import json
import logging
from datetime import datetime
from enum import Enum
from pathlib import Path
from textwrap import dedent
from typing import Any, Literal, Self, cast

import yaml
from datasets import Dataset, load_dataset
from pydantic import BaseModel, field_validator

from dynaword.descriptive_stats import DescriptiveStatsOverview
from dynaword.plots import create_descriptive_statistics_plots
from dynaword.typings import DOMAIN, LICENSE, LICENSE_NAMES_MAPPING

logger = logging.getLogger(__name__)


LICENSE_HEADER = "## License Information"


class DEFAULT_SECTION_TAGS(Enum):
    desc_stats = "DESC-STATS"
    sample = "SAMPLE"
    dataset_plots = "DATASET PLOTS"
    short_description = "SHORT DESCRIPTION"


DATASET_PLOTS_template = """
<p align="center">
<img src="./images/dist_document_length.png" width="600" style="margin-right: 10px;" />
</p>
"""


SAMPLE_template = """
```py
{sample}
```

### Data Fields

An entry in the dataset consists of the following fields:

- `id` (`str`): An unique identifier for each document.
- `text`(`str`): The content of the document.
- `source` (`str`): The source of the document (see [Source Data](#source-data)).
- `added` (`str`): An date for when the document was added to this collection.
- `created` (`str`): An date range for when the document was originally created.
- `token_count` (`int`): The number of tokens in the sample computed using the Llama 8B tokenizer
"""


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)


def create_sample_str(dataset: Dataset, max_str_len: int = 100):
    sample = dataset[0]
    for k in sample:
        if isinstance(sample[k], str) and len(sample[k]) > max_str_len:
            sample[k] = sample[k][:max_str_len] + "[...]"
        if isinstance(sample[k], datetime):
            sample[k] = str(sample[k])

    json_sample = json.dumps(sample, indent=2, ensure_ascii=False)
    sample_str = SAMPLE_template.format(sample=json_sample)

    return sample_str


class DataSheet(BaseModel):
    pretty_name: str
    license: LICENSE
    license_name: str | None
    language: list[Literal["da"]]
    domains: list[DOMAIN] | None  # None for main readme # TODO: make literal
    path: Path
    frontmatter: dict[str, Any]
    body: str

    # check that licence name is compatible with license
    @field_validator("license_name")  # type: ignore
    def check_license_name(cls, v: str | None, values: dict[str, Any]) -> str | None:
        if v is not None and v in LICENSE_NAMES_MAPPING:
            if values["license"] != LICENSE_NAMES_MAPPING[v]:
                raise ValueError(
                    f"License name '{v}' does not match license '{values['license']}'"
                )
        return v

    @property
    def short_description(self) -> str:
        short_description = self.get_tag_content(DEFAULT_SECTION_TAGS.short_description)
        if short_description.endswith("."):
            short_description = short_description[:-1]
        return short_description

    @property
    def license_information(self) -> str:
        return self.get_section_by_header(LICENSE_HEADER)

    @property
    def frontmatter_as_str(self) -> str:
        return yaml.dump(self.frontmatter, indent=2, sort_keys=False)

    def to_str(self) -> str:
        return f"---\n{self.frontmatter_as_str.strip()}\n---\n\n{self.body.strip()}\n"

    def get_dataset(self, **kwargs) -> Dataset:
        ds_path = self.path.parent
        ds = load_dataset(ds_path.as_posix(), split="train", **kwargs)
        ds = cast(Dataset, ds)
        return ds

    def get_descritive_stats(self) -> DescriptiveStatsOverview:
        path = self.path.parent / "descriptive_stats.json"
        return DescriptiveStatsOverview.from_disk(path)

    def get_section_indices_by_header(self, header: str) -> tuple[int, int]:
        level = header.split(" ")[0].count("#")

        next_is_end_section = False
        end_header = None
        for _header in self.get_headers(levels=list(range(1, level + 1))):
            if header.strip() == _header.strip():
                next_is_end_section = True
                continue

            if next_is_end_section:
                end_header = _header
                break

        if next_is_end_section is None:
            raise ValueError(f"The header '{header}' is not found in the text.")

        start_idx = self.body.find(header)
        if end_header:
            end_idx = self.body[start_idx:].find(end_header) + start_idx
        else:
            end_idx = len(self.body)

        return start_idx, end_idx

    def get_section_by_header(self, header: str) -> str:
        s, e = self.get_section_indices_by_header(header)
        return self.body[s:e]

    def get_headers(self, levels: list[int] = [1, 2, 3, 4]) -> list[str]:
        def __contains_level(text: str) -> bool:
            if text.startswith("#"):
                for level in levels:
                    if text.startswith("#" * level):
                        return True
            return False

        return [line for line in self.body.splitlines() if __contains_level(line)]

