from pypdf import PdfReader
from docx import Document
import openpyxl
from typing import Union
import io
import logging
from bs4 import BeautifulSoup
logger = logging.getLogger(__name__)

class DocumentProcessor:
    @staticmethod
    def _cell_to_text(v) -> str:
       if v is None:
           return ""
       s = str(v).strip()
       return s if s else ""

    @staticmethod
    def _sheet_rows_text_openpyxl(sheet) -> list[str]:
       out: list[str] = []
       for row in sheet.iter_rows(values_only=True):
           vals = [DocumentProcessor._cell_to_text(c) for c in row]
           vals = [x for x in vals if x]
           if vals:
               out.append(" | ".join(vals))
       return out

    @staticmethod
    def _sheet_cols_text_openpyxl(sheet) -> list[str]:
       out: list[str] = []
       max_col = sheet.max_column or 0
       max_row = sheet.max_row or 0
       for c in range(1, max_col + 1):
           vals: list[str] = []
           for r in range(1, max_row + 1):
               v = DocumentProcessor._cell_to_text(sheet.cell(r, c).value)
               if v:
                   vals.append(v)
           if vals:
               col_letter = openpyxl.utils.get_column_letter(c)
               out.append(f"COL {col_letter} TOP_DOWN: " + " || ".join(vals))
               out.append(f"COL {col_letter} BOTTOM_UP: " + " || ".join(reversed(vals)))
       return out

    @staticmethod
    def _sheet_rows_text_xlrd(sheet) -> list[str]:
       out: list[str] = []
       for row_idx in range(sheet.nrows):
           row = sheet.row_values(row_idx)
           vals = [DocumentProcessor._cell_to_text(c) for c in row]
           vals = [x for x in vals if x]
           if vals:
               out.append(" | ".join(vals))
       return out

    @staticmethod
    def _sheet_cols_text_xlrd(sheet) -> list[str]:
       out: list[str] = []
       for c in range(sheet.ncols):
           vals: list[str] = []
           for r in range(sheet.nrows):
               v = DocumentProcessor._cell_to_text(sheet.cell_value(r, c))
               if v:
                   vals.append(v)
           if vals:
               out.append(f"COL {c+1} TOP_DOWN: " + " || ".join(vals))
               out.append(f"COL {c+1} BOTTOM_UP: " + " || ".join(reversed(vals)))
       return out

    def normalize_email_html(html_content: str) -> str:
       """
       Очищает HTML письма и нормализует таблицы
       """

       soup = BeautifulSoup(html_content, "html.parser")

       # удаляем скрипты и стили
       for tag in soup(["script", "style"]):
           tag.decompose()

       # нормализуем таблицы
       for table in soup.find_all("table"):
           table["style"] = "border-collapse: collapse; width: 100%;"

           for cell in table.find_all(["td", "th"]):
               cell["style"] = "border:1px solid #ccc;padding:6px;"

       return str(soup)
    def extract_text(self, content: bytes, filename: str) -> str:
       ext = filename.lower().split('.')[-1]
    
       # Изображения не обрабатываем
       if ext in ['png', 'jpg', 'jpeg', 'gif', 'bmp', 'tiff', 'webp']:
           return ""
    
       if ext == 'pdf':
           return self._extract_pdf(content)
       elif ext in ['docx', 'doc']:
           return self._extract_docx(content)
       elif ext in ['xlsx', 'xls']:
           return self._extract_excel(content)
       elif ext == 'txt':
           return content.decode('utf-8')
       else:
           raise ValueError(f"Unsupported format: {ext}")
    def _extract_pdf(self, content: bytes) -> str:
        pdf = PdfReader(io.BytesIO(content))
        return "\n".join(page.extract_text() for page in pdf.pages)
    
    def _extract_docx(self, content: bytes) -> str:
        doc = Document(io.BytesIO(content))
        return "\n".join(paragraph.text for paragraph in doc.paragraphs)
    
    def _extract_excel(self, content: bytes) -> str:
        try:
            # сначала пробуем openpyxl (для .xlsx)
            wb = openpyxl.load_workbook(io.BytesIO(content))
            text = []
            for sheet in wb.worksheets:
                text.append(f"=== SHEET: {sheet.title} ===")
                # Сохраняем совместимость: построчное чтение.
                rows_text = self._sheet_rows_text_openpyxl(sheet)
                if rows_text:
                    text.append("[ROWS]")
                    text.extend(rows_text)
                # Новый режим: чтение по колонкам (общие данные часто внизу столбца).
                cols_text = self._sheet_cols_text_openpyxl(sheet)
                if cols_text:
                    text.append("[COLUMNS]")
                    text.extend(cols_text)
            return "\n".join(text)
        except Exception as e:
            # если не получилось, возможно это .xls, пробуем xlrd
            try:
                import xlrd
                workbook = xlrd.open_workbook(file_contents=content)
                text = []
                for sheet in workbook.sheets():
                    text.append(f"=== SHEET: {sheet.name} ===")
                    rows_text = self._sheet_rows_text_xlrd(sheet)
                    if rows_text:
                        text.append("[ROWS]")
                        text.extend(rows_text)
                    cols_text = self._sheet_cols_text_xlrd(sheet)
                    if cols_text:
                        text.append("[COLUMNS]")
                        text.extend(cols_text)
                return "\n".join(text)
            except ImportError:
                logger.error("xlrd not installed, cannot parse .xls files")
                return ""
            except Exception as e2:
                logger.error(f"Failed to parse Excel with xlrd: {e2}")
                return ""