import { BadRequestException, ConflictException, Injectable, NotFoundException } from '@nestjs/common';
import { Prisma } from '@prisma/client';
import { PrismaService } from '../../prisma/prisma.service';
import { AuditService } from '../audit/audit.service';
import { AuditAction } from '../audit/audit.types';

export interface BatchCreateResult {
  created: Array<{ id: string; sourceGroupId: string; targetGroupId: string; sourceGroup: { name: string }; targetGroup: { name: string } }>;
  skipped: string[];
}

const routeInclude = {
  sourceGroup: { select: { name: true, tenantId: true } },
  targetGroup: { select: { name: true, tenantId: true } },
} as const;

@Injectable()
export class RoutesService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly audit: AuditService,
  ) {}

  list(tenantId: string, sourceGroupId?: string) {
    return this.prisma.syncRoute.findMany({
      where: {
        tenantId,
        ...(sourceGroupId ? { sourceGroupId } : {}),
      },
      include: {
        sourceGroup: { select: { name: true } },
        targetGroup: { select: { name: true } },
      },
      orderBy: { createdAt: 'desc' },
    });
  }

  async create(tenantId: string, sourceGroupId: string, targetGroupId: string) {
    if (!sourceGroupId || !targetGroupId) {
      throw new BadRequestException('sourceGroupId and targetGroupId are required');
    }
    if (sourceGroupId === targetGroupId) {
      throw new BadRequestException('Source and target groups cannot be the same');
    }

    // Source must be owned by this tenant AND active; target can be owned OR shared AND active
    const [source, target] = await Promise.all([
      this.prisma.group.findFirst({ where: { id: sourceGroupId, tenantId, isActive: true }, select: { id: true } }),
      this.prisma.group.findFirst({
        where: {
          id: targetGroupId,
          isActive: true,
          OR: [
            { tenantId },
            { groupAccesses: { some: { tenantId } } },
          ],
        },
        select: { id: true },
      }),
    ]);
    if (!source) throw new BadRequestException('Source group is not available or the bot has been removed from it');
    if (!target) throw new BadRequestException('Target group is not available or the bot has been removed from it');

    try {
      const route = await this.prisma.syncRoute.create({
        data: { tenantId, sourceGroupId, targetGroupId },
        include: {
          sourceGroup: { select: { name: true } },
          targetGroup: { select: { name: true } },
        },
      });
      await this.audit.log({
        tenantId,
        action: AuditAction.ROUTE_CREATED,
        resourceType: 'SyncRoute',
        resourceId: route.id,
        payload: { sourceGroupId, targetGroupId },
      });
      return route;
    } catch (e) {
      if (e instanceof Prisma.PrismaClientKnownRequestError) {
        if (e.code === 'P2002') {
          throw new ConflictException('A route between these groups already exists');
        }
      }
      throw e;
    }
  }

  async createBatch(tenantId: string, sourceGroupId: string, targetGroupIds: string[]) {
    if (!sourceGroupId || !targetGroupIds.length) {
      throw new BadRequestException('sourceGroupId and at least one targetGroupId are required');
    }

    if (targetGroupIds.includes(sourceGroupId)) {
      throw new BadRequestException('Source and target groups cannot be the same');
    }

    // Source group must exist in this tenant AND be active
    const source = await this.prisma.group.findFirst({ where: { id: sourceGroupId, tenantId, isActive: true }, select: { id: true } });
    if (!source) {
      throw new BadRequestException('Source group is not available or the bot has been removed from it');
    }

    // All target groups must be owned OR shared AND active
    const targets = await this.prisma.group.findMany({
      where: {
        id: { in: targetGroupIds },
        isActive: true,
        OR: [
          { tenantId },
          { groupAccesses: { some: { tenantId } } },
        ],
      },
      select: { id: true, name: true },
    });
    if (targets.length !== targetGroupIds.length) {
      const found = new Set(targets.map((t) => t.id));
      const missing = targetGroupIds.filter((id) => !found.has(id));
      throw new BadRequestException(`Target groups not found or not shared: ${missing.join(', ')}`);
    }

    // Check for existing conflicts — reject the whole batch
    const existing = await this.prisma.syncRoute.findMany({
      where: { tenantId, sourceGroupId, targetGroupId: { in: targetGroupIds } },
      select: { targetGroupId: true },
    });
    if (existing.length > 0) {
      const names = existing.map((e) => {
        const t = targets.find((t) => t.id === e.targetGroupId);
        return t?.name ?? e.targetGroupId;
      });
      throw new ConflictException(`Routes already exist for: ${names.join(', ')}`);
    }

    const created = await this.prisma.$transaction(
      targetGroupIds.map((targetGroupId) =>
        this.prisma.syncRoute.create({
          data: { tenantId, sourceGroupId, targetGroupId },
          include: {
            sourceGroup: { select: { name: true } },
            targetGroup: { select: { name: true } },
          },
        }),
      ),
    );

    await this.audit.log({
      tenantId,
      action: AuditAction.ROUTE_CREATED,
      resourceType: 'SyncRoute',
      resourceId: created.map((r) => r.id).join(','),
      payload: { sourceGroupId, targetGroupIds, count: created.length },
    });

    return created;
  }

  async remove(tenantId: string, id: string) {
    // Verify ownership before delete
    const existing = await this.prisma.syncRoute.findFirst({ where: { id, tenantId } });
    if (!existing) throw new NotFoundException(`Route ${id} not found`);

    try {
      await this.prisma.syncRoute.delete({ where: { id } });
      await this.audit.log({
        tenantId,
        action: AuditAction.ROUTE_DELETED,
        resourceType: 'SyncRoute',
        resourceId: id,
      });
    } catch (e) {
      if (e instanceof Prisma.PrismaClientKnownRequestError && e.code === 'P2025') {
        throw new NotFoundException(`Route ${id} not found`);
      }
      throw e;
    }
  }
}