import { readFileSync, readdirSync, readlinkSync } from 'fs';
import { execFileSync } from 'child_process';

function read_file(path) {
	try {
		return readFileSync(path, 'utf8');
	} catch {
		return null;
	}
}

function get_exe(pid) {
	try {
		return readlinkSync(`/proc/${pid}/exe`);
	} catch {
		return null;
	}
}

function get_cmdline(pid) {
	const raw = read_file(`/proc/${pid}/cmdline`);
	if (!raw) {
		return null;
	}
	return raw.replace(/\0/g, ' ').trim();
}

function get_ppid(pid) {
	const status = read_file(`/proc/${pid}/status`);
	if (!status) {
		return null;
	}
	const match = status.match(/^PPid:\s+(\d+)/m);
	return match ? parseInt(match[1]) : null;
}

//const DOCKER_COMM_PATTERN = /^docker-compose$/;
const CLAUDE_CMDLINE_SIGNATURE = 'claude --dangerously-skip-permissions';
const DOCKER_COMM_PATTERN = /^docker-compose$/;

function get_comm(pid) {
	return read_file(`/proc/${pid}/comm`)?.trim() ?? null;
}

export function list_docker_pids() {
	const results = [];
	for (const entry of readdirSync('/proc')) {
		if (!/^\d+$/.test(entry)) {
			continue;
		}
		const comm = get_comm(entry);
		if (!comm || !DOCKER_COMM_PATTERN.test(comm)) {
			continue;
		}
		const cmdline = get_cmdline(entry);
		if (cmdline && cmdline.includes(CLAUDE_CMDLINE_SIGNATURE)) {
			results.push({ pid: entry, comm, cmdline });
		}
	}
	return results;
}

export function walk_to_konsole(pid) {
	let current = String(pid);
	const visited = new Set();
	const chain = [];
	while (current && current !== '0' && !visited.has(current)) {
		visited.add(current);
		const exe = get_exe(current);
		chain.push({ pid: current, exe });
		if (exe === '/usr/bin/konsole') {
			return { konsole_pid: current, chain };
		}
		current = String(get_ppid(current));
	}
	return { konsole_pid: null, chain };
}

function get_net_client_list() {
	try {
		const out = execFileSync('xprop', ['-root', '_NET_CLIENT_LIST'], { encoding: 'utf8' });
		// Format: _NET_CLIENT_LIST(WINDOW): window id # 0x..., 0x..., ...
		const match = out.match(/window id # (.+)/);
		if (!match) {
			return [];
		}
		return match[1].split(',').map(s => parseInt(s.trim(), 16)).filter(Boolean);
	} catch {
		return [];
	}
}

function get_window_pid(window_id) {
	try {
		const hex = '0x' + window_id.toString(16);
		const out = execFileSync('xprop', ['-id', hex, '_NET_WM_PID'], { encoding: 'utf8' });
		const match = out.match(/= (\d+)/);
		return match ? parseInt(match[1]) : null;
	} catch {
		return null;
	}
}

export function window_id_for_pid(pid) {
	const target_pid = parseInt(pid);
	for (const wid of get_net_client_list()) {
		if (get_window_pid(wid) === target_pid) {
			return '0x' + wid.toString(16);
		}
	}
	return null;
}

export function find_claude_window_by_process_tree({ debug = false } = {}) {
	const docker_pids = list_docker_pids();
	if (debug) {
		console.error(`[find-window] docker pids (${docker_pids.length}):`);
		for (const { pid, comm, cmdline } of docker_pids) {
			console.error(`  pid=${pid} comm=${comm} cmdline=${cmdline}`);
		}
	}

	for (const { pid } of docker_pids) {
		const { konsole_pid, chain } = walk_to_konsole(pid);
		if (debug) {
			const chain_str = chain.map(e => `${e.pid}(${e.exe?.split('/').pop() ?? '?'})`).join(' → ');
			console.error(`[find-window] pid=${pid} chain: ${chain_str}`);
		}
		if (!konsole_pid) {
			continue;
		}
		if (debug) {
			console.error(`[find-window] found konsole pid=${konsole_pid}, looking up window...`);
		}
		const window_id = window_id_for_pid(konsole_pid);
		if (debug) {
			console.error(`[find-window] window id: ${window_id ?? 'not found'}`);
		}
		if (window_id) {
			return window_id;
		}
	}
	return null;
}

export function find_claude_window_by_title(title = 'claude-docker') {
	try {
		const result = execFileSync(
			'xdotool', ['search', '--name', title],
			{ encoding: 'utf8' }
		);
		const ids = result.trim().split('\n').filter(Boolean);
		return ids[0] ?? null;
	} catch {
		return null;
	}
}

export function find_claude_window({ debug = false } = {}) {
	return find_claude_window_by_process_tree({ debug }) ?? find_claude_window_by_title();
}