import { browser } from '$app/environment';

// Client-side only functions
export const scopes = [
	'https://www.googleapis.com/auth/gmail.send',
	'https://www.googleapis.com/auth/userinfo.email',
	'https://www.googleapis.com/auth/drive.readonly',
	'https://www.googleapis.com/auth/spreadsheets.readonly'
];

/**
 * Initialize Google Auth (placeholder for client-side)
 */
export async function initGoogleAuth(): Promise<void> {
	if (!browser) return;
	// Google Auth initialization is handled by the OAuth flow
	// No initialization needed for our server-side approach
}

/**
 * Get the Google Auth URL
 * @returns URL for Google OAuth
 */
export function getAuthUrl(): string {
	if (!browser) return '';
	// This should be obtained from the server
	return '/auth/google';
}

/**
 * Check if an access token is valid
 * @param accessToken - Google access token to validate
 * @returns True if the token is valid
 */
export async function isTokenValid(accessToken: string): Promise<boolean> {
	if (!browser) return false;
	
	try {
		const response = await fetch(`https://www.googleapis.com/oauth2/v1/tokeninfo?access_token=${accessToken}`);
		const data = await response.json();
		
		if (response.ok && data.expires_in && data.expires_in > 0) {
			return true;
		}
		return false;
	} catch (error) {
		console.error('Error validating token:', error);
		return false;
	}
}

/**
 * Refresh an access token using the refresh token
 * @param refreshToken - Google refresh token
 * @returns New access token or null if failed
 */
export async function refreshAccessToken(refreshToken: string): Promise<string | null> {
	try {
		const response = await fetch('/private/api/google/auth/refresh', {
			method: 'POST',
			headers: {
				'Content-Type': 'application/json'
			},
			body: JSON.stringify({ refreshToken })
		});
		
		if (response.ok) {
			const data = await response.json();
			return data.accessToken;
		}
		return null;
	} catch (error) {
		console.error('Error refreshing token:', error);
		return null;
	}
}

/**
 * Get Google user information
 * @param accessToken - Google access token
 * @returns User info including email, name, and picture
 */
export async function getUserInfo(accessToken: string): Promise<{ email: string; name: string; picture: string } | null> {
	try {
		const response = await fetch('/private/api/google/auth/userinfo', {
			headers: {
				'Authorization': `Bearer ${accessToken}`
			}
		});
		
		if (response.ok) {
			return await response.json();
		}
		return null;
	} catch (error) {
		console.error('Error fetching user info:', error);
		return null;
	}
}

/**
 * Authenticate with Google using OAuth popup flow
 * @returns Authentication result with success status and tokens
 */
export async function authenticateWithGoogle(): Promise<{
	success: boolean;
	refreshToken?: string;
	userEmail?: string;
	error?: string;
}> {
	if (!browser) {
		return { success: false, error: 'Not in browser environment' };
	}

	return new Promise((resolve) => {
		try {
			// Open popup window for OAuth
			const popup = window.open(
				'/auth/google',
				'google-auth',
				'width=500,height=600,scrollbars=yes,resizable=yes,left=' + 
				Math.round(window.screen.width / 2 - 250) + ',top=' + 
				Math.round(window.screen.height / 2 - 300)
			);

			if (!popup) {
				resolve({ success: false, error: 'Failed to open popup window. Please allow popups for this site.' });
				return;
			}

			let authCompleted = false;
			let popupTimer: number | null = null;
			
			// Store current timestamp to detect changes in localStorage
			const startTimestamp = localStorage.getItem('google_auth_timestamp') ?? '0';
			
			// Poll localStorage for auth completion
			const pollInterval = setInterval(() => {
				try {
					const currentTimestamp = localStorage.getItem('google_auth_timestamp');
					
					// If timestamp has changed, auth is complete
					if (currentTimestamp && currentTimestamp !== startTimestamp) {
						handleAuthSuccess();
					}
				} catch (e) {
					console.error('Error checking auth timestamp:', e);
				}
			}, 500); // Poll every 500ms
			
			// Common handler for authentication success
			function handleAuthSuccess() {
				if (authCompleted) return; // Prevent duplicate handling
				
				authCompleted = true;
				
				// Clean up timers
				clearInterval(pollInterval);
				if (popupTimer) clearTimeout(popupTimer);
				
				// Get tokens from localStorage
				const refreshToken = localStorage.getItem('google_refresh_token');
				const userEmail = localStorage.getItem('google_user_email');
				
				if (refreshToken) {
					resolve({
						success: true,
						refreshToken,
						userEmail: userEmail ?? undefined
					});
				} else {
					resolve({ success: false, error: 'No refresh token found after authentication' });
				}
			}
			
			// Clean up function to handle all cleanup in one place
			const cleanUp = () => {
				clearInterval(pollInterval);
				if (popupTimer) clearTimeout(popupTimer);
			};

			// Set a timeout for initial auth check
			popupTimer = setTimeout(() => {
				if (!authCompleted) {
					cleanUp();
					// Check if tokens were stored by the popup before it was closed
					const refreshToken = localStorage.getItem('google_refresh_token');
					const userEmail = localStorage.getItem('google_user_email');
					
					if (refreshToken) {
						resolve({
							success: true,
							refreshToken,
							userEmail: userEmail ?? undefined
						});
					} else {
						resolve({ success: false, error: 'Authentication timeout or cancelled' });
					}
				}
			}, 30 * 1000) as unknown as number;

			// Final cleanup timeout
			setTimeout(() => {
				if (!authCompleted) {
					cleanUp();
					resolve({ success: false, error: 'Authentication timeout' });
				}
			}, 60 * 1000);

		} catch (error) {
			console.error('Error connecting to Google:', error);
			resolve({ success: false, error: error instanceof Error ? error.message : 'Unknown error' });
		}
	});
}

/**
 * Revoke a Google access token
 * @param accessToken - Google access token to revoke
 * @returns True if revocation was successful
 */
export async function revokeToken(accessToken: string): Promise<boolean> {
	try {
		const response = await fetch('/private/api/google/auth/revoke', {
			method: 'POST',
			headers: {
				'Content-Type': 'application/json'
			},
			body: JSON.stringify({ accessToken })
		});
		
		return response.ok;
	} catch (error) {
		console.error('Error revoking token:', error);
		return false;
	}
}