using GLib;

namespace Spry.Cli {

    /**
     * `spry docker` — generates the multi-stage `Dockerfile` (and
     * `.dockerignore`) for a spry application and optionally assembles the
     * build context and runs podman/docker.
     *
     * The Web-Stack trees carry fixes not present on their remotes, so the
     * image build COPYs every stack library from the local Web-Stack
     * checkout. The context layout the Dockerfile expects is invercargill/,
     * invercargill-json/, astralis/, invercargill-sql/,
     * invercargill-sql-inversion/, statum/, spry/ and the application as
     * app/; inversion, the one dependency outside Web-Stack, is cloned
     * inside the image pinned to a reviewed commit.
     */
    public class Docker : Object {

        /**
         * The Web-Stack projects COPYed into the build context, in the
         * dependency order the Dockerfile builds them.
         */
        private const string[] STACK_PROJECTS = {
            "Invercargill", "Invercargill-Json", "Astralis", "Invercargill-Sql",
            "Invercargill-Sql-Inversion", "Statum", "Spry"
        };

        /** Writes `Dockerfile` and `.dockerignore` into `app_dir`. */
        public static void generate(string app_dir, string app_name) throws Error {
            var vars = new HashTable<string, string>(str_hash, str_equal);
            vars.insert("APP_NAME", app_name);

            Generator.write_file(Path.build_filename(app_dir, "Dockerfile"),
                Generator.fill(Templates.DOCKERFILE, vars));
            Generator.write_file(Path.build_filename(app_dir, ".dockerignore"),
                Templates.DOCKERIGNORE);
            stdout.printf("Generated %s\n", Path.build_filename(app_dir, "Dockerfile"));
            stdout.printf("Generated %s\n", Path.build_filename(app_dir, ".dockerignore"));
        }

        /**
         * Assembles the build context under `app_dir/.docker-build/context`
         * (every Web-Stack project from `stack_dir`, the app itself as
         * app/) and builds the image with podman or docker, whichever is
         * found.
         */
        public static void build(string app_dir, string app_name, string image_tag, string stack_dir) throws Error {
            var staging = Path.build_filename(app_dir, ".docker-build");
            Generator.remove_tree(staging);
            var context = Path.build_filename(staging, "context");
            foreach (var project in STACK_PROJECTS) {
                Generator.copy_tree(find_stack_project(stack_dir, project),
                    Path.build_filename(context, project.down()));
            }
            Generator.copy_tree(app_dir, Path.build_filename(context, "app"));
            Generator.write_file(Path.build_filename(context, ".dockerignore"),
                "*/builddir/\n*/.git/\n*.sqlite*\napp/.docker-build/\napp/web-config.json\n");

            var builder = Environment.find_program_in_path("podman")
                ?? Environment.find_program_in_path("docker");
            if (builder == null) {
                throw Generator.cli_error("neither podman nor docker found on PATH");
            }

            var dockerfile = Path.build_filename(context, "app", "Dockerfile");
            stdout.printf("Running: %s build -t %s -f %s %s\n", (!)builder, image_tag, dockerfile, context);
            var launcher = new SubprocessLauncher(SubprocessFlags.NONE);
            var process = launcher.spawnv({ (!)builder, "build", "-t", image_tag, "-f", dockerfile, context });
            process.wait_check();
            stdout.printf("Built %s\n", image_tag);
        }

        private static string find_stack_project(string stack_dir, string name) throws Error {
            foreach (var candidate in new string[] { name, name.down() }) {
                var path = Path.build_filename(stack_dir, candidate);
                if (FileUtils.test(path, FileTest.IS_DIR) && has_meson_manifest(path)) {
                    return path;
                }
            }
            throw Generator.cli_error("%s not found in %s — pass --stack-dir <path-to-Web-Stack>", name, stack_dir);
        }

        /**
         * True when `path` carries a meson manifest, either at its root or
         * in `src/` (Invercargill and Invercargill-Json build from src/).
         */
        private static bool has_meson_manifest(string path) {
            return FileUtils.test(Path.build_filename(path, "meson.build"), FileTest.EXISTS)
                || FileUtils.test(Path.build_filename(path, "src", "meson.build"), FileTest.EXISTS);
        }
    }
}