import { throttle } from "lodash";
import type { GlobalSettings } from "../interface";
import { BasicEventEmitter } from "../utils/eventEmitter";
import { A4_HEIGHT, A4_WIDTH } from "../constants";

function defaultGlobalSetting(): GlobalSettings {
    return {
        DPI: 96,
        scale: 1,
        paperHeight: A4_HEIGHT,
        paperWidth: A4_WIDTH,
        grid: "none",
        landscape: false,
    };
}

export class GlobalSettingsHandler {
    private STORAGE_SETTINGS_KEY = "settings";
    public readonly emitter = new BasicEventEmitter<{
        "settings-update": [];
    }>();
    private _settings: GlobalSettings = defaultGlobalSetting();
    private store!: LocalForage;

    async init(store: LocalForage) {
        this.store = store;
        this._settings = (await this.store.getItem<GlobalSettings>(this.STORAGE_SETTINGS_KEY)) || this._settings;
    }
    setSettings(settings: Partial<GlobalSettings>) {
        const entries = Object.entries(settings);
        let emitUpdate = false;
        for (const [key, value] of entries) {
            const diff = (this._settings as any)[key] !== value;
            (this._settings as any)[key] = value;
            if (diff) {
                emitUpdate = true;
            }
        }
        if (emitUpdate) {
            this.emitter.emit("settings-update");
            this.save();
        }
    }
    async clear() {
        this._settings = defaultGlobalSetting();
        await this.store.setItem(this.STORAGE_SETTINGS_KEY, this._settings);
    }
    get settings() {
        return { ...this._settings };
    }
    private save = throttle(async () => {
        await this.store.setItem(this.STORAGE_SETTINGS_KEY, this._settings);
    }, 1000);
}