"""
evalport.py — Evaluation port protocol for pluggable scoring.

Defines the interface between the framework and evaluation backends.
EvalPort is a protocol (structural typing) — any object with the right
methods can serve as an evaluation backend.
"""
from __future__ import annotations

from dataclasses import dataclass, field
from typing import Any, Protocol, runtime_checkable


@dataclass
class ScoreBundle:
    """A collection of named scores for one evaluation."""
    scores: dict[str, float] = field(default_factory=dict)
    metadata: dict[str, Any] = field(default_factory=dict)
    passed: bool = True
    failure_reasons: list[str] = field(default_factory=list)

    def __getitem__(self, key: str) -> float:
        return self.scores[key]

    def get(self, key: str, default: float = 0.0) -> float:
        return self.scores.get(key, default)


@dataclass
class EvalCase:
    """A single evaluation test case."""
    id: str
    input_purpose: str
    input_state: dict[str, Any] = field(default_factory=dict)
    expected: dict[str, Any] = field(default_factory=dict)
    max_steps: int = 20
    category: str = "general"
    difficulty: str = "medium"
    split: str = "test"              # "train", "validation", "test"
    tags: list[str] = field(default_factory=list)


@runtime_checkable
class EvalPort(Protocol):
    """
    Protocol for evaluation backends.

    Implement this to plug in custom scoring logic.
    The framework calls evaluate() after each task and score_bundle()
    to aggregate results.
    """

    def evaluate(self, case: EvalCase, result_state: dict[str, Any], trajectory: Any) -> ScoreBundle:
        """Evaluate a single completed task."""
        ...

    def score_bundle(self, bundles: list[ScoreBundle]) -> dict[str, float]:
        """Aggregate multiple ScoreBundles into summary metrics."""
        ...


class DictEvalPort:
    """
    Simple evaluation port that checks expected keys in the final state.

    Usage:
        port = DictEvalPort()
        case = EvalCase(id="t1", input_purpose="...",
                        expected={"task_complete": True})
        bundle = port.evaluate(case, result_state={"task_complete": True}, trajectory=None)
        assert bundle.passed
    """

    def evaluate(
        self, case: EvalCase, result_state: dict[str, Any], trajectory: Any = None,
    ) -> ScoreBundle:
        scores = {}
        failures = []

        if not case.expected:
            # No expected values — score by Φ
            if trajectory and hasattr(trajectory, "final_phi"):
                phi = trajectory.final_phi or 0
                scores["phi"] = phi
                if phi < 7.0:
                    failures.append(f"final_phi={phi:.1f} < 7.0")
            return ScoreBundle(
                scores=scores, passed=len(failures) == 0,
                failure_reasons=failures,
            )

        # Check each expected key
        matches = 0
        for key, expected_val in case.expected.items():
            actual = result_state.get(key)
            is_match = actual == expected_val
            scores[f"match_{key}"] = 1.0 if is_match else 0.0
            if is_match:
                matches += 1
            else:
                failures.append(f"{key}: expected={expected_val}, got={actual}")

        scores["exact_match"] = matches / len(case.expected) if case.expected else 1.0
        return ScoreBundle(
            scores=scores,
            passed=len(failures) == 0,
            failure_reasons=failures,
        )

    def score_bundle(self, bundles: list[ScoreBundle]) -> dict[str, float]:
        if not bundles:
            return {}
        n = len(bundles)
        pass_rate = sum(1 for b in bundles if b.passed) / n

        # Average all score keys
        all_keys = set()
        for b in bundles:
            all_keys.update(b.scores.keys())

        avgs = {}
        for key in all_keys:
            vals = [b.scores.get(key, 0) for b in bundles]
            avgs[f"avg_{key}"] = sum(vals) / len(vals)

        avgs["pass_rate"] = pass_rate
        avgs["n"] = float(n)
        return avgs