import { Router } from "express";
import type { Db } from "@paperclipai/db";
import { assertBoard, assertCompanyAccess } from "./authz.js";
import { chatService } from "../services/chat.js";
import { sendPushToAll } from "../services/pushService.js";
import { issueService } from "../services/issues.js";
import { assistantMemoryService } from "../services/assistant-memory.js";
import { nexusSettingsService } from "../services/nexus-settings.js";
import { puterProxyService } from "../services/puter-proxy.js";
import { z } from "zod";
import {
  createConversationSchema,
  updateConversationSchema,
  createMessageSchema,
  handoffSchema,
  searchMessagesSchema,
  branchConversationSchema,
} from "@paperclipai/shared";

export function chatRoutes(db: Db): Router {
  const router = Router();
  const svc = chatService(db);
  const issueSvc = issueService(db);

  // GET /api/companies/:companyId/conversations
  router.get("/companies/:companyId/conversations", async (req, res) => {
    assertBoard(req);
    assertCompanyAccess(req, req.params.companyId!);
    const { cursor, limit, includeArchived, search, agentId } = req.query;
    const result = await svc.listConversations(req.params.companyId!, {
      cursor: cursor as string | undefined,
      limit: limit ? Number(limit) : undefined,
      includeArchived: includeArchived === "true",
      search: search as string | undefined,
      agentId: agentId as string | undefined,
    });
    res.json(result);
  });

  // POST /api/companies/:companyId/conversations
  router.post("/companies/:companyId/conversations", async (req, res) => {
    assertBoard(req);
    assertCompanyAccess(req, req.params.companyId!);
    const data = createConversationSchema.parse(req.body);
    const conversation = await svc.createConversation(req.params.companyId!, data);
    res.status(201).json(conversation);
  });

  // GET /api/conversations/:id
  router.get("/conversations/:id", async (req, res) => {
    assertBoard(req);
    const conversation = await svc.getConversation(req.params.id!);
    res.json(conversation);
  });

  // PATCH /api/conversations/:id
  router.patch("/conversations/:id", async (req, res) => {
    assertBoard(req);
    const data = updateConversationSchema.parse(req.body);
    const conversation = await svc.updateConversation(req.params.id!, data);
    res.json(conversation);
  });

  // DELETE /api/conversations/:id
  router.delete("/conversations/:id", async (req, res) => {
    assertBoard(req);
    await svc.softDeleteConversation(req.params.id!);
    res.status(204).end();
  });

  // GET /api/conversations/:id/messages
  router.get("/conversations/:id/messages", async (req, res) => {
    assertBoard(req);
    const { cursor, limit } = req.query;
    const result = await svc.listMessages(req.params.id!, {
      cursor: cursor as string | undefined,
      limit: limit ? Number(limit) : undefined,
    });
    res.json(result);
  });

  // POST /api/conversations/:id/messages
  router.post("/conversations/:id/messages", async (req, res) => {
    assertBoard(req);
    const data = createMessageSchema.parse(req.body);
    const message = await svc.addMessage(req.params.id!, data);
    res.status(201).json(message);
  });

  // POST /api/conversations/:id/stream -- SSE streaming endpoint (CHAT-01, PERF-02)
  router.post("/conversations/:id/stream", async (req, res) => {
    assertBoard(req);
    const { content, agentId, voiceMode } = req.body as {
      content: string; agentId?: string; voiceMode?: "text" | "voice_input" | "full_voice";
    };
    if (!content || typeof content !== "string") {
      res.status(400).json({ error: "content is required" });
      return;
    }

    // Resolve conversation and settings BEFORE flushing headers (Pitfall 3)
    const conversation = await svc.getConversation(req.params.id!);
    const settings = await nexusSettingsService().get();
    const isAssistant = settings.mode !== "project_builder";

    // Load memory facts if in assistant mode
    const memory = isAssistant
      ? await assistantMemoryService().get(conversation.companyId)
      : { facts: [] as string[], updatedAt: null };

    // Try resolving puter token — fall back to echo if not configured
    let puterTokenAvailable = false;
    try {
      await puterProxyService(db).resolveToken(conversation.companyId);
      puterTokenAvailable = true;
    } catch {
      // No puter token — will fall back to echo stub
    }

    // Build messages array for AI call
    const recentMsgs = await svc.listMessages(req.params.id!, { limit: 20 });
    // listMessages returns newest-first; reverse for chronological order
    const chronological = [...recentMsgs.items].reverse();

    const messagesWithMemory: Array<{ role: string; content: string }> = [];

