import { type NextRequest, NextResponse } from "next/server";
import { neonAuth } from "@/lib/auth/server";
import { prisma } from "@/lib/prisma";
import type { ChatSession } from "@/lib/types";

// MIGRATED: Removed "export const dynamic = 'force-dynamic'" - dynamic by default with Cache Components

export async function GET(
  _request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  const { id } = await params;

  if (!id) {
    return NextResponse.json(
      { error: "Session ID is required" },
      { status: 400 }
    );
  }

  // Verify user is authenticated
  const { session: authSession, user: authUser } = await neonAuth();
  if (!authSession || !authUser?.email) {
    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
  }

  // Look up user in our database to get companyId for authorization
  const user = await prisma.user.findUnique({
    where: { email: authUser.email },
    select: { companyId: true },
  });

  if (!user) {
    return NextResponse.json({ error: "User not found" }, { status: 401 });
  }

  try {
    const prismaSession = await prisma.session.findUnique({
      where: { id },
      include: {
        messages: {
          orderBy: { order: "asc" },
        },
      },
    });

    if (!prismaSession) {
      return NextResponse.json({ error: "Session not found" }, { status: 404 });
    }

    // Verify user has access to this session (same company)
    if (prismaSession.companyId !== user.companyId) {
      return NextResponse.json({ error: "Forbidden" }, { status: 403 });
    }

    // Map Prisma session object to ChatSession type
    const session: ChatSession = {
      // Spread prismaSession to include all its properties
      ...prismaSession,
      // Override properties that need conversion or specific mapping
      id: prismaSession.id, // ChatSession.id from Prisma.Session.id
      sessionId: prismaSession.id, // ChatSession.sessionId from Prisma.Session.id
      startTime: new Date(prismaSession.startTime),
      endTime: prismaSession.endTime ? new Date(prismaSession.endTime) : null,
      createdAt: new Date(prismaSession.createdAt),
      // Prisma.Session does not have an `updatedAt` field. We'll use `createdAt` as a fallback.
      // Or, if your business logic implies an update timestamp elsewhere, use that.
      updatedAt: new Date(prismaSession.createdAt), // Fallback to createdAt
      // Prisma.Session does not have a `userId` field.
      userId: null, // Explicitly set to null or map if available from another source
      // Ensure nullable fields from Prisma are correctly mapped to ChatSession's optional or nullable fields
      category: prismaSession.category ?? null,
      language: prismaSession.language ?? null,
      country: prismaSession.country ?? null,
      ipAddress: prismaSession.ipAddress ?? null,
      sentiment: prismaSession.sentiment ?? null,
      messagesSent: prismaSession.messagesSent ?? undefined, // Use undefined if ChatSession expects number | undefined
      avgResponseTime: prismaSession.avgResponseTime ?? null,
      escalated: prismaSession.escalated ?? undefined,
      forwardedHr: prismaSession.forwardedHr ?? undefined,
      initialMsg: prismaSession.initialMsg ?? undefined,
      fullTranscriptUrl: prismaSession.fullTranscriptUrl ?? null,
      summary: prismaSession.summary ?? null, // New field
      transcriptContent: null, // Not available in Session model
      messages:
        prismaSession.messages?.map((msg) => ({
          id: msg.id,
          sessionId: msg.sessionId,
          timestamp: msg.timestamp ? new Date(msg.timestamp) : new Date(),
          role: msg.role,
          content: msg.content,
          order: msg.order,
          createdAt: new Date(msg.createdAt),
        })) ?? [], // New field - parsed messages
    };

    return NextResponse.json({ session });
  } catch (error) {
    const errorMessage =
      error instanceof Error ? error.message : "An unknown error occurred";
    return NextResponse.json(
      { error: "Failed to fetch session", details: errorMessage },
      { status: 500 }
    );
  }
}