feat: TTS服务 + 数字人面试组件 (P1)

backend/src/app.module.ts

@@ -23,6 +23,7 @@ import { ProgressModule } from './modules/progress/progress.module'
 import { ContributionModule } from './modules/contribution/contribution.module'
 import { DailyQuestionModule } from './modules/daily-question/daily-question.module'
 import { ScheduleModule } from './modules/schedule/schedule.module'
+import { TtsModule } from './modules/tts/tts.module'
 
 const MONGODB_URI = process.env.MONGODB_URI || 'mongodb://localhost:27017/zhiyin'
 
@@ -54,6 +55,7 @@ const MONGODB_URI = process.env.MONGODB_URI || 'mongodb://localhost:27017/zhiyin
     ContributionModule,
     DailyQuestionModule,
     ScheduleModule,
+    TtsModule,
   ],
   providers: [
     JwtStrategy,

backend/src/modules/interview/interview.controller.ts

@@ -28,7 +28,9 @@ export class InterviewController {
     @Param('id') id: string,
     @CurrentUser('userId') userId: string,
     @Body('answer') answer: string,
+    @Body('avatar') avatar?: boolean,
   ) {
+    if (avatar) return this.interviewService.answerWithAvatar(id, userId, answer)
     return this.interviewService.answer(id, userId, answer)
   }
 

backend/src/modules/interview/interview.module.ts

@@ -5,6 +5,7 @@ import { InterviewService } from './interview.service'
 import { Interview, InterviewSchema } from './interview.schema'
 import { Progress, ProgressSchema } from '../schemas/progress.schema'
 import { UserModule } from '../user/user.module'
+import { TtsModule } from '../tts/tts.module'
 
 @Module({
   imports: [
@@ -13,6 +14,7 @@ import { UserModule } from '../user/user.module'
       { name: Progress.name, schema: ProgressSchema },
     ]),
     UserModule,
+    TtsModule,
   ],
   controllers: [InterviewController],
   providers: [InterviewService],

backend/src/modules/interview/interview.service.ts

@@ -6,6 +6,7 @@ import { Progress, ProgressDocument } from '../schemas/progress.schema'
 import { AiService } from '../ai/ai.service'
 import { UserService } from '../user/user.service'
 import { QuotaService } from '../user/quota.service'
+import { TtsService } from '../tts/tts.service'
 import { analyzeSpeech } from '../../common/utils/filler-words'
 
 @Injectable()
@@ -16,6 +17,7 @@ export class InterviewService {
     private aiService: AiService,
     private userService: UserService,
     private quotaService: QuotaService,
+    private ttsService: TtsService,
   ) {}
 
   async create(userId: string, position: string) {
@@ -99,6 +101,20 @@ ${conversationHistory}
     }
   }
 
+  async answerWithAvatar(interviewId: string, userId: string, answer: string) {
+    const base = await this.answer(interviewId, userId, answer)
+    const aiMsg = base.messages?.find(m => m.role === 'ai')
+    if (aiMsg?.content) {
+      try {
+        const tts = await this.ttsService.synthesize(aiMsg.content)
+        return { ...base, ttsHash: tts.hash, ttsDurationMs: tts.durationMs }
+      } catch {
+        // TTS failure is non-critical, return without audio
+      }
+    }
+    return base
+  }
+
   async complete(interviewId: string, userId: string) {
     const interview = await this.interviewModel.findOne({ _id: interviewId, userId }).exec()
     if (!interview) throw new HttpException('面试不存在', HttpStatus.NOT_FOUND)

