from __future__ import annotations

import argparse
import csv
import hashlib
import json
import os
import re
import shutil
from collections import Counter
from pathlib import Path
from typing import Any


IMAGE_EXTENSIONS = {".jpg", ".jpeg", ".png", ".bmp", ".webp"}
VIDEO_EXTENSIONS = {".mp4", ".mov", ".avi", ".mkv"}
ATTRIBUTES = ("weave", "material", "usage", "features")


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description="Build the canonical VidTouch Hub release.")
    parser.add_argument("--source", type=Path, required=True)
    parser.add_argument("--output", type=Path, required=True)
    return parser.parse_args()


def parse_labels(path: Path) -> dict[str, dict[str, Any]]:
    labels: dict[str, dict[str, Any]] = {}
    with path.open("r", encoding="utf-8") as handle:
        for line_number, raw in enumerate(handle, 1):
            line = raw.strip()
            if not line or line.startswith("#"):
                continue
            parts = line.split()
            if len(parts) < 4:
                raise ValueError(f"Invalid label line {line_number}: {raw!r}")
            fabric_id, weave, material, usage, *features = parts
            if fabric_id in labels:
                raise ValueError(f"Duplicate Fabric ID in labels: {fabric_id}")
            labels[fabric_id] = {
                "fabric_id": fabric_id,
                "weave": weave,
                "material": material,
                "usage": usage,
                "features": features,
            }
    return labels


def parse_fabric_id(path: Path) -> str:
    match = re.match(r"^([A-Za-z0-9]+)", path.stem)
    if not match:
        raise ValueError(f"Cannot parse Fabric ID from {path.name}")
    return match.group(1)


def sha256(path: Path) -> str:
    digest = hashlib.sha256()
    with path.open("rb") as handle:
        for chunk in iter(lambda: handle.read(8 * 1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def link_or_copy(source: Path, destination: Path) -> None:
    destination.parent.mkdir(parents=True, exist_ok=True)
    if destination.exists():
        destination.unlink()
    try:
        os.link(source, destination)
    except OSError:
        shutil.copy2(source, destination)


def scan_media(
    folder: Path,
    extensions: set[str],
    labels: dict[str, dict[str, Any]],
) -> tuple[list[Path], list[str]]:
    retained: list[Path] = []
    excluded: list[str] = []
    for path in sorted(folder.iterdir(), key=lambda item: item.name):
        if not path.is_file() or path.suffix.lower() not in extensions:
            continue
        if parse_fabric_id(path) in labels:
            retained.append(path)
        else:
            excluded.append(path.name)
    return retained, excluded


def write_csv(path: Path, fieldnames: list[str], rows: list[dict[str, Any]]) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    with path.open("w", encoding="utf-8", newline="") as handle:
        writer = csv.DictWriter(handle, fieldnames=fieldnames)
        writer.writeheader()
        writer.writerows(rows)


def main() -> None:
    args = parse_args()
    source = args.source.resolve()
    output = args.output.resolve()

    labels_path = source / "label.txt"
    split_dir = source / "experiments" / "vidtouch_method" / "splits"
    labels = parse_labels(labels_path)
    split = json.loads((split_dir / "fabric_common_v2.json").read_text(encoding="utf-8"))

    partition_by_id: dict[str, str] = {}
    for partition, key in (("train", "train_ids"), ("validation", "val_ids"), ("test", "test_ids")):
        for fabric_id in split[key]:
            if fabric_id in partition_by_id:
                raise ValueError(f"Fabric ID appears in multiple partitions: {fabric_id}")
            partition_by_id[fabric_id] = partition
    if set(partition_by_id) != set(labels):
        raise ValueError("Frozen split does not cover exactly the canonical Fabric IDs.")

    images, excluded_images = scan_media(source / "RGBs", IMAGE_EXTENSIONS, labels)
    videos, excluded_videos = scan_media(source / "TACs", VIDEO_EXTENSIONS, labels)

    image_counts = Counter(parse_fabric_id(path) for path in images)
    video_counts = Counter(parse_fabric_id(path) for path in videos)
    missing_images = sorted(set(labels) - set(image_counts))
    missing_videos = sorted(set(labels) - set(video_counts))
    if missing_images or missing_videos:
        raise ValueError(
            f"Missing media: RGB={missing_images}, tactile={missing_videos}"
        )

