// Google Drive Picker API configuration
const API_KEY = 'YOUR_API_KEY';
const CLIENT_ID = 'YOUR_CLIENT_ID';
const SCOPE = ['https://www.googleapis.com/auth/drive.readonly'];

let pickerApiLoaded = false;
let oauthToken: string | null = null;

export const loadGoogleDriveApi = () => {
    return new Promise((resolve, reject) => {
        const script = document.createElement('script');
        script.src = 'https://apis.google.com/js/api.js';
        script.onload = () => {
            gapi.load('picker', () => {
                pickerApiLoaded = true;
                resolve(true);
            });
        };
        script.onerror = reject;
        document.body.appendChild(script);
    });
};

export const loadGoogleAuthApi = () => {
    return new Promise((resolve, reject) => {
        const script = document.createElement('script');
        script.src = 'https://accounts.google.com/gsi/client';
        script.onload = resolve;
        script.onerror = reject;
        document.body.appendChild(script);
    });
};

export const getAuthToken = async () => {
    if (!oauthToken) {
        const tokenClient = google.accounts.oauth2.initTokenClient({
            client_id: CLIENT_ID,
            scope: SCOPE.join(' '),
            callback: (response: any) => {
                if (response.access_token) {
                    oauthToken = response.access_token;
                }
            },
        });
        await tokenClient.requestAccessToken();
    }
    return oauthToken;
};

export const createPicker = async () => {
    if (!pickerApiLoaded) {
        await loadGoogleDriveApi();
    }

    const token = await getAuthToken();
    if (!token) {
        throw new Error('Unable to get OAuth token');
    }

    const picker = new google.picker.PickerBuilder()
        .addView(google.picker.ViewId.DOCS)
        .setOAuthToken(token)
        .setDeveloperKey(API_KEY)
        .setCallback((data: any) => {
            if (data[google.picker.Response.ACTION] === google.picker.Action.PICKED) {
                const doc = data[google.picker.Response.DOCUMENTS][0];
                const fileId = doc[google.picker.Document.ID];
                const fileName = doc[google.picker.Document.NAME];
                const fileUrl = doc[google.picker.Document.URL];
                
                return {
                    id: fileId,
                    name: fileName,
                    url: fileUrl
                };
            }
        })
        .build();
    picker.setVisible(true);
};