"""Document merger for combining multiple DOCX files into one"""

import os
import glob
from docx import Document
from docx.enum.text import WD_BREAK
from typing import List


class DocumentMerger:
    """Merge multiple DOCX files into a single document with page breaks"""

    def __init__(self):
        pass

    def _add_page_break(self, doc: Document):
        """
        Add a page break at the end of document

        Args:
            doc: DOCX document object
        """
        paragraph = doc.add_paragraph()
        run = paragraph.add_run()
        run.add_break(WD_BREAK.PAGE)

    def _copy_paragraph(self, source_para, target_doc: Document):
        """
        Copy paragraph with all formatting to target document

        Args:
            source_para: Source paragraph to copy
            target_doc: Target document to copy to
        """
        # Create new paragraph with same style
        new_para = target_doc.add_paragraph(style=source_para.style)
        new_para.alignment = source_para.alignment

        # Copy all runs with formatting
        for run in source_para.runs:
            new_run = new_para.add_run(run.text)
            new_run.bold = run.bold
            new_run.italic = run.italic
            new_run.underline = run.underline

            # Copy font properties
            if run.font.size:
                new_run.font.size = run.font.size
            if run.font.name:
                new_run.font.name = run.font.name

    def _copy_table(self, source_table, target_doc: Document):
        """
        Copy table with all formatting to target document

        Args:
            source_table: Source table to copy
            target_doc: Target document to copy to
        """
        rows = len(source_table.rows)
        cols = len(source_table.columns)

        # Create new table
        new_table = target_doc.add_table(rows=rows, cols=cols)

        # Copy table style
        if source_table.style:
            new_table.style = source_table.style

        # Copy cell contents
        for i, row in enumerate(source_table.rows):
            for j, cell in enumerate(row.cells):
                new_cell = new_table.rows[i].cells[j]

                # Remove default paragraph
                new_cell.text = ''

                # Copy each paragraph in the cell
                for para in cell.paragraphs:
                    new_para = new_cell.add_paragraph(style=para.style)
                    new_para.alignment = para.alignment

                    # Copy runs with formatting
                    for run in para.runs:
                        new_run = new_para.add_run(run.text)
                        new_run.bold = run.bold
                        new_run.italic = run.italic
                        new_run.underline = run.underline

                        if run.font.size:
                            new_run.font.size = run.font.size
                        if run.font.name:
                            new_run.font.name = run.font.name

                # Remove the first empty paragraph that was auto-created
                if len(new_cell.paragraphs) > len(cell.paragraphs):
                    p = new_cell.paragraphs[0]._element
                    p.getparent().remove(p)

    def merge_files(self, docx_files: List[str], output_file: str):
        """
        Merge multiple DOCX files into a single document

        Args:
            docx_files: List of paths to DOCX files to merge
            output_file: Path to output merged document
        """
        if not docx_files:
            raise ValueError("No DOCX files provided to merge")

        # Sort files to ensure consistent order
        docx_files = sorted(docx_files)

        # Start with the first document as base
        merged_doc = Document(docx_files[0])

        # Process remaining documents
        for docx_file in docx_files[1:]:
            # Add page break before next document
            self._add_page_break(merged_doc)

            # Load the document to merge
            sub_doc = Document(docx_file)

            # Copy all paragraphs
            for paragraph in sub_doc.paragraphs:
                self._copy_paragraph(paragraph, merged_doc)

            # Copy all tables
            for table in sub_doc.tables:
                self._copy_table(table, merged_doc)

        # Save merged document
        merged_doc.save(output_file)

    def merge_from_folder(self, input_folder: str, output_file: str, pattern: str = '*.docx') -> int:
        """
        Merge all DOCX files from a folder into a single document

        Args:
            input_folder: Folder containing DOCX files
            output_file: Path to output merged document
            pattern: File pattern to match (default: *.docx)

        Returns:
            Number of documents merged
        """
        # Find all matching DOCX files
        search_pattern = os.path.join(input_folder, pattern)
        docx_files = glob.glob(search_pattern)

        if not docx_files:
            raise ValueError(f"No DOCX files found in {input_folder} matching pattern {pattern}")

        # Merge files
        self.merge_files(docx_files, output_file)

        return len(docx_files)