import os
import uuid
from typing import List, Optional
from fastapi import APIRouter, Depends, HTTPException, UploadFile, File, Form
from sqlalchemy.orm import Session
import httpx
from openai import AsyncOpenAI
from app.core.database import get_db
from app.core.auth import get_current_user
from app.core.config import settings
from app.models.models import User, AIEndpoint, ChatMessage, UploadedFile
from app.schemas.schemas import (
    ChatRequest,
    ChatResponse,
    ChatMessageResponse,
    UploadedFileResponse
)

router = APIRouter(prefix="/chat", tags=["Chat"])


# Ensure upload directory exists
os.makedirs(settings.UPLOAD_DIR, exist_ok=True)


@router.post("/upload", response_model=UploadedFileResponse)
async def upload_file(
    file: UploadFile = File(...),
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    # Check file size
    contents = await file.read()
    if len(contents) > settings.MAX_FILE_SIZE:
        raise HTTPException(
            status_code=400,
            detail=f"File size exceeds maximum allowed size of {settings.MAX_FILE_SIZE} bytes"
        )
    
    # Generate unique filename
    file_extension = os.path.splitext(file.filename)[1]
    unique_filename = f"{uuid.uuid4()}{file_extension}"
    file_path = os.path.join(settings.UPLOAD_DIR, unique_filename)
    
    # Save file
    with open(file_path, "wb") as f:
        f.write(contents)
    
    # Create database record
    uploaded_file = UploadedFile(
        user_id=current_user.id,
        filename=unique_filename,
        original_filename=file.filename,
        file_path=file_path,
        file_size=len(contents),
        file_type=file.content_type
    )
    db.add(uploaded_file)
    db.commit()
    db.refresh(uploaded_file)
    
    return uploaded_file


@router.get("/files", response_model=List[UploadedFileResponse])
def list_files(
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    files = db.query(UploadedFile).filter(UploadedFile.user_id == current_user.id).all()
    return files


@router.delete("/files/{file_id}")
def delete_file(
    file_id: int,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    uploaded_file = db.query(UploadedFile).filter(
        UploadedFile.id == file_id,
        UploadedFile.user_id == current_user.id
    ).first()
    
    if not uploaded_file:
        raise HTTPException(status_code=404, detail="File not found")
    
    # Delete file from filesystem
    if os.path.exists(uploaded_file.file_path):
        os.remove(uploaded_file.file_path)
    
    db.delete(uploaded_file)
    db.commit()
    
    return {"message": "File deleted successfully"}


@router.post("/message", response_model=ChatResponse)
async def send_message(
    request: ChatRequest,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    # Get the AI endpoint
    endpoint = None
    if request.endpoint_id:
        endpoint = db.query(AIEndpoint).filter(
            AIEndpoint.id == request.endpoint_id,
            AIEndpoint.is_active == True
        ).first()
    else:
        # Get default endpoint
        endpoint = db.query(AIEndpoint).filter(
            AIEndpoint.is_default == True,
            AIEndpoint.is_active == True
        ).first()
    
    if not endpoint:
        raise HTTPException(
            status_code=400,
            detail="No active AI endpoint available"
        )
    
    # Save user message
    user_message = ChatMessage(
        user_id=current_user.id,
        role="user",
        content=request.message,
        endpoint_id=endpoint.id
    )
    db.add(user_message)
    db.commit()
    
    # Build messages for API call
    messages = []
    if request.conversation_history:
        for msg in request.conversation_history:
            messages.append({"role": msg.role, "content": msg.content})
    messages.append({"role": "user", "content": request.message})
    
    # Call AI endpoint
    try:
        response_content = await call_ai_endpoint(endpoint, messages)
    except Exception as e:
        raise HTTPException(
            status_code=500,
            detail=f"Error calling AI endpoint: {str(e)}"
        )
    
    # Save assistant message
    assistant_message = ChatMessage(
        user_id=current_user.id,
        role="assistant",
        content=response_content,
        endpoint_id=endpoint.id
    )
    db.add(assistant_message)
    db.commit()
    
    return ChatResponse(
        response=response_content,
        endpoint_id=endpoint.id,
        model=endpoint.model_name
    )


async def call_ai_endpoint(endpoint: AIEndpoint, messages: List[dict]) -> str:
    if endpoint.endpoint_type == "openai":
        return await call_openai_compatible(endpoint, messages)
    elif endpoint.endpoint_type == "ollama":
        return await call_ollama(endpoint, messages)
    else:
        raise ValueError(f"Unknown endpoint type: {endpoint.endpoint_type}")


async def call_openai_compatible(endpoint: AIEndpoint, messages: List[dict]) -> str:
    """Call OpenAI-compatible API (works with OpenAI, local AI servers, etc.)"""
    client = AsyncOpenAI(
        api_key=endpoint.api_key or "not-needed",
        base_url=endpoint.base_url
    )
    
    response = await client.chat.completions.create(
        model=endpoint.model_name,
        messages=messages
    )
    
    return response.choices[0].message.content


async def call_ollama(endpoint: AIEndpoint, messages: List[dict]) -> str:
    """Call Ollama API"""
    async with httpx.AsyncClient() as client:
        response = await client.post(
            f"{endpoint.base_url.rstrip('/')}/api/chat",
            json={
                "model": endpoint.model_name,
                "messages": messages,
                "stream": False
            },
            timeout=60.0
        )
        response.raise_for_status()
        data = response.json()
        return data["message"]["content"]


@router.get("/history", response_model=List[ChatMessageResponse])
def get_history(
    limit: int = 50,
    endpoint_id: Optional[int] = None,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    query = db.query(ChatMessage).filter(ChatMessage.user_id == current_user.id)
    
    if endpoint_id:
        query = query.filter(ChatMessage.endpoint_id == endpoint_id)
    
    messages = query.order_by(ChatMessage.created_at.desc()).limit(limit).all()
    return list(reversed(messages))


@router.delete("/history")
def clear_history(
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    db.query(ChatMessage).filter(ChatMessage.user_id == current_user.id).delete()
    db.commit()
    return {"message": "Chat history cleared successfully"}