"""The classroom's look: its measurements and its palette.

The DVD control bar, Parent Call and the Presentations library all draw
themselves, and they share this so they cannot drift apart: one set of
measurements, one palette, one look.
"""

import os
from pathlib import Path

from classroom_config import scaled

TEMPLATE = Path("/etc/ekklesia-classroom/overlay/style.css.in")

# Every measurement in the template, at UI_SCALE=1.0.
MEASUREMENTS = {
    "dock-radius": 24,
    "dock-padding-v": 8,
    "dock-padding-h": 10,
    "button-radius": 16,
    "button-padding": 6,
    "button-size": 44,
    "button-spinner": 38,
    "clock-radius": 16,
    "clock-padding-v": 7,
    "clock-padding-h": 12,
    "clock-font": 17,
}


def render(scale, template=None):
    """Resolve the measurement tokens in the stylesheet template."""
    css = (template or TEMPLATE).read_text()

    for token, value in MEASUREMENTS.items():
        css = css.replace(f"@{token}@", str(scaled(value, scale)))

    return css


# ---------------------------------------------------------- the palette

def load_colours():
    """The session's own palette, read from the colour scheme in use.

    There is one set of design tokens in this classroom, and they live in
    a Plasma colour scheme. Reading them here rather than repeating them
    means this card follows classroom-theme light and dark without
    knowing that either exists.
    """
    palette = {
        "window": "#141c20", "view": "#0f171a", "text": "#e6edef",
        "dim": "#93a5aa", "accent": "#4fb3a8", "on_accent": "#0e1518",
        "negative": "#e36a6a", "neutral": "#e0b15c", "positive": "#6fcf97",
        "line": "#25333a",
    }

    scheme = "EkklesiaDark"

    for path in (
        os.path.expanduser("~/.config/kdeglobals"),
        "/etc/ekklesia-classroom/xdg/kdeglobals",
        "/etc/xdg/kdeglobals",
    ):
        try:
            with open(path, "r", encoding="utf-8") as handle:
                section = None
                for line in handle:
                    line = line.strip()
                    if line.startswith("["):
                        section = line
                    elif section and section.startswith("[General]") and \
                            line.startswith("ColorScheme="):
                        scheme = line.split("=", 1)[1].strip()
                        break
        except OSError:
            continue
        else:
            if scheme:
                break

    def rgb(value):
        parts = [part.strip() for part in value.split(",")]
        if len(parts) != 3:
            return None
        try:
            return "#%02x%02x%02x" % tuple(int(part) for part in parts)
        except ValueError:
            return None

    try:
        with open(f"/usr/share/color-schemes/{scheme}.colors", "r",
                  encoding="utf-8") as handle:
            group = None
            for line in handle:
                line = line.strip()
                if line.startswith("["):
                    group = line
                    continue
                if "=" not in line or group is None:
                    continue
                key, value = (part.strip() for part in line.split("=", 1))
                colour = rgb(value)
                if colour is None:
                    continue
                if group == "[Colors:Window]":
                    if key == "BackgroundNormal":
                        palette["window"] = colour
                    elif key == "ForegroundNormal":
                        palette["text"] = colour
                    elif key == "ForegroundInactive":
                        palette["dim"] = colour
                    elif key == "ForegroundNegative":
                        palette["negative"] = colour
                    elif key == "ForegroundNeutral":
                        palette["neutral"] = colour
                    elif key == "ForegroundPositive":
                        palette["positive"] = colour
                    elif key == "BackgroundAlternate":
                        palette["line"] = colour
                elif group == "[Colors:View]" and key == "BackgroundNormal":
                    palette["view"] = colour
                elif group == "[Colors:Selection]":
                    if key == "BackgroundNormal":
                        palette["accent"] = colour
                    elif key == "ForegroundNormal":
                        palette["on_accent"] = colour
    except OSError:
        pass

    return palette