    def get_tag_idx(self, tag: str | DEFAULT_SECTION_TAGS) -> tuple[int, int]:
        if isinstance(tag, Enum):
            tag = tag.value
        tag_start = f"<!-- START-{tag} -->"
        tag_end = f"<!-- END-{tag} -->"
        start_idx = self.body.find(tag_start)
        end_idx = self.body.find(tag_end)
        if end_idx != -1 and start_idx != -1 and start_idx < end_idx:
            return start_idx, end_idx
        raise ValueError(f"tag ({tag}) not found in readme")

    def get_tag_content(self, tag: str | DEFAULT_SECTION_TAGS) -> str:
        if isinstance(tag, Enum):
            tag = tag.value
        s, e = self.get_tag_idx(tag=tag)
        tag_start = f"<!-- START-{tag} -->"
        return self.body[s + len(tag_start) : e].strip()

    def add_descriptive_stats(
        self, descriptive_stats: DescriptiveStatsOverview | None = None
    ) -> str:
        if descriptive_stats is None:
            d_stats = DescriptiveStatsOverview.from_dataset(self.get_dataset())
        else:
            d_stats = descriptive_stats

        if len(self.language) != 1 and self.language[0] != "da":
            raise NotImplementedError(
                "This script only handles the language codes 'da'"
            )
        languages = "dan, dansk, Danish"

        package = dedent(f"""
        - **Language**: {languages}\n""")

        if self.domains:
            domains = ", ".join(self.domains)
            package += f"- **Domains**: {domains}\n"

        package += (
            dedent(f"""
        - **Number of samples**: {human_readable_large_int(d_stats.number_of_samples)}
        - **Number of tokens (Llama 3)**: {human_readable_large_int(d_stats.number_of_tokens)}
        - **Average document length (characters)**: {d_stats.average_document_length:.2f}
        """).strip()
            + "\n"
        )

        return self.replace_tag(
            package=package,
            tag=DEFAULT_SECTION_TAGS.desc_stats,
        )

    def add_dataset_plots(self, dataset: Dataset, create_plot: bool = True) -> str:
        if create_plot:
            create_descriptive_statistics_plots(
                dataset=dataset, save_dir=self.path.parent
            )
        return self.replace_tag(
            package=DATASET_PLOTS_template, tag=DEFAULT_SECTION_TAGS.dataset_plots
        )

    def add_sample_and_description(self, dataset: Dataset) -> str:
        return self.replace_tag(
            package=create_sample_str(dataset), tag=DEFAULT_SECTION_TAGS.sample
        )

    def replace_tag(self, package: str, tag: str | DEFAULT_SECTION_TAGS) -> str:
        """Add replace a tag in the datasheet body.

        Args:
            package: What you want to replace it with
            tag: What tag you want to replace

        Returns:
            The entire body text
        """
        if isinstance(tag, Enum):
            tag = tag.value
        tag_start = f"<!-- START-{tag} -->"
        tag_end = f"<!-- END-{tag} -->"

        if self.body.count(tag_start) != 1 or self.body.count(tag_end) != 1:
            raise ValueError(
                f"The markers ({tag_start} ... {tag_end}) does not appear in the markdown. Markers should appear exactly once in the markdown."
            )

        start_md, _, remainder = self.body.partition(tag_start)
        _, _, end_md = remainder.partition(tag_end)

        return f"{start_md}{tag_start}\n{package.strip()}\n{tag_end}{end_md}"

    @staticmethod
    def get_frontmatter_and_body(file_path: Path) -> tuple[dict[str, Any], str]:
        with file_path.open("r") as f:
            content = f.read()
        if content.startswith("---"):
            end_idx = content.find("---", 3)
            start_idx_body = end_idx + 3
            if end_idx != -1:
                frontmatter = content[3:end_idx].strip()
                return yaml.safe_load(frontmatter), content[start_idx_body:]
        raise ValueError(f"No frontmatter found in file: {file_path}")

    @classmethod
    def load_from_path(cls, readme_path: Path) -> Self:
        frontmatter, body = cls.get_frontmatter_and_body(readme_path)
        return cls(
            frontmatter=frontmatter,
            body=body,
            license=frontmatter["license"],
            language=frontmatter["language"],
            pretty_name=frontmatter["pretty_name"],
            domains=frontmatter["domains"] if "domains" in frontmatter else None,
            license_name=frontmatter["license_name"]
            if "license_name" in frontmatter
            else None,
            path=readme_path,
        )

    def write_to_path(self, readme_path: Path | None = None) -> None:
        if readme_path is None:
            readme_path = self.path
        with readme_path.open("w") as f:
            f.write(self.to_str())


if __name__ == "__main__":
    from dynaword.paths import repo_path

    sheet = DataSheet.load_from_path(repo_path / "data" / "dannet" / "dannet.md")
    ds = sheet.get_dataset()

    sheet.body = sheet.add_descriptive_stats(descriptive_stats=None)
    sheet.write_to_path()