"""Evaluation functions for MacroLens benchmark."""

from __future__ import annotations

import json
from datetime import datetime, timezone
from pathlib import Path
from typing import Any

import numpy as np
import pandas as pd

from ._compat import (
    evaluate_generation,
    evaluate_re_valuation,
    evaluate_scenario_forecast,
    evaluate_valuation,
)
from ._meta import BENCHMARK_NAME, BENCHMARK_VERSION

_TASK_ALIASES: dict[str, str] = {
    # Task 1 (TSF)
    "1": "TSF",
    "tsf": "TSF",
    "time_series": "TSF",
    "forecasting": "TSF",
    # Task 2 (Val-PT)
    "2": "A",
    "a": "A",
    "valuation": "A",
    "val-pt": "A",
    # Task 3 (Stmt-Gen)
    "3": "B",
    "b": "B",
    "statement": "B",
    "stmt-gen": "B",
    # Task 4 (Scen-Ret)
    "4": "C",
    "c": "C",
    "scenario": "C",
    "scen-ret": "C",
    # Task 5 (Priv-Val)
    "5": "D",
    "d": "D",
    "private_valuation": "D",
    "priv-val": "D",
    # Task 6 (Gen-Eval)
    "6": "E",
    "e": "E",
    "generator": "E",
    "gen-eval": "E",
    # Task 7 (RE-Val)
    "7": "F",
    "f": "F",
    "real_estate": "F",
    "re-val": "F",
}


def _evaluate_tsf(
    predictions: np.ndarray,
    targets: np.ndarray,
) -> dict[str, Any]:
    """Compute TSF metrics: MSE, RMSE, MAE, Directional Accuracy.

    Parameters
    ----------
    predictions : np.ndarray
        Shape ``(N, horizon)`` or ``(N,)`` — predicted values.
    targets : np.ndarray
        Shape ``(N, horizon)`` or ``(N,)`` — ground-truth values.
    """
    predictions = np.asarray(predictions, dtype=np.float64)
    targets = np.asarray(targets, dtype=np.float64)

    if predictions.shape != targets.shape:
        raise ValueError(
            f"Shape mismatch: predictions {predictions.shape} "
            f"vs targets {targets.shape}"
        )

    mse = float(np.mean((predictions - targets) ** 2))
    rmse = float(np.sqrt(mse))
    mae = float(np.mean(np.abs(predictions - targets)))

    # Directional accuracy: compare sign of consecutive differences
    if predictions.ndim == 2 and predictions.shape[1] > 1:
        pred_diff = np.diff(predictions, axis=1)
        target_diff = np.diff(targets, axis=1)
        da = float(np.mean(np.sign(pred_diff) == np.sign(target_diff)))
    elif predictions.ndim == 1 and len(predictions) > 1:
        pred_diff = np.diff(predictions)
        target_diff = np.diff(targets)
        da = float(np.mean(np.sign(pred_diff) == np.sign(target_diff)))
    else:
        da = 0.0

    return {
        "mse": round(mse, 6),
        "rmse": round(rmse, 6),
        "mae": round(mae, 6),
        "directional_accuracy": round(da, 4),
        "n_instances": int(predictions.shape[0]),
    }


def evaluate(
    task: str,
    predictions: pd.DataFrame | np.ndarray | None = None,
    targets: np.ndarray | None = None,
    ground_truth: pd.DataFrame | None = None,
    **kwargs: Any,
) -> dict[str, Any]:
    """Evaluate predictions on a MacroLens task.

    Parameters
    ----------
    task : str
        Task identifier: ``"tsf"``, ``"A"``, ``"B"``, or ``"C"``.
    predictions : DataFrame or ndarray
        Model predictions. Format depends on the task (see below).
    targets : ndarray, optional
        Ground-truth values for TSF (shape matches ``predictions``).
    ground_truth : DataFrame, optional
        Ground-truth DataFrame for Tasks A, B, C.
    **kwargs
        Additional arguments passed to the underlying evaluator.

    Returns
    -------
    dict
        Task-specific metrics dictionary.

    Examples
    --------
    **TSF** — pass parallel arrays of predictions and targets::

        results = macrolens.evaluate("tsf", predictions=preds, targets=targets)
        # preds, targets: np.ndarray of shape (N, horizon)

    **Task 2 (Val-PT)** — pass DataFrames::

        results = macrolens.evaluate(
            "A",
            predictions=pred_df,   # cols: ticker, date, predicted_equity_value
            ground_truth=gt_df,    # cols: ticker, date, actual_market_cap
        )

    **Task 3 (Stmt-Gen)** — pass DataFrames::

        results = macrolens.evaluate(
            "B",
            predictions=pred_df,   # cols: ticker, field, value
            ground_truth=gt_df,    # cols: ticker, field, value
        )

