tsup.config.ts

import { readFileSync, openSync, writeSync, close, readdirSync } from 'fs'
import { resolve, extname } from 'path'
import { defineConfig } from 'tsup'

async function prependLicense(): Promise<void> {
    const outDir = resolve(process.cwd(), 'dist/')
    const filenames = readdirSync(outDir, {
        withFileTypes: true
    })
    const packInfo = JSON.parse(readFileSync('package.json').toString())
    