    // Inject memory as system message if applicable
    if (isAssistant && memory.facts.length > 0) {
      const memoryText = `[Memory from previous sessions]\n${memory.facts.map((f) => "- " + f).join("\n")}\n\nUse these facts to personalize your responses. Do not mention that you have a memory system unless asked.`;
      const capped = memoryText.slice(0, 2000);
      messagesWithMemory.push({ role: "system", content: capped });
    }

    // Add recent conversation history
    for (const msg of chronological) {
      if (msg.role === "user" || msg.role === "assistant") {
        messagesWithMemory.push({ role: msg.role, content: msg.content });
      }
    }

    // Add the new user message
    messagesWithMemory.push({ role: "user", content });

    // Inject dual-output formatting prompt when voice mode is full_voice (VPIPE-06)
    if (voiceMode === "full_voice") {
      messagesWithMemory.push({
        role: "system",
        content: [
          "Format your response with EXACTLY these two labeled sections:",
          "",
          "SPOKEN: [Natural speech prose only. No markdown. No bullet points. No code blocks. Max 2-3 sentences for spoken delivery.]",
          "",
          "DETAILED: [Your full response with all detail, code blocks, and markdown formatting.]",
        ].join("\n"),
      });
    }

    // Set SSE headers and flush BEFORE any generation (PERF-02)
    res.setHeader("Content-Type", "text/event-stream");
    res.setHeader("Cache-Control", "no-cache");
    res.setHeader("Connection", "keep-alive");
    res.setHeader("X-Accel-Buffering", "no");
    res.flushHeaders();
    res.write(":ok\n\n");

    const abort = new AbortController();
    req.on("close", () => abort.abort());

    try {
      let fullContent = "";

      // Choose stream source: real AI or echo fallback
      const tokenStream = puterTokenAvailable
        ? puterProxyService(db).chatStream(conversation.companyId, agentId || undefined, messagesWithMemory, undefined, abort.signal)
        : svc.streamEcho(content, abort.signal);

      for await (const token of tokenStream) {
        if (!res.writable) break;
        fullContent += token;
        res.write(`data: ${JSON.stringify({ type: "token", token })}\n\n`);
      }
      if (res.writable && !abort.signal.aborted) {
        const message = await svc.addMessage(req.params.id!, {
          role: "assistant",
          content: fullContent.trim(),
          agentId: agentId || undefined,
          messageType: voiceMode === "full_voice" ? "voice_full"
            : voiceMode === "voice_input" ? "voice_input"
            : undefined,
        });
        res.write(`data: ${JSON.stringify({ type: "done", messageId: message.id, content: fullContent.trim() })}\n\n`);

        // Fire push notification for offline subscribers (PWA-06)
        sendPushToAll(db, conversation.companyId, {
          title: "New agent response",
          body: fullContent.trim().slice(0, 100),
          data: { url: `/chat/${conversation.id}` },
        }).catch(() => {}); // non-blocking

        // Append a brief memory fact after each assistant turn (non-blocking)
        if (isAssistant) {
          const fact = `User asked about: ${content.slice(0, 100)}. Assistant topic: ${fullContent.slice(0, 100)}`;
          assistantMemoryService().append(conversation.companyId, fact).catch(() => {});
        }
      }
    } catch (err) {
      if (res.writable && !abort.signal.aborted) {
        res.write(`data: ${JSON.stringify({ type: "error", error: "Stream error" })}\n\n`);
      }
    } finally {
      res.end();
    }
  });

  // PATCH /api/conversations/:id/messages/:msgId -- Edit message content
  router.patch("/conversations/:id/messages/:msgId", async (req, res) => {
    assertBoard(req);
    const { content } = req.body;
    if (!content || typeof content !== "string") {
      res.status(400).json({ error: "content is required" });
      return;
    }
    const message = await svc.editMessage(req.params.msgId!, content);
    if (!message) {
      res.status(404).json({ error: "Message not found" });
      return;
    }
    res.json(message);
  });

  // DELETE /api/conversations/:id/messages/after/:msgId -- Truncate messages after a given message
  router.delete("/conversations/:id/messages/after/:msgId", async (req, res) => {
    assertBoard(req);
    await svc.truncateMessagesAfter(req.params.id!, req.params.msgId!);
    res.status(204).end();
  });

  // POST /api/conversations/:id/handoff -- Brainstormer handoff to PM: inserts handoff + task_created messages and creates an issue
  router.post("/conversations/:id/handoff", async (req, res) => {
    assertBoard(req);
    const data = handoffSchema.parse(req.body);

