import { Router } from "@oak/oak";
import { ALLOWED_ORIGINS } from "../config.ts";
import { verifyJWT } from "../lib/jwt.ts";
import {
  broadcastChatMessage,
  broadcastChatMessageDeleted,
  broadcastChatMessageUpdated,
  broadcastCommentLikeUpdate,
  broadcastPresence,
  broadcastTyping,
  broadcastVoteUpdate,
  getOnlineUsers,
  handleClientPong,
  isUserChatOpen,
  register,
  setClientTyping,
  unregister,
  type WsClient,
} from "../services/ws-service.ts";
import {
  createChatMessage,
  deleteChatMessage,
  updateChatMessage,
} from "../services/chat-service.ts";
import { notifyMentions } from "../services/notification-service.ts";
import { hasPermission } from "../lib/permissions.ts";
import {
  castVote,
  getUserVotes,
  removeVote,
} from "../services/vote-service.ts";
import {
  castCommentLike,
  getUserCommentLikes,
  removeCommentLike,
} from "../services/comment-like-service.ts";
import { getUnreadCount } from "../services/notification-service.ts";
import { getUserById } from "../services/user-service.ts";
import {
  APIException,
  type ClientToServerMessage,
} from "../model/interfaces.ts";

const router = new Router();

function isAllowedOrigin(origin: string): boolean {
  return ALLOWED_ORIGINS.includes(origin);
}

router.get("/ws", async (ctx) => {
  const origin = ctx.request.headers.get("origin") ?? "";
  if (!isAllowedOrigin(origin)) {
    ctx.response.status = 403;
    return;
  }

  if (!ctx.isUpgradable) {
    ctx.response.status = 426;
    return;
  }

  const token = ctx.request.url.searchParams.get("token");
  const authPayload = token ? await verifyJWT(token) : null;

  const socket = ctx.upgrade();

  const avatarMime = authPayload
    ? getUserById(authPayload.userId).avatarMime
    : undefined;

  const client: WsClient = {
    socket,
    userId: authPayload?.userId,
    username: authPayload?.username,
    role: authPayload?.role,
    avatarMime,
  };

  // Use addEventListener — more reliable than onopen= with Deno.serve
  socket.addEventListener("open", () => {
    register(client);
    broadcastPresence();

    try {
      const myVotes = authPayload ? getUserVotes(authPayload.userId) : [];
      const myCommentLikes = authPayload
        ? getUserCommentLikes(authPayload.userId)
        : [];
      const unreadNotificationCount = authPayload
        ? getUnreadCount(authPayload.userId)
        : 0;
      socket.send(JSON.stringify({
        type: "welcome",
        users: getOnlineUsers(),
        myVotes,
        myCommentLikes,
        unreadNotificationCount,
      }));
    } catch (err) {
      console.error("[ws] welcome send failed:", err);
    }
  });

  socket.addEventListener("message", (event) => {
    let msg: ClientToServerMessage;
    try {
      msg = JSON.parse(event.data as string);
    } catch {
      return;
    }

    switch (msg.type) {
      case "ping":
        socket.send(JSON.stringify({ type: "pong" }));
        break;
      case "pong":
        handleClientPong(client);
        break;
      case "vote_cast":
        handleVote(client, msg.dumpId, "cast");
        break;
      case "vote_remove":
        handleVote(client, msg.dumpId, "remove");
        break;
      case "comment_like_cast":
        handleCommentLike(client, msg.commentId, "cast");
        break;
      case "comment_like_remove":
        handleCommentLike(client, msg.commentId, "remove");
        break;
      case "chat_send":
        handleChatSend(client, msg.body, msg.replyToId);
        break;
      case "chat_typing":
        if (client.userId) setClientTyping(client, msg.typing);
        break;
      case "chat_focus":
        client.chatOpen = msg.open;
        break;
      case "chat_edit":
        handleChatEdit(client, msg.id, msg.body);
        break;
      case "chat_delete":
        handleChatDelete(client, msg.id);
        break;
    }
  });

  socket.addEventListener("close", () => {
    unregister(client);
    broadcastPresence();
    // If they were mid-compose, drop them from the typing set right away.
    if (client.typingAt) broadcastTyping();
  });
});

