import uuid
import boto3
from fastapi import FastAPI, HTTPException, Depends
from sqlalchemy import create_engine, Column, String, ForeignKey
from sqlalchemy.orm import sessionmaker, Session, declarative_base, relationship

from app.config import settings

# --- 数据库初始化 ---
engine = create_engine(settings.database_url)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

# --- S3 客户端初始化 ---
s3_client = boto3.client(
    's3',
    aws_access_key_id=settings.s3_access_key,
    aws_secret_access_key=settings.s3_secret_key,
    endpoint_url=settings.s3_endpoint,
    region_name=settings.s3_region
)

# --- 数据模型 ---
class Project(Base):
    __tablename__ = "projects"
    id = Column(String, primary_key=True, default=lambda: str(uuid.uuid4()))
    name = Column(String, nullable=False)
    # cascade="all, delete-orphan" 确保在 db.delete(project) 时自动删除关联的 Markdown 记录
    markdowns = relationship("Markdown", back_populates="project", cascade="all, delete-orphan")

class Markdown(Base):
    __tablename__ = "markdowns"
    id = Column(String, primary_key=True, default=lambda: str(uuid.uuid4()))
    title = Column(String, nullable=False)
    s3_key = Column(String, nullable=False)
    project_id = Column(String, ForeignKey("projects.id", ondelete="CASCADE"))
    project = relationship("Project", back_populates="markdowns")

Base.metadata.create_all(bind=engine)

app = FastAPI()

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

# --- API 接口 ---

@app.get("/health")
def health():
    return {"status": "ok"}

@app.post("/projects")
def create_project(name: str, db: Session = Depends(get_db)):
    project = Project(name=name)
    db.add(project)
    db.commit()
    db.refresh(project)
    return project

@app.post("/projects/{project_id}/markdowns")
def upload_markdown(project_id: str, title: str, content: str, db: Session = Depends(get_db)):
    project = db.query(Project).filter(Project.id == project_id).first()
    if not project:
        raise HTTPException(status_code=404, detail="Project not found")
    
    # 1. 存入 S3
    s3_key = f"projects/{project_id}/{uuid.uuid4()}.md"
    s3_client.put_object(
        Bucket=settings.s3_bucket_name,
        Key=s3_key,
        Body=content,
        ContentType="text/markdown"
    )

    # 2. 存入数据库
    md_record = Markdown(title=title, s3_key=s3_key, project_id=project_id)
    db.add(md_record)
    db.commit()
    return {"id": md_record.id, "s3_key": s3_key}

@app.delete("/projects/{project_id}")
def delete_project(project_id: str, db: Session = Depends(get_db)):
    project = db.query(Project).filter(Project.id == project_id).first()
    if not project:
        raise HTTPException(status_code=404, detail="Project not found")
    
    # 1. 清理 S3 中的文件
    markdowns = db.query(Markdown).filter(Markdown.project_id == project_id).all()
    if markdowns:
        keys = [{'Key': md.s3_key} for md in markdowns]
        s3_client.delete_objects(
            Bucket=settings.s3_bucket_name,
            Delete={'Objects': keys}
        )
    
    # 2. 从数据库删除项目 (SQLAlchemy 会自动处理 markdowns 表的级联删除)
    db.delete(project)
    db.commit()
    return {"message": f"Project {project_id} and its files have been purged."}