"""Standalone pre/post-train evaluator for the drug-target-validation env.

Loads a Hugging-Face causal-LM (or local checkpoint), runs ``--episodes``
fresh ``DrugTargetEnvironment`` rollouts using the same prompt-build /
parser as ``training/training_script.py``, and writes one JSONL row per
episode to ``--out``.

Each row carries:

* deterministic seed + scenario / target context,
* the action sequence + per-step rewards the model produced,
* whether the episode terminated with a submitted report,
* whether the submitted go/no_go matches the hidden ``correct_decision``,
* per-component reward totals derived from
  ``RewardBreakdown.to_dict()`` keys, summed over the trajectory.

The evaluator is intentionally model-agnostic: any HF-compatible
causal-LM works, including the SFT warm-start checkpoint that lives at
``runs/sft-warmstart`` and the GRPO output at ``runs/grpo-output``. A
final summary line is printed for the orchestration log.

CLI::

    python -m training.evaluate \\
        --model_name <hub-id-or-local-path> \\
        --episodes 8 --max_steps 25 \\
        --difficulty mixed \\
        --tag pre_train \\
        --out evidence/pre_eval.jsonl \\
        --record_components
"""

from __future__ import annotations

import argparse
import json
import logging
import sys
import time
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any, Dict, List, Optional

from models import ActionType, DrugTargetAction, ValidationObservation
from server.hackathon_environment import DrugTargetEnvironment, MAX_STEPS
from training.training_script import (
    build_training_prompt,
    ensure_terminal_payload,
    parse_action_completion,
)


logging.basicConfig(level=logging.INFO, format="%(asctime)s [%(levelname)s] %(message)s")
logger = logging.getLogger("training.evaluate")


# Reward component column names mirror ``RewardBreakdown.to_dict()`` so
# the JSONL is directly pivotable against the dashboard cards.
_REWARD_COMPONENTS = (
    "evidence_coverage",
    "decision_accuracy",
    "credit_efficiency",
    "reasoning_coherence",
    "novelty",
    "penalty",
    "shaping",
    "terminal",
)


# A maximally-defensive fallback when the model emits unparseable text.
# Mirrors ``training/training_script.OpenEnvReward.invalid_action_penalty``
# so the model is consistently penalised for non-JSON output.
_INVALID_ACTION_PENALTY = -2.0


@dataclass
class EpisodeResult:
    """Single-episode evaluation record (becomes one JSONL row)."""

    episode: int
    scenario: Optional[str]
    target_gene: str
    indication: str
    tag: str
    seed: int
    n_steps: int
    cumulative_reward: float
    submitted: bool
    submitted_decision: Optional[str]
    correct_decision: Optional[str]
    decision_accuracy: float
    evidence_coverage: float
    credits_used: int
    credits_total: int
    action_sequence: List[str]
    step_rewards: List[float]
    invalid_actions: int
    reward_components_total: Dict[str, float] = field(default_factory=dict)

    def to_jsonl(self) -> str:
        return json.dumps({
            "episode": self.episode,
            "scenario": self.scenario,
            "target_gene": self.target_gene,
            "indication": self.indication,
            "tag": self.tag,
            "seed": self.seed,
            "n_steps": self.n_steps,
            "cumulative_reward": round(self.cumulative_reward, 6),
            "submitted": self.submitted,
            "submitted_decision": self.submitted_decision,
            "correct_decision": self.correct_decision,
            "decision_accuracy": round(self.decision_accuracy, 6),
            "evidence_coverage": round(self.evidence_coverage, 6),
            "credits_used": self.credits_used,
            "credits_total": self.credits_total,
            "action_sequence": self.action_sequence,
            "step_rewards": [round(float(r), 6) for r in self.step_rewards],
            "invalid_actions": self.invalid_actions,
            "reward_components_total": {
                k: round(float(v), 6)
                for k, v in self.reward_components_total.items()
            },
        }, ensure_ascii=False)


