import { NextRequest, NextResponse } from "next/server";
import { getServerSession } from "next-auth";
import { prisma } from "../../../../lib/prisma";
import { sessionMetrics } from "../../../../lib/metrics";
import { authOptions } from "../../../../lib/auth";
import { ChatSession } from "../../../../lib/types";

interface SessionUser {
  email: string;
  name?: string;
}

interface SessionData {
  user: SessionUser;
}

export async function GET(request: NextRequest) {
  const session = (await getServerSession(authOptions)) as SessionData | null;
  if (!session?.user) {
    return NextResponse.json({ error: "Not logged in" }, { status: 401 });
  }

  const user = await prisma.user.findUnique({
    where: { email: session.user.email },
    select: {
      id: true,
      companyId: true,
      company: {
        select: {
          id: true,
          name: true,
          csvUrl: true,
          status: true,
        }
      },
    },
  });

  if (!user) {
    return NextResponse.json({ error: "No user" }, { status: 401 });
  }

  // Get date range from query parameters
  const { searchParams } = new URL(request.url);
  const startDate = searchParams.get("startDate");
  const endDate = searchParams.get("endDate");

  // Build where clause with optional date filtering
  const whereClause: any = {
    companyId: user.companyId,
  };

  if (startDate && endDate) {
    whereClause.startTime = {
      gte: new Date(startDate),
      lte: new Date(endDate + "T23:59:59.999Z"), // Include full end date
    };
  }

  // Fetch sessions without messages first for better performance
  const prismaSessions = await prisma.session.findMany({
    where: whereClause,
    select: {
      id: true,
      companyId: true,
      startTime: true,
      endTime: true,
      createdAt: true,
      category: true,
      language: true,
      country: true,
      ipAddress: true,
      sentiment: true,
      messagesSent: true,
      avgResponseTime: true,
      escalated: true,
      forwardedHr: true,
      initialMsg: true,
      fullTranscriptUrl: true,
      summary: true,
    },
  });

  // Batch fetch questions for all sessions at once if needed for metrics
  const sessionIds = prismaSessions.map(s => s.id);
  const sessionQuestions = await prisma.sessionQuestion.findMany({
    where: { sessionId: { in: sessionIds } },
    include: { question: true },
    orderBy: { order: 'asc' },
  });

  // Group questions by session
  const questionsBySession = sessionQuestions.reduce((acc, sq) => {
    if (!acc[sq.sessionId]) acc[sq.sessionId] = [];
    acc[sq.sessionId].push(sq.question.content);
    return acc;
  }, {} as Record<string, string[]>);

  // Convert Prisma sessions to ChatSession[] type for sessionMetrics
  const chatSessions: ChatSession[] = prismaSessions.map((ps) => {
    // Get questions for this session or empty array
    const questions = questionsBySession[ps.id] || [];
    
    // Convert questions to mock messages for backward compatibility
    const mockMessages = questions.map((q, index) => ({
      id: `question-${index}`,
      sessionId: ps.id,
      timestamp: ps.createdAt,
      role: "User",
      content: q,
      order: index,
      createdAt: ps.createdAt,
    }));

    return {
      id: ps.id,
      sessionId: ps.id,
      companyId: ps.companyId,
      startTime: new Date(ps.startTime),
      endTime: ps.endTime ? new Date(ps.endTime) : null,
      transcriptContent: "",
      createdAt: new Date(ps.createdAt),
      updatedAt: new Date(ps.createdAt),
      category: ps.category || undefined,
      language: ps.language || undefined,
      country: ps.country || undefined,
      ipAddress: ps.ipAddress || undefined,
      sentiment: ps.sentiment === null ? undefined : ps.sentiment,
      messagesSent: ps.messagesSent === null ? undefined : ps.messagesSent,
      avgResponseTime: ps.avgResponseTime === null ? undefined : ps.avgResponseTime,
      escalated: ps.escalated || false,
      forwardedHr: ps.forwardedHr || false,
      initialMsg: ps.initialMsg || undefined,
      fullTranscriptUrl: ps.fullTranscriptUrl || undefined,
      summary: ps.summary || undefined,
      messages: mockMessages, // Use questions as messages for metrics
      userId: undefined,
    };
  });

  // Pass company config to metrics
  const companyConfigForMetrics = {
    // Add company-specific configuration here in the future
  };

  const metrics = sessionMetrics(chatSessions, companyConfigForMetrics);

  // Calculate date range from sessions
  let dateRange: { minDate: string; maxDate: string } | null = null;
  if (prismaSessions.length > 0) {
    const dates = prismaSessions
      .map((s) => new Date(s.startTime))
      .sort((a, b) => a.getTime() - b.getTime());
    dateRange = {
      minDate: dates[0].toISOString().split("T")[0], // First session date
      maxDate: dates[dates.length - 1].toISOString().split("T")[0], // Last session date
    };
  }

  return NextResponse.json({
    metrics,
    csvUrl: user.company.csvUrl,
    company: user.company,
    dateRange,
  });
}