    expected = {
        "fabrics": 144,
        "rgb_images": 435,
        "tactile_videos": 432,
        "partitions": {"train": 100, "validation": 22, "test": 22},
        "label_cardinality": {"weave": 39, "material": 60, "usage": 46, "features": 100},
    }
    label_cardinality = {
        "weave": len({row["weave"] for row in labels.values()}),
        "material": len({row["material"] for row in labels.values()}),
        "usage": len({row["usage"] for row in labels.values()}),
        "features": len({feature for row in labels.values() for feature in row["features"]}),
    }
    actual = {
        "fabrics": len(labels),
        "rgb_images": len(images),
        "tactile_videos": len(videos),
        "partitions": dict(Counter(partition_by_id.values())),
        "label_cardinality": label_cardinality,
    }
    if actual != expected:
        raise ValueError(f"Release statistics differ from the frozen specification: {actual}")

    for relative in (
        "RGBs",
        "TACs",
        "metadata",
        "splits",
    ):
        (output / relative).mkdir(parents=True, exist_ok=True)

    link_or_copy(labels_path, output / "label.txt")
    for split_name in (
        "fabric_common_v2.json",
        "fabric_common_v2_lowshot25.json",
        "fabric_common_v2_lowshot50.json",
    ):
        link_or_copy(split_dir / split_name, output / "splits" / split_name)

    fabric_rows: list[dict[str, Any]] = []
    for fabric_id in sorted(labels):
        label = labels[fabric_id]
        fabric_rows.append(
            {
                "fabric_id": fabric_id,
                "split": partition_by_id[fabric_id],
                "weave": label["weave"],
                "material": label["material"],
                "usage": label["usage"],
                "features": json.dumps(label["features"], ensure_ascii=True),
                "rgb_count": image_counts[fabric_id],
                "tactile_count": video_counts[fabric_id],
            }
        )
    write_csv(
        output / "metadata" / "fabrics.csv",
        ["fabric_id", "split", "weave", "material", "usage", "features", "rgb_count", "tactile_count"],
        fabric_rows,
    )

    observation_rows: list[dict[str, Any]] = []
    for modality, paths, destination_name in (
        ("rgb", images, "RGBs"),
        ("tactile", videos, "TACs"),
    ):
        modality_rows: list[dict[str, Any]] = []
        for path in paths:
            fabric_id = parse_fabric_id(path)
            label = labels[fabric_id]
            link_or_copy(path, output / destination_name / path.name)
            row = {
                "file_name": path.name,
                "fabric_id": fabric_id,
                "split": partition_by_id[fabric_id],
                "weave": label["weave"],
                "material": label["material"],
                "usage": label["usage"],
                "features": json.dumps(label["features"], ensure_ascii=True),
            }
            modality_rows.append(row)
            observation_rows.append(
                {
                    "path": f"{destination_name}/{path.name}",
                    "modality": modality,
                    **{key: value for key, value in row.items() if key != "file_name"},
                }
            )
        write_csv(
            output / destination_name / "metadata.csv",
            ["file_name", "fabric_id", "split", "weave", "material", "usage", "features"],
            modality_rows,
        )

    write_csv(
        output / "metadata" / "observations.csv",
        ["path", "modality", "fabric_id", "split", "weave", "material", "usage", "features"],
        observation_rows,
    )

    release_manifest = {
        "release_name": "VidTouch canonical release",
        "release_version": "1.0.0",
        "statistics": actual,
        "rgb_per_fabric_distribution": dict(sorted(Counter(image_counts.values()).items())),
        "tactile_per_fabric_distribution": dict(sorted(Counter(video_counts.values()).items())),
        "excluded_unannotated_source_media": {
            "rgb": excluded_images,
            "tactile": excluded_videos,
        },
        "canonical_label_sha256": sha256(labels_path),
        "frozen_split_sha256": sha256(split_dir / "fabric_common_v2.json"),
        "assignment_sha256": split["metadata"]["assignment_sha256"],
        "data_manifest_sha256": split["metadata"]["data_manifest_sha256"],
    }
    (output / "release_manifest.json").write_text(
        json.dumps(release_manifest, indent=2, ensure_ascii=True) + "\n",
        encoding="utf-8",
    )

    checksum_paths = sorted(
        path
        for path in output.rglob("*")
        if path.is_file() and path.name != "checksums.sha256"
    )
    with (output / "checksums.sha256").open("w", encoding="utf-8", newline="\n") as handle:
        for path in checksum_paths:
            relative = path.relative_to(output).as_posix()
            handle.write(f"{sha256(path)}  {relative}\n")

    print(json.dumps(release_manifest, indent=2))


if __name__ == "__main__":
    main()