#!/usr/bin/env python3
"""Generate train samples for cups_cot with structured, parse-friendly CoT text."""

from __future__ import annotations

import argparse
import json
import os
import random
import re
from concurrent.futures import ProcessPoolExecutor, ThreadPoolExecutor, as_completed
from pathlib import Path

from generators.cups_shuffle import (
    CupsShuffleConfig,
    _jitter_color as _cups_jitter_color,
    _shuffle_keyframes as _cups_shuffle_keyframes,
    generate_cups_shuffle,
)


PROJECT_ROOT = Path(__file__).resolve().parents[1]
ROOT = PROJECT_ROOT
CATEGORY = "cups_cot"
SEED_PATTERN = re.compile(r"cups_cot_train_s(\d+)\.mp4$")


def _label_from_index(index: int) -> str:
    return chr(ord("A") + int(index))


def _default_id_from_rel_path(rel_path: str) -> str:
    value = Path(rel_path).with_suffix("").as_posix().replace("/", "_").strip("_")
    return value or "sample"


def _split_category(name: str) -> tuple[str, str]:
    if name == "cups_cot":
        return "cups_cot", "cups_cot"
    if name.startswith("hidden_container_"):
        return "hidden_container", name.replace("hidden_container_", "", 1)
    if name == "random_dots":
        return "biological", "random_dots"
    if "_" in name:
        major, sub = name.split("_", 1)
        return major, sub
    return name, name


def _make_cups_cfg(seed: int) -> CupsShuffleConfig:
    return CupsShuffleConfig(
        width=1280,
        height=720,
        fps=30,
        intro_duration=2.0,
        cover_duration=2.0,
        shuffle_duration=16.0,
        swaps=4,
        seed=int(seed),
        ball_radius=18,
        cup_count=4,
    )


def _consume_style_rng(cfg: CupsShuffleConfig, rng: random.Random) -> None:
    if not cfg.randomize_style:
        return
    cfg.size_scale = rng.uniform(0.92, 1.08)
    cfg.arc_scale = rng.uniform(0.9, 1.2)
    cfg.lane_scale = rng.uniform(0.9, 1.15)
    cfg.cup_color = _cups_jitter_color(cfg.cup_color, rng, 14)
    cfg.cup_shade = _cups_jitter_color(cfg.cup_shade, rng, 12)
    cfg.cup_outline = _cups_jitter_color(cfg.cup_outline, rng, 12)
    cfg.cup_rim = _cups_jitter_color(cfg.cup_rim, rng, 14)
    cfg.cup_inner = _cups_jitter_color(cfg.cup_inner, rng, 8)
    cfg.cup_highlight = _cups_jitter_color(cfg.cup_highlight, rng, 16)


def _derive_trace(seed: int) -> dict:
    cfg = _make_cups_cfg(seed)
    rng = random.Random(cfg.seed)
    _consume_style_rng(cfg, rng)

    ball_cup_id = rng.randint(0, cfg.cup_count - 1)
    keyframes = _cups_shuffle_keyframes(cfg, cfg.cup_count)
    if len(keyframes) != cfg.swaps + 1:
        raise RuntimeError(
            f"Unexpected keyframe length for seed={seed}: "
            f"{len(keyframes)} (expected {cfg.swaps + 1})"
        )

    swaps: list[tuple[str, str]] = []
    for step in range(cfg.swaps):
        prev_order = keyframes[step]
        next_order = keyframes[step + 1]
        diff_positions = [
            idx
            for idx, (prev_cup, next_cup) in enumerate(zip(prev_order, next_order))
            if prev_cup != next_cup
        ]
        if len(diff_positions) != 2:
            raise RuntimeError(
                f"Seed {seed} step {step + 1}: expected 2 changed positions, got "
                f"{len(diff_positions)}"
            )
        left_label = _label_from_index(prev_order[diff_positions[0]])
        right_label = _label_from_index(prev_order[diff_positions[1]])
        cup_a, cup_b = sorted((left_label, right_label))
        swaps.append((cup_a, cup_b))

    final_order = keyframes[-1]
    final_order_labels = [_label_from_index(cup_id) for cup_id in final_order]
    final_pos = final_order.index(ball_cup_id)
    answer = _label_from_index(final_pos)

    return {
        "ball_start_under": _label_from_index(ball_cup_id),
        "swap_count": int(cfg.swaps),
        "swaps": swaps,
        "final_order": final_order_labels,
        "ball_end_under": answer,
    }


