"""
Statistics for teacher-forcing HTML token lengths (same encoding as train_compressor).

Uses Qwen3-VL tokenizer with encode(..., add_special_tokens=False) to match
_rebuild_sequence (excluding the trailing eos added in training).

Usage:
  PYTHONPATH=. python scripts/stats_html_token_lengths.py
  PYTHONPATH=. python scripts/stats_html_token_lengths.py --model_id Qwen/Qwen3-VL-8B-Instruct
"""

from __future__ import annotations

import argparse
import json
import os
import sys
from pathlib import Path

os.environ.setdefault("HF_ENDPOINT", "https://hf-mirror.com")
os.environ.setdefault("HF_HOME", os.environ.get("HF_HOME", "/root/rivermind-data/huggingface"))

PROJECT_ROOT = Path(__file__).resolve().parent.parent


def collect_lengths(html_paths: list[Path], tokenizer) -> list[int]:
    lengths: list[int] = []
    for p in html_paths:
        try:
            text = p.read_text(encoding="utf-8", errors="ignore")
        except OSError:
            continue
        ids = tokenizer.encode(text, add_special_tokens=False)
        lengths.append(len(ids))
    return lengths


def percentile(sorted_vals: list[int], q: float) -> float:
    """Linear interpolation, q in [0,1]."""
    if not sorted_vals:
        return 0.0
    n = len(sorted_vals)
    if n == 1:
        return float(sorted_vals[0])
    pos = (n - 1) * q
    lo = int(pos)
    hi = min(lo + 1, n - 1)
    w = pos - lo
    return sorted_vals[lo] * (1 - w) + sorted_vals[hi] * w


def main() -> int:
    ap = argparse.ArgumentParser()
    ap.add_argument("--model_id", default="Qwen/Qwen3-VL-8B-Instruct")
    ap.add_argument("--websight_dir", type=Path, default=PROJECT_ROOT / "data" / "websight")
    ap.add_argument("--gt_html_dir", type=Path, default=PROJECT_ROOT / "data" / "gt_html")
    ap.add_argument("--json_out", type=Path, default=None, help="Optional path to write summary JSON.")
    args = ap.parse_args()

    from transformers import AutoTokenizer

    tok = AutoTokenizer.from_pretrained(args.model_id, trust_remote_code=True)

    ws = sorted(args.websight_dir.glob("*.html")) if args.websight_dir.is_dir() else []
    gt = sorted(args.gt_html_dir.glob("*.html")) if args.gt_html_dir.is_dir() else []

    len_ws = collect_lengths(ws, tok)
    len_gt = collect_lengths(gt, tok)
    merged = len_ws + len_gt

    def summarize(name: str, vals: list[int]) -> dict:
        if not vals:
            return {"name": name, "n": 0}
        s = sorted(vals)
        return {
            "name": name,
            "n": len(vals),
            "min": s[0],
            "max": s[-1],
            "mean": round(sum(s) / len(s), 1),
            "p50": int(percentile(s, 0.50)),
            "p90": int(percentile(s, 0.90)),
            "p95": int(percentile(s, 0.95)),
            "p99": int(percentile(s, 0.99)),
        }

    out = {
        "model_id": args.model_id,
        "websight": summarize("websight", len_ws),
        "gt_html": summarize("gt_html (Design2Code eval GT)", len_gt),
        "merged": summarize("merged (websight + gt_html)", merged),
        "recommend_max_html_tokens": {},
    }

    if merged:
        s = sorted(merged)
        p95 = int(percentile(s, 0.95))
        p99 = int(percentile(s, 0.99))
        ws_p99 = int(percentile(sorted(len_ws), 0.99)) if len_ws else 0
        out["recommend_max_html_tokens"] = {
            "websight_only_suggest": min(max(ws_p99 + 128, 1024), 2048),
            "design2code_gt_reality": (
                "gt_html is very long (often 20k–80k+ tokens). Any fixed cap heavily truncates CE on eval-GT."
            ),
            "mixed_train_practical": {
                "8192": "Still truncates most Design2Code HTML but keeps speed reasonable",
                "16384": "Better tail for long pages if VRAM/time allow",
                "2048": "Fine for WebSight-dominated runs; largely drops Design2Code GT tail",
            },
            "note": "See websight vs gt_html blocks; do not use merged p95 alone when mixing splits.",
        }

    print(json.dumps(out, indent=2, ensure_ascii=False))

    if args.json_out:
        args.json_out.parent.mkdir(parents=True, exist_ok=True)
        args.json_out.write_text(json.dumps(out, indent=2, ensure_ascii=False), encoding="utf-8")
        print(f"Wrote {args.json_out}", file=sys.stderr)

    return 0


if __name__ == "__main__":
    raise SystemExit(main())