def _parse_args(argv: Optional[List[str]] = None) -> argparse.Namespace:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--model_name", required=True,
                        help="HF hub id or local path (must be HF-compatible).")
    parser.add_argument("--episodes", type=int, default=8)
    parser.add_argument("--max_steps", type=int, default=25)
    parser.add_argument(
        "--difficulty",
        choices=["easy", "medium", "hard", "mixed"],
        default="mixed",
        help="Filter scenario library to this difficulty tier.",
    )
    parser.add_argument(
        "--scenario_name",
        default=None,
        help="Optional scenario name override; default samples from the full library.",
    )
    parser.add_argument("--tag", required=True,
                        help="Free-form tag (e.g. pre_train, post_train) — copied into each row.")
    parser.add_argument("--out", required=True,
                        help="Output JSONL path (parent dir is created).")
    parser.add_argument("--seed_base", type=int, default=10_000)
    parser.add_argument("--max_new_tokens", type=int, default=384)
    parser.add_argument("--temperature", type=float, default=0.7)
    parser.add_argument("--top_p", type=float, default=0.9)
    parser.add_argument(
        "--record_components",
        action="store_true",
        default=True,
        help=(
            "Record per-episode reward component totals "
            "(evidence_coverage, decision_accuracy, ...). On by default."
        ),
    )
    parser.add_argument(
        "--no_record_components",
        dest="record_components",
        action="store_false",
        help="Skip per-component recording (writes empty dict).",
    )
    parser.add_argument(
        "--trust_remote_code",
        action="store_true",
        help="Pass trust_remote_code=True to model/tokenizer loading.",
    )
    parser.add_argument(
        "--no_sample",
        action="store_true",
        help="Use greedy decoding (do_sample=False).",
    )
    return parser.parse_args(argv)


def _filter_scenarios(env: DrugTargetEnvironment, difficulty: str) -> None:
    """Restrict the env's task generator to scenarios of the given tier."""
    if difficulty == "mixed":
        return
    env._task_gen.scenarios = [
        s for s in env._task_gen.scenarios if s.difficulty == difficulty
    ]
    if not env._task_gen.scenarios:
        raise SystemExit(
            f"No scenarios match difficulty={difficulty!r} "
            f"(allowed: easy, medium, hard, mixed)."
        )


def _load_model(model_name: str, *, trust_remote_code: bool):
    """Best-effort HF causal-LM load with sensible dtype + device pick."""
    import torch
    from transformers import AutoModelForCausalLM, AutoTokenizer

    use_cuda = torch.cuda.is_available()
    bf16 = bool(getattr(torch.cuda, "is_bf16_supported", lambda: False)()) if use_cuda else False
    dtype = torch.bfloat16 if bf16 else (torch.float16 if use_cuda else torch.float32)

    logger.info("loading tokenizer for %s", model_name)
    tokenizer = AutoTokenizer.from_pretrained(model_name, trust_remote_code=trust_remote_code)
    if tokenizer.pad_token is None and tokenizer.eos_token is not None:
        tokenizer.pad_token = tokenizer.eos_token

    logger.info("loading model for %s (cuda=%s, dtype=%s)", model_name, use_cuda, dtype)
    model = AutoModelForCausalLM.from_pretrained(
        model_name,
        trust_remote_code=trust_remote_code,
        torch_dtype=dtype,
    )
    if use_cuda:
        model = model.to("cuda")
    model.eval()
    return tokenizer, model


def _generate_action_text(
    *,
    tokenizer,
    model,
    prompt: str,
    max_new_tokens: int,
    temperature: float,
    top_p: float,
    do_sample: bool,
) -> str:
    """Run ``model.generate`` once and return only the new completion text."""
    import torch

    inputs = tokenizer(prompt, return_tensors="pt", truncation=True, max_length=2048)
    inputs = {k: v.to(model.device) for k, v in inputs.items()}
    prompt_len = int(inputs["input_ids"].shape[1])

    gen_kwargs = {
        "max_new_tokens": int(max_new_tokens),
        "do_sample": bool(do_sample),
        "pad_token_id": tokenizer.pad_token_id,
    }
    if do_sample:
        gen_kwargs["temperature"] = float(temperature)
        gen_kwargs["top_p"] = float(top_p)

    with torch.no_grad():
        out_ids = model.generate(**inputs, **gen_kwargs)
    new_tokens = out_ids[0][prompt_len:]
    return tokenizer.decode(new_tokens, skip_special_tokens=True).strip()


def _accumulate_components(
    totals: Dict[str, float],
    breakdown: Dict[str, float],
) -> None:
    """Sum step / terminal reward-breakdown values into the running totals.

    ``DrugTargetEnvironment`` already merges step + terminal breakdowns into
    a single dict per step (terminal keys carry a ``term_`` prefix). We
    therefore look up both shapes for each canonical component and add
    them together so the totals are *per-episode*, not per-step.
    """
    for comp in _REWARD_COMPONENTS:
        v = breakdown.get(comp)
        if isinstance(v, (int, float)):
            totals[comp] = totals.get(comp, 0.0) + float(v)
        v = breakdown.get(f"term_{comp}")
        if isinstance(v, (int, float)):
            totals[comp] = totals.get(comp, 0.0) + float(v)


def _final_episode_metrics(
    env: DrugTargetEnvironment,
    last_breakdown: Dict[str, float],
) -> Dict[str, Any]:
    """Pull terminal evidence_coverage + decision_accuracy + ground truth.

