import { BadRequestException, Injectable, Logger } from '@nestjs/common';
import type { BatchReviewPreviewItem } from '@dukang/shared-types';
import { mapSupportTicketTypeToDevPlanTask } from '@dukang/shared-types';
import { PrismaService } from '../../common/prisma/prisma.module';
import { LlmChatClient } from '../../integrations/llm/llm-chat.client';
import { KnowledgeRetrievalService } from '../../integrations/llm/knowledge-retrieval.service';
import { DevPlanService } from './dev-plan.service';

const DEFAULT_REVIEW_PROMPT = [
  '你是杜康好客技术支持工单审核助手。',
  '根据工单内容与知识库片段，给出审批建议：通过(APPROVE)或驳回(REJECT)。',
  '通过时可建议拆分为 1~3 条开发任务（content + type: BUG/REQUIREMENT/OPTIMIZATION）。',
  '仅输出 JSON，格式：',
  '{"decision":"APPROVE|REJECT","rejectReason":"驳回时必填","note":"通过时附注","reportMarkdown":"markdown摘要","suggestedTasks":[{"content":"...","type":"BUG"}]}',
].join('\n');

@Injectable()
export class SupportTicketReviewAiService {
  private readonly logger = new Logger(SupportTicketReviewAiService.name);

  constructor(
    private readonly prisma: PrismaService,
    private readonly llm: LlmChatClient,
    private readonly kb: KnowledgeRetrievalService,
    private readonly devPlan: DevPlanService,
  ) {}

  async preview(ticketIds: string[]): Promise<{ items: BatchReviewPreviewItem[] }> {
    if (!ticketIds.length) throw new BadRequestException('请选择工单');
    const settings = await this.devPlan.getSettingsRaw();
    if (!settings.reviewAssistantLlmConfigId) {
      throw new BadRequestException('请先在开发设置中配置审核 AI 助手的语言模型');
    }
    const llmCfg = await this.prisma.llmApiConfig.findUnique({
      where: { id: settings.reviewAssistantLlmConfigId },
    });
    if (!llmCfg?.enabled) throw new BadRequestException('审核 AI 助手绑定的语言模型未启用');

    const ids = ticketIds.map(BigInt);
    const tickets = await this.prisma.commonSupportTicket.findMany({
      where: { id: { in: ids }, status: 'PENDING_REVIEW' },
    });
    if (tickets.length !== ids.length) {
      throw new BadRequestException('部分工单不存在或不在待评审状态');
    }

    const items: BatchReviewPreviewItem[] = [];
    for (const ticket of tickets) {
      let kbBlock = '';
      if (settings.reviewAssistantKnowledgeBaseId) {
        try {
          kbBlock = await this.kb.buildContext(
            settings.reviewAssistantKnowledgeBaseId,
            `${ticket.title}\n${ticket.content ?? ''}`,
          );
        } catch (e) {
          this.logger.warn(`review kb failed: ${String(e)}`);
        }
      }

      const userPrompt = [
        `工单号：${ticket.ticketNo}`,
        `类型：${ticket.ticketType}`,
        `标题：${ticket.title}`,
        `内容：${ticket.content ?? '（无）'}`,
        kbBlock ? `\n知识库片段：\n${kbBlock}` : '',
      ].join('\n');

      const system = settings.reviewAssistantPrompt?.trim() || DEFAULT_REVIEW_PROMPT;
      const raw = await this.llm.chat({
        baseUrl: llmCfg.baseUrl,
        apiKey: llmCfg.apiKey,
        model: llmCfg.modelName,
        temperature: 0.2,
        maxTokens: 2048,
        messages: [
          { role: 'system', content: system },
          { role: 'user', content: userPrompt },
        ],
      });

      const parsed = parseReviewJson(raw, ticket.ticketType);
      items.push({
        ticketId: String(ticket.id),
        ticketNo: ticket.ticketNo,
        title: ticket.title,
        decision: parsed.decision,
        rejectReason: parsed.rejectReason,
        note: parsed.note,
        reportMarkdown: parsed.reportMarkdown,
        suggestedTasks: parsed.suggestedTasks,
      });
    }

    return { items };
  }
}

function parseReviewJson(
  raw: string,
  ticketType: 'BUG' | 'SUGGESTION' | 'OTHER',
): {
  decision: 'APPROVE' | 'REJECT';
  rejectReason?: string;
  note?: string;
  reportMarkdown: string;
  suggestedTasks: Array<{ content: string; type: 'BUG' | 'REQUIREMENT' | 'OPTIMIZATION' }>;
} {
  const jsonMatch = raw.match(/\{[\s\S]*\}/);
  const fallbackType = mapSupportTicketTypeToDevPlanTask(ticketType);
  if (!jsonMatch) {
    return {
      decision: 'APPROVE',
      note: 'AI 未返回结构化结果，请人工确认',
      reportMarkdown: raw.slice(0, 2000),
      suggestedTasks: [{ content: '待人工填写任务内容', type: fallbackType }],
    };
  }
  try {
    const obj = JSON.parse(jsonMatch[0]) as {
      decision?: string;
      rejectReason?: string;
      note?: string;
      reportMarkdown?: string;
      suggestedTasks?: Array<{ content?: string; type?: string }>;
    };
    const decision = obj.decision === 'REJECT' ? 'REJECT' : 'APPROVE';
    const suggestedTasks =
      decision === 'APPROVE'
        ? (obj.suggestedTasks ?? [])
            .filter((t) => t.content?.trim())
            .map((t) => ({
              content: t.content!.trim(),
              type: (['BUG', 'REQUIREMENT', 'OPTIMIZATION'].includes(String(t.type))
                ? t.type
                : fallbackType) as 'BUG' | 'REQUIREMENT' | 'OPTIMIZATION',
            }))
        : [];
    if (decision === 'APPROVE' && !suggestedTasks.length) {
      suggestedTasks.push({ content: '待人工填写任务内容', type: fallbackType });
    }
    return {
      decision,
      rejectReason: obj.rejectReason?.trim() || undefined,
      note: obj.note?.trim() || undefined,
      reportMarkdown: obj.reportMarkdown?.trim() || raw.slice(0, 2000),
      suggestedTasks,
    };
  } catch {
    return {
      decision: 'APPROVE',
      note: 'AI 返回解析失败，请人工确认',
      reportMarkdown: raw.slice(0, 2000),
      suggestedTasks: [{ content: '待人工填写任务内容', type: fallbackType }],
    };
  }
}