import { Router } from "express";
import {
  createSession,
  getSession,
  findSessionByDiagram,
  syncEntities,
  addMessage,
  clearHistory,
  deleteSession,
  getStats
} from "../services/sessionStore.js";
import { getSessionUsage, getGlobalUsage, formatCost } from "../services/usageTracker.js";

const router = Router();

/**
 * GET /api/session/debug/stats
 * Get session statistics (for debugging)
 * Query params:
 *   - details=true: Include full entity and conversation data
 * NOTE: Must be before /:id routes to avoid matching "debug" as an id
 */
router.get("/debug/stats", (req, res) => {
  const includeDetails = req.query.details === 'true';
  const stats = getStats(includeDetails);
  console.log('[Session Debug] Stats requested:', JSON.stringify(stats, null, 2));
  res.json(stats);
});

/**
 * GET /api/session/usage/global
 * Get global token usage and cost statistics
 * NOTE: Must be before /:id routes
 */
router.get("/usage/global", (req, res) => {
  const usage = getGlobalUsage();
  res.json({
    ...usage,
    totalCostFormatted: formatCost(usage.totalCost),
    uptimeFormatted: `${Math.round(usage.uptime / 1000 / 60)} minutes`
  });
});

/**
 * GET /api/session/:id/usage
 * Get token usage and cost for a specific session
 */
router.get("/:id/usage", (req, res) => {
  const usage = getSessionUsage(req.params.id);

  if (!usage) {
    return res.status(404).json({ error: "No usage data for session" });
  }

  res.json({
    ...usage,
    totalCostFormatted: formatCost(usage.totalCost)
  });
});

/**
 * POST /api/session/create
 * Create a new session or return existing one for a diagram
 */
router.post("/create", (req, res) => {
  const { diagramId } = req.body;

  if (!diagramId) {
    return res.status(400).json({ error: "diagramId is required" });
  }

  // Check for existing session
  let session = findSessionByDiagram(diagramId);
  if (session) {
    console.log(`[Session] Resuming existing session ${session.id} for diagram ${diagramId} (${session.conversationHistory.length} messages, ${session.entities.length} entities)`);
    return res.json({
      session,
      isNew: false
    });
  }

  // Create new session
  session = createSession(diagramId);
  console.log(`[Session] Created new session ${session.id} for diagram ${diagramId}`);
  res.json({
    session,
    isNew: true
  });
});

/**
 * GET /api/session/:id
 * Get session details including history
 */
router.get("/:id", (req, res) => {
  const session = getSession(req.params.id);

  if (!session) {
    return res.status(404).json({ error: "Session not found" });
  }

  res.json({ session });
});

/**
 * PUT /api/session/:id/sync
 * Sync entities from client to server
 */
router.put("/:id/sync", (req, res) => {
  const { entities } = req.body;

  if (!entities || !Array.isArray(entities)) {
    return res.status(400).json({ error: "entities array is required" });
  }

  const session = syncEntities(req.params.id, entities);

  if (!session) {
    return res.status(404).json({ error: "Session not found" });
  }

  console.log(`[Session ${req.params.id}] Synced ${entities.length} entities:`,
    entities.map(e => `${e.text || '(no label)'} (${e.template})`).join(', ') || 'none');

  res.json({ success: true, entityCount: entities.length });
});

/**
 * POST /api/session/:id/message
 * Add a message to history (used after successful Claude response)
 */
router.post("/:id/message", (req, res) => {
  const { role, content, toolResults } = req.body;

  if (!role || !content) {
    return res.status(400).json({ error: "role and content are required" });
  }

  const session = addMessage(req.params.id, { role, content, toolResults });

  if (!session) {
    return res.status(404).json({ error: "Session not found" });
  }

  res.json({ success: true, messageCount: session.conversationHistory.length });
});

/**
 * DELETE /api/session/:id/history
 * Clear conversation history
 */
router.delete("/:id/history", (req, res) => {
  const session = clearHistory(req.params.id);

  if (!session) {
    return res.status(404).json({ error: "Session not found" });
  }

  res.json({ success: true });
});

/**
 * DELETE /api/session/:id
 * Delete a session entirely
 */
router.delete("/:id", (req, res) => {
  const deleted = deleteSession(req.params.id);

  if (!deleted) {
    return res.status(404).json({ error: "Session not found" });
  }

  res.json({ success: true });
});

export default router;