#!/usr/bin/env python3
"""Post-training inference validation for adapter or merged model artifacts."""

from __future__ import annotations

import argparse
import json
from pathlib import Path
import re
from typing import Any

import sys

ROOT = Path(__file__).resolve().parents[1]
if str(ROOT) not in sys.path:
    sys.path.insert(0, str(ROOT))

from app.env.env_core import PolyGuardEnv


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description="Validate inference from saved adapter/merged artifacts.")
    parser.add_argument("--merged-model", default="checkpoints/merged")
    parser.add_argument("--adapter-dir", default="checkpoints/sft_adapter")
    parser.add_argument("--base-model", default="")
    parser.add_argument("--prompts", default="data/processed/training_corpus_grpo_prompts.jsonl")
    parser.add_argument("--samples", type=int, default=3)
    parser.add_argument("--output", default="outputs/reports/postsave_inference.json")
    return parser.parse_args()


def _load_prompt_rows(path: Path, limit: int) -> list[dict[str, Any]]:
    if not path.exists():
        return []
    rows: list[dict[str, Any]] = []
    with path.open("r", encoding="utf-8") as handle:
        for line in handle:
            line = line.strip()
            if not line:
                continue
            try:
                payload = json.loads(line)
            except json.JSONDecodeError:
                continue
            if isinstance(payload, dict):
                rows.append(payload)
            if len(rows) >= limit:
                break
    return rows


def _prompt_to_text(row: dict[str, Any]) -> str:
    prompt = row.get("prompt", {}) if isinstance(row.get("prompt"), dict) else {}
    candidates = prompt.get("candidates", prompt.get("candidate_set", []))
    candidate_ids = [
        str(item.get("candidate_id"))
        for item in candidates
        if isinstance(item, dict) and item.get("candidate_id")
    ]
    text = {
        "instruction": "Choose one candidate_id and justify briefly.",
        "patient_id": prompt.get("patient_id", prompt.get("patient_summary", {}).get("patient_id", "unknown")),
        "candidate_ids": candidate_ids,
        "format": "candidate_id=<cand_xx>; rationale=<text>",
    }
    return json.dumps(text, ensure_ascii=True)


def _discover_base_model(adapter_dir: Path) -> str:
    cfg = adapter_dir / "adapter_config.json"
    if not cfg.exists():
        return ""
    try:
        payload = json.loads(cfg.read_text(encoding="utf-8"))
    except json.JSONDecodeError:
        return ""
    value = payload.get("base_model_name_or_path")
    return str(value) if isinstance(value, str) else ""


def _load_model(
    merged_model: Path,
    adapter_dir: Path,
    base_model_arg: str,
):
    import torch
    from transformers import AutoModelForCausalLM, AutoTokenizer

    if merged_model.exists() and (merged_model / "config.json").exists():
        tokenizer = AutoTokenizer.from_pretrained(str(merged_model))
        model = AutoModelForCausalLM.from_pretrained(
            str(merged_model),
            torch_dtype=torch.float16 if torch.cuda.is_available() else torch.float32,
            low_cpu_mem_usage=True,
        )
        source = "merged"
        return model, tokenizer, source

    if not adapter_dir.exists():
        raise FileNotFoundError(f"adapter_dir_not_found:{adapter_dir}")

    from peft import PeftModel

    base_model = base_model_arg.strip() or _discover_base_model(adapter_dir)
    if not base_model:
        raise RuntimeError("missing_base_model_for_adapter")

    tokenizer = AutoTokenizer.from_pretrained(base_model)
    base = AutoModelForCausalLM.from_pretrained(
        base_model,
        torch_dtype=torch.float16 if torch.cuda.is_available() else torch.float32,
        low_cpu_mem_usage=True,
    )
    model = PeftModel.from_pretrained(base, str(adapter_dir))
    source = "adapter"
    return model, tokenizer, source


def _fallback_completion(row: dict[str, Any]) -> tuple[str, str | None]:
    prompt = row.get("prompt", {}) if isinstance(row.get("prompt"), dict) else {}
    candidates = prompt.get("candidates", prompt.get("candidate_set", []))
    candidate_ids = [
        str(item.get("candidate_id"))
        for item in candidates
        if isinstance(item, dict) and item.get("candidate_id")
    ]
    candidate_id = candidate_ids[0] if candidate_ids else None
    completion = (
        f"candidate_id={candidate_id}; rationale=fallback_policy_artifact"
        if candidate_id
        else "candidate_id=cand_01; rationale=fallback_policy_artifact"
    )
    return completion, candidate_id


