// ---------------------------------------------------------------------------
// CLI Detector -- Real auto-detection of Google Antigravity CLI
// ---------------------------------------------------------------------------
// Multi-strategy detection:
//   1. ANTIGRAVITY_CLI_PATH env var
//   2. Search system PATH
//   3. Check common install locations
//   4. Check npm global installs
//   5. Probe for Gemini CLI as alternative
// ---------------------------------------------------------------------------

import { execSync } from 'child_process';
import fs from 'fs';
import path from 'path';
import os from 'os';

export interface CLIDetectionResult {
    detected: boolean;
    path: string | null;
    version: string | null;
    method: string;
    candidates: string[];
}

const CLI_NAMES = [
    'antigravity',
    'antigravity.exe',
    'antigravity.cmd',
    'gemini',
    'gemini.exe',
    'gemini.cmd',
];

export async function detectCLI(): Promise<CLIDetectionResult> {
    const candidates: string[] = [];
    const result: CLIDetectionResult = {
        detected: false,
        path: null,
        version: null,
        method: 'none',
        candidates,
    };

    // Strategy 1: Environment variable
    const envPath = process.env.ANTIGRAVITY_CLI_PATH;
    if (envPath) {
        candidates.push(`[env] ${envPath}`);
        const version = tryGetVersion(envPath);
        if (version) {
            result.detected = true;
            result.path = envPath;
            result.version = version;
            result.method = 'env:ANTIGRAVITY_CLI_PATH';
            return result;
        }
    }

    // Strategy 2: Search system PATH using `where` (Windows) or `which` (Unix)
    for (const name of CLI_NAMES) {
        const found = findOnPath(name);
        if (found) {
            candidates.push(`[PATH] ${found}`);
            const version = tryGetVersion(found);
            if (version) {
                result.detected = true;
                result.path = found;
                result.version = version;
                result.method = `PATH:${name}`;
                return result;
            }
        }
    }

    // Strategy 3: Common install locations
    const commonPaths = getCommonInstallPaths();
    for (const candidate of commonPaths) {
        candidates.push(`[common] ${candidate}`);
        if (fs.existsSync(candidate)) {
            const version = tryGetVersion(candidate);
            if (version) {
                result.detected = true;
                result.path = candidate;
                result.version = version;
                result.method = 'common-path';
                return result;
            }
        }
    }

    // Strategy 4: npm global bin
    try {
        const npmBin = execSync('npm root -g', { timeout: 5000 }).toString().trim();
        const npmParent = path.dirname(npmBin);
        for (const name of CLI_NAMES) {
            const candidate = path.join(npmParent, name);
            candidates.push(`[npm-global] ${candidate}`);
            if (fs.existsSync(candidate)) {
                const version = tryGetVersion(candidate);
                if (version) {
                    result.detected = true;
                    result.path = candidate;
                    result.version = version;
                    result.method = 'npm-global';
                    return result;
                }
            }
        }
    } catch {
        // npm not available
    }

    // Strategy 5: Try bare command execution as last resort
    for (const name of ['antigravity', 'gemini']) {
        candidates.push(`[bare] ${name}`);
        const version = tryGetVersion(name);
        if (version) {
            result.detected = true;
            result.path = name;
            result.version = version;
            result.method = `bare:${name}`;
            return result;
        }
    }

    return result;
}

function findOnPath(name: string): string | null {
    try {
        const cmd = process.platform === 'win32' ? `where ${name}` : `which ${name}`;
        const result = execSync(cmd, { timeout: 5000, stdio: ['pipe', 'pipe', 'pipe'] })
            .toString()
            .trim()
            .split('\n')[0]
            .trim();
        return result || null;
    } catch {
        return null;
    }
}

function tryGetVersion(cliPath: string): string | null {
    const commands = [
        `"${cliPath}" --version`,
        `"${cliPath}" -v`,
        `"${cliPath}" version`,
    ];

    for (const cmd of commands) {
        try {
            const output = execSync(cmd, {
                timeout: 8000,
                stdio: ['pipe', 'pipe', 'pipe'],
                env: { ...process.env },
            }).toString().trim();

            if (output && output.length < 200) {
                return output;
            }
        } catch {
            // continue to next command variant
        }
    }
    return null;
}

function getCommonInstallPaths(): string[] {
    const home = os.homedir();
    const paths: string[] = [];

    if (process.platform === 'win32') {
        paths.push(
            path.join(home, 'AppData', 'Local', 'Programs', 'antigravity', 'antigravity.exe'),
            path.join(home, 'AppData', 'Local', 'antigravity', 'antigravity.exe'),
            path.join(home, 'AppData', 'Roaming', 'npm', 'antigravity.cmd'),
            'C:\\Program Files\\Google\\Antigravity\\antigravity.exe',
            'C:\\Program Files (x86)\\Google\\Antigravity\\antigravity.exe',
            path.join(home, '.local', 'bin', 'antigravity'),
            // Gemini CLI alternatives
            path.join(home, 'AppData', 'Local', 'Programs', 'gemini', 'gemini.exe'),
            path.join(home, 'AppData', 'Roaming', 'npm', 'gemini.cmd'),
        );
    } else {
        paths.push(
            '/usr/local/bin/antigravity',
            '/usr/bin/antigravity',
            path.join(home, '.local', 'bin', 'antigravity'),
            path.join(home, '.npm-global', 'bin', 'antigravity'),
            '/usr/local/bin/gemini',
            path.join(home, '.local', 'bin', 'gemini'),
        );
    }

    return paths;
}