import { Handlers } from "$fresh/server.ts";
import { get_task_manager } from "../../server.ts";
import type { Task, TaskProgress } from "../../task.ts";
import type {
    TaskClientSocketData,
    TaskServerSocketData,
} from "../../server/task.ts";
import { ExitTarget } from "../../signal_handler.ts";

export const handler: Handlers<Task[]> = {
    GET(req, _ctx) {
        const t = get_task_manager();
        const { socket, response } = Deno.upgradeWebSocket(req);
        const handle = (
            e: CustomEvent<Task | TaskProgress | { task: Task; error: string }>,
        ) => {
            if (socket.readyState === socket.OPEN) {
                socket.send(JSON.stringify({ type: e.type, detail: e.detail }));
            }
        };
        const close_handle = () => {
            sendMessage({ type: "close" });
            socket.close();
        };
        const removeListener = () => {
            t.removeEventListener("new_task", handle);
            t.removeEventListener("task_started", handle);
            t.removeEventListener("task_finished", handle);
            t.removeEventListener("task_progress", handle);
            t.removeEventListener("task_error", handle);
            t.removeEventListener("task_updated", handle);
            ExitTarget.removeEventListener("close", close_handle);
        };
        function sendMessage(mes: TaskServerSocketData) {
            if (socket.readyState === socket.OPEN) {
                socket.send(JSON.stringify(mes));
            }
        }
        socket.onclose = () => {
            removeListener();
        };
        socket.onerror = () => {
            removeListener();
            console.error("WebSocket error.");
        };
        socket.onmessage = (e) => {
            try {
                const d: TaskClientSocketData = JSON.parse(e.data);
                if (d.type == "close") {
                    sendMessage({ type: "close" });
                    socket.close();
                } else if (d.type == "new_download_task") {
                    t.add_download_task(d.gid, d.token, d.cfg);
                } else if (d.type == "new_export_zip_task") {
                    t.add_export_zip_task(d.gid, d.cfg);
                } else if (d.type == "task_list") {
                    t.get_task_list().then((tasks) => {
                        sendMessage({
                            type: "tasks",
                            tasks,
                            running: t.get_running_task(),
                        });
                    });
                }
            } catch (_) {
                null;
            }
        };
        socket.onopen = () => {
            t.addEventListener("new_task", handle);
            t.addEventListener("task_started", handle);
            t.addEventListener("task_finished", handle);
            t.addEventListener("task_progress", handle);
            t.addEventListener("task_error", handle);
            t.addEventListener("task_updated", handle);
            ExitTarget.addEventListener("close", close_handle);
        };
        return response;
    },
};