"""Read UDT's palette output and render it as CSS custom properties.

UDT writes the structural palette to ~/.config/rofi/udt/palette.rasi and the
wallpaper accent to ~/.cache/udt/udt-accent.rasi. deck-it reads both rather
than restating the colours, so a scheme or wallpaper change reaches the tablet.
"""

import re
from pathlib import Path

PALETTE_LINE = re.compile(r"^\s*([a-z0-9]+)\s*:\s*(#[0-9a-fA-F]{6,8});", re.M)
ACCENT = re.compile(r"accent:\s*(#[0-9a-fA-F]{6,8})")
BORDER = re.compile(r"rgb\(\s*([0-9a-fA-F]{6})\s*\)")

PALETTE_PATH = Path.home() / ".config" / "rofi" / "udt" / "palette.rasi"
ACCENT_PATH = Path.home() / ".cache" / "udt" / "udt-accent.rasi"
BORDER_PATH = Path.home() / ".cache" / "udt" / "udt-border.lua"

# Catppuccin Macchiato, used before UDT has ever generated its files.
FALLBACK = {
    "base": "#24273a", "mantle": "#1e2030", "crust": "#181926",
    "surface0": "#363a4f", "surface1": "#494d64", "surface2": "#5b6078",
    "text": "#cad3f5", "subtext0": "#a5adcb", "subtext1": "#b8c0e0",
    "overlay0": "#6e738d", "red": "#ed8796", "green": "#a6da95",
    "yellow": "#eed49f", "teal": "#8bd5ca", "blue": "#8aadf4",
    "lavender": "#b7bdf8", "peach": "#f5a97f", "mauve": "#c6a0f6",
    "accent": "#b7bdf8",
}


def parse_palette(text: str) -> dict[str, str]:
    return dict(PALETTE_LINE.findall(text))


def parse_accent(text: str) -> str | None:
    m = ACCENT.search(text)
    return m[1] if m else None


def parse_border(text: str) -> list[str]:
    """The three hues Hyprland rotates in the window border, as hex."""
    return ["#" + value.lower() for value in BORDER.findall(text)]


def css(colors: dict, accent: str | None, border: list[str] | None = None) -> str:
    lines = [":root {"]
    lines += [f"  --udt-{name}: {value};" for name, value in colors.items()]
    lines.append(f"  --udt-accent: {accent or FALLBACK['accent']};")
    stops = border if border and len(border) >= 3 else [
        FALLBACK["mauve"], FALLBACK["lavender"], FALLBACK["blue"]]
    for index, value in enumerate(stops[:3], 1):
        lines.append(f"  --udt-border-{index}: {value};")
    lines.append("}")
    return "\n".join(lines) + "\n"


def load() -> str:
    """Render the live UDT palette as CSS, falling back if it is not installed."""
    try:
        colors = parse_palette(PALETTE_PATH.read_text())
    except OSError:
        colors = {}
    if not colors:
        colors = dict(FALLBACK)
    try:
        accent = parse_accent(ACCENT_PATH.read_text())
    except OSError:
        accent = None
    try:
        border = parse_border(BORDER_PATH.read_text())
    except OSError:
        border = None
    return css(colors, accent, border)