import fs from 'fs/promises';
import crypto from 'crypto';
import path from 'path';
import glob from 'fast-glob';

/**
 * Rigstate ContextHasher: Generates cryptographic signatures for architectural modules.
 * Used for drift detection and "Digital Sealing" of verified states.
 */
export async function generateContextHashes(cwd: string, patterns: string[]): Promise<Record<string, string>> {
    const hashes: Record<string, string> = {};

    const files = await glob(patterns, {
        cwd,
        absolute: true,
        onlyFiles: true,
        ignore: ['**/node_modules/**', '**/.git/**', '**/dist/**', '**/.next/**']
    });

    for (const file of files) {
        try {
            const content = await fs.readFile(file, 'utf-8');
            const relativePath = path.relative(cwd, file);

            // Normalize line endings and whitespace for more robust hashing
            const normalizedContent = content.replace(/\r\n/g, '\n').trim();

            const hash = crypto.createHash('sha256').update(normalizedContent).digest('hex');
            hashes[relativePath] = hash;
        } catch (error) {
            console.warn(`[Hasher] Could not read file ${file}:`, error);
        }
    }

    return hashes;
}

/**
 * Verifies local drift against a previously accepted baseline.
 */
export function detectDrift(currentHashes: Record<string, string>, baselineHashes: Record<string, string>) {
    const drift: { file: string; type: 'MODIFIED' | 'MISSING' | 'NEW' }[] = [];

    // Check for modifications and missing files
    for (const [file, hash] of Object.entries(baselineHashes)) {
        if (!currentHashes[file]) {
            drift.push({ file, type: 'MISSING' });
        } else if (currentHashes[file] !== hash) {
            drift.push({ file, type: 'MODIFIED' });
        }
    }

    // Check for new files (optional, maybe not relevant for architectural baseline)
    for (const file of Object.keys(currentHashes)) {
        if (!baselineHashes[file]) {
            drift.push({ file, type: 'NEW' });
        }
    }

    return drift;
}