import { ctx } from "./context.ts";
import logger from "./logger.ts";
import schema from "./schema/mod.ts";
import { asc, inArray } from "drizzle-orm";
import type { SelectEvent } from "./schema/event.ts";
import { assureAdminAuth, parseTapEvent } from "@atproto/tap";
import { addToBatch, flushBatch } from "./batch.ts";

const PAGE_SIZE = 100;
const BATCH_SEND_SIZE = 50;
const ADMIN_PASSWORD = Deno.env.get("TAP_ADMIN_PASSWORD")!;

interface ClientState {
  socket: WebSocket;
  isPaginating: boolean;
  queue: SelectEvent[];
  dids?: string[];
}

const connectedClients = new Map<WebSocket, ClientState>();

function safeSend(
  socket: WebSocket,
  message: string,
  eventCount?: number,
): boolean {
  try {
    if (socket.readyState === WebSocket.OPEN) {
      socket.send(message);
      if (eventCount !== undefined && eventCount % 50 === 0) {
        logger.info`📤 Sent ${eventCount} events, readyState: ${socket.readyState}`;
      }
      return true;
    } else {
      logger.error`❌ Cannot send - socket readyState: ${socket.readyState}`;
    }
  } catch (error) {
    logger.error`Failed to send message: ${error}`;
    logger.error`Socket readyState: ${socket.readyState}`;
  }
  return false;
}

function formatEvent(evt: SelectEvent): string {
  const { createdAt: _createdAt, record, ...rest } = evt;
  if (record) {
    return JSON.stringify({ ...rest, record: JSON.parse(record) });
  }
  return JSON.stringify(rest);
}

export function broadcastEvent(evt: SelectEvent) {
  const message = formatEvent(evt);

  for (const [socket, state] of connectedClients.entries()) {
    if (socket.readyState === WebSocket.OPEN) {
      if (
        state.dids &&
        state.dids.length > 0 &&
        !state.dids.includes(evt.did)
      ) {
        continue; // Skip events not matching the DID filter
      }

      if (state.isPaginating) {
        state.queue.push(evt);
      } else {
        safeSend(socket, message);
      }
    }
  }
}

Deno.serve(
  { port: parseInt(Deno.env.get("WS_PORT") || "2481") },
  async (req) => {
    if (req.method === "POST") {
      try {
        assureAdminAuth(ADMIN_PASSWORD, req.headers.get("authorization")!);
      } catch {
        logger.warn`Unauthorized access attempt ${req.headers.get("authorization")}`;
        return new Response(null, { status: 401 });
      }
      const evt = parseTapEvent(await req.json());
      switch (evt.type) {
        case "identity": {
          addToBatch({
            id: evt.id,
            type: evt.type,
            did: evt.did,
            handle: evt.handle,
            status: evt.status,
            isActive: evt.isActive,
            action: null,
            rev: null,
            collection: null,
            rkey: null,
            record: null,
            cid: null,
            live: null,
          });
          logger.info`New identity: ${evt.did} ${evt.handle} ${evt.status}`;
          break;
        }
        case "record": {
          addToBatch({
            id: evt.id,
            type: evt.type,
            action: evt.action,
            did: evt.did,
            rev: evt.rev,
            collection: evt.collection,
            rkey: evt.rkey,
            record: JSON.stringify(evt.record),
            cid: evt.cid,
            live: evt.live,
            handle: null,
            status: null,
            isActive: null,
          });
          const uri = `at://${evt.did}/${evt.collection}/${evt.rkey}`;
          logger.info`New record: ${uri}`;
          break;
        }
      }

      return new Response(null, { status: 200 });
    }

    if (req.headers.get("upgrade") != "websocket") {
      return new Response(null, { status: 426 });
    }

    const { socket, response } = Deno.upgradeWebSocket(req);

    const url = new URL(req.url);
    const didsParam = url.searchParams.get("dids");
    const dids = didsParam
      ? didsParam
          .split(",")
          .map((d) => d.trim())
          .filter((d) => d.length > 0)
      : undefined;

    socket.addEventListener("open", () => {
      logger.info`✅ Client connected! Socket state: ${socket.readyState}`;
      if (dids && dids.length > 0) {
        logger.info`🔍 Filtering by DIDs: ${dids.join(", ")}`;
      }

      connectedClients.set(socket, {
        socket,
        isPaginating: true,
        queue: [],
        dids,
      });

      safeSend(
        socket,
        JSON.stringify({
          type: "connected",
          message: "Ready to stream events",
        }),
      );
      logger.info`📤 Sent connection confirmation`;

      (async () => {
        try {
          let page = 0;
          let hasMore = true;
          let totalEvents = 0;

          logger.info`📖 Starting pagination...`;

          try {
            const testQuery = await ctx.db
              .select()
              .from(schema.events)
              .limit(1)
              .execute();
            logger.info`✅ Database test query successful, found ${testQuery.length} sample event(s)`;
          } catch (dbError) {
            logger.error`❌ Database test query failed: ${dbError}`;
            throw dbError;
          }

          while (hasMore && socket.readyState === WebSocket.OPEN) {
            let query = ctx.db.select().from(schema.events).$dynamic();

