import {
  BadRequestException,
  ForbiddenException,
  Injectable,
  UnauthorizedException,
} from '@nestjs/common';
import type {
  ApplyBillingPlanRequest,
  BillingAccountDto,
  BillingAccountStatus,
  BillingPlanCode,
  OrgModuleKey,
  SubscriptionSummaryDto,
} from '@mento/shared';
import {
  BILLING_PLAN_DAYS,
  BILLING_PLAN_DEFAULT_MAX_ORGS,
  defaultEnabledModules,
  isOrgModuleKey,
} from '@mento/shared';
import { PrismaService } from '../prisma/prisma.service';

function daysRemaining(expiresAt: Date, now = new Date()): number {
  const ms = expiresAt.getTime() - now.getTime();
  return Math.max(0, Math.ceil(ms / (24 * 60 * 60 * 1000)));
}

function toSummary(row: {
  planCode: string;
  status: string;
  startsAt: Date;
  expiresAt: Date;
  maxOrganizations: number;
}): SubscriptionSummaryDto {
  const remaining = daysRemaining(row.expiresAt);
  const status = (row.status as BillingAccountStatus) ?? 'active';
  return {
    planCode: row.planCode as BillingPlanCode,
    status,
    startsAt: row.startsAt.toISOString(),
    expiresAt: row.expiresAt.toISOString(),
    maxOrganizations: row.maxOrganizations,
    daysRemaining: remaining,
    warn: remaining > 0 && remaining <= 3,
  };
}

@Injectable()
export class BillingService {
  constructor(private readonly prisma: PrismaService) {}

  toDto(row: {
    id: string;
    ownerUserId: string;
    planCode: string;
    status: string;
    startsAt: Date;
    expiresAt: Date;
    maxOrganizations: number;
    externalPaymentRef: string | null;
    notes: string | null;
  }): BillingAccountDto {
    const summary = toSummary(row);
    return {
      id: row.id,
      ownerUserId: row.ownerUserId,
      ...summary,
      externalPaymentRef: row.externalPaymentRef,
      notes: row.notes,
    };
  }

  async getByOwnerUserId(ownerUserId: string) {
    return this.prisma.billingAccount.findUnique({ where: { ownerUserId } });
  }

  async ensureTrialForOwner(
    ownerUserId: string,
    opts?: { maxOrganizations?: number },
  ) {
    const existing = await this.getByOwnerUserId(ownerUserId);
    if (existing) return existing;
    const now = new Date();
    const expiresAt = new Date(now.getTime() + 15 * 24 * 60 * 60 * 1000);
    return this.prisma.billingAccount.create({
      data: {
        ownerUserId,
        planCode: 'trial',
        status: 'active',
        startsAt: now,
        expiresAt,
        maxOrganizations: Math.max(1, opts?.maxOrganizations ?? 1),
      },
    });
  }

  /** اشتراک محیط = BillingAccount اولین مالک فعال — برای عضو زیرمجموعه حساب جدید ساخته نمی‌شود */
  async resolveForOrganization(organizationId: string) {
    const owner = await this.prisma.membership.findFirst({
      where: {
        organizationId,
        role: 'owner',
        isActive: true,
      },
      orderBy: { createdAt: 'asc' },
      select: { userId: true },
    });
    if (!owner) return null;
    return this.getByOwnerUserId(owner.userId);
  }

  async requireActiveForOrganization(organizationId: string): Promise<SubscriptionSummaryDto> {
    const account = await this.resolveForOrganization(organizationId);
    if (!account) {
      throw new UnauthorizedException(
        'اشتراک این محیط یافت نشد؛ مالک باید از پنل سوپرادمین پلن داشته باشد',
      );
    }
    return this.assertActive(account);
  }

  async requireActiveForOwner(ownerUserId: string): Promise<SubscriptionSummaryDto> {
    const account = await this.getByOwnerUserId(ownerUserId);
    if (!account) {
      throw new UnauthorizedException(
        'اشتراک یافت نشد؛ ابتدا پلن را از سوپرادمین اعمال کنید',
      );
    }
    return this.assertActive(account);
  }

  private async assertActive(account: {
    id: string;
    planCode: string;
    status: string;
    startsAt: Date;
    expiresAt: Date;
    maxOrganizations: number;
  }): Promise<SubscriptionSummaryDto> {
    const now = new Date();
    if (account.status === 'suspended') {
      throw new UnauthorizedException('اشتراک این حساب معلق شده است');
    }
    if (account.status === 'expired' || account.expiresAt.getTime() < now.getTime()) {
      if (account.status !== 'expired') {
        await this.prisma.billingAccount.update({
          where: { id: account.id },
          data: { status: 'expired' },
        });
      }
      throw new UnauthorizedException('اشتراک منقضی شده است');
    }
    return toSummary(account);
  }

