"""
Backtest execution and history endpoints.
"""
from typing import Any

from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy.orm import Session

from api.models.database import get_db
from api.models.schemas import (
    BacktestListResponse,
    BacktestRequest,
    BacktestResult,
    CompareRequest,
    CompareResult,
)
from api.services.runner import get_runner
from api.services.storage import get_storage
from engine.logging_config import get_logger

router = APIRouter()
logger = get_logger(__name__)


@router.post("/backtest", response_model=BacktestResult)
async def run_backtest(
    request: BacktestRequest,
    db: Session = Depends(get_db),
):
    """
    Execute a backtest with the specified configuration.
    
    Runs the strategy on historical data and returns metrics,
    equity curve, and trade records. Results are automatically saved.
    """
    runner = get_runner()
    storage = get_storage()
    
    try:
        # Execute backtest
        result = runner.run(request)
        
        # Save to database
        storage.save_run(db, result)
        
        logger.info(
            "Backtest completed and saved: %s (return=%.2f%%, sharpe=%.2f)",
            result.run_id,
            result.metrics.total_return,
            result.metrics.sharpe_ratio,
        )
        
        return result
        
    except KeyError as e:
        raise HTTPException(status_code=400, detail=f"Invalid strategy: {e}")
    except FileNotFoundError as e:
        raise HTTPException(status_code=404, detail=f"Data not found: {e}")
    except Exception as e:
        logger.error("Backtest failed: %s", e, exc_info=True)
        raise HTTPException(status_code=500, detail=str(e))


@router.get("/backtests", response_model=BacktestListResponse)
async def list_backtests(
    limit: int = Query(50, ge=1, le=200),
    offset: int = Query(0, ge=0),
    strategy: str | None = None,
    symbol: str | None = None,
    db: Session = Depends(get_db),
):
    """
    List saved backtest runs with optional filtering.
    
    Returns summaries for quick display in the history sidebar.
    """
    storage = get_storage()
    
    runs, total = storage.list_runs(
        db, 
        limit=limit, 
        offset=offset,
        strategy=strategy,
        symbol=symbol,
    )
    
    return BacktestListResponse(runs=runs, total=total)


@router.get("/backtest/{run_id}", response_model=BacktestResult)
async def get_backtest(
    run_id: str,
    db: Session = Depends(get_db),
):
    """
    Retrieve a specific backtest run by ID.
    
    Returns full result including equity curve and trades.
    """
    storage = get_storage()
    
    result = storage.get_run(db, run_id)
    
    if not result:
        raise HTTPException(status_code=404, detail=f"Run not found: {run_id}")
    
    return result


@router.delete("/backtest/{run_id}")
async def delete_backtest(
    run_id: str,
    db: Session = Depends(get_db),
):
    """
    Delete a backtest run.
    """
    storage = get_storage()
    
    deleted = storage.delete_run(db, run_id)
    
    if not deleted:
        raise HTTPException(status_code=404, detail=f"Run not found: {run_id}")
    
    return {"status": "deleted", "run_id": run_id}


@router.post("/compare", response_model=CompareResult)
async def compare_runs(
    request: CompareRequest,
    db: Session = Depends(get_db),
):
    """
    Compare multiple backtest runs (2-5 runs).
    
    Returns full results for each run plus parameter differences.
    """
    storage = get_storage()
    
    runs = storage.get_runs_by_ids(db, request.run_ids)
    
    if len(runs) != len(request.run_ids):
        found_ids = {r.run_id for r in runs}
        missing = [rid for rid in request.run_ids if rid not in found_ids]
        raise HTTPException(
            status_code=404, 
            detail=f"Runs not found: {missing}"
        )
    
    # Calculate parameter differences
    param_diff = _calculate_param_diff(runs)
    
    return CompareResult(runs=runs, param_diff=param_diff)


def _calculate_param_diff(runs: list[BacktestResult]) -> dict[str, list[Any]]:
    """
    Find parameters that differ between runs.
    
    Returns dict mapping param name to list of values (one per run).
    """
    if not runs:
        return {}
    
    # Collect all param keys
    all_keys: set[str] = set()
    for run in runs:
        all_keys.update(run.params.keys())
    
    # Also include strategy and key config
    all_keys.update(['strategy', 'symbol', 'leverage', 'timeframe'])
    
    diff: dict[str, list[Any]] = {}
    
    for key in sorted(all_keys):
        values = []
        for run in runs:
            if key == 'strategy':
                values.append(run.strategy)
            elif key == 'symbol':
                values.append(run.symbol)
            elif key == 'leverage':
                values.append(run.leverage)
            elif key == 'timeframe':
                values.append(run.timeframe)
            else:
                values.append(run.params.get(key))
        
        # Only include if values differ
        if len(set(str(v) for v in values)) > 1:
            diff[key] = values
    
    return diff