onmessage = function (e) {
    var request = e.data;

    var result_files = {};
    result_files.delete_list = [];
    result_files.update_list = [];

    switch (request.command) {
        case "compare":
            compare_file_info(request.local_file_info, request.remote_file_info, result_files);
            send_command("delete", result_files.delete_list);
            send_command("update", result_files.update_list);
            send_command("finish", []);
            break;
        case "finish":
            send_command("finish");
            break;
    }
};

function compare_file_info(local_file_info, remote_file_info, result_files) {
    if (!remote_file_info) {
        result_files.delete_list = result_files.delete_list.concat(generate_file_list(local_file_info));
    } else if (!local_file_info) {
        result_files.update_list = result_files.update_list.concat(generate_file_list(remote_file_info));
    } else if (local_file_info.is_dir !== remote_file_info.is_dir) {
        result_files.delete_list = result_files.delete_list.concat(generate_file_list(local_file_info));
        result_files.update_list = result_files.update_list.concat(generate_file_list(remote_file_info));
    } else if (local_file_info.sha_512 !== remote_file_info.sha_512) {
        if (local_file_info.is_dir) {
            var visited_children = new Set();
            for (var i in local_file_info.children) {
                compare_file_info(local_file_info.children[i], remote_file_info.children[i], result_files);
                visited_children.add(i);
            }
            for (var i in remote_file_info.children) {
                if (!visited_children.has(i)) {
                    result_files.update_list = result_files.update_list.concat(
                        generate_file_list(remote_file_info.children[i])
                    );
                }
            }
        } else {
            result_files.update_list = result_files.update_list.concat(generate_file_list(remote_file_info));
        }
    }
}

function generate_file_list(file_info) {
    if (!file_info) {
        return [];
    }

    var file_list = [];
    if (file_info.is_dir) {
        for (var i in file_info.children) {
            file_list = file_list.concat(generate_file_list(file_info.children[i]));
        }
    }
    file_list.push({
        file_name: file_info.file_name,
        is_dir: file_info.is_dir,
        is_file: file_info.is_file,
        sha_512: file_info.sha_512,
    });
    return file_list;
}

// command: delete, update, finish
function send_command(command, file_list) {
    var command_data = {
        command: command,
        file_list: file_list,
    };
    postMessage(command_data);
}