Source code for trader.chat.backtest_format

"""Formatting a `BacktestResult` for the chat CLI.

Deliberately **not** run through the model at all: every number here already
came out of `run_backtest`, so there is nothing for a second LLM call to add
except a chance to misstate one of them. Issue #15 asks for "the same results
summary the backtest CLI command produces" — this mirrors
`trader.cli.main.backtest`'s own `typer.echo` lines line for line rather than
re-deriving a second copy of that formatting.
"""

from trader.backtest.engine import BacktestResult

__all__ = ["format_backtest_result"]




def format_backtest_result(result: BacktestResult, bar_count: int) -> str:
    """The same summary `trader backtest` prints, as one block of text."""
    lines = [
        f"{result.strategy_id} on {result.symbol}  ({bar_count} bars)",
        f"  starting value:  {result.starting_value}",
        f"  ending value:    {result.ending_value}",
        f"  total return:    {result.total_return_pct:.2f}%",
        f"  max drawdown:    {result.max_drawdown_pct:.2f}%",
        f"  wins / losses:   {result.win_count} / {result.loss_count}",
        f"  trades:          {len(result.trades)}",
        "",
        f"  buy & hold:      {result.benchmark_return_pct:.2f}%",
        f"  buy & hold value:{result.benchmark_ending_value:>12.2f}",
        f"  excess vs hold:  {result.excess_return_pct:+.2f}%",
    ]
    return "\n".join(lines)