import os
from fastapi import APIRouter, HTTPException
from sqlalchemy import text
from qdrant_client import QdrantClient
from qdrant_client.models import Distance, VectorParams, PayloadSchemaType
from alembic.config import Config
from alembic import command
from fastapi.concurrency import run_in_threadpool

from ..database import engine
from ..config import get_settings

router = APIRouter()

@router.post("/reset-db")
async def reset_db(password: str = None):
    if password != "ketanD048":
        raise HTTPException(status_code=403, detail="Invalid reset password.")
    
    settings = get_settings()
    
    try:
        # 1. Wipe Postgres natively (drop schema and recreate)
        async with engine.begin() as conn:
            # We use CASCADE to drop everything including tables, types, etc.
            await conn.execute(text('DROP SCHEMA public CASCADE'))
            await conn.execute(text('CREATE SCHEMA public'))
            await conn.execute(text('GRANT ALL ON SCHEMA public TO public'))
        
        # 2. Wipe Qdrant Collection
        q = QdrantClient(url=settings.qdrant_url, api_key=settings.qdrant_api_key)
        try:
            q.delete_collection(settings.collection_name)
        except Exception:
            # OK if collection didn't exist
            pass
            
        q.create_collection(
            collection_name=settings.collection_name, 
            vectors_config=VectorParams(size=settings.vector_size, distance=Distance.COSINE)
        )
        
        # Reinject indices required by the pipeline
        q.create_payload_index(
            collection_name=settings.collection_name,
            field_name="session_id",
            field_schema=PayloadSchemaType.KEYWORD
        )
        q.create_payload_index(
            collection_name=settings.collection_name,
            field_name="years_of_experience",
            field_schema=PayloadSchemaType.FLOAT
        )

        # 3. Run Alembic Migrations to restore schema
        # We assume the API is running from the 'backend' directory where alembic.ini resides.
        # If not, we attempt to find it relative to this file.
        base_path = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
        ini_path = os.path.join(base_path, "alembic.ini")
        
        if not os.path.exists(ini_path):
            # Fallback for different envs
            ini_path = "alembic.ini"

        def _run_migrations():
            alembic_cfg = Config(ini_path)
            # Ensure the script location is absolute to avoid confusion
            alembic_cfg.set_main_option("script_location", os.path.join(base_path, "alembic"))
            command.upgrade(alembic_cfg, "head")

        await run_in_threadpool(_run_migrations)

        return {"status": "success", "message": "Database and Vector Store have been reset and migrations reapplied."}
    except Exception as e:
        print(f"RESET ERROR: {e}")
        raise HTTPException(status_code=500, detail=str(e))