#!/usr/bin/env python3
"""Embed Open Sans / Open Sans Light TTFs into a docx so it renders correctly
even on machines that don't have the fonts installed. Mirrors the (unobfuscated)
embedding scheme found in the Cloud Drift case-study docx: fontKey all-zeros,
plain .ttf parts referenced directly."""
import shutil
import zipfile
import re
import sys

DOCX = sys.argv[1] if len(sys.argv) > 1 else "clouddrift-reference.docx"
FONT_DIR = "fonts"

FONTS = {
    "Open Sans Light": {
        "regular": "OpenSansLight-regular.ttf",
        "bold": "OpenSansLight-bold.ttf",
        "italic": "OpenSansLight-italic.ttf",
        "boldItalic": "OpenSansLight-boldItalic.ttf",
    },
    "Open Sans": {
        "regular": "OpenSans-regular.ttf",
        "bold": "OpenSans-bold.ttf",
        "italic": "OpenSans-italic.ttf",
        "boldItalic": "OpenSans-boldItalic.ttf",
    },
}

NS_R = "http://schemas.openxmlformats.org/officeDocument/2006/relationships"
FONT_REL_TYPE = f"{NS_R}/font".replace(NS_R, "http://schemas.openxmlformats.org/officeDocument/2006/relationships") + "/font"
FONT_REL_TYPE = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/font"


def build_font_table_and_rels():
    rid = 1
    font_entries = []
    rels = []
    file_map = {}
    for name, variants in FONTS.items():
        embeds = []
        for kind, fname in variants.items():
            tag = {
                "regular": "w:embedRegular",
                "bold": "w:embedBold",
                "italic": "w:embedItalic",
                "boldItalic": "w:embedBoldItalic",
            }[kind]
            rId = f"rIdFont{rid}"
            embeds.append(
                f'<{tag} r:id="{rId}" w:fontKey="{{00000000-0000-0000-0000-000000000000}}" w:subsetted="0"/>'
            )
            rels.append(
                f'<Relationship Id="{rId}" Type="{FONT_REL_TYPE}" Target="fonts/{fname}"/>'
            )
            file_map[rId] = fname
            rid += 1
        font_entries.append(f'<w:font w:name="{name}">{"".join(embeds)}</w:font>')

    font_table_xml = (
        '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
        '<w:fonts xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" '
        'xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">'
        + "".join(font_entries)
        + "</w:fonts>"
    )
    rels_xml = (
        '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
        '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">'
        + "".join(rels)
        + "</Relationships>"
    )
    return font_table_xml, rels_xml, file_map


def patch_settings(xml_text):
    if "embedTrueTypeFonts" in xml_text:
        return xml_text
    return re.sub(
        r"(<w:settings[^>]*>)",
        r'\1<w:embedTrueTypeFonts w:val="1"/>',
        xml_text,
        count=1,
    )


def patch_content_types(xml_text):
    if 'Extension="ttf"' in xml_text:
        return xml_text
    return xml_text.replace(
        "<Types ",
        "<Types ",
    ).replace(
        '<Default Extension="rels"',
        '<Default Extension="ttf" ContentType="application/x-font-ttf"/><Default Extension="rels"',
    )


def main():
    font_table_xml, rels_xml, file_map = build_font_table_and_rels()

    tmp = DOCX + ".tmp"
    with zipfile.ZipFile(DOCX, "r") as zin:
        names = zin.namelist()
        with zipfile.ZipFile(tmp, "w", zipfile.ZIP_DEFLATED) as zout:
            for item in zin.infolist():
                data = zin.read(item.filename)
                if item.filename == "word/fontTable.xml":
                    data = font_table_xml.encode("utf-8")
                elif item.filename == "word/settings.xml":
                    data = patch_settings(data.decode("utf-8")).encode("utf-8")
                elif item.filename == "[Content_Types].xml":
                    data = patch_content_types(data.decode("utf-8")).encode("utf-8")
                zout.writestr(item, data)

            if "word/_rels/fontTable.xml.rels" not in names:
                zout.writestr("word/_rels/fontTable.xml.rels", rels_xml)

            for rId, fname in file_map.items():
                with open(f"{FONT_DIR}/{fname}", "rb") as f:
                    zout.writestr(f"word/fonts/{fname}", f.read())

    shutil.move(tmp, DOCX)
    print("Embedded fonts into", DOCX)


if __name__ == "__main__":
    main()