import OpenAI from 'openai';
import { logger } from '@/lib/logger';

const openai = new OpenAI(); // uses OPENAI_API_KEY from env

interface ScanResult {
  establishment: string | null;
  date: string | null;
  amount: number | null;
  currency: string | null;
  lineItems: Array<{ description: string; amount: number }>;
  confidence: number;
}

export async function scanReceipt(
  imageBuffer: Buffer,
  mimeType: string,
): Promise<ScanResult> {
  try {
    const base64 = imageBuffer.toString('base64');
    const response = await openai.chat.completions.create({
      model: 'gpt-4o',
      messages: [
        {
          role: 'user',
          content: [
            {
              type: 'text',
              text: 'Extract receipt data as JSON: { establishment, date (ISO), amount (number), currency (3-letter code), lineItems: [{ description, amount }], confidence (0-1) }. Return ONLY valid JSON.',
            },
            {
              type: 'image_url',
              image_url: { url: `data:${mimeType};base64,${base64}` },
            },
          ],
        },
      ],
      max_tokens: 1000,
    });

    const content = response.choices[0]?.message?.content ?? '{}';
    const cleaned = content.replace(/```json\n?|\n?```/g, '').trim();
    return JSON.parse(cleaned) as ScanResult;
  } catch (err) {
    logger.error({ err }, 'Receipt scan failed');
    return {
      establishment: null,
      date: null,
      amount: null,
      currency: null,
      lineItems: [],
      confidence: 0,
    };
  }
}