#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# File: src/scitex_writer/_utils/_csv_latex.py

"""
CSV <-> LaTeX table conversion utilities.
"""

from __future__ import annotations

import logging
import re
from pathlib import Path
from typing import Optional, Union

logger = logging.getLogger(__name__)


def csv2latex(
    csv_path: Union[str, Path],
    output_path: Optional[Union[str, Path]] = None,
    caption: Optional[str] = None,
    label: Optional[str] = None,
    escape: bool = True,
    longtable: bool = False,
    index: bool = False,
    column_format: Optional[str] = None,
    **kwargs,
) -> str:
    """
    Convert CSV file to LaTeX table.

    Parameters
    ----------
    csv_path : str or Path
        Path to CSV file
    output_path : str or Path, optional
        If provided, save LaTeX to this file
    caption : str, optional
        Table caption
    label : str, optional
        Table label for referencing
    escape : bool, default True
        Escape special LaTeX characters
    longtable : bool, default False
        Use longtable environment for multi-page tables
    index : bool, default False
        Include DataFrame index in output
    column_format : str, optional
        LaTeX column format (e.g., 'lcr', 'l|cc|r')
    **kwargs
        Additional arguments passed to pandas.DataFrame.to_latex()

    Returns
    -------
    str
        LaTeX table string

    Examples
    --------
    >>> latex = csv2latex("data.csv", caption="Results", label="tab:results")
    >>> csv2latex("data.csv", "table.tex")  # Save to file
    """
    import pandas as pd

    csv_path = Path(csv_path)
    if not csv_path.exists():
        raise FileNotFoundError(f"CSV file not found: {csv_path}")

    # Load CSV
    df = pd.read_csv(csv_path)

    # Build to_latex arguments
    latex_kwargs = {
        "index": index,
        "escape": escape,
        "caption": caption,
        "label": label,
    }

    if longtable:
        latex_kwargs["longtable"] = True

    if column_format:
        latex_kwargs["column_format"] = column_format

    # Merge with user kwargs
    latex_kwargs.update(kwargs)

    # Convert to LaTeX
    latex_content = df.to_latex(**latex_kwargs)

    # Save if output path provided
    if output_path:
        output_path = Path(output_path)
        output_path.parent.mkdir(parents=True, exist_ok=True)
        with open(output_path, "w") as f:
            f.write(latex_content)
        logger.info(f"Saved LaTeX table to {output_path}")

    return latex_content


def latex2csv(
    latex_path: Union[str, Path],
    output_path: Optional[Union[str, Path]] = None,
    table_index: int = 0,
):
    """
    Convert LaTeX table to CSV/DataFrame.

    Parameters
    ----------
    latex_path : str or Path
        Path to LaTeX file containing table
    output_path : str or Path, optional
        If provided, save CSV to this file
    table_index : int, default 0
        Which table to extract if multiple tables exist

    Returns
    -------
    pd.DataFrame
        Extracted table as DataFrame

    Examples
    --------
    >>> df = latex2csv("table.tex")
    >>> df = latex2csv("table.tex", "output.csv")
    """
    import pandas as pd

    latex_path = Path(latex_path)
    if not latex_path.exists():
        raise FileNotFoundError(f"LaTeX file not found: {latex_path}")

    with open(latex_path) as f:
        content = f.read()

    # Extract table content (between \begin{tabular} and \end{tabular})
    # Also handle longtable
    patterns = [
        r"\\begin\{tabular\}.*?\n(.*?)\\end\{tabular\}",
        r"\\begin\{longtable\}.*?\n(.*?)\\end\{longtable\}",
    ]

    tables = []
    for pattern in patterns:
        matches = re.findall(pattern, content, re.DOTALL)
        tables.extend(matches)

    if not tables:
        raise ValueError("No table found in LaTeX file")

    if table_index >= len(tables):
        raise IndexError(
            f"Table index {table_index} out of range. Found {len(tables)} tables."
        )

    table_content = tables[table_index]

    # Parse table rows
    rows = []
    for line in table_content.split("\n"):
        line = line.strip()
        if not line or line.startswith("\\"):
            continue
        if "&" in line:
            # Remove trailing \\ and split by &
            line = re.sub(r"\\\\.*$", "", line)
            cells = [cell.strip() for cell in line.split("&")]
            rows.append(cells)

    if not rows:
        raise ValueError("Could not parse table rows")

    # Create DataFrame (first row as header if it looks like headers)
    if len(rows) > 1:
        df = pd.DataFrame(rows[1:], columns=rows[0])
    else:
        df = pd.DataFrame(rows)

    # Save if output path provided
    if output_path:
        output_path = Path(output_path)
        output_path.parent.mkdir(parents=True, exist_ok=True)
        df.to_csv(output_path, index=False)
        logger.info(f"Saved CSV to {output_path}")

    return df


__all__ = ["csv2latex", "latex2csv"]

# EOF