from fastapi import APIRouter, Depends, UploadFile, File, HTTPException
from typing import List
from sqlalchemy.orm import Session
from services.s3_service import s3_service
from api.auth import get_current_user
from core.database import get_db
from models import db_models
from models.schemas import SourceFileResponse
from services.rag_service import rag_service

router = APIRouter(prefix="/api/sources", tags=["sources"])

@router.post("/upload", response_model=dict)
async def upload_source(
    file: UploadFile = File(...),
    current_user: db_models.User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    try:
        content = await file.read()
        file_info = await s3_service.upload_file(
            file_content=content,
            filename=file.filename,
            user_id=str(current_user.id)
        )
        
        # Save metadata to database
        db_source = db_models.Source(
            filename=file.filename,
            s3_key=file_info["key"],
            s3_url=file_info["public_url"], # Store public URL in DB
            size=len(content),
            user_id=current_user.id
        )
        db.add(db_source)
        db.commit()
        db.refresh(db_source)

        return {
            "id": db_source.id,
            "filename": file.filename, 
            "key": file_info["key"], 
            "public_url": file_info["public_url"],
            "private_url": file_info["private_url"],
            "message": "Upload successful"
        }
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))

@router.get("/list", response_model=List[SourceFileResponse])
async def list_sources(
    current_user: db_models.User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    try:
        # Join Source with RAGDocument to get indexing info if it exists
        results = db.query(
            db_models.Source,
            db_models.RAGDocument.id.label("rag_id"),
            db_models.RAGDocument.azure_doc_id
        ).outerjoin(
            db_models.RAGDocument, 
            db_models.Source.id == db_models.RAGDocument.source_id
        ).filter(
            db_models.Source.user_id == current_user.id
        ).all()
        
        response_sources = []
        for source, rag_id, azure_doc_id in results:
            response_sources.append({
                "id": source.id,
                "filename": source.filename,
                "s3_key": source.s3_key,
                "public_url": source.s3_url,
                "private_url": s3_service.get_presigned_url(source.s3_key),
                "size": source.size,
                "created_at": source.created_at,
                "rag_id": rag_id,
                "azure_doc_id": azure_doc_id
            })
        return response_sources
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))

@router.delete("/{source_id}")
async def delete_source(
    source_id: int,
    current_user: db_models.User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    source = db.query(db_models.Source).filter(
        db_models.Source.id == source_id,
        db_models.Source.user_id == current_user.id
    ).first()
    
    if not source:
        raise HTTPException(status_code=404, detail="Source not found")
    
    try:
        # 1. Handle RAG Document (Delete completely as it's useless without the source)
        rag_doc = db.query(db_models.RAGDocument).filter(
            db_models.RAGDocument.source_id == source.id
        ).first()
        
        if rag_doc:
            # Delete from Azure Search
            rag_service.delete_document(rag_doc.azure_doc_id)
            # Delete from DB
            db.delete(rag_doc)

        # 2. Handle other dependencies (Delete everything linked to this source)
        # We must delete children (Flashcards, Questions) before parents (Sets) because of SQL constraints
        
        # Delete Flashcards
        flashcard_set_ids = [s.id for s in db.query(db_models.FlashcardSet).filter(db_models.FlashcardSet.source_id == source.id).all()]
        if flashcard_set_ids:
            db.query(db_models.Flashcard).filter(db_models.Flashcard.flashcard_set_id.in_(flashcard_set_ids)).delete(synchronize_session=False)
        
        # Delete Quiz Questions
        quiz_set_ids = [s.id for s in db.query(db_models.QuizSet).filter(db_models.QuizSet.source_id == source.id).all()]
        if quiz_set_ids:
            db.query(db_models.QuizQuestion).filter(db_models.QuizQuestion.quiz_set_id.in_(quiz_set_ids)).delete(synchronize_session=False)

        # Now delete the sets and other items
        db.query(db_models.MindMap).filter(db_models.MindMap.source_id == source.id).delete()
        db.query(db_models.FlashcardSet).filter(db_models.FlashcardSet.source_id == source.id).delete()
        db.query(db_models.QuizSet).filter(db_models.QuizSet.source_id == source.id).delete()
        db.query(db_models.Report).filter(db_models.Report.source_id == source.id).delete()
        db.query(db_models.VideoSummary).filter(db_models.VideoSummary.source_id == source.id).delete()
        
        db.commit() # Commit deletions 

        # 3. Delete from S3 if it exists
        if source.s3_key:
            await s3_service.delete_file(source.s3_key)
        
        # 4. Delete the Source itself from Database
        db.delete(source)
        db.commit()
        
        return {"message": "Source and all associated generated content (mind maps, quizzes, etc.) deleted successfully."}
        
    except Exception as e:
        db.rollback()
        raise HTTPException(status_code=500, detail=f"Failed to delete source: {str(e)}")