCopyFlags.OVERWRITE);
                    stdout.printf("[spry] compile_commands.json copied to the project root\n");
                }
            }
            catch (Error e) {
            }
        }
    }
}