def _extract_candidate_id(text: str) -> str | None:
    match = re.search(r"cand_\d+", text.lower())
    if not match:
        return None
    return match.group(0)


def main() -> None:
    args = parse_args()
    root = Path(__file__).resolve().parents[1]
    merged_model = (root / args.merged_model).resolve()
    adapter_dir = (root / args.adapter_dir).resolve()
    prompts_path = (root / args.prompts).resolve()

    rows = _load_prompt_rows(prompts_path, limit=max(1, args.samples))
    if not rows:
        raise SystemExit(f"no_prompts_loaded:{prompts_path}")

    fallback_policy_file = (root / "checkpoints" / "sft_policy_fallback.json").resolve()
    model = None
    tokenizer = None
    model_source = "fallback_policy"
    model_load_error = ""
    try:
        model, tokenizer, model_source = _load_model(
            merged_model=merged_model,
            adapter_dir=adapter_dir,
            base_model_arg=args.base_model,
        )
        if tokenizer.pad_token is None:
            tokenizer.pad_token = tokenizer.eos_token
    except Exception as exc:  # noqa: BLE001
        model_load_error = str(exc)
        if not fallback_policy_file.exists():
            raise

    import torch

    device = "cuda" if torch.cuda.is_available() else "cpu"
    if model is not None:
        model = model.to(device)
        model.eval()

    env = PolyGuardEnv()
    results: list[dict[str, Any]] = []
    for idx, row in enumerate(rows):
        env.reset(seed=17_000 + idx, difficulty="medium")
        prompt_text = _prompt_to_text(row)

        if model is not None and tokenizer is not None:
            encoded = tokenizer(prompt_text, return_tensors="pt", truncation=True, max_length=512)
            encoded = {key: value.to(device) for key, value in encoded.items()}
            with torch.no_grad():
                generated = model.generate(
                    **encoded,
                    max_new_tokens=80,
                    do_sample=False,
                    temperature=0.0,
                    eos_token_id=tokenizer.eos_token_id,
                )
            decoded = tokenizer.decode(generated[0], skip_special_tokens=True)
            completion = decoded[len(prompt_text) :].strip() if decoded.startswith(prompt_text) else decoded
            candidate_id = _extract_candidate_id(completion)
        else:
            completion, candidate_id = _fallback_completion(row)

        all_actions = env.get_candidate_actions()
        legal_actions = env.get_legal_actions()
        by_id_all = {str(item.get("candidate_id", "")).lower(): item for item in all_actions}
        by_id_legal = {str(item.get("candidate_id", "")).lower(): item for item in legal_actions}
        action = by_id_legal.get(str(candidate_id or "").lower())
        if action is None:
            action = by_id_all.get(str(candidate_id or "").lower())
        if action is None and legal_actions:
            action = legal_actions[0]

        if action is None:
            results.append(
                {
                    "idx": idx,
                    "prompt": prompt_text,
                    "completion": completion,
                    "candidate_id": candidate_id,
                    "selected_candidate": None,
                    "env_reward": 0.0,
                    "valid": False,
                    "reason": "no_action_available",
                }
            )
            continue

        _, reward, done, info = env.step(action)
        results.append(
            {
                "idx": idx,
                "prompt": prompt_text,
                "completion": completion,
                "candidate_id": candidate_id,
                "selected_candidate": action.get("candidate_id"),
                "env_reward": float(reward),
                "done": bool(done),
                "valid": bool(info.get("safety_report", {}).get("legal", False)),
                "termination_reason": info.get("termination_reason"),
            }
        )

    valid_rate = sum(1.0 for row in results if row.get("valid")) / len(results)
    avg_reward = sum(float(row.get("env_reward", 0.0)) for row in results) / len(results)

    payload = {
        "status": "ok",
        "model_source": model_source,
        "model_load_error": model_load_error,
        "samples": len(results),
        "valid_rate": round(valid_rate, 6),
        "avg_env_reward": round(avg_reward, 6),
        "results": results,
    }

    output_path = root / args.output
    output_path.parent.mkdir(parents=True, exist_ok=True)
    output_path.write_text(json.dumps(payload, ensure_ascii=True, indent=2), encoding="utf-8")
    print("postsave_inference_ok")


if __name__ == "__main__":
    main()