backend/src/modules/tts/tts.controller.ts

@@ -0,0 +1,33 @@
+import { Controller, Get, Post, Body, Param, Res, HttpException, HttpStatus } from '@nestjs/common'
+import { Response } from 'express'
+import * as fs from 'fs'
+import { TtsService } from './tts.service'
+import { Public } from '../../common/decorators/public.decorator'
+
+@Controller('tts')
+export class TtsController {
+  constructor(private ttsService: TtsService) {}
+
+  @Public()
+  @Post('synthesize')
+  async synthesize(@Body('text') text: string, @Body('voice') voice?: string) {
+    if (!text || text.length > 500) {
+      throw new HttpException('文本不能为空且不超过500字', HttpStatus.BAD_REQUEST)
+    }
+    const result = await this.ttsService.synthesize(text, voice)
+    return { hash: result.hash, durationMs: result.durationMs }
+  }
+
+  @Public()
+  @Get('audio/:hash')
+  async getAudio(@Param('hash') hash: string, @Res() res: Response) {
+    const filePath = this.ttsService.getCachedPath(hash)
+    if (!filePath) {
+      throw new HttpException('音频不存在', HttpStatus.NOT_FOUND)
+    }
+    const stream = fs.createReadStream(filePath)
+    res.setHeader('Content-Type', 'audio/mpeg')
+    res.setHeader('Cache-Control', 'public, max-age=31536000')
+    stream.pipe(res)
+  }
+}

backend/src/modules/tts/tts.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common'
+import { TtsController } from './tts.controller'
+import { TtsService } from './tts.service'
+
+@Module({
+  controllers: [TtsController],
+  providers: [TtsService],
+  exports: [TtsService],
+})
+export class TtsModule {}

backend/src/modules/tts/tts.service.ts

@@ -0,0 +1,67 @@
+import * as crypto from 'crypto'
+import * as fs from 'fs'
+import * as path from 'path'
+import { execSync } from 'child_process'
+import { Injectable, Logger } from '@nestjs/common'
+
+const CACHE_DIR = '/tmp/tts-cache'
+
+interface TtsResult {
+  hash: string
+  filePath: string
+  durationMs: number
+}
+
+@Injectable()
+export class TtsService {
+  private readonly logger = new Logger(TtsService.name)
+
+  constructor() {
+    if (!fs.existsSync(CACHE_DIR)) {
+      fs.mkdirSync(CACHE_DIR, { recursive: true })
+    }
+  }
+
+  async synthesize(text: string, voice: string = 'zh-CN-XiaoxiaoNeural'): Promise<TtsResult> {
+    const hash = crypto.createHash('md5').update(text + voice).digest('hex')
+    const filePath = path.join(CACHE_DIR, `${hash}.mp3`)
+
+    if (fs.existsSync(filePath)) {
+      const durationMs = await this.getDuration(filePath)
+      return { hash, filePath, durationMs }
+    }
+
+    try {
+      execSync(
+        `edge-tts --voice "${voice}" --text "${this.escapeText(text)}" --write-media "${filePath}"`,
+        { timeout: 30000 },
+      )
+      const durationMs = await this.getDuration(filePath)
+      this.logger.log(`TTS generated: hash=${hash} text="${text.slice(0, 40)}..." duration=${durationMs}ms`)
+      return { hash, filePath, durationMs }
+    } catch (e) {
+      this.logger.error(`TTS failed: ${e.message}`)
+      throw e
+    }
+  }
+
+  getCachedPath(hash: string): string | null {
+    const filePath = path.join(CACHE_DIR, `${hash}.mp3`)
+    return fs.existsSync(filePath) ? filePath : null
+  }
+
+  private escapeText(text: string): string {
+    return text.replace(/"/g, '\\"').replace(/\n/g, ' ').replace(/\r/g, '')
+  }
+
+  private async getDuration(filePath: string): Promise<number> {
+    try {
+      // Estimate duration from file size (~16kbps for mp3 at 22050Hz)
+      const stat = fs.statSync(filePath)
+      const bytesPerMs = 16 * 1024 / 8 / 1000  // 16kbps → bytes per ms
+      return Math.round(stat.size / bytesPerMs)
+    } catch {
+      return 3000
+    }
+  }
+}