  async assertCanCreateOrganization(ownerUserId: string) {
    let account = await this.getByOwnerUserId(ownerUserId);
    if (!account) {
      // اولین محیط مالک: trial خودکار
      account = await this.ensureTrialForOwner(ownerUserId, { maxOrganizations: 1 });
    }
    const summary = await this.assertActive(account);
    const ownedCount = await this.prisma.membership.count({
      where: { userId: ownerUserId, role: 'owner', isActive: true },
    });
    if (ownedCount >= summary.maxOrganizations) {
      throw new ForbiddenException(
        `سقف تعداد محیط برای این اشتراک ${summary.maxOrganizations} است`,
      );
    }
  }

  async applyPlan(
    ownerUserId: string,
    dto: ApplyBillingPlanRequest,
  ): Promise<BillingAccountDto> {
    const ownerMembership = await this.prisma.membership.findFirst({
      where: { userId: ownerUserId, role: 'owner', isActive: true },
      select: { id: true },
    });
    if (!ownerMembership) {
      throw new BadRequestException(
        'اشتراک فقط برای مالک محیط تعریف می‌شود؛ این کاربر مالک هیچ محیطی نیست',
      );
    }

    const planCode = dto.planCode;
    const now = new Date();
    let expiresAt: Date;
    let maxOrganizations: number;

    if (planCode === 'custom') {
      if (!dto.expiresAt) {
        throw new BadRequestException('برای پلن سفارشی تاریخ انقضا لازم است');
      }
      expiresAt = new Date(dto.expiresAt);
      if (Number.isNaN(expiresAt.getTime())) {
        throw new BadRequestException('تاریخ انقضا معتبر نیست');
      }
      maxOrganizations = Math.max(1, dto.maxOrganizations ?? 1);
    } else {
      const days = BILLING_PLAN_DAYS[planCode];
      expiresAt = dto.expiresAt
        ? new Date(dto.expiresAt)
        : new Date(now.getTime() + days * 24 * 60 * 60 * 1000);
      if (Number.isNaN(expiresAt.getTime())) {
        throw new BadRequestException('تاریخ انقضا معتبر نیست');
      }
      maxOrganizations = Math.max(
        1,
        dto.maxOrganizations ?? BILLING_PLAN_DEFAULT_MAX_ORGS[planCode],
      );
    }

    const status: BillingAccountStatus =
      dto.status ??
      (expiresAt.getTime() < now.getTime() ? 'expired' : 'active');

    const existing = await this.getByOwnerUserId(ownerUserId);
    const row = existing
      ? await this.prisma.billingAccount.update({
          where: { id: existing.id },
          data: {
            planCode,
            status,
            startsAt: existing.startsAt ?? now,
            expiresAt,
            maxOrganizations,
            ...(dto.notes !== undefined ? { notes: dto.notes } : {}),
          },
        })
      : await this.prisma.billingAccount.create({
          data: {
            ownerUserId,
            planCode,
            status,
            startsAt: now,
            expiresAt,
            maxOrganizations,
            notes: dto.notes ?? null,
          },
        });
    return this.toDto(row);
  }

  async setOrgModules(organizationId: string, modules: string[]) {
    const cleaned = [
      ...new Set(
        modules.filter(isOrgModuleKey),
      ),
    ] as OrgModuleKey[];
    await this.prisma.organization.update({
      where: { id: organizationId },
      data: { enabledModules: cleaned },
    });
    return cleaned;
  }

  normalizeModules(raw: string[] | null | undefined): OrgModuleKey[] {
    if (!raw?.length) return defaultEnabledModules();
    const cleaned = raw.filter(isOrgModuleKey) as OrgModuleKey[];
    return cleaned.length ? cleaned : defaultEnabledModules();
  }

  async requireModule(organizationId: string, module: OrgModuleKey) {
    const org = await this.prisma.organization.findUnique({
      where: { id: organizationId },
      select: { enabledModules: true },
    });
    if (!org) throw new ForbiddenException('محیط پیدا نشد');
    const enabled = this.normalizeModules(org.enabledModules);
    if (!enabled.includes(module)) {
      throw new ForbiddenException('این ماژول برای این محیط فعال نیست');
    }
  }

  defaultModulesForNewOrg(): OrgModuleKey[] {
    return defaultEnabledModules();
  }

  async countExpiringSoon() {
    const now = new Date();
    const in3 = new Date(now.getTime() + 3 * 24 * 60 * 60 * 1000);
    return this.prisma.billingAccount.count({
      where: {
        status: 'active',
        expiresAt: { gt: now, lte: in3 },
      },
    });
  }

  async countExpired() {
    return this.prisma.billingAccount.count({
      where: {
        OR: [
          { status: 'expired' },
          { status: 'active', expiresAt: { lt: new Date() } },
        ],
      },
    });
  }
}