imageProcessor.js

const sharp = require('sharp');

/**
 * Compresses an image buffer to WebP format, targeting a size of 50-60KB.
 * @param {Buffer} buffer - The input image buffer.
 * @returns {Promise<Buffer>} - The compressed WebP image buffer.
 */
async function compressToWebP(buffer) {
    let quality = 80;
    let minQuality = 1;
    let maxQuality = 100;
    let outputBuffer;
    let iterations = 0;
    const maxIterations = 7; // Binary search for quality

    // Initial check: if already small at high quality, just use that
    outputBuffer = await sharp(buffer)
        .webp({ quality: 100 })
        .toBuffer();

    if (outputBuffer.length <= 60 * 1024) {
        return outputBuffer;
    }

    // Binary search for the sweet spot quality
    while (iterations < maxIterations) {
        quality = Math.floor((minQuality + maxQuality) / 2);
        outputBuffer = await sharp(buffer)
            .webp({ quality })
            .toBuffer();

        const sizeKB = outputBuffer.length / 1024;

        if (sizeKB > 60) {
            maxQuality = quality - 1;
        } else if (sizeKB < 50) {
            minQuality = quality + 1;
        } else {
            // Found a quality that lands us in the 50-60KB range
            return outputBuffer;
        }
        iterations++;
    }

    // Best effort return
    return outputBuffer;
}

module.exports = {
    compressToWebP
};