/**
 * Utility for WhatsApp Embedded Signup via Meta SDK
 */
import { logWarn } from './logger';

declare global {
    interface Window {
        FB: any;
        fbAsyncInit: () => void;
    }
}

const META_APP_ID = import.meta.env.VITE_META_APP_ID;

export const initMetaSDK = () => {
    if (!META_APP_ID) {
        logWarn("[META-SDK] VITE_META_APP_ID is missing. Embedded signup will not work.");
        return;
    }

    const initOptions = {
        appId  : META_APP_ID,
        cookie : true,
        xfbml  : true,
        version: 'v22.0'
    };

    if (window.FB) {
        window.FB.init(initOptions);
    } else {
        window.fbAsyncInit = function() {
            window.FB.init(initOptions);
        };
    }
};

export interface MetaSignupResult {
    code: string;
    waba_id: string;
    phone_number_id: string;
}

export const launchEmbeddedSignup = (): Promise<MetaSignupResult> => {
    return new Promise((resolve, reject) => {
        if (!window.FB) {
            return reject(new Error("Le SDK Meta n'est pas chargé."));
        }

        // Collect both the OAuth code (from FB.login) and the WABA/phone IDs
        // (from WA_EMBEDDED_SIGNUP_EVENT) before resolving — they arrive independently.
        const collected: Partial<MetaSignupResult> = {};
        let settled = false;

        const tryResolve = () => {
            if (settled) return;
            if (collected.code && collected.waba_id && collected.phone_number_id) {
                settled = true;
                window.removeEventListener('message', sessionHandler);
                resolve(collected as MetaSignupResult);
            }
        };

        const sessionHandler = (event: MessageEvent) => {
            if (event.origin !== "https://www.facebook.com") return;
            try {
                const data = JSON.parse(event.data as string);
                if (data.type === 'WA_EMBEDDED_SIGNUP_EVENT') {
                    if (data.event === 'FINISH') {
                        collected.waba_id = data.data.waba_id;
                        collected.phone_number_id = data.data.phone_number_id;
                        tryResolve();
                    } else if (data.event === 'CANCEL' && !settled) {
                        settled = true;
                        window.removeEventListener('message', sessionHandler);
                        reject(new Error("L'utilisateur a annulé l'onboarding."));
                    }
                }
            } catch {
                // Not our event
            }
        };

        window.addEventListener('message', sessionHandler);

        window.FB.login((response: any) => {
            if (response.authResponse?.code) {
                collected.code = response.authResponse.code;
                tryResolve();
            } else if (!settled) {
                settled = true;
                window.removeEventListener('message', sessionHandler);
                reject(new Error("Connexion Facebook échouée ou annulée."));
            }
        }, {
            config_id: import.meta.env.VITE_META_CONFIG_ID || '',
            response_type: 'code',
            override_default_response_type: true,
            scope: 'whatsapp_business_management,whatsapp_business_messaging',
            extras: { feature: 'whatsapp_embedded_signup' }
        });
    });
};