apps/api/src/services/whatsapp-utils.ts

import axios from 'axios';
import { Readable } from 'stream';

export function normalizeCommand(text: string): string {
    return text
        .trim()
        .toLowerCase()
        .replace(/[.,!?;:]+$/, "") // Remove trailing punctuation
        .toUpperCase();
}

export function detectIntent(text: string): 'YES' | 'NO' | 'UNKNOWN' {
    const normalized = text.trim().toLowerCase().replace(/[.,!?;:]+$/, "");
    const yesWords = ['oui', 'ouais', 'wi', 'waaw', 'yes', 'yep', 'ok', 'd’accord', 'daccord', 'da’accord'];
    const noWords = ['non', 'déet', 'deet', 'no', 'nah', 'nein'];

    if (yesWords.some(w => normalized.includes(w))) return 'YES';
    if (noWords.some(w => normalized.includes(w))) return 'NO';
    return 'UNKNOWN';
}

export function levenshteinDistance(a: string, b: string): number {
    const matrix: number[][] = [];
    for (let i = 0; i <= b.length; i++) matrix[i] = [i];
    for (let j = 0; j <= a.length; j++) matrix[0][j] = j;

    for (let i = 1; i <= b.length; i++) {
        for (let j = 1; j <= a.length; j++) {
            if (b.charAt(i - 1) === a.charAt(j - 1)) {
                matrix[i][j] = matrix[i - 1][j - 1];
            } else {
                matrix[i][j] = Math.min(
                    matrix[i - 1][j - 1] + 1, // substitution
                    matrix[i][j - 1] + 1,     // insertion
                    matrix[i - 1][j] + 1      // deletion
                );
            }
        }
    }
    return matrix[b.length][a.length];
}

export function isFuzzyMatch(text: string, target: string, threshold = 0.8): boolean {
    const normalized = text.trim().toUpperCase();
    const tar = target.toUpperCase();
    if (normalized === tar) return true;
    if (normalized.includes(tar) || tar.includes(normalized)) return true;

    const distance = levenshteinDistance(normalized, tar);
    const maxLength = Math.max(normalized.length, tar.length);
    const similarity = 1 - distance / maxLength;
    return similarity >= threshold;
}



/**
 * Download a WhatsApp media file from the Graph API as a stream.
 * @param mediaId - The media ID from the WhatsApp webhook payload
 * @param accessToken - WHATSAPP_ACCESS_TOKEN
 * @returns { stream, mimeType, fileSize }
 */
export async function downloadMedia(
    mediaId: string,
    accessToken: string
): Promise<{ stream: Readable; mimeType: string; fileSize: number }> {
    // Step 1: Get the media URL
    const metaRes = await axios.get(
        `https://graph.facebook.com/${process.env.META_GRAPH_API_VERSION || 'v22.0'}/${mediaId}`,
        { headers: { Authorization: `Bearer ${accessToken}` } }
    );
    const { url, mime_type, file_size } = metaRes.data;

    if (!url) throw new Error(`[downloadMedia] No URL returned for media ${mediaId}`);

    // Step 2: Download the binary content as a stream
    const mediaRes = await axios.get(url, {
        headers: { Authorization: `Bearer ${accessToken}` },
        responseType: 'stream',
        timeout: 30_000
    });

    return {
        stream: mediaRes.data,
        mimeType: mime_type || 'application/octet-stream',
        fileSize: file_size || 0
    };
}