#!/usr/bin/env python3
"""Generate conf/custom.css from the Australis source in this directory.

Homepage serves exactly two files out of its config dir — custom.css and
custom.js — with no static route for anything alongside them. A @font-face
pointing at a vendored .woff2 would therefore 404, so the faces have to be
inlined as data: URIs. That is the whole reason this build step exists.

Usage:  python3 stacks/homepage/theme/build.py
Then:   scripts/deploy-stack.sh esh-docker-vm homepage --conf
"""

import base64
import pathlib
import re
import sys

HERE = pathlib.Path(__file__).resolve().parent
SRC = HERE / "australis.css.in"
OUT = HERE.parent / "conf" / "custom.css"

# The canonical token file. Present on a box with the australis-design skill
# installed; absent elsewhere, in which case the drift check is skipped rather
# than failing the build.
CANON = pathlib.Path.home() / ".claude/skills/australis-design/colors_and_type.css"

# One VARIABLE face per family — the whole 100-900 axis in a single file, so
# there is no per-weight fan-out. Latin subset only.
FONTS = [
    ("Inter", "Inter-Variable.woff2"),
    ("Space Grotesk", "SpaceGrotesk-Variable.woff2"),
    ("JetBrains Mono", "JetBrainsMono-Variable.woff2"),
]

# Tokens the generated sheet cannot work without. A vendoring mistake that
# drops the :root block produces a stylesheet that parses fine and renders
# nothing, so assert on the values rather than trusting the copy.
REQUIRED_TOKENS = ["--aus-black", "--aus-cyan", "--bg-1", "--font-mono"]


def font_faces() -> str:
    out = []
    for family, filename in FONTS:
        path = HERE / "fonts" / filename
        if not path.exists():
            sys.exit(f"missing font: {path}")
        b64 = base64.b64encode(path.read_bytes()).decode("ascii")
        out.append(
            f"@font-face {{\n"
            f'  font-family: "{family}";\n'
            f"  src: url(data:font/woff2;base64,{b64}) format('woff2');\n"
            f"  font-weight: 100 900;\n"  # variable axis
            f"  font-style: normal;\n"
            f"  font-display: swap;\n"
            f"}}"
        )
    return "\n".join(out)


def check_canon_drift(css: str) -> None:
    """Warn if a token here no longer matches the Australis skill's value.

    Non-fatal on purpose: the skill is a per-workstation install, so a missing
    file is normal and must not break a build on a box that lacks it. A *value*
    mismatch is worth shouting about — that is the palette forking, which is
    exactly how the theme this one replaced went wrong.
    """
    if not CANON.exists():
        print(f"note: {CANON} not present — canonical drift check skipped")
        return

    canon = dict(re.findall(r"(--aus-[a-z0-9-]+):\s*(#[0-9a-fA-F]{6});", CANON.read_text()))
    ours = dict(re.findall(r"(--aus-[a-z0-9-]+):\s*(#[0-9a-fA-F]{6});", css))
    if not canon:
        print(f"note: parsed no --aus-* tokens from {CANON} — drift check skipped")
        return

    drift = [(k, v, canon[k]) for k, v in ours.items() if k in canon and v.lower() != canon[k].lower()]
    missing = sorted(set(ours) - set(canon))
    for key, mine, theirs in drift:
        print(f"DRIFT: {key} is {mine} here, {theirs} in the skill", file=sys.stderr)
    for key in missing:
        print(f"note: {key} is not a canonical token", file=sys.stderr)
    if drift:
        print(
            f"WARNING: {len(drift)} token(s) diverge from the canonical palette. "
            "Reconcile before deploying — a derived palette is how the previous "
            "theme forked from the design system.",
            file=sys.stderr,
        )
    else:
        print(f"canonical palette check: {len(ours)} tokens match {CANON.name}")


def main() -> None:
    if not SRC.exists():
        sys.exit(f"missing source: {SRC}")
    src = SRC.read_text()
    if "/* @@FONTS@@ */" not in src:
        sys.exit(f"{SRC.name} lost its @@FONTS@@ placeholder")

    css = src.replace("/* @@FONTS@@ */", font_faces())

    for token in REQUIRED_TOKENS:
        if token not in css:
            sys.exit(f"generated css has no {token} — the token block did not survive")

    check_canon_drift(css)
    OUT.write_text(css)
    print(f"wrote {OUT} ({len(css) / 1024:.0f} KB)")


if __name__ == "__main__":
    main()