import { NextRequest, NextResponse } from "next/server";
import { Pool } from "pg";
import { requireAdmin, requireSuperAdmin, getSession } from "@/lib/auth-utils";

const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
});

// GET /api/admin/users/[id] - Get a single user
export async function GET(
  request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  const { error } = await requireAdmin();
  if (error) return error;

  try {
    const { id } = await params;
    
    const result = await pool.query(
      `SELECT 
        id, name, email, email_verified, image, role, banned, 
        banned_reason, ban_expires, requires_setup, created_at, updated_at
       FROM "user" WHERE id = $1`,
      [id]
    );

    if (result.rows.length === 0) {
      return NextResponse.json({ error: "User not found" }, { status: 404 });
    }

    // Get user's sessions
    const sessions = await pool.query(
      `SELECT id, ip_address, user_agent, created_at, expires_at
       FROM "session" WHERE user_id = $1 ORDER BY created_at DESC`,
      [id]
    );

    return NextResponse.json({
      user: result.rows[0],
      sessions: sessions.rows,
    });
  } catch (error) {
    console.error("Error fetching user:", error);
    return NextResponse.json(
      { error: "Failed to fetch user" },
      { status: 500 }
    );
  }
}

// PATCH /api/admin/users/[id] - Update a user
export async function PATCH(
  request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  const { session, error } = await requireSuperAdmin();
  if (error) return error;

  try {
    const { id } = await params;
    const body = await request.json();
    const { name, email, role, banned, banned_reason } = body;

    // Check if user exists
    const existingUser = await pool.query(
      'SELECT id, role FROM "user" WHERE id = $1',
      [id]
    );

    if (existingUser.rows.length === 0) {
      return NextResponse.json({ error: "User not found" }, { status: 404 });
    }

    // Prevent modifying own role
    if (session?.user.id === id && role && role !== existingUser.rows[0].role) {
      return NextResponse.json(
        { error: "Cannot modify your own role" },
        { status: 400 }
      );
    }

    // Build update query dynamically
    const updates: string[] = [];
    const values: (string | boolean | null)[] = [];
    let paramIndex = 1;

    if (name !== undefined) {
      updates.push(`name = $${paramIndex++}`);
      values.push(name);
    }
    if (email !== undefined) {
      updates.push(`email = $${paramIndex++}`);
      values.push(email);
    }
    if (role !== undefined) {
      updates.push(`role = $${paramIndex++}`);
      values.push(role);
    }
    if (banned !== undefined) {
      updates.push(`banned = $${paramIndex++}`);
      values.push(banned);
      if (banned && banned_reason) {
        updates.push(`banned_reason = $${paramIndex++}`);
        values.push(banned_reason);
      } else if (!banned) {
        updates.push(`banned_reason = NULL`);
        updates.push(`ban_expires = NULL`);
      }
    }

    if (updates.length === 0) {
      return NextResponse.json(
        { error: "No fields to update" },
        { status: 400 }
      );
    }

    updates.push(`updated_at = NOW()`);
    values.push(id);

    const result = await pool.query(
      `UPDATE "user" SET ${updates.join(", ")} WHERE id = $${paramIndex}
       RETURNING id, name, email, role, banned, banned_reason, updated_at`,
      values
    );

    return NextResponse.json({ user: result.rows[0] });
  } catch (error) {
    console.error("Error updating user:", error);
    return NextResponse.json(
      { error: "Failed to update user" },
      { status: 500 }
    );
  }
}

// DELETE /api/admin/users/[id] - Delete a user
export async function DELETE(
  request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  const { session, error } = await requireSuperAdmin();
  if (error) return error;

  try {
    const { id } = await params;

    // Prevent self-deletion
    if (session?.user.id === id) {
      return NextResponse.json(
        { error: "Cannot delete your own account" },
        { status: 400 }
      );
    }

    // Check if user exists
    const existingUser = await pool.query(
      'SELECT id FROM "user" WHERE id = $1',
      [id]
    );

    if (existingUser.rows.length === 0) {
      return NextResponse.json({ error: "User not found" }, { status: 404 });
    }

    // Delete user (cascades to sessions and accounts)
    await pool.query('DELETE FROM "user" WHERE id = $1', [id]);

    return NextResponse.json({ success: true });
  } catch (error) {
    console.error("Error deleting user:", error);
    return NextResponse.json(
      { error: "Failed to delete user" },
      { status: 500 }
    );
  }
}