# -*- coding: utf-8 -*-
"""Headless file parsing helpers used by both Streamlit and R3-Free executor."""
from __future__ import annotations

import io
import logging
import os
from pathlib import Path
from typing import BinaryIO, Iterable

from docx import Document
from config import APP_CONFIG

try:
    import pandas as pd
    PANDAS_AVAILABLE = True
except ImportError:
    PANDAS_AVAILABLE = False

try:
    import pymupdf
    PYMUPDF_AVAILABLE = True
except ImportError:
    PYMUPDF_AVAILABLE = False


def _name(file) -> str:
    if isinstance(file, (str, os.PathLike, Path)):
        return os.fspath(file)
    return str(getattr(file, "name", "uploaded_file"))


def _read_bytes(file) -> bytes:
    if isinstance(file, (str, os.PathLike, Path)):
        return Path(file).read_bytes()
    try:
        file.seek(0)
    except Exception:
        pass
    if hasattr(file, "getvalue"):
        data = file.getvalue()
    else:
        data = file.read()
    try:
        file.seek(0)
    except Exception:
        pass
    return bytes(data or b"")


def _binary_stream(file) -> io.BytesIO | BinaryIO:
    if isinstance(file, (str, os.PathLike, Path)):
        return io.BytesIO(Path(file).read_bytes())
    try:
        file.seek(0)
    except Exception:
        pass
    return file


def extract_text_from_files(uploaded_files: Iterable, max_chars=None):
    if max_chars is None:
        max_chars = APP_CONFIG.get("max_extract_chars", 150000)

    extracted_text = ""
    for file in uploaded_files or []:
        filename = _name(file)
        lower_name = filename.lower()
        try:
            if lower_name.endswith(".pdf") and PYMUPDF_AVAILABLE:
                pdf_bytes = _read_bytes(file)
                with pymupdf.open(stream=pdf_bytes, filetype="pdf") as pdf_doc:
                    for page in pdf_doc:
                        text = page.get_text()
                        if text:
                            extracted_text += text + "\n"
                        if len(extracted_text) > max_chars:
                            break
            elif lower_name.endswith((".docx", ".doc")):
                stream = _binary_stream(file)
                doc = Document(stream)
                for para in doc.paragraphs:
                    extracted_text += para.text + "\n"
                    if len(extracted_text) > max_chars:
                        break
            else:
                extracted_text += _read_bytes(file).decode("utf-8", errors="ignore") + "\n"

            if len(extracted_text) > max_chars:
                logging.warning("File %s was truncated safely to %s characters.", filename, max_chars)
                break
        except Exception as exc:
            logging.warning("File parse failed for %s: %s", filename, exc)
        finally:
            if not isinstance(file, (str, os.PathLike, Path)):
                try:
                    file.seek(0)
                except Exception:
                    pass
    return extracted_text[:max_chars]


def extract_data_from_files(uploaded_file, max_chars=20000):
    if not uploaded_file:
        return ""

    filename = _name(uploaded_file)
    lower_name = filename.lower()
    try:
        if PANDAS_AVAILABLE:
            source = os.fspath(uploaded_file) if isinstance(uploaded_file, (str, os.PathLike, Path)) else uploaded_file
            if not isinstance(uploaded_file, (str, os.PathLike, Path)):
                try:
                    uploaded_file.seek(0)
                except Exception:
                    pass
            df = pd.read_csv(source) if lower_name.endswith(".csv") else pd.read_excel(source)
            if len(df) > 100:
                logging.warning("Data file %s truncated safely to first 100 rows.", filename)
                df = df.head(100)
            return df.to_markdown(index=False)
        return _read_bytes(uploaded_file).decode("utf-8", errors="ignore")[:max_chars]
    except Exception as exc:
        logging.warning("Data parse failed for %s: %s", filename, exc)
        return ""
    finally:
        if not isinstance(uploaded_file, (str, os.PathLike, Path)):
            try:
                uploaded_file.seek(0)
            except Exception:
                pass