    **Task 4 (Scen-Ret)** — pass DataFrames::

        results = macrolens.evaluate(
            "C",
            predictions=pred_df,   # cols: scenario_id, ticker, predicted_return_pct
            ground_truth=gt_df,    # cols: scenario_id, ticker, actual_return_pct
        )
    """
    canonical = _TASK_ALIASES.get(task.lower(), task.upper())

    if canonical == "TSF":
        if predictions is None or targets is None:
            raise ValueError(
                "TSF evaluation requires both `predictions` and `targets` arrays."
            )
        return _evaluate_tsf(np.asarray(predictions), np.asarray(targets))

    if canonical == "A":
        if not isinstance(predictions, pd.DataFrame) or ground_truth is None:
            raise ValueError(
                "Task 2 (Val-PT) requires `predictions` (DataFrame with cols: "
                "ticker, date, predicted_equity_value) and "
                "`ground_truth` (DataFrame with cols: ticker, date, actual_market_cap)."
            )
        _validate_columns(predictions, ["ticker", "date", "predicted_equity_value"], "predictions")
        return evaluate_valuation(predictions, ground_truth, **kwargs)

    if canonical == "B":
        if not isinstance(predictions, pd.DataFrame) or ground_truth is None:
            raise ValueError(
                "Task 3 (Stmt-Gen) requires `predictions` (DataFrame with cols: "
                "ticker, field, value) and `ground_truth` (same format)."
            )
        _validate_columns(predictions, ["ticker", "field", "value"], "predictions")
        return evaluate_generation(predictions, ground_truth, **kwargs)

    if canonical == "C":
        if not isinstance(predictions, pd.DataFrame) or ground_truth is None:
            raise ValueError(
                "Task 4 (Scen-Ret) requires `predictions` (DataFrame with cols: "
                "scenario_id, ticker, predicted_return_pct) and "
                "`ground_truth` (DataFrame with cols: scenario_id, ticker, actual_return_pct)."
            )
        _validate_columns(
            predictions, ["scenario_id", "ticker", "predicted_return_pct"], "predictions"
        )
        return evaluate_scenario_forecast(predictions, ground_truth, **kwargs)

    if canonical == "D":
        # Task D (Priv-Val) uses the same evaluation as Task A
        if not isinstance(predictions, pd.DataFrame) or ground_truth is None:
            raise ValueError(
                "Task 5 (Priv-Val) requires `predictions` (DataFrame with cols: "
                "ticker, date, predicted_equity_value) and "
                "`ground_truth` (DataFrame with cols: ticker, date, actual_market_cap)."
            )
        _validate_columns(predictions, ["ticker", "date", "predicted_equity_value"], "predictions")
        return evaluate_valuation(predictions, ground_truth, **kwargs)

    if canonical == "E":
        # Task E (Gen-Eval) uses the same evaluation as Task B (per-field MAPE)
        if not isinstance(predictions, pd.DataFrame) or ground_truth is None:
            raise ValueError(
                "Task 6 (Gen-Eval) requires `predictions` (DataFrame with cols: "
                "ticker, field, value) and `ground_truth` (same format). "
                "Use 'generator_field' as the field column name."
            )
        # Normalise: Gen-Eval GT uses 'generator_field' instead of 'field'
        gt = ground_truth.copy()
        if "generator_field" in gt.columns and "field" not in gt.columns:
            gt = gt.rename(columns={"generator_field": "field"})
        preds = predictions.copy()
        if "generator_field" in preds.columns and "field" not in preds.columns:
            preds = preds.rename(columns={"generator_field": "field"})
        _validate_columns(preds, ["ticker", "field", "value"], "predictions")
        return evaluate_generation(preds, gt, **kwargs)

    if canonical == "F":
        # Task F (RE-Val) uses evaluate_re_valuation
        if not isinstance(predictions, pd.DataFrame) or ground_truth is None:
            raise ValueError(
                "Task 7 (RE-Val) requires `predictions` (DataFrame with rent/price "
                "predictions) and `ground_truth` (DataFrame with actual rent/price)."
            )
        return evaluate_re_valuation(predictions, ground_truth, **kwargs)

    raise ValueError(
        f"Unknown task '{task}'. Valid: 'tsf', 'A', 'B', 'C', 'D', 'E', 'F' "
        "(or aliases like 'valuation', 'private_valuation', 'real_estate', etc.)"
    )


def _validate_columns(df: pd.DataFrame, required: list[str], name: str) -> None:
    """Raise ValueError if required columns are missing."""
    missing = [c for c in required if c not in df.columns]
    if missing:
        raise ValueError(
            f"{name} DataFrame is missing columns: {missing}. "
            f"Expected: {required}. Got: {df.columns.tolist()}"
        )


def format_submission(
    results: dict[str, Any],
    task: str = "tsf",
    method_name: str | None = None,
    granularity: str = "daily",
    output_path: str | Path | None = None,
) -> dict[str, Any]:
    """Format evaluation results as a benchmark submission.

    Parameters
    ----------
    results : dict
        Metrics dictionary returned by :func:`evaluate`.
    task : str
        Task identifier.
    method_name : str, optional
        Name of the method/model.
    granularity : str
        Data granularity used.
    output_path : str or Path, optional
        If provided, write the submission JSON to this path.

    Returns
    -------
    dict
        Formatted submission dictionary.

    Example
    -------
    >>> sub = macrolens.format_submission(results, task="tsf", method_name="MyModel")
    >>> sub["benchmark"]
    'MacroLens'
    """
    submission = {
        "benchmark": BENCHMARK_NAME,
        "version": BENCHMARK_VERSION,
        "task": _TASK_ALIASES.get(task.lower(), task.upper()),
        "granularity": granularity,
        "method": method_name or "unnamed",
        "results": results,
        "timestamp": datetime.now(timezone.utc).isoformat(),
    }

    if output_path is not None:
        Path(output_path).write_text(json.dumps(submission, indent=2, default=str))

    return submission