import { Injectable, Logger, OnApplicationBootstrap } from '@nestjs/common';
import { Cron } from '@nestjs/schedule';
import type { Prisma } from '@prisma/client';
import { PrismaService } from '../prisma/prisma.service';
import { occursOn } from './recurrence';
import { routineRule } from './routine-mapper';
import { dayKeyToDate, tehranDateTime, tehranDayKey } from './routine-dates';

export const DEFAULT_REMIND_MINUTES = 30;

@Injectable()
export class RoutineGeneratorService implements OnApplicationBootstrap {
  private readonly logger = new Logger(RoutineGeneratorService.name);
  private overdueRunning = false;

  constructor(private readonly prisma: PrismaService) {}

  onApplicationBootstrap() {
    // جبران cron از دست رفته (ری‌استارت سرور حوالی نیمه‌شب)
    setTimeout(() => {
      void this.generateForDay(tehranDayKey()).catch((err) =>
        this.logger.warn(`bootstrap generate failed: ${err instanceof Error ? err.message : err}`),
      );
      void this.markOverdue();
    }, 8000);
  }

  @Cron('5 0 * * *', { timeZone: 'Asia/Tehran' })
  async generateToday(): Promise<void> {
    try {
      const count = await this.generateForDay(tehranDayKey());
      if (count) this.logger.log(`generated ${count} routine tasks`);
    } catch (err) {
      this.logger.warn(`daily generate failed: ${err instanceof Error ? err.message : err}`);
    }
  }

  /** ساخت Taskهای یک روز برای روتین‌های فعال (idempotent). */
  async generateForDay(
    day: string,
    filter: { organizationId?: string; routineId?: string } = {},
  ): Promise<number> {
    const date = dayKeyToDate(day);
    const routines = await this.prisma.routine.findMany({
      where: {
        isActive: true,
        deletedAt: null,
        startDate: { lte: date },
        OR: [{ endDate: null }, { endDate: { gte: date } }],
        ...(filter.organizationId ? { organizationId: filter.organizationId } : {}),
        ...(filter.routineId ? { id: filter.routineId } : {}),
      },
      include: { team: { select: { members: { select: { userId: true } } } } },
    });
    if (!routines.length) return 0;

    const candidates = new Set<string>();
    const planned: Array<{ routine: (typeof routines)[number]; userIds: string[] }> = [];
    for (const routine of routines) {
      if (!occursOn(routineRule(routine), day)) continue;
      const userIds = routine.assigneeId
        ? [routine.assigneeId]
        : [...new Set(routine.team?.members.map((m) => m.userId) ?? [])];
      if (!userIds.length) continue;
      userIds.forEach((id) => candidates.add(`${routine.organizationId}:${id}`));
      planned.push({ routine, userIds });
    }
    if (!planned.length) return 0;

    const memberships = await this.prisma.membership.findMany({
      where: {
        isActive: true,
        userId: { in: [...candidates].map((c) => c.split(':')[1]!) },
        organizationId: { in: [...new Set(planned.map((p) => p.routine.organizationId))] },
        user: { isActive: true },
      },
      select: { userId: true, organizationId: true },
    });
    const active = new Set(memberships.map((m) => `${m.organizationId}:${m.userId}`));
    const offsets = await this.reminderOffsets(memberships);

    const rows: Prisma.RoutineTaskCreateManyInput[] = [];
    for (const { routine, userIds } of planned) {
      const dueAt = tehranDateTime(day, routine.timeOfDay);
      for (const assigneeId of userIds) {
        const key = `${routine.organizationId}:${assigneeId}`;
        if (!active.has(key)) continue;
        const minutes = routine.reminderMinutesBefore ?? offsets.get(key) ?? null;
        const reminderAt = minutes != null ? new Date(dueAt.getTime() - minutes * 60_000) : null;
        rows.push({
          organizationId: routine.organizationId,
          routineId: routine.id,
          assigneeId,
          title: routine.title,
          description: routine.description,
          categoryId: routine.categoryId,
          priority: routine.priority,
          scheduledFor: date,
          dueAt,
          reminderAt,
          source: 'routine',
          isMandatory: routine.isMandatory,
          createdById: routine.createdById,
        });
      }
    }
    if (!rows.length) return 0;
    const result = await this.prisma.routineTask.createMany({ data: rows, skipDuplicates: true });
    return result.count;
  }

  /** دقیقه‌های یادآور پیش‌فرض هر کاربر (تنظیمات شخصی؛ بدون تنظیم = ۳۰) */
  async reminderOffsets(
    pairs: Array<{ organizationId: string; userId: string }>,
  ): Promise<Map<string, number | null>> {
    const map = new Map<string, number | null>();
    for (const p of pairs) map.set(`${p.organizationId}:${p.userId}`, DEFAULT_REMIND_MINUTES);
    if (!pairs.length) return map;
    const settings = await this.prisma.routineUserSettings.findMany({
      where: { userId: { in: [...new Set(pairs.map((p) => p.userId))] } },
      select: { organizationId: true, userId: true, remindBeforeMinutes: true },
    });
    for (const s of settings) {
      const key = `${s.organizationId}:${s.userId}`;
      if (map.has(key)) map.set(key, s.remindBeforeMinutes);
    }
    return map;
  }

  @Cron('*/5 * * * *')
  async markOverdue(): Promise<void> {
    if (this.overdueRunning) return;
    this.overdueRunning = true;
    try {
      const now = new Date();
      for (let i = 0; i < 20; i += 1) {
        const due = await this.prisma.routineTask.findMany({
          where: { status: { in: ['todo', 'in_progress'] }, dueAt: { lt: now } },
          select: { id: true, organizationId: true, status: true },
          take: 500,
        });
        if (!due.length) break;
        await this.prisma.$transaction([
          this.prisma.routineTask.updateMany({
            where: { id: { in: due.map((t) => t.id) }, status: { in: ['todo', 'in_progress'] } },
            data: { status: 'overdue' },
          }),
          this.prisma.routineTaskEvent.createMany({
            data: due.map((t) => ({
              organizationId: t.organizationId,
              taskId: t.id,
              type: 'status_changed',
              fromStatus: t.status,
              toStatus: 'overdue' as const,
              note: 'مهلت انجام گذشت',
            })),
          }),
        ]);
        if (due.length < 500) break;
      }
    } catch (err) {
      this.logger.warn(`overdue run failed: ${err instanceof Error ? err.message : err}`);
    } finally {
      this.overdueRunning = false;
    }
  }
}