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"""
Collect performance metrics of published traditional or end-to-end image
codecs.
"""
import argparse
import json
import multiprocessing as mp
import sys

from collections import defaultdict
from itertools import starmap
from pathlib import Path
from typing import List

from .codecs import AV1, BPG, HM, JPEG, JPEG2000, TFCI, VTM, Codec, WebP

# from torchvision.datasets.folder
IMG_EXTENSIONS = (
    ".jpg",
    ".jpeg",
    ".png",
    ".ppm",
    ".bmp",
    ".pgm",
    ".tif",
    ".tiff",
    ".webp",
)

codecs = [JPEG, WebP, JPEG2000, BPG, TFCI, VTM, HM, AV1]


# we need the quality index (not value) to compute the stats later
def func(codec, i, *args):
    rv = codec.run(*args)
    return i, rv


def collect(
    codec: Codec,
    dataset: str,
    qps: List[int],
    metrics: List[str],
    num_jobs: int = 1,
):
    if not Path(dataset).is_dir():
        raise OSError(f"No such directory: {dataset}")

    filepaths = []
    for ext in IMG_EXTENSIONS:
        filepaths.extend(Path(dataset).rglob(f"*{ext}"))

    pool = mp.Pool(num_jobs) if num_jobs > 1 else None

    if len(filepaths) == 0:
        print("No images found in the dataset directory")
        sys.exit(1)

    args = [
        (codec, i, f, q, metrics) for i, q in enumerate(qps) for f in sorted(filepaths)
    ]

    if pool:
        rv = pool.starmap(func, args)
    else:
        rv = list(starmap(func, args))

    results = [defaultdict(float) for _ in range(len(qps))]

    for i, metrics in rv:
        for k, v in metrics.items():
            results[i][k] += v

    # aggregate results for all images
    for i, _ in enumerate(results):
        for k, v in results[i].items():
            results[i][k] = v / len(filepaths)

    # list of dict -> dict of list
    out = defaultdict(list)
    for r in results:
        for k, v in r.items():
            out[k].append(v)
    return out


def setup_args():
    description = "Collect codec metrics."
    parser = argparse.ArgumentParser(description=description)
    subparsers = parser.add_subparsers(dest="codec", help="Select codec")
    subparsers.required = True
    return parser, subparsers


def setup_common_args(parser):
    parser.add_argument("dataset", type=str)
    parser.add_argument(
        "-j",
        "--num-jobs",
        type=int,
        metavar="N",
        default=1,
        help="number of parallel jobs (default: %(default)s)",
    )
    parser.add_argument(
        "-q",
        "--qps",
        dest="qps",
        type=str,
        default="75",
        help="list of quality/quantization parameter (default: %(default)s)",
    )
    parser.add_argument(
        "--metrics",
        dest="metrics",
        default=["psnr-rgb", "ms-ssim-rgb"],
        nargs="+",
        help="do not return PSNR and MS-SSIM metrics (use for very small images)",
    )


def main(argv):
    parser, subparsers = setup_args()
    for c in codecs:
        cparser = subparsers.add_parser(c.__name__.lower(), help=f"{c.__name__}")
        setup_common_args(cparser)
        c.setup_args(cparser)
    args = parser.parse_args(argv)

    codec_cls = next(c for c in codecs if c.__name__.lower() == args.codec)
    codec = codec_cls(args)
    qps = [int(q) for q in args.qps.split(",") if q]
    results = collect(
        codec,
        args.dataset,
        sorted(qps),
        args.metrics,
        args.num_jobs,
    )

    output = {
        "name": codec.name,
        "description": codec.description,
        "results": results,
    }

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


if __name__ == "__main__":
    main(sys.argv[1:])