def _build_cot_text(trace: dict) -> str:
    lines = [
        "COT_VERSION:1",
        "TASK:cups_cot",
        "CUP_LABELS:A,B,C,D",
        "LABEL_SEMANTICS:IDENTITY_FIXED",
        "INIT_ORDER_LEFT_TO_RIGHT:A,B,C,D",
        f"BALL_START_UNDER:{trace['ball_start_under']}",
        f"SWAP_COUNT:{trace['swap_count']}",
    ]
    for idx, (cup_a, cup_b) in enumerate(trace["swaps"], start=1):
        lines.append(f"SWAP_{idx:02d}:{cup_a}<->{cup_b}")
    lines.extend(
        [
            f"FINAL_ORDER_LEFT_TO_RIGHT:{','.join(trace['final_order'])}",
            f"BALL_END_UNDER:{trace['ball_end_under']}",
            f"**Answer:{trace['ball_end_under']}**",
        ]
    )
    return "\n".join(lines)


def _build_question() -> str:
    return (
        "Based on the video, track cup swaps step by step and determine which cup "
        "covers the red ball at the end. Cups are labeled A, B, C, and D from left "
        "to right at the start. Answer in the format **Answer:X**."
    )


def _build_entry(rel_path: str, text: str, question: str, answer: str) -> dict:
    major, sub = _split_category(CATEGORY)
    abs_video = str((ROOT / rel_path).resolve())
    return {
        "id": _default_id_from_rel_path(rel_path),
        "path": rel_path,
        "category": CATEGORY,
        "major": major,
        "sub": sub,
        "text": text,
        "question": question,
        "answer": answer,
        "data_split": "train",
        "video_path": abs_video,
        "image_gt": "",
        "image_paths": [],
    }


def _load_dataset(path: Path) -> list[dict]:
    if not path.exists():
        return []
    try:
        raw = json.loads(path.read_text(encoding="utf-8"))
    except json.JSONDecodeError:
        return []
    if isinstance(raw, dict) and isinstance(raw.get("items"), list):
        raw = raw["items"]
    if not isinstance(raw, list):
        return []
    return [dict(item) for item in raw if isinstance(item, dict)]


def _existing_seed_set(existing_entries: list[dict]) -> set[int]:
    used: set[int] = set()
    for item in existing_entries:
        if str(item.get("category") or "").strip() != CATEGORY:
            continue
        path_text = str(item.get("path") or "").strip()
        match = SEED_PATTERN.search(path_text)
        if match:
            used.add(int(match.group(1)))

    video_dir = ROOT / "videos" / CATEGORY
    if video_dir.exists():
        for file_path in video_dir.glob("*.mp4"):
            match = SEED_PATTERN.search(file_path.name)
            if match:
                used.add(int(match.group(1)))
    return used


def _pick_seed_list(count: int, seed_start: int, used: set[int]) -> list[int]:
    seeds: list[int] = []
    cursor = int(seed_start)
    while len(seeds) < int(count):
        if cursor not in used:
            seeds.append(cursor)
        cursor += 1
    return seeds


def _upsert_entries(existing_entries: list[dict], new_entries: list[dict]) -> list[dict]:
    new_by_path = {
        str(entry.get("path") or "").strip(): entry
        for entry in new_entries
        if str(entry.get("path") or "").strip()
    }
    out: list[dict] = []
    replaced_paths: set[str] = set()
    for item in existing_entries:
        path_text = str(item.get("path") or "").strip()
        if path_text and path_text in new_by_path:
            out.append(new_by_path[path_text])
            replaced_paths.add(path_text)
        else:
            out.append(item)

    for entry in new_entries:
        path_text = str(entry.get("path") or "").strip()
        if path_text and path_text not in replaced_paths:
            out.append(entry)
    return out


def _write_json(path: Path, payload: object) -> None:
    path.write_text(json.dumps(payload, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")


def _generate_one(seed: int, force_render: bool = False) -> dict:
    out_path = ROOT / "videos" / CATEGORY / f"{CATEGORY}_train_s{int(seed)}.mp4"
    out_path.parent.mkdir(parents=True, exist_ok=True)
    should_render = bool(force_render) or not (out_path.exists() and out_path.stat().st_size > 0)

    rendered_answer = ""
    if should_render:
        render_cfg = _make_cups_cfg(seed)
        _, rendered_answer = generate_cups_shuffle(
            str(out_path),
            render_cfg,
            return_answer=True,
        )

    trace = _derive_trace(seed)
    answer = str(trace["ball_end_under"])
    if rendered_answer and rendered_answer != answer:
        raise RuntimeError(
            f"Answer mismatch for seed={seed}: rendered={rendered_answer}, "
            f"trace={answer}"
        )