function handleVote(
  client: WsClient,
  dumpId: string,
  action: "cast" | "remove",
): void {
  const { socket } = client;

  if (!client.userId) {
    socket.send(
      JSON.stringify({ type: "error", message: "Authentication required" }),
    );
    return;
  }

  try {
    const newCount = action === "cast"
      ? castVote(dumpId, client.userId)
      : removeVote(dumpId, client.userId);

    socket.send(JSON.stringify({
      type: "vote_ack",
      dumpId,
      action,
      success: true,
      voteCount: newCount,
    }));

    broadcastVoteUpdate(dumpId, newCount, client.userId, action);
  } catch (err) {
    const message = err instanceof APIException ? err.message : "Vote failed";
    socket.send(JSON.stringify({ type: "error", message, dumpId, action }));
  }
}

function handleCommentLike(
  client: WsClient,
  commentId: string,
  action: "cast" | "remove",
): void {
  const { socket } = client;

  if (!client.userId) {
    socket.send(
      JSON.stringify({ type: "error", message: "Authentication required" }),
    );
    return;
  }

  try {
    const newCount = action === "cast"
      ? castCommentLike(commentId, client.userId)
      : removeCommentLike(commentId, client.userId);

    socket.send(JSON.stringify({
      type: "comment_like_ack",
      commentId,
      action,
      likeCount: newCount,
    }));

    broadcastCommentLikeUpdate(commentId, newCount, client.userId, action);
  } catch (err) {
    const message = err instanceof APIException ? err.message : "Like failed";
    socket.send(JSON.stringify({ type: "error", message, commentId, action }));
  }
}

function handleChatSend(
  client: WsClient,
  body: string,
  replyToId?: string,
): void {
  const { socket } = client;

  if (!client.userId) {
    socket.send(
      JSON.stringify({ type: "error", message: "Authentication required" }),
    );
    return;
  }

  try {
    const message = createChatMessage(client.userId, body, replyToId);
    // Sending a message ends composition — clear the typing flag before the
    // message broadcast so the indicator doesn't linger next to it.
    setClientTyping(client, false);
    // Broadcast to everyone including the sender, so the sender's own message
    // simply arrives over the socket — no optimistic-send machinery needed.
    broadcastChatMessage(message);
    // Skip mention notifications for users who already have the chat open —
    // they've seen the message live.
    notifyMentions(
      client.userId,
      message.body,
      "chat",
      message.id,
      "",
      undefined,
      isUserChatOpen,
    );
  } catch (err) {
    const message = err instanceof APIException
      ? err.message
      : "Failed to send message";
    socket.send(JSON.stringify({ type: "error", message }));
  }
}

function canModerateChat(client: WsClient): boolean {
  return !!client.role && hasPermission(client.role, "chat:moderate");
}

function handleChatEdit(client: WsClient, id: string, body: string): void {
  const { socket } = client;

  if (!client.userId) {
    socket.send(
      JSON.stringify({ type: "error", message: "Authentication required" }),
    );
    return;
  }

  try {
    const message = updateChatMessage(
      id,
      body,
      client.userId,
      canModerateChat(client),
    );
    broadcastChatMessageUpdated(message);
    // A newly added @mention in an edit should still notify (deduped per
    // message+user), skipping anyone already reading the chat.
    notifyMentions(
      client.userId,
      message.body,
      "chat",
      message.id,
      "",
      undefined,
      isUserChatOpen,
    );
  } catch (err) {
    const message = err instanceof APIException
      ? err.message
      : "Failed to edit message";
    socket.send(JSON.stringify({ type: "error", message }));
  }
}

function handleChatDelete(client: WsClient, id: string): void {
  const { socket } = client;

  if (!client.userId) {
    socket.send(
      JSON.stringify({ type: "error", message: "Authentication required" }),
    );
    return;
  }

  try {
    deleteChatMessage(id, canModerateChat(client));
    broadcastChatMessageDeleted(id);
  } catch (err) {
    const message = err instanceof APIException
      ? err.message
      : "Failed to delete message";
    socket.send(JSON.stringify({ type: "error", message }));
  }
}

export default router;