import re

import jsonfile

THEMES_FILE = "themes.json"
DESKTOP_FILE = "desktop.json"
THEME_MODES = ["dark", "light"]
COLOR_KEYS = [
    "accent",
    "selection",
    "muted",
    "background",
    "dark_background",
    "lighter_background",
    "foreground",
    "red",
    "yellow",
    "orange",
    "green",
    "cyan",
    "blue",
    "magenta",
]
HEX_COLOR_PATTERN = re.compile(r"^#(?:[0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})$")
ID_PATTERN = re.compile(r"^[a-z0-9]+(?:-[a-z0-9]+)*$")


def load_themes() -> list[dict]:
    return jsonfile.load(THEMES_FILE)


def save_themes(themes: list[dict]) -> None:
    jsonfile.save(THEMES_FILE, themes)


def find_theme(themes: list[dict], theme_id: str) -> dict | None:
    return next((theme for theme in themes if theme.get("id") == theme_id), None)


def default_theme_id() -> str | None:
    try:
        return jsonfile.load(DESKTOP_FILE).get("defaultTheme")
    except (OSError, ValueError):
        return None


def set_default_theme(theme_id: str) -> None:
    desktop = jsonfile.load(DESKTOP_FILE)
    desktop["defaultTheme"] = theme_id
    jsonfile.save(DESKTOP_FILE, desktop)


def check_theme(theme: dict) -> dict:
    if not ID_PATTERN.match(theme.get("id", "")):
        raise ValueError("Theme id must be lowercase letters, numbers and dashes")
    if theme.get("mode") not in THEME_MODES:
        raise ValueError("Mode must be dark or light")
    for key in COLOR_KEYS:
        if not HEX_COLOR_PATTERN.match(theme.get("colors", {}).get(key, "")):
            raise ValueError(f"{key} must be a hex color like #818cf8")
    for color in theme.get("activeBorder") or []:
        if not HEX_COLOR_PATTERN.match(color):
            raise ValueError("Active border colors must be hex colors")
    return theme


def save_theme(original_id: str | None, theme: dict) -> None:
    check_theme(theme)
    themes = load_themes()
    duplicate = find_theme(themes, theme["id"])
    if duplicate and theme["id"] != original_id:
        raise ValueError(f"A theme with the id {theme['id']} already exists")
    if original_id is None:
        themes.append(theme)
    else:
        index = next(index for index, item in enumerate(themes) if item.get("id") == original_id)
        themes[index] = theme
        if original_id != theme["id"] and default_theme_id() == original_id:
            set_default_theme(theme["id"])
    save_themes(themes)


def remove_theme(theme_id: str) -> None:
    if default_theme_id() == theme_id:
        raise ValueError("That is the default theme. Pick another default first")
    themes = [theme for theme in load_themes() if theme.get("id") != theme_id]
    save_themes(themes)