import { watch, readFileSync } from 'fs';
import { readdir, readFile, stat } from 'fs/promises';
import { resolve, basename, extname, join, dirname } from 'path';
import { fileURLToPath } from 'url';

const __dirname = dirname(fileURLToPath(import.meta.url));

function loadEnv(): void {
    const envPath = resolve(__dirname, '.env');
    try {
        const content = readFileSync(envPath, 'utf-8');
        for (const line of content.split(/\r?\n/)) {
            const trimmed = line.trim();
            if (!trimmed || trimmed.startsWith('#')) continue;
            const [key, value] = trimmed.split('=', 2);
            if (key && value !== undefined) {
                process.env[key.trim()] = value.trim().replace(/^"|"$/g, '');
            }
        }
        console.log('Loaded configuration from .env');
    } catch {
        console.error('FATAL: Could not read .env file.');
        process.exit(1);
    }
}

loadEnv();

const { INGEST_BASE_URL, API_TOKEN } = process.env;

if (!INGEST_BASE_URL || !API_TOKEN) {
    console.error('FATAL: INGEST_BASE_URL and API_TOKEN must be defined in .env');
    process.exit(1);
}

const WATCH_PATH = resolve(__dirname, '..', '..', '..', 'script-output', 'signal_export');
const DEBOUNCE_DELAY_MS = 250;
const debounceTimers = new Map<string, NodeJS.Timeout>();

async function sendToWebhook(filePath: string, mtimeMs: number): Promise<void> {
    const combinatorName = basename(filePath, extname(filePath));
    const url = `${INGEST_BASE_URL}/api/ingest/${encodeURIComponent(combinatorName)}?token=${API_TOKEN}`;

    try {
        const content = await readFile(filePath, 'utf-8');
        if (!content.trim()) return;
        JSON.parse(content); // validate before sending

        console.log(`Sending '${combinatorName}' (mtime: ${new Date(mtimeMs).toISOString()})`);

        const response = await fetch(url, {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
                'X-File-Mtime': String(mtimeMs),
            },
            body: content,
        });

        if (!response.ok) {
            throw new Error(`HTTP ${response.status} ${response.statusText}`);
        }

        console.log(`OK '${combinatorName}' → ${response.status}`);
    } catch (err: any) {
        if (err instanceof SyntaxError) {
            console.error(`Skip '${combinatorName}': invalid JSON`);
        } else {
            console.error(`Error '${combinatorName}':`, err.message);
        }
    }
}

function handleFileChange(filename: string | null): void {
    if (!filename?.endsWith('.json')) return;

    const existing = debounceTimers.get(filename);
    if (existing) clearTimeout(existing);

    const timer = setTimeout(async () => {
        const fullPath = join(WATCH_PATH, filename);
        try {
            const stats = await stat(fullPath);
            if (stats.isFile()) {
                await sendToWebhook(fullPath, stats.mtimeMs);
            }
        } catch {
            // file removed before processing — ignore
        } finally {
            debounceTimers.delete(filename);
        }
    }, DEBOUNCE_DELAY_MS);

    debounceTimers.set(filename, timer);
}

async function initialScan(): Promise<void> {
    console.log(`Initial scan: ${WATCH_PATH}`);
    try {
        const files = (await readdir(WATCH_PATH)).filter(f => f.endsWith('.json'));
        console.log(`Found ${files.length} file(s)`);
        for (const file of files) {
            const fullPath = join(WATCH_PATH, file);
            const stats = await stat(fullPath);
            await sendToWebhook(fullPath, stats.mtimeMs);
        }
    } catch (err: any) {
        console.error(`Initial scan failed: ${err.message}`);
    }
}

(async () => {
    await initialScan();

    console.log(`Watching: ${WATCH_PATH}`);
    try {
        watch(WATCH_PATH, (eventType, filename) => {
            if (filename) {
                console.log(`[${new Date().toLocaleTimeString()}] ${eventType}: ${filename}`);
                handleFileChange(filename);
            }
        });
        console.log('Watcher running. Ctrl+C to stop.');
    } catch (err: any) {
        console.error(`FATAL: Watcher failed: ${err.message}`);
        process.exit(1);
    }
})();