    ``env._latent`` is rebound on every step, so we read it *after* the
    final ``env.step`` call; the post-terminal breakdown carries the
    ``term_*`` keys that the reward computer wrote out.
    """
    latent = env._latent
    correct_decision: Optional[str] = None
    submitted = False
    if latent is not None:
        correct_decision = latent.target.correct_decision
        submitted = bool(latent.progress.report_submitted)

    evidence_cov = float(
        last_breakdown.get("term_evidence_coverage")
        or last_breakdown.get("evidence_coverage")
        or 0.0
    )
    decision_acc = float(
        last_breakdown.get("term_decision_accuracy")
        or last_breakdown.get("decision_accuracy")
        or 0.0
    )
    return {
        "correct_decision": correct_decision,
        "submitted": submitted,
        "evidence_coverage": evidence_cov,
        "decision_accuracy": decision_acc,
    }


def evaluate_episode(
    *,
    episode_idx: int,
    seed: int,
    args: argparse.Namespace,
    tokenizer,
    model,
) -> EpisodeResult:
    """Run a single evaluation episode end-to-end."""
    env = DrugTargetEnvironment(
        scenario_name=args.scenario_name,
        domain_randomise=False,
    )
    _filter_scenarios(env, args.difficulty)
    obs: ValidationObservation = env.reset(seed=seed)

    target_gene = obs.target_gene
    indication = obs.indication
    scenario_name = args.scenario_name or getattr(env._task, "scenario_name", None) \
        or getattr(env._task, "target_gene", None)

    action_sequence: List[str] = []
    step_rewards: List[float] = []
    cumulative = 0.0
    invalid = 0
    submitted_decision: Optional[str] = None
    components_total: Dict[str, float] = {c: 0.0 for c in _REWARD_COMPONENTS}
    last_breakdown: Dict[str, float] = {}
    n_steps = 0

    cap = min(int(args.max_steps), MAX_STEPS)
    for step_idx in range(cap):
        if obs.done:
            break
        prompt = build_training_prompt(obs)
        completion = _generate_action_text(
            tokenizer=tokenizer,
            model=model,
            prompt=prompt,
            max_new_tokens=args.max_new_tokens,
            temperature=args.temperature,
            top_p=args.top_p,
            do_sample=not args.no_sample,
        )
        action = parse_action_completion(completion)

        if action is None:
            invalid += 1
            cumulative += _INVALID_ACTION_PENALTY
            step_rewards.append(_INVALID_ACTION_PENALTY)
            action_sequence.append("__invalid__")
            n_steps += 1
            # We deliberately do *not* call env.step on garbage output —
            # the env would raise; instead we charge the standard invalid
            # action penalty (mirrors the GRPO reward function) and try
            # again on the next step. This means n_steps reflects all
            # generation attempts, not just env-ticks.
            continue

        action = ensure_terminal_payload(obs, action)
        try:
            obs = env.step(action)
        except Exception as exc:
            logger.warning(
                "episode %d step %d: env.step raised (%s); episode terminated",
                episode_idx, step_idx, exc,
            )
            cumulative += _INVALID_ACTION_PENALTY
            step_rewards.append(_INVALID_ACTION_PENALTY)
            action_sequence.append(action.action_type.value)
            n_steps += 1
            invalid += 1
            break

        action_sequence.append(action.action_type.value)
        step_reward = float(obs.reward or 0.0)
        cumulative += step_reward
        step_rewards.append(step_reward)
        last_breakdown = dict(obs.step_reward_breakdown or {})
        if args.record_components:
            _accumulate_components(components_total, last_breakdown)
        if action.action_type == ActionType.SUBMIT_VALIDATION_REPORT:
            submitted_decision = action.final_decision
        n_steps += 1

    final = _final_episode_metrics(env, last_breakdown)
    correct_decision = final["correct_decision"]
    submitted = final["submitted"]

    if not submitted:
        # Backstop the field with whatever the model last picked, so the
        # JSONL row is still inspectable.
        for at in reversed(action_sequence):
            if at == ActionType.SUBMIT_VALIDATION_REPORT.value:
                # action_sequence is parallel with step_rewards; this is
                # only reached when the env rejected the submission.
                break

