import { NextResponse } from "next/server";
import { prisma } from "@/lib/prisma";
import { requireRole } from "@/lib/auth";
import { validateSchedule, type ScheduleBody } from "@/lib/schedule";

/** All schedules of this institution with resolved names. */
export async function GET() {
  const session = await requireRole("INSTITUTION_ADMIN");
  if (!session || !session.institutionId) {
    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
  }
  const institutionId = session.institutionId;

  const [schedules, selections] = await Promise.all([
    prisma.classSchedule.findMany({
      where: { institutionId },
      orderBy: [{ isActive: "asc" }, { classItemId: "asc" }, { startTime: "asc" }],
      include: { staff: { select: { name: true, nameBn: true } } },
    }),
    prisma.academicSelection.findMany({
      where: { institutionId },
      select: { academicItem: { select: { id: true, name: true, nameBn: true } } },
    }),
  ]);

  const names = new Map(
    selections.map((s) => [
      s.academicItem.id,
      { name: s.academicItem.name, nameBn: s.academicItem.nameBn },
    ])
  );
  const label = (id: number | null) => (id ? names.get(id)?.name ?? null : null);
  const active = schedules.filter((s) => s.isActive);

  return NextResponse.json({
    summary: {
      total: schedules.length,
      active: active.length,
      classes: new Set(active.map((s) => s.classItemId).filter(Boolean)).size,
      teachers: new Set(active.map((s) => s.staffId).filter(Boolean)).size,
    },
    schedules: schedules.map((s) => ({
      id: s.id,
      staffId: s.staffId,
      teacherName: s.staff?.name ?? null,
      teacherNameBn: s.staff?.nameBn ?? null,
      sessionItemId: s.sessionItemId,
      sessionName: label(s.sessionItemId),
      departmentItemId: s.departmentItemId,
      departmentName: label(s.departmentItemId),
      classItemId: s.classItemId,
      className: label(s.classItemId),
      sectionItemId: s.sectionItemId,
      sectionName: label(s.sectionItemId),
      groupItemId: s.groupItemId,
      groupName: label(s.groupItemId),
      subjectItemId: s.subjectItemId,
      subjectName: label(s.subjectItemId),
      roomItemId: s.roomItemId,
      roomName: label(s.roomItemId),
      days: s.days,
      startTime: s.startTime,
      endTime: s.endTime,
      note: s.note,
      isActive: s.isActive,
    })),
  });
}

/** Create a schedule entry (with teacher/room/class clash detection). */
export async function POST(req: Request) {
  const session = await requireRole("INSTITUTION_ADMIN");
  if (!session || !session.institutionId) {
    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
  }

  try {
    const body = (await req.json()) as ScheduleBody;
    const result = await validateSchedule(session.institutionId, body);
    if ("error" in result) {
      return NextResponse.json({ error: result.error }, { status: result.status });
    }

    const schedule = await prisma.classSchedule.create({
      data: { institutionId: session.institutionId, ...result.data },
    });
    return NextResponse.json({ schedule });
  } catch {
    return NextResponse.json({ error: "Could not create schedule" }, { status: 500 });
  }
}