    // Resolve companyId from conversation
    const conversation = await svc.getConversation(req.params.id!);
    const companyId = conversation.companyId;

    // 1. Insert handoff system message
    const handoffMsg = await svc.addSystemMessage(req.params.id!, {
      content: `Brainstormer \u2192 PM: spec handed off`,
      messageType: "handoff",
    });

    // 2. Create issue from spec
    const specDescription = [
      `**What:** ${data.spec.what}`,
      `**Why:** ${data.spec.why}`,
      data.spec.constraints ? `**Constraints:** ${data.spec.constraints}` : "",
      data.spec.success ? `**Success:** ${data.spec.success}` : "",
    ].filter(Boolean).join("\n\n");

    const issue = await issueSvc.create(companyId, {
      title: data.spec.what.slice(0, 100),
      description: specDescription,
      status: "backlog",
      priority: "medium",
    });

    // 3. Insert task_created system message
    await svc.addSystemMessage(req.params.id!, {
      content: JSON.stringify({
        taskId: issue.identifier,
        taskTitle: issue.title,
        taskUrl: `/issues/${issue.id}`,
      }),
      messageType: "task_created",
    });

    res.json({ handoffMessageId: handoffMsg.id, issues: [issue] });
  });

  // POST /api/conversations/:id/status-update -- Agent completion notification in chat
  router.post("/conversations/:id/status-update", async (req, res) => {
    assertBoard(req);
    const { agentName, taskId, taskTitle, taskUrl } = req.body;
    if (!agentName || !taskId) {
      res.status(400).json({ error: "agentName and taskId are required" });
      return;
    }

    const message = await svc.addSystemMessage(req.params.id!, {
      content: JSON.stringify({ agentName, taskId, taskTitle, taskUrl }),
      messageType: "status_update",
    });

    res.status(201).json(message);
  });

  // GET /api/companies/:companyId/messages/search
  router.get("/companies/:companyId/messages/search", async (req, res) => {
    assertBoard(req);
    assertCompanyAccess(req, req.params.companyId!);
    let parsed: { q: string; limit?: number };
    try {
      parsed = searchMessagesSchema.parse({ q: req.query.q, limit: req.query.limit });
    } catch {
      res.status(400).json({ error: "Query must be at least 2 characters" });
      return;
    }
    const result = await svc.searchMessages(req.params.companyId!, parsed.q, { limit: parsed.limit });
    res.json(result);
  });

  // POST /api/conversations/:id/bookmarks -- Toggle bookmark for a message
  router.post("/conversations/:id/bookmarks", async (req, res) => {
    assertBoard(req);
    const messageId = z.string().uuid().safeParse(req.body.messageId);
    if (!messageId.success) {
      res.status(400).json({ error: "messageId must be a valid UUID" });
      return;
    }
    const conversationId = req.params.id!;
    const conversation = await svc.getConversation(conversationId);
    const result = await svc.toggleBookmark(conversation.companyId, messageId.data, conversationId);
    res.json(result);
  });

  // GET /api/companies/:companyId/bookmarks
  router.get("/companies/:companyId/bookmarks", async (req, res) => {
    assertBoard(req);
    assertCompanyAccess(req, req.params.companyId!);
    const conversationId = req.query.conversationId as string | undefined;
    const result = await svc.getBookmarks(req.params.companyId!, { conversationId });
    res.json(result);
  });

  // POST /api/conversations/:id/branch -- Branch conversation from a message
  router.post("/conversations/:id/branch", async (req, res) => {
    assertBoard(req);
    const parsed = branchConversationSchema.parse(req.body);
    const conv = await svc.getConversation(req.params.id!);
    const newConversation = await svc.branchConversation(req.params.id!, parsed.branchFromMessageId, conv.companyId);
    res.status(201).json(newConversation);
  });

  // GET /api/conversations/:id/branches -- List child conversations
  router.get("/conversations/:id/branches", async (req, res) => {
    assertBoard(req);
    const branches = await svc.listBranches(req.params.id!);
    res.json({ items: branches });
  });

  // GET /api/conversations/:id/export -- Export conversation as Markdown or JSON file
  router.get("/conversations/:id/export", async (req, res) => {
    assertBoard(req);
    const format = req.query.format === "json" ? "json" : "markdown";
    const { content, filename } = await svc.exportConversation(req.params.id!, format);
    const mime = format === "json" ? "application/json" : "text/markdown";
    res.setHeader("Content-Disposition", `attachment; filename="${filename}"`);
    res.setHeader("Content-Type", mime);
    res.send(content);
  });

  return router;
}