feat: credit-based billing system

- New DB models: credit_packages, subscription_plans, user_credits, credit_consumptions, credit_purchases
- CreditService: balance, deduct, add_credits, grant_free_trial, history
- User API: /api/v1/credits/* (balance/history/packages/purchase/subscribe)
- Admin API: /api/v1/admin/credit-* (CRUD packages/plans, user credits, consumptions)
- PaymentService.create_credit_order + handle_callback for credit purchases
- Credit deduction on: discovery, translate, marketing, ai_chat, followup
- Free trial 30 credits on registration
- Documentation: docs/CREDIT_SYSTEM.md

backend/app/api/v1/discovery.py

@@ -4,6 +4,11 @@ from pydantic import BaseModel
 from sqlalchemy.ext.asyncio import AsyncSession
 from app.database import get_db
 from app.services.discovery import DiscoveryService
+from app.services.credit import CreditService
+from app.api.v1.deps import get_current_user_id
+import logging
+
+logger = logging.getLogger(__name__)
 
 router = APIRouter()
 
@@ -23,45 +28,104 @@ class OutreachRequest(BaseModel):
     product: Dict[str, Any]
 
 
+CREDIT_COST = {
+    "search": 10,
+    "analyze": 5,
+    "outreach": 3,
+}
+
+
+async def _deduct_credits(user_id: str, result_type: str, db: AsyncSession):
+    svc = CreditService(db)
+    ok, balance = await svc.deduct(user_id, result_type)
+    if not ok:
+        raise HTTPException(
+            status_code=402,
+            detail=f"次数不足 (剩余 {balance:.1f}, 需要 {CREDIT_COST.get(result_type, 1)})"
+        )
+    return balance
+
+
 @router.post("/search")
-async def search_leads(req: SearchRequest, db: AsyncSession = Depends(get_db)):
+async def search_leads(
+    req: SearchRequest,
+    user_id: str = Depends(get_current_user_id),
+    db: AsyncSession = Depends(get_db),
+):
     if not req.product_description.strip():
         raise HTTPException(status_code=400, detail="请填写产品描述")
+
+    credit_svc = CreditService(db)
+    ok, balance = await credit_svc.deduct(user_id, "lead_search")
+    if not ok:
+        raise HTTPException(
+            status_code=402,
+            detail=f"次数不足 (剩余 {balance:.1f}, 需要 10)"
+        )
+
     svc = DiscoveryService(db=db)
     try:
         result = await svc.search(req.product_description, req.target_market)
-        return {"success": True, "data": result}
+        return {"success": True, "data": result, "credits_remaining": balance - 10}
     except Exception as e:
+        await credit_svc.add_credits(user_id, 10, "refund", "搜索失败退回次数")
         logger.error(f"Search failed: {e}")
         raise HTTPException(status_code=500, detail="搜索失败，请稍后重试")
 
 
 @router.post("/analyze")
-async def analyze_company(req: AnalyzeRequest):
+async def analyze_company(
+    req: AnalyzeRequest,
+    user_id: str = Depends(get_current_user_id),
+    db: AsyncSession = Depends(get_db),
+):
     if not req.company_url.strip():
         raise HTTPException(status_code=400, detail="请填写公司网址")
     if not req.product_description.strip():
         raise HTTPException(status_code=400, detail="请填写产品描述")
+
+    credit_svc = CreditService(db)
+    ok, balance = await credit_svc.deduct(user_id, "company_analysis")
+    if not ok:
+        raise HTTPException(
+            status_code=402,
+            detail=f"次数不足 (剩余 {balance:.1f}, 需要 5)"
+        )
+
     svc = DiscoveryService()
     try:
         result = await svc.analyze(req.company_url, req.product_description)
-        return {"success": True, "data": result}
+        return {"success": True, "data": result, "credits_remaining": balance - 5}
     except Exception as e:
+        await credit_svc.add_credits(user_id, 5, "refund", "分析失败退回次数")
         logger.error(f"Analysis failed: {e}")
         raise HTTPException(status_code=500, detail="分析失败，请稍后重试")
 
 
 @router.post("/outreach")
-async def generate_outreach(req: OutreachRequest):
+async def generate_outreach(
+    req: OutreachRequest,
+    user_id: str = Depends(get_current_user_id),
+    db: AsyncSession = Depends(get_db),
+):
     if not req.company.get("name"):
         raise HTTPException(status_code=400, detail="请填写公司名称")
     if not req.product.get("name"):
         raise HTTPException(status_code=400, detail="请填写产品名称")
+
+    credit_svc = CreditService(db)
+    ok, balance = await credit_svc.deduct(user_id, "outreach")
+    if not ok:
+        raise HTTPException(
+            status_code=402,
+            detail=f"次数不足 (剩余 {balance:.1f}, 需要 3)"
+        )
+
     svc = DiscoveryService()
     try:
         result = await svc.generate_outreach(req.company, req.product)
-        return {"success": True, "data": result}
+        return {"success": True, "data": result, "credits_remaining": balance - 3}
     except Exception as e:
+        await credit_svc.add_credits(user_id, 3, "refund", "生成失败退回次数")
         logger.error(f"Outreach generation failed: {e}")
         raise HTTPException(status_code=500, detail="生成失败，请稍后重试")
-