"""Every colour a page draws comes from the design-system tokens (#5092).

- Every var(--x) a template or stylesheet uses is defined somewhere Steward
  serves, so nothing silently falls back to the browser default.
- The base stylesheet states no colour or heavy weight of its own: values
  are theme.css tokens (generated from design system 6) or aliases of them.
- Hex colours written into templates can only go down: each page moved onto
  the tokens lowers HEX_CEILING (milestone 477 retires the rest).
"""
import pathlib
import re

import steward
from tests._templates import template_files as _templates

_REPO = pathlib.Path(steward.__file__).parent.parent
_STATIC = _REPO / "steward" / "static"
_COMMENTS = re.compile(r"\{#.*?#\}|<!--.*?-->|/\*.*?\*/", re.S)
_DEFINED = re.compile(r"(--[\w-]+)\s*:")
_USED = re.compile(r"var\(\s*(--[\w-]+)")
# A hex colour where a colour goes: after a CSS ':', '(' or ',', or as a quoted JS
# string -- but not an HTML attribute's value (href="#abc" is a link to an id).
_HEX = re.compile(r"""(?:[:(,]\s*|(?<![\w-]=)['"])#(?:[0-9a-fA-F]{8}|[0-9a-fA-F]{6}|[0-9a-fA-F]{3})(?![0-9a-zA-Z_-])""")

HEX_CEILING = 47  # 75 at #5092, 58 at #5095, 56 at #5121, 54 at #5122, 47 with Ansible runs on tokens (#5125); only lower it


def _sheets():
    return [p for p in _STATIC.rglob("*.css") if "vendor" not in p.parts]


def _text(p):
    return _COMMENTS.sub("", p.read_text())


def undefined_vars(texts) -> set[str]:
    defined, used = set(), set()
    for t in texts:
        defined |= set(_DEFINED.findall(t))
        used |= set(_USED.findall(t))
    return used - defined


def hex_colours(text: str) -> list[str]:
    return _HEX.findall(_COMMENTS.sub("", text))


def test_the_guards_can_fail():
    assert undefined_vars([":root { --a: 1; } .x { color: var(--a); background: var(--b); }"]) == {"--b"}
    page = '<div style="color:#fff;background: rgb(0 0 0)" hx-target="#add-form"></div><script>c = "#4aa86a"</script>'
    assert len(hex_colours(page)) == 2
    assert hex_colours("{# color:#fff #}<a href=\"#abc\">") == []


def test_every_css_variable_used_is_defined():
    texts = [_text(p) for p in [*_templates(), *_sheets()]]
    assert not undefined_vars(texts)


def test_the_base_stylesheet_states_no_colour_or_heavy_weight_of_its_own():
    css = _text(_STATIC / "steward.css")
    assert not re.findall(r"#[0-9a-fA-F]{3,8}\b|rgba?\(|hsla?\(", css)
    assert not re.findall(r"font-weight\s*:\s*(?:[6-9]00|bold)", css)


def test_hex_colours_in_templates_only_go_down():
    count = sum(len(hex_colours(p.read_text())) for p in _templates())
    assert count <= HEX_CEILING, (
        f"{count} hex colours in templates, ceiling {HEX_CEILING}: use a token (theme.css / steward.css)")