import xterm from '@xterm/headless';
import type { Terminal as XtermTerminalType } from '@xterm/headless';
import { Terminal } from '../src/terminal.js';

// Extract Terminal class from the module
const XtermTerminal = xterm.Terminal;

/**
 * Virtual terminal for testing using xterm.js for accurate terminal emulation
 */
export class VirtualTerminal implements Terminal {
	private xterm: XtermTerminalType;
	private inputHandler?: (data: string) => void;
	private resizeHandler?: () => void;
	private _columns: number;
	private _rows: number;

	constructor(columns = 80, rows = 24) {
		this._columns = columns;
		this._rows = rows;

		// Create xterm instance with specified dimensions
		this.xterm = new XtermTerminal({
			cols: columns,
			rows: rows,
			// Disable all interactive features for testing
			disableStdin: true,
			allowProposedApi: true,
		});
	}

	start(onInput: (data: string) => void, onResize: () => void): void {
		this.inputHandler = onInput;
		this.resizeHandler = onResize;
		// No need for raw mode in virtual terminal
	}

	stop(): void {
		this.inputHandler = undefined;
		this.resizeHandler = undefined;
	}

	write(data: string): void {
		this.xterm.write(data);
	}

	get columns(): number {
		return this._columns;
	}

	get rows(): number {
		return this._rows;
	}

	// Test-specific methods not in Terminal interface

	/**
	 * Simulate keyboard input
	 */
	sendInput(data: string): void {
		if (this.inputHandler) {
			this.inputHandler(data);
		}
	}

	/**
	 * Resize the terminal
	 */
	resize(columns: number, rows: number): void {
		this._columns = columns;
		this._rows = rows;
		this.xterm.resize(columns, rows);
		if (this.resizeHandler) {
			this.resizeHandler();
		}
	}

	/**
	 * Wait for all pending writes to complete. Viewport and scroll buffer will be updated.
	 */
	async flush(): Promise<void> {
		// Write an empty string to ensure all previous writes are flushed
		return new Promise<void>((resolve) => {
			this.xterm.write('', () => resolve());
		});
	}

	/**
	 * Flush and get viewport - convenience method for tests
	 */
	async flushAndGetViewport(): Promise<string[]> {
		await this.flush();
		return this.getViewport();
	}

	/**
	 * Get the visible viewport (what's currently on screen)
	 * Note: You should use getViewportAfterWrite() for testing after writing data
	 */
	getViewport(): string[] {
		const lines: string[] = [];
		const buffer = this.xterm.buffer.active;

		// Get only the visible lines (viewport)
		for (let i = 0; i < this.xterm.rows; i++) {
			const line = buffer.getLine(buffer.viewportY + i);
			if (line) {
				lines.push(line.translateToString(true));
			} else {
				lines.push('');
			}
		}

		return lines;
	}

	/**
	 * Get the entire scroll buffer
	 */
	getScrollBuffer(): string[] {
		const lines: string[] = [];
		const buffer = this.xterm.buffer.active;

		// Get all lines in the buffer (including scrollback)
		for (let i = 0; i < buffer.length; i++) {
			const line = buffer.getLine(i);
			if (line) {
				lines.push(line.translateToString(true));
			} else {
				lines.push('');
			}
		}

		return lines;
	}

	/**
	 * Clear the terminal viewport
	 */
	clear(): void {
		this.xterm.clear();
	}

	/**
	 * Reset the terminal completely
	 */
	reset(): void {
		this.xterm.reset();
	}

	/**
	 * Get cursor position
	 */
	getCursorPosition(): { x: number; y: number } {
		const buffer = this.xterm.buffer.active;
		return {
			x: buffer.cursorX,
			y: buffer.cursorY
		};
	}
}