"""
A simple CLI to updates descriptive statistics on all datasets.

Example use:

    python update_descriptive_statistics.py --dataset wikisource

"""

import argparse
import json
import logging
from dataclasses import dataclass
from pathlib import Path
from textwrap import dedent
from typing import Self, cast

from datasets import Dataset, load_dataset
from git_utilities import check_is_ancestor, get_current_revision, get_latest_revision

logger = logging.getLogger(__name__)

repo_path = Path(__file__).parent.parent


def human_readable_large_int(value: int) -> str:
    thresholds = [
        (1_000_000_000, "B"),
        (1_000_000, "M"),
        (1_000, "K"),
    ]
    for threshold, label in thresholds:
        if value > threshold:
            return f"{value/threshold:.2f}{label}"

    return str(value)


@dataclass()
class DescriptiveStatsOverview:
    number_of_samples: int
    average_document_length: float
    language: str = "dan, dansk, Danish"

    @classmethod
    def from_dataset(cls, dataset: Dataset) -> Self:
        return cls(
            number_of_samples=len(dataset),
            average_document_length=cls.calculate_average_document_length(dataset),
        )

    @staticmethod
    def calculate_average_document_length(dataset: Dataset) -> float:
        texts = sum(len(t) for t in dataset["text"])
        return texts / len(dataset)

    def to_markdown(self) -> str:
        format = dedent(f"""

        - **Language**: {self.language}
        - **Number of samples**: {human_readable_large_int(self.number_of_samples)}
        - **Average document length (characters)**: {self.average_document_length:.2f}

        """)
        return format

    def add_to_markdown(self, markdown: str) -> str:
        start_identifier = "<!-- START-DESC-STATS -->"
        end_identifier = "<!-- END-DESC-STATS -->"

        if markdown.count(start_identifier) != 1 or markdown.count(end_identifier) != 1:
            raise ValueError("Markers should appear exactly once in the markdown.")

        start_md, _, remainder = markdown.partition(start_identifier)
        _, _, end_md = remainder.partition(end_identifier)

        stats = self.to_markdown()
        return f"{start_md}{start_identifier}{stats}{end_identifier}{end_md}"

    def to_disk(self, path: Path):
        data = self.__dict__
        data["revision"] = get_current_revision()
        with path.with_suffix(".json").open("w") as f:
            json.dump(self.__dict__, f)


def update_statitics(
    dataset_path: Path,
    name: str,
    readme_name: None | str = None,
    force: bool = False,
) -> None:
    rev = get_latest_revision(dataset_path)

    desc_stats_path = dataset_path / "descriptive_stats.json"
    if desc_stats_path.exists() and force is False:
        with desc_stats_path.open("r") as f:
            last_update = json.load(f).get("revision", None)

        if last_update is None:
            logging.warning(f"revision is not defined in {desc_stats_path}.")
        elif check_is_ancestor(ancestor_rev=last_update, rev=rev):
            logging.info(
                f"descriptive statistics for '{name}' is already up to date, skipping."
            )
            return

    logger.info(f"Updating statistics for {name}")
    ds = load_dataset(str(repo_path), name, split="train")
    ds = cast(Dataset, ds)
    desc_stats = DescriptiveStatsOverview.from_dataset(ds)

    readme_name = f"{name}.md" if readme_name is None else readme_name
    markdown_path = dataset_path / readme_name
    with markdown_path.open("r") as f:
        new_markdown = desc_stats.add_to_markdown(f.read())
    with markdown_path.open("w") as f:
        f.write(new_markdown)

    desc_stats.to_disk(desc_stats_path)


def create_parser():
    parser = argparse.ArgumentParser(
        description="Calculated descriptive statistics of the datasets in tha data folder"
    )
    parser.add_argument(
        "--dataset",
        default=None,
        type=str,
        help="Use to specify if you only want to compute the statistics from a singular dataset.",
    )
    parser.add_argument(
        "--logging_level",
        default=20,
        type=int,
        help="Sets the logging level. Default to 20 (INFO), other reasonable levels are 10 (DEBUG) and 30 (WARNING).",
    )
    parser.add_argument(
        "--force",
        type=bool,
        default=False,
        action=argparse.BooleanOptionalAction,
        help="Should the statistics be forcefully recomputed. By default it checks the difference in commit ids.",
    )
    parser.add_argument(
        "--repo_path",
        default=str(repo_path),
        type=str,
        help="The repository where to calculate the descriptive statistics from",
    )
    return parser


def main(
    dataset: str | None = None,
    logging_level: int = 20,
    force: bool = False,
    repo_path: Path = repo_path,
):
    logging.basicConfig(level=logging_level)

    if dataset:
        dataset_path = repo_path / "data" / dataset
        update_statitics(repo_path, dataset_path.name, force=force)
        return

    datasets = (repo_path / "data").glob("*")
    for dataset_path in datasets:
        update_statitics(dataset_path, dataset_path.name, force=force)

    update_statitics(repo_path, "default", "README.md", force=force)


if __name__ == "__main__":
    parser = create_parser()
    args = parser.parse_args()

    main(
        args.dataset,
        logging_level=args.logging_level,
        force=args.force,
        repo_path=Path(args.repo_path),
    )