            // Apply DID filter if specified
            if (dids && dids.length > 0) {
              query = query.where(inArray(schema.events.did, dids));
            }

            const events = await query
              .orderBy(asc(schema.events.createdAt))
              .offset(page * PAGE_SIZE)
              .limit(PAGE_SIZE)
              .execute();

            if (page % 10 === 0) {
              logger.info`📄 Fetching page ${page}... (${totalEvents} events sent so far)`;
            }

            // Batch send events for better performance
            const batchMessages: string[] = [];
            for (let i = 0; i < events.length; i++) {
              const evt = events[i];

              if (socket.readyState !== WebSocket.OPEN) {
                logger.info`⚠️  Socket closed during pagination at event ${totalEvents}`;
                return;
              }

              batchMessages.push(formatEvent(evt));

              // Send batch when full or at end of page
              if (
                batchMessages.length >= BATCH_SEND_SIZE ||
                i === events.length - 1
              ) {
                const batchMessage = `[${batchMessages.join(",")}]`;
                const success = safeSend(socket, batchMessage, totalEvents);

                if (success) {
                  totalEvents += batchMessages.length;
                  batchMessages.length = 0; // Clear batch
                } else {
                  logger.error`❌ Failed to send batch at ${totalEvents}, stopping pagination`;
                  return;
                }
              }
            }

            hasMore = events.length === PAGE_SIZE;
            page++;

            if (hasMore && page % 5 === 0) {
              await new Promise((resolve) => setTimeout(resolve, 20));
            }
          }

          logger.info`📤 Sent all historical events: ${totalEvents} total (${page} pages)`;

          const clientState = connectedClients.get(socket);
          if (clientState && socket.readyState === WebSocket.OPEN) {
            const queuedCount = clientState.queue.length;

            if (queuedCount > 0) {
              logger.info`📦 Sending ${queuedCount} queued events...`;

              // Batch send queued events
              const queueMessages: string[] = [];
              for (const evt of clientState.queue) {
                if (socket.readyState !== WebSocket.OPEN) break;

                queueMessages.push(formatEvent(evt));

                if (queueMessages.length >= BATCH_SEND_SIZE) {
                  safeSend(socket, `[${queueMessages.join(",")}]`);
                  queueMessages.length = 0;
                }
              }

              if (queueMessages.length > 0) {
                safeSend(socket, `[${queueMessages.join(",")}]`);
              }

              clientState.queue = [];
            }

            clientState.isPaginating = false;
            logger.info`🔄 Now streaming real-time events...`;
          }
        } catch (error) {
          logger.error`Pagination error: ${error}`;
          logger.error`Stack: ${error instanceof Error ? error.stack : ""}`;

          safeSend(
            socket,
            JSON.stringify({
              type: "error",
              message: "Failed to load historical events",
            }),
          );

          const clientState = connectedClients.get(socket);
          if (clientState) {
            clientState.isPaginating = false;
          }
        }
      })().catch((err) => {
        logger.error`Unhandled error in pagination loop: ${err}`;
        logger.error`Stack: ${err instanceof Error ? err.stack : ""}`;
      });
    });

    socket.addEventListener("message", (event) => {
      try {
        if (event.data === "ping") {
          safeSend(socket, "pong");
        }
      } catch (error) {
        logger.error`Error handling message: ${error}`;
      }
    });

    socket.addEventListener("close", (event) => {
      const clientState = connectedClients.get(socket);
      connectedClients.delete(socket);

      logger.info`❌ Client disconnected. Code: ${event.code}, Reason: ${event.reason || "none"}, Clean: ${event.wasClean}`;
      logger.info`   Active clients: ${connectedClients.size}`;

      if (clientState) {
        logger.info`   Was paginating: ${clientState.isPaginating}`;
        logger.info`   Queued events: ${clientState.queue.length}`;
      }

      if (event.code === 1006) {
        logger.error`⚠️  Abnormal closure (1006) detected - connection dropped unexpectedly`;
        logger.error`   Possible causes:`;
        logger.error`   - Client overwhelmed with messages (try reducing PAGE_SIZE)`;
        logger.error`   - Network timeout or interruption`;
        logger.error`   - Server sent messages too fast`;
        logger.error`   - Uncaught exception in message handling`;
      }
    });

    socket.addEventListener("error", (error) => {
      logger.error`❌ WebSocket error occurred`;
      logger.error`   Error: ${error}`;
      logger.error`   ReadyState: ${socket.readyState}`;
      const clientState = connectedClients.get(socket);
      if (clientState) {
        logger.error`   Was paginating: ${clientState.isPaginating}`;
        logger.error`   Queued events: ${clientState.queue.length}`;
      }
      connectedClients.delete(socket);
    });

    return response;
  },
);

globalThis.addEventListener("beforeunload", () => {
  flushBatch();
});

const url = `ws://localhost:${Deno.env.get("WS_PORT") || 2481}`;
logger.info`🚀 Tap WebSocket server is running! ${url}`;