export class McpBrowserError extends Error {
	constructor(
		message: string,
		readonly hint?: string,
	) {
		super(message);
		this.name = this.constructor.name;
	}
}

export class NotConnectedError extends McpBrowserError {
	constructor() {
		super('Not connected to a browser', 'Call browser_connect first to connect to the browser.');
	}
}

export class AlreadyConnectedError extends McpBrowserError {
	constructor() {
		super(
			'Already connected to a browser',
			'Disconnect first with browser_disconnect before connecting again.',
		);
	}
}

export class PageNotFoundError extends McpBrowserError {
	constructor(readonly pageId: string) {
		super(
			`Page not found: ${pageId}`,
			'The page may have been closed. List open pages with browser_tab_list.',
		);
	}
}

export class StaleRefError extends McpBrowserError {
	constructor(readonly ref: string) {
		super(
			`Stale element ref: ${ref}`,
			'The ref is from a previous snapshot. Take a fresh snapshot with browser_snapshot and use the new refs.',
		);
	}
}

export class UnsupportedOperationError extends McpBrowserError {
	constructor(
		readonly operation: string,
		readonly adapterName: string,
	) {
		super(
			`Operation not supported: ${operation}`,
			`This operation is not available for ${adapterName} sessions.`,
		);
	}
}

export class BrowserNotAvailableError extends McpBrowserError {
	constructor(
		readonly browser: string,
		readonly availableBrowsers: string[] = [],
		readonly installInstructions?: string,
	) {
		const alternatives =
			availableBrowsers.length > 0
				? `Compatible Chromium-based browsers found: ${availableBrowsers.join(', ')}. ` +
					`Call browser_connect with { "browser": "${availableBrowsers[0]}" } to use it instead.`
				: 'No compatible Chromium-based browsers (Chrome, Brave, Edge, Chromium) were found on this system.';
		const install = installInstructions ? `\n${installInstructions}` : '';
		super(`Browser not available: ${browser}`, `${alternatives}${install}`);
	}
}

export type ConnectionLostReason =
	| 'browser_closed'
	| 'extension_disconnected'
	| 'debugger_detached'
	| 'network_error'
	| 'heartbeat_timeout';

const connectionLostMessages: Record<ConnectionLostReason, string> = {
	browser_closed: 'The browser was closed',
	extension_disconnected: 'The browser extension disconnected',
	debugger_detached: 'The Chrome debugger was detached (banner dismissed or DevTools closed)',
	network_error: 'The connection to the browser extension was lost',
	heartbeat_timeout: 'The browser extension stopped responding',
};

export class ConnectionLostError extends McpBrowserError {
	constructor(readonly reason: ConnectionLostReason) {
		super(
			`Browser connection lost: ${connectionLostMessages[reason]}`,
			'Call browser_connect to reconnect.',
		);
	}
}

export class BrowserExecutableNotFoundError extends McpBrowserError {
	constructor(readonly browser: string) {
		super(
			`No executable path for ${browser}`,
			`The browser "${browser}" was detected but has no executable path configured. ` +
				'Verify the browser is properly installed or provide an explicit executablePath in the config.',
		);
	}
}

export type ExtensionNotConnectedPhase = 'browser_not_launched' | 'extension_missing' | 'unknown';

export class ExtensionNotConnectedError extends McpBrowserError {
	constructor(
		readonly timeoutMs: number,
		readonly phase: ExtensionNotConnectedPhase = 'unknown',
		readonly extensionInstructions?: string,
	) {
		const phaseHint =
			phase === 'browser_not_launched'
				? 'The browser process may not have started. Check that the browser is installed and accessible.'
				: phase === 'extension_missing'
					? 'The browser opened but the user did not confirm the browser connection in time. Ask the user to look for the n8n AI Browser Bridge extension popup in their browser and click Connect. If the user does not see the popup, the extension may not be installed.'
					: 'The extension did not connect within the timeout period.';
		const install = extensionInstructions ? `\n${extensionInstructions}` : '';
		super(
			`Extension connection timed out after ${timeoutMs}ms`,
			`${phaseHint}${install}\nThen call browser_connect again.`,
		);
	}
}