    rel_path = out_path.relative_to(ROOT).as_posix()
    entry = _build_entry(
        rel_path=rel_path,
        text=_build_cot_text(trace),
        question=_build_question(),
        answer=answer,
    )
    return {
        "seed": int(seed),
        "status": "rendered" if should_render else "reused",
        "entry": entry,
        "rel_path": rel_path,
    }


def main() -> None:
    parser = argparse.ArgumentParser(description="Generate cups_cot train samples.")
    parser.add_argument("--count", type=int, default=50, help="Number of new samples to generate.")
    parser.add_argument("--seed-start", type=int, default=95000, help="Seed start for this batch.")
    parser.add_argument("--workers", type=int, default=0, help="Parallel workers; 0 means auto.")
    parser.add_argument(
        "--executor",
        choices=("thread", "process"),
        default="thread",
        help="Parallel backend.",
    )
    parser.add_argument(
        "--dataset",
        default="video_dataset_train.json",
        help="Train dataset JSON path.",
    )
    parser.add_argument("--force-render", action="store_true", help="Re-render even if target video already exists.")
    parser.add_argument("--dry-run", action="store_true", help="Build plan only.")
    parser.add_argument(
        "--plan-output",
        default="tmp_cups_cot_plan.json",
        help="Write planned seeds/tasks to this JSON file.",
    )
    parser.add_argument(
        "--records-output",
        default="tmp_cups_cot_records.json",
        help="Write generation records to this JSON file.",
    )
    args = parser.parse_args()

    if args.count <= 0:
        raise SystemExit("--count must be > 0")

    dataset_path = Path(args.dataset)
    if not dataset_path.is_absolute():
        dataset_path = ROOT / dataset_path
    plan_path = Path(args.plan_output)
    if not plan_path.is_absolute():
        plan_path = ROOT / plan_path
    records_path = Path(args.records_output)
    if not records_path.is_absolute():
        records_path = ROOT / records_path

    existing_entries = _load_dataset(dataset_path)
    used_seeds = _existing_seed_set(existing_entries)
    seeds = _pick_seed_list(args.count, args.seed_start, used_seeds)

    plan = {
        "category": CATEGORY,
        "count": int(args.count),
        "seed_start_arg": int(args.seed_start),
        "seed_list": seeds,
        "dataset_path": str(dataset_path),
        "executor": args.executor,
    }
    _write_json(plan_path, plan)

    print(f"Existing train entries: {len(existing_entries)}")
    print(f"Planned new {CATEGORY} items: {len(seeds)}")
    print(f"Seed list: {seeds[0]}..{seeds[-1]}")
    print(f"Plan written to: {plan_path}")
    if args.dry_run:
        return

    max_workers = int(args.workers) if int(args.workers) > 0 else min(8, max(1, os.cpu_count() or 1))
    print(f"Using workers: {max_workers} ({args.executor})")

    executor_cls = ThreadPoolExecutor if args.executor == "thread" else ProcessPoolExecutor
    results: list[dict] = []
    failures: list[dict] = []
    with executor_cls(max_workers=max_workers) as executor:
        future_map = {
            executor.submit(_generate_one, seed, bool(args.force_render)): seed
            for seed in seeds
        }
        for done_count, future in enumerate(as_completed(future_map), start=1):
            seed = future_map[future]
            try:
                result = future.result()
            except Exception as exc:  # noqa: BLE001
                failures.append({"seed": int(seed), "error": repr(exc)})
            else:
                results.append(result)
            if done_count % 10 == 0 or done_count == len(seeds):
                print(f"Progress: {done_count}/{len(seeds)}, failures={len(failures)}")

    if failures:
        fail_path = ROOT / "tmp_cups_cot_failures.json"
        _write_json(fail_path, failures)
        raise SystemExit(f"Generation failed for {len(failures)} seeds. See {fail_path}")

    results.sort(key=lambda item: int(item["seed"]))
    new_entries = [dict(item["entry"]) for item in results]
    merged_entries = _upsert_entries(existing_entries, new_entries)
    _write_json(dataset_path, merged_entries)

    records = {
        "category": CATEGORY,
        "count": len(results),
        "seed_list": [int(item["seed"]) for item in results],
        "status_counter": {
            "rendered": sum(1 for item in results if item["status"] == "rendered"),
            "reused": sum(1 for item in results if item["status"] == "reused"),
        },
        "records": results,
    }
    _write_json(records_path, records)

    print(f"Wrote dataset: {dataset_path}")
    print(f"Wrote records: {records_path}")
    print(f"Train size: {len(existing_entries)} -> {len(merged_entries)}")


if __name__ == "__main__":
    main()