office_translator/translators/watermark.py

"""
Watermark module for Free-tier output files.

Strategy: Add a subtle, professional footer/header that:
  - Clearly marks the file as "Free plan" output
  - Doesn't destroy the document's usability
  - Motivates upgrade without frustrating the user

DOCX: Footer with light-gray text + link
PPTX: Small text box bottom-right on each slide
XLSX: Footer text on each sheet
"""
from pathlib import Path
from typing import Optional

from docx import Document
from docx.oxml import OxmlElement
from docx.oxml.ns import qn
from docx.enum.text import WD_ALIGN_PARAGRAPH

from core.logging import get_logger

logger = get_logger(__name__)

WATERMARK_TEXT = "Translated with Office Translator — Free Plan"
WATERMARK_URL = "wordly.art"
WATERMARK_COLOR = "B0B0B0"  # Light gray


def add_watermark_docx(output_path: Path) -> None:
    """Add a subtle footer watermark to a DOCX file."""
    try:
        document = Document(str(output_path))

        for section in document.sections:
            # Enable footer
            footer = section.footer
            footer.is_linked_to_previous = False

            if not footer.paragraphs:
                footer.add_paragraph()

            para = footer.paragraphs[0]
            para.alignment = WD_ALIGN_PARAGRAPH.CENTER

            # Clear existing content
            for run in para.runs:
                run.clear()

            # Add watermark run
            run = para.add_run(WATERMARK_TEXT)
            run.font.size = 8  # Pt — small
            run.font.color.rgb = None  # Will set via XML

            # Set color via XML (more reliable)
            rPr = run._r.get_or_add_rPr()
            color_elem = OxmlElement("w:color")
            color_elem.set(qn("w:val"), WATERMARK_COLOR)
            rPr.append(color_elem)

        document.save(str(output_path))
        logger.info("watermark_added", file=str(output_path))

    except Exception as e:
        logger.error("watermark_docx_error", error=str(e))
        # Don't fail the whole translation if watermark fails


def add_watermark_pptx(output_path: Path) -> None:
    """Add a small watermark text box to each slide."""
    try:
        from pptx import Presentation
        from pptx.util import Inches, Pt, Emu
        from pptx.dml.color import RGBColor
        from pptx.enum.text import PP_ALIGN

        prs = Presentation(str(output_path))

        for slide in prs.slides:
            # Add text box at bottom-right
            left = Inches(5.5)
            top = Inches(7.0)
            width = Inches(3.5)
            height = Inches(0.4)

            txBox = slide.shapes.add_textbox(left, top, width, height)
            tf = txBox.text_frame
            tf.word_wrap = True

            p = tf.paragraphs[0]
            p.alignment = PP_ALIGN.RIGHT
            run = p.add_run()
            run.text = WATERMARK_TEXT
            run.font.size = Pt(7)
            run.font.color.rgb = RGBColor(0xB0, 0xB0, 0xB0)

        prs.save(str(output_path))
        logger.info("watermark_added_pptx", file=str(output_path))

    except Exception as e:
        logger.error("watermark_pptx_error", error=str(e))


def add_watermark_xlsx(output_path: Path) -> None:
    """Add a footer watermark to each sheet."""
    try:
        from openpyxl import load_workbook
        from openpyxl.worksheet.header_footer import HeaderFooter

        wb = load_workbook(str(output_path))

        for ws in wb.worksheets:
            if ws.sheet_properties.pageSetUpPr is None:
                from openpyxl.worksheet.properties import PageSetupProperties
                ws.sheet_properties.pageSetUpPr = PageSetupProperties()

            ws.oddFooter.center.text = WATERMARK_TEXT
            ws.oddFooter.center.font = "Arial,Regular"
            ws.oddFooter.center.size = 8

        wb.save(str(output_path))
        wb.close()
        logger.info("watermark_added_xlsx", file=str(output_path))

    except Exception as e:
        logger.error("watermark_xlsx_error", error=str(e))


def add_watermark_pdf(output_path: Path) -> None:
    """Add a subtle footer watermark on every page of a PDF using PyMuPDF."""
    try:
        import fitz

        doc = fitz.open(str(output_path))
        for page in doc:
            rect = page.rect
            # Position at bottom center
            text_point = fitz.Point(
                rect.width / 2 - 100,
                rect.height - 15
            )
            page.insert_text(
                text_point,
                WATERMARK_TEXT,
                fontsize=7,
                color=(0.69, 0.69, 0.69),  # #B0B0B0
                fontname="helv",
            )
        doc.save(str(output_path), incremental=True, encryption=0)
        doc.close()
        logger.info("watermark_added_pdf", file=str(output_path))
    except Exception as e:
        logger.error("watermark_pdf_error", error=str(e))


def add_watermark(output_path: Path, file_extension: str) -> None:
    """Apply watermark based on file type."""
    ext = file_extension.lower()
    if ext == ".docx":
        add_watermark_docx(output_path)
    elif ext == ".pptx":
        add_watermark_pptx(output_path)
    elif ext == ".xlsx":
        add_watermark_xlsx(output_path)
    elif ext == ".pdf":
        add_watermark_pdf(output_path)
    else:
        logger.info("watermark_skipped", extension=ext)