#!/usr/bin/env python3
# Builds artwork/banner.svg, the README's banner: the logo above the "JARL"
# wordmark, laid out as on the web UI's login page. It reads both from the
# web UI's own sources, so it matches the login page:
#
#   internal/web/static/assets/logo.js   the logo's paths (from scripts/logo.py)
#   internal/web/static/assets/brand.js  the wordmark's letters and rule
#
# The letters and rule take the UI's text and accent colors, switching to
# the dark theme's when the viewer prefers dark. Needs only Python; run from
# the repository root after changing either file (scripts/logo.py runs it):
#
#   python3 scripts/banner.py
import re
import sys

ASSETS = "internal/web/static/assets"
OUT = "artwork/banner.svg"

# The UI's --text and --accent (style.css), light and dark.
STYLE = (".t{fill:#1d2330}.a{fill:#2f5fb3}.l{fill:none;stroke:#2f5fb3;stroke-width:2.6}"
         ".d{fill:#2f5fb3;font:700 12.5px system-ui,sans-serif;letter-spacing:.5px}"
         "@media (prefers-color-scheme:dark){.t{fill:#e3e7ee}.a,.d{fill:#6d9be8}.l{stroke:#6d9be8}}")
CLASSES = {"fill": "a", "line": "l", "dns": "d"}

# The login page's sizes in pixels (style.css): a 104px logo, 10px above a
# 220px wordmark whose viewBox is 288 units wide.
UNIT = 288 / 220
LOGO = round(104 * UNIT, 1)
GAP = round(10 * UNIT, 1)


def attrs(src):
    """Turns a JS object literal's body ({ cx: 106, "text-anchor": "middle" })
    into SVG attributes."""
    out = []
    for key, val in re.findall(r'"?([\w-]+)"?:\s*("[^"]*"|[\d.]+)', src):
        val = val.strip('"')
        out.append(f'class="{CLASSES[val]}"' if key == "class" else f'{key}="{val}"')
    return " ".join(out)


def main():
    logo = open(f"{ASSETS}/logo.js").read()
    view_box = re.search(r'viewBox = "([^"]*)"', logo).group(1)
    transform = re.search(r'transform = "([^"]*)"', logo).group(1)
    layers = re.findall(r'\["(#\w+)", "([^"]*)"\]', logo)

    brand = open(f"{ASSETS}/brand.js").read()
    letters = re.findall(r'\{ x: (\d+), d: "([^"]*)" \}', brand)
    rule = brand[brand.index("const ruleG"):]
    rule = rule[:rule.index(");\n")]
    rule_at = re.search(r'class: "wordmark-rule", transform: "([^"]*)"', rule).group(1)
    shapes = re.findall(r'el\("(path|circle|text)", \{ ([^}]*) \}(?:, "([^"]*)")?\)', rule)
    mark_box = re.search(r'viewBox: "(-4 -4 288 162)"', brand).group(1)
    if len(layers) < 2 or len(letters) != 4 or len(shapes) < 5:
        sys.exit("banner.py: logo.js or brand.js no longer looks as expected; update the script")

    width, height = 288, LOGO + GAP + 162
    svg = [f'<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 {width} {height:g}" role="img" aria-label="Jarl">',
           f"<!-- Generated by scripts/banner.py from {ASSETS}/logo.js and brand.js. -->",
           f"<title>Jarl</title><style>{STYLE}</style>",
           f'<svg x="{(width - LOGO) / 2:g}" width="{LOGO:g}" height="{LOGO:g}" viewBox="{view_box}">'
           f'<g transform="{transform}">'
           + "".join(f'<path fill="{fill}" d="{d}"/>' for fill, d in layers) + "</g></svg>",
           f'<svg y="{LOGO + GAP:g}" width="288" height="162" viewBox="{mark_box}">'
           '<g class="t" fill-rule="evenodd">'
           + "".join(f'<path transform="translate({x} 0)" d="{d}"/>' for x, d in letters) + "</g>"
           f'<g transform="{rule_at}">'
           + "".join(f"<{tag} {attrs(a)}>{text}</{tag}>" if text else f"<{tag} {attrs(a)}/>" for tag, a, text in shapes)
           + "</g></svg>",
           "</svg>"]
    with open(OUT, "w") as f:
        f.write("\n".join(svg) + "\n")
    print(f"{OUT}: {width}x{height:g}")


if __name__ == "__main__":
    sys.exit(main())