#!/usr/bin/env python3
"""Build stratified bucket manifest from princeton-vl/LayeredDepth-Syn."""

from __future__ import annotations

import argparse
import csv
import json
from pathlib import Path

import numpy as np

from .preprocess import (
    DEFAULT_LAYER_IDS,
    compressed_layer_count_per_pixel,
    load_depth_layers_from_row,
    sort_depth_with_mask,
)

DEFAULT_BATCH_MIX = {"1": 0.25, "2": 0.25, "3": 0.25, "4": 0.25}


def assign_bucket(
    compressed_count: np.ndarray,
    valid_fraction: float,
    *,
    bucket_mode: str,
    majority_fraction: float,
    min_valid_fraction: float,
) -> str:
    if valid_fraction < min_valid_fraction:
        return "1"

    if bucket_mode == "scene_max":
        scene_value = int(np.max(compressed_count))
    else:
        counts = np.arange(1, 5)
        fractions = [(compressed_count >= count).mean() for count in counts]
        scene_value = 1
        for count, fraction in zip(counts, fractions):
            if fraction >= majority_fraction:
                scene_value = int(count)

    return str(max(1, min(4, scene_value)))


def build_manifest(
    *,
    dataset_name: str = "princeton-vl/LayeredDepth-Syn",
    split: str = "train",
    cache_dir: str | None = None,
    max_samples: int | None = None,
    output_dir: str | Path = "artifacts/layereddepth_stratified",
    bucket_mode: str = "scene_max",
    majority_fraction: float = 0.10,
    min_valid_fraction: float = 0.01,
    abs_gap_threshold: float = 1e-4,
    rel_gap_threshold: float = 0.0,
) -> dict:
    from datasets import load_dataset

    output_dir = Path(output_dir)
    output_dir.mkdir(parents=True, exist_ok=True)

    kwargs = {"split": split, "streaming": False}
    if cache_dir:
        kwargs["cache_dir"] = cache_dir
    dataset = load_dataset(dataset_name, **kwargs)

    rows = []
    buckets: dict[str, list[int]] = {str(i): [] for i in range(1, 5)}

    for row_index, row in enumerate(dataset):
        if max_samples is not None and row_index >= max_samples:
            break

        depth = load_depth_layers_from_row(row, layer_ids=DEFAULT_LAYER_IDS)
        sorted_depth, sorted_mask = sort_depth_with_mask(depth)
        compressed = compressed_layer_count_per_pixel(
            sorted_depth,
            sorted_mask,
            abs_gap_threshold=abs_gap_threshold,
            rel_gap_threshold=rel_gap_threshold,
        )
        raw_count = sorted_mask.sum(axis=-1)
        valid_fraction = float((raw_count > 0).mean())
        bucket = assign_bucket(
            compressed,
            valid_fraction,
            bucket_mode=bucket_mode,
            majority_fraction=majority_fraction,
            min_valid_fraction=min_valid_fraction,
        )
        buckets[bucket].append(row_index)

        rows.append(
            {
                "row_index": row_index,
                "sample_key": str(row.get("__key__", row_index)),
                "valid_fraction": valid_fraction,
                "scene_max_compressed": int(np.max(compressed)),
                "compressed_ge2_fraction": float((compressed >= 2).mean()),
                "compressed_ge3_fraction": float((compressed >= 3).mean()),
                "compressed_ge4_fraction": float((compressed >= 4).mean()),
                "bucket": bucket,
            }
        )

    if not rows:
        raise RuntimeError("No rows scanned.")

    summary = {
        "dataset": dataset_name,
        "split": split,
        "samples_scanned": len(rows),
        "bucket_mode": bucket_mode,
        "majority_fraction": majority_fraction,
        "min_valid_fraction": min_valid_fraction,
        "bucket_histogram": {k: len(v) for k, v in sorted(buckets.items(), key=lambda x: int(x[0]))},
        "batch_mix": DEFAULT_BATCH_MIX,
    }
    manifest = {"meta": summary, "batch_mix": DEFAULT_BATCH_MIX, "buckets": buckets}

    (output_dir / "summary.json").write_text(json.dumps(summary, indent=2), encoding="utf-8")
    (output_dir / "bucket_manifest.json").write_text(json.dumps(manifest, indent=2), encoding="utf-8")
    with (output_dir / "sample_buckets.csv").open("w", newline="", encoding="utf-8") as handle:
        writer = csv.DictWriter(handle, fieldnames=list(rows[0].keys()))
        writer.writeheader()
        writer.writerows(rows)

    return summary


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--dataset", default="princeton-vl/LayeredDepth-Syn")
    parser.add_argument("--split", default="train")
    parser.add_argument("--cache-dir", default=None)
    parser.add_argument("--max-samples", type=int, default=None)
    parser.add_argument("--output-dir", default="artifacts/layereddepth_stratified")
    parser.add_argument("--bucket-mode", choices=("scene_max", "scene_majority"), default="scene_max")
    parser.add_argument("--majority-fraction", type=float, default=0.10)
    parser.add_argument("--min-valid-fraction", type=float, default=0.01)
    args = parser.parse_args()

    summary = build_manifest(
        dataset_name=args.dataset,
        split=args.split,
        cache_dir=args.cache_dir,
        max_samples=args.max_samples,
        output_dir=args.output_dir,
        bucket_mode=args.bucket_mode,
        majority_fraction=args.majority_fraction,
        min_valid_fraction=args.min_valid_fraction,
    )
    print(json.dumps(summary, indent=2))


if __name__ == "__main__":
    main()