import { WalletType } from 'rnwalletman';
import AsyncStorage from '@react-native-async-storage/async-storage';

const DEFAULT_DOMAIN = '192.168.1.198:16000';
const STORAGE_KEY = 'server_domain';

let _domain = DEFAULT_DOMAIN;

export async function loadServerDomain(): Promise<string> {
    const saved = await AsyncStorage.getItem(STORAGE_KEY);
    if (saved) _domain = saved;
    return _domain;
}

export async function saveServerDomain(domain: string): Promise<void> {
    _domain = domain;
    await AsyncStorage.setItem(STORAGE_KEY, domain);
}

export function getServerDomain(): string {
    return _domain;
}

class Api {
    public static get BASE_URL() { return `http://${_domain}`; }
    public static get WS_URL() { return `ws://${_domain}/ws`; }

    private static _instance: Api | null = null;
    private userId: number = 0;

    private constructor() {}

    public setUserId(userId: number) {
        this.userId = userId;
    }

    public getUserId(): number {
        return this.userId;
    }

    public static get instance() {
        if (Api._instance === null) {
            Api._instance = new Api();
        }
        return Api._instance;
    }

    private headers(): Record<string, string> {
        const h: Record<string, string> = { 'Content-Type': 'application/json' };
        if (this.userId > 0) {
            h['X-User-ID'] = String(this.userId);
        }
        return h;
    }

    public async login(username: string, password: string): Promise<number> {
        const res = await fetch(`${Api.BASE_URL}/login`, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ username, password }),
        });
        const data = await res.json();
        if (!data.success) throw new Error(data.message);
        this.userId = data.data.userId;
        return this.userId;
    }

    public async register(walletType: WalletType, params: any) {
        const res = await fetch(`${Api.BASE_URL}/register`, {
            method: 'POST',
            headers: this.headers(),
            body: JSON.stringify({ walletType, params }),
        });
        const data = await res.json();
        if (!data.success) throw new Error(data.message);
        return data;
    }

    public async requestOTP(walletType: WalletType, mobile: string, params: any = {}) {
        const res = await fetch(`${Api.BASE_URL}/request-otp`, {
            method: 'POST',
            headers: this.headers(),
            body: JSON.stringify({ walletType, mobile, params }),
        });
        const data = await res.json();
        if (!data.success) throw new Error(data.message);
        return data;
    }

    public async verifyOTP(walletType: WalletType, mobile: string, otp: string, params: any = {}) {
        const res = await fetch(`${Api.BASE_URL}/verify-otp`, {
            method: 'POST',
            headers: this.headers(),
            body: JSON.stringify({ walletType, mobile, otp, params }),
        });
        const data = await res.json();
        if (!data.success) throw new Error(data.message);
        return data;
    }
}

export default Api;