"""
Evaluate the Pocket Automator real-world benchmark locally.

Run:
    python scripts/generate_pocket_benchmark.py
    python -m src.evaluate_pocket_benchmark
    python -m src.evaluate_pocket_benchmark --model-path ./trained_model/adapter
"""

from __future__ import annotations

import argparse
import json
from pathlib import Path

import torch
from peft import PeftModel
from transformers import AutoModelForCausalLM, AutoTokenizer

from src.classifier_prompt import build_intent_messages
from src.paths import TRAINED_MODEL_DIR
from src.pocket_benchmark import (
    BENCHMARK_PROMPTS_PATH,
    load_benchmark_prompts,
    record_result,
    save_benchmark_outputs,
)
from src.skill_utils import extract_intent

BASE_MODEL = "Qwen/Qwen2.5-3B-Instruct"
MAX_SEQ_LENGTH = 2048
MAX_NEW_TOKENS = 128
DEFAULT_MODEL_PATH = TRAINED_MODEL_DIR / "adapter"
FALLBACK_MODEL_PATH = TRAINED_MODEL_DIR / "merged"


def pick_device() -> str:
    if torch.cuda.is_available():
        return "cuda"
    if torch.backends.mps.is_available():
        return "mps"
    return "cpu"


def is_adapter_path(model_path: Path) -> bool:
    return (model_path / "adapter_config.json").exists()


def is_complete_merged_model(model_path: Path) -> bool:
    config_path = model_path / "config.json"
    if not config_path.exists() or config_path.stat().st_size == 0:
        return False

    index_path = model_path / "model.safetensors.index.json"
    if index_path.exists():
        index = json.loads(index_path.read_text(encoding="utf-8"))
        shard_names = set(index.get("weight_map", {}).values())
        return all(
            (model_path / shard).exists() and (model_path / shard).stat().st_size > 0
            for shard in shard_names
        )

    single_shard = model_path / "model.safetensors"
    return single_shard.exists() and single_shard.stat().st_size > 0


def resolve_model_path(path: str) -> Path:
    model_path = Path(path)
    if model_path.exists():
        if is_adapter_path(model_path):
            return model_path
        if is_complete_merged_model(model_path):
            return model_path
        print(f"Warning: {model_path} looks incomplete; trying adapter fallback.")

    adapter_path = DEFAULT_MODEL_PATH
    if adapter_path.exists() and is_adapter_path(adapter_path):
        print(f"Using LoRA adapter at {adapter_path}")
        return adapter_path

    merged_path = FALLBACK_MODEL_PATH
    if merged_path.exists() and is_complete_merged_model(merged_path):
        print(f"Using merged model at {merged_path}")
        return merged_path

    raise FileNotFoundError(
        "No usable trained model found. Expected a complete merged model or "
        f"LoRA adapter at {DEFAULT_MODEL_PATH}."
    )


def load_model(model_path: Path, device: str):
    dtype = torch.float16 if device in {"cuda", "mps"} else torch.float32

    if is_adapter_path(model_path):
        print(f"Loading base model: {BASE_MODEL}")
        tokenizer = AutoTokenizer.from_pretrained(model_path)
        base_model = AutoModelForCausalLM.from_pretrained(
            BASE_MODEL,
            dtype=dtype,
            low_cpu_mem_usage=True,
        )
        model = PeftModel.from_pretrained(base_model, str(model_path))
    else:
        print("Loading merged model weights")
        tokenizer = AutoTokenizer.from_pretrained(model_path)
        model = AutoModelForCausalLM.from_pretrained(
            model_path,
            dtype=dtype,
            low_cpu_mem_usage=True,
        )

    model.to(device)
    model.eval()
    return model, tokenizer


def generate_intent(model, tokenizer, prompt: str, device: str) -> str:
    messages = build_intent_messages(prompt)
    inputs = tokenizer.apply_chat_template(
        messages,
        tokenize=True,
        add_generation_prompt=True,
        return_tensors="pt",
    ).to(device)

    with torch.inference_mode():
        outputs = model.generate(
            input_ids=inputs,
            max_new_tokens=MAX_NEW_TOKENS,
            use_cache=True,
            do_sample=False,
        )

    generated = outputs[0][inputs.shape[1] :]
    return tokenizer.decode(generated, skip_special_tokens=True).strip()


def evaluate(model, tokenizer, cases: list[dict], device: str) -> list[dict]:
    results: list[dict] = []

    for index, case in enumerate(cases, start=1):
        prompt = case["prompt"]
        raw_output = generate_intent(model, tokenizer, prompt, device)
        predicted = extract_intent(raw_output)
        result = record_result(case, raw_output, predicted)
        results.append(result)

        print(f"--- [{index}/{len(cases)}] {case.get('id', 'n/a')} ---")
        print(f"Prompt:    {prompt}")
        print(f"Expected:  {json.dumps(case['expected'], separators=(',', ':'))}")
        print(
            f"Predicted: {json.dumps(predicted, separators=(',', ':')) if predicted else raw_output}"
        )
        print(f"Skill:     {'PASS' if result['skill_correct'] else 'FAIL'}")
        print(f"Params:    {'PASS' if result['parameter_correct'] else 'FAIL'}")
        print(f"Exact JSON:{'PASS' if result['exact_json_match'] else 'FAIL'}")
        print()

    return results


def main() -> None:
    parser = argparse.ArgumentParser(description="Evaluate Pocket Automator benchmark.")
    parser.add_argument(
        "--model-path",
        default=str(DEFAULT_MODEL_PATH),
        help=f"Path to LoRA adapter or merged model (default: {DEFAULT_MODEL_PATH})",
    )
    parser.add_argument(
        "--benchmark-path",
        default=str(BENCHMARK_PROMPTS_PATH),
        help=f"Path to benchmark prompts JSON (default: {BENCHMARK_PROMPTS_PATH})",
    )
    args = parser.parse_args()

    benchmark_path = Path(args.benchmark_path)
    if not benchmark_path.exists():
        raise FileNotFoundError(
            f"Benchmark prompts not found at {benchmark_path}. "
            "Run `python scripts/generate_pocket_benchmark.py` first."
        )

    cases = load_benchmark_prompts(benchmark_path)
    device = pick_device()
    model_path = resolve_model_path(args.model_path)
    print(f"Device: {device}")
    print(f"Loading model from {model_path.resolve()}")
    model, tokenizer = load_model(model_path, device)
    print(f"Running Pocket Automator benchmark on {len(cases)} prompts...\n")

    results = evaluate(model, tokenizer, cases, device)
    metrics, report = save_benchmark_outputs(results)

    print("--- Pocket Automator Benchmark Summary ---")
    print(report)


if __name__ == "__main__":
    main()