/**
 * 管理端主题状态（yh-theme，定稿 07-seam-pure.html，方案《管理端整体主题迁移方案》§6.5）。
 * 档位全部挂在 <html>：data-theme × side-deep|side-light × grad-on|grad-off × side-plain，
 * 皮肤规则在 assets/styles/yh-theme.css（生成物）。与门户皮肤包（templates/themes）正交。
 */
export const THEME_NAMES = ["blue", "ocean", "ink", "violet", "teal"] as const;
export type ThemeName = (typeof THEME_NAMES)[number];

/** 定稿默认档：blue + side-deep + grad-on + 侧栏跟随（D1 拍板 deep） */
export interface ThemeState {
    theme: ThemeName;
    /** 侧栏深色（false=浅色档） */
    sideDeep: boolean;
    /** 顶栏渐变（联动侧栏竖向渐变） */
    gradOn: boolean;
    /** 侧栏颜色跟随顶栏品牌色（false=中性灰 side-plain） */
    sideFollow: boolean;
}

export const THEME_STORAGE_KEY = "yh-theme";

export const DEFAULT_THEME_STATE: ThemeState = {
    theme: "blue",
    sideDeep: true,
    gradOn: true,
    sideFollow: true,
};

/** 宽松解析：任一字段非法/缺失即回退默认档（脏数据不阻塞启动） */
export function parseThemeState(raw: string | null): ThemeState {
    if (!raw) return { ...DEFAULT_THEME_STATE };
    try {
        const o = JSON.parse(raw);
        if (!o || typeof o !== "object") return { ...DEFAULT_THEME_STATE };
        return {
            theme: THEME_NAMES.includes(o.theme) ? o.theme : DEFAULT_THEME_STATE.theme,
            sideDeep: typeof o.sideDeep === "boolean" ? o.sideDeep : DEFAULT_THEME_STATE.sideDeep,
            gradOn: typeof o.gradOn === "boolean" ? o.gradOn : DEFAULT_THEME_STATE.gradOn,
            sideFollow: typeof o.sideFollow === "boolean" ? o.sideFollow : DEFAULT_THEME_STATE.sideFollow,
        };
    } catch {
        return { ...DEFAULT_THEME_STATE };
    }
}

interface StorageLike {
    getItem(k: string): string | null;
    setItem(k: string, v: string): void;
}

export function loadThemeState(storage: StorageLike | undefined = globalThis.localStorage): ThemeState {
    if (!storage) return { ...DEFAULT_THEME_STATE };
    return parseThemeState(storage.getItem(THEME_STORAGE_KEY));
}

export function saveThemeState(
    state: ThemeState,
    storage: StorageLike | undefined = globalThis.localStorage
): void {
    try {
        storage?.setItem(THEME_STORAGE_KEY, JSON.stringify(state));
    } catch {
        /* 隐私模式/配额失败静默：仅丢持久化，不丢本次会话生效 */
    }
}

/** 把状态落到根元素档位类名（幂等：先清后挂），返回传入的 state 便于链式 */
export function applyThemeState(
    state: ThemeState,
    root: HTMLElement = document.documentElement
): ThemeState {
    root.dataset.theme = state.theme;
    root.classList.toggle("side-deep", state.sideDeep);
    root.classList.toggle("side-light", !state.sideDeep);
    root.classList.toggle("grad-on", state.gradOn);
    root.classList.toggle("grad-off", !state.gradOn);
    root.classList.toggle("side-plain", !state.sideFollow);
    return state;
}

/** 启动引导：main.ts 于挂载前调用，消除首帧闪色 */
export function initTheme(): ThemeState {
    return applyThemeState(loadThemeState());
}