import * as vision from '@google-cloud/vision';
import jsQR from "jsqr";
import {PNG} from 'pngjs';
import sharp from "sharp";


const regex = /(?<txnId>FT\w{10})/


async function detectFromImageQr(buffer: Buffer) {
    const image = sharp(buffer)
    const png = PNG.sync.read(await image.png().toBuffer())
    const code = jsQR(Uint8ClampedArray.from(png.data), png.width, png.height);
    return code?.data
}

async function detectFromImageText(buffer: Buffer, apiKey: string) {
    const client = new vision.ImageAnnotatorClient({
        key: apiKey
    });

    const [result] = await client.annotateImage({
        image: {content: buffer},
        features: [{type: 'TEXT_DETECTION'}],
    });

    const annotations = result.fullTextAnnotation;
    return regex.exec(annotations?.text ?? '')?.groups?.['txnId'];
}

export async function detectTransactionId(buffer: Buffer, params: {
    googleVisionAPIKey?: string,
}): Promise<DetectTransactionIdResult | null> {
    let start = Date.now()
    const fromQr = await detectFromImageQr(buffer)
    if (fromQr)
        return {
            value: fromQr,
            detectedFrom: 'QR_CODE',
            timeTaken: Date.now() - start,
        }

    if (params.googleVisionAPIKey) {
        const fromText = await detectFromImageText(buffer, params.googleVisionAPIKey);
        if (fromText)
            return {
                value: fromText,
                detectedFrom: 'TEXT_RECOGNITION',
                timeTaken: Date.now() - start,
            }
    }

    return null;
}

export type DetectTransactionIdResult = {
    value: string,
    detectedFrom: 'QR_CODE' | 'TEXT_RECOGNITION',
    timeTaken: number,
}