    return EpisodeResult(
        episode=episode_idx,
        scenario=scenario_name,
        target_gene=target_gene,
        indication=indication,
        tag=args.tag,
        seed=seed,
        n_steps=n_steps,
        cumulative_reward=cumulative,
        submitted=submitted,
        submitted_decision=submitted_decision,
        correct_decision=correct_decision,
        decision_accuracy=float(final["decision_accuracy"]),
        evidence_coverage=float(final["evidence_coverage"]),
        credits_used=int(getattr(obs, "credits_total", 0) - getattr(obs, "credits_remaining", 0)),
        credits_total=int(getattr(obs, "credits_total", 0)),
        action_sequence=action_sequence,
        step_rewards=step_rewards,
        invalid_actions=invalid,
        reward_components_total=components_total if args.record_components else {},
    )


def _summary(results: List[EpisodeResult]) -> Dict[str, float]:
    """Aggregate stats for the human-readable log line."""
    n = len(results)
    if n == 0:
        return {"n": 0}
    rewards = [r.cumulative_reward for r in results]
    submitted = [1.0 if r.submitted else 0.0 for r in results]
    decision_match = [
        1.0 if (r.submitted and r.submitted_decision == r.correct_decision) else 0.0
        for r in results
    ]
    success = [
        1.0 if (
            r.submitted
            and r.submitted_decision == r.correct_decision
            and r.cumulative_reward > 0
        ) else 0.0
        for r in results
    ]
    return {
        "n": n,
        "mean_reward": sum(rewards) / n,
        "median_reward": sorted(rewards)[n // 2],
        "submission_rate": sum(submitted) / n,
        "decision_match_rate": sum(decision_match) / n,
        "success_rate": sum(success) / n,
        "mean_evidence_coverage": sum(r.evidence_coverage for r in results) / n,
        "mean_decision_accuracy": sum(r.decision_accuracy for r in results) / n,
    }


def main(argv: Optional[List[str]] = None) -> int:
    args = _parse_args(argv)
    out_path = Path(args.out)
    out_path.parent.mkdir(parents=True, exist_ok=True)

    t0 = time.time()
    tokenizer, model = _load_model(
        args.model_name,
        trust_remote_code=args.trust_remote_code,
    )
    load_s = time.time() - t0

    logger.info(
        "starting eval: model=%s episodes=%d max_steps=%d tag=%s difficulty=%s",
        args.model_name, args.episodes, args.max_steps, args.tag, args.difficulty,
    )

    results: List[EpisodeResult] = []
    eval_t0 = time.time()
    with open(out_path, "w", encoding="utf-8") as f:
        for i in range(int(args.episodes)):
            seed = int(args.seed_base) + i
            try:
                result = evaluate_episode(
                    episode_idx=i,
                    seed=seed,
                    args=args,
                    tokenizer=tokenizer,
                    model=model,
                )
            except Exception as exc:
                logger.exception("episode %d failed: %s", i, exc)
                result = EpisodeResult(
                    episode=i,
                    scenario=args.scenario_name,
                    target_gene="UNKNOWN",
                    indication="unspecified",
                    tag=args.tag,
                    seed=seed,
                    n_steps=0,
                    cumulative_reward=_INVALID_ACTION_PENALTY,
                    submitted=False,
                    submitted_decision=None,
                    correct_decision=None,
                    decision_accuracy=0.0,
                    evidence_coverage=0.0,
                    credits_used=0,
                    credits_total=0,
                    action_sequence=[],
                    step_rewards=[],
                    invalid_actions=1,
                    reward_components_total={c: 0.0 for c in _REWARD_COMPONENTS},
                )
            f.write(result.to_jsonl() + "\n")
            f.flush()
            results.append(result)
            logger.info(
                "[%s ep=%d] reward=%+.3f steps=%d submitted=%s decision=%s/%s "
                "coverage=%.2f decision_acc=%.2f",
                args.tag, i, result.cumulative_reward, result.n_steps,
                result.submitted, result.submitted_decision,
                result.correct_decision, result.evidence_coverage,
                result.decision_accuracy,
            )

    eval_s = time.time() - eval_t0
    summary = _summary(results)
    summary.update({
        "load_duration_s": round(load_s, 2),
        "eval_duration_s": round(eval_s, 2),
        "model_name": args.model_name,
        "tag": args.tag,
        "out": str(out_path),
    })
    logger.info("[eval-summary tag=%s] %s", args.tag, json.dumps(summary, indent=2))
    return 0


if __name__ == "__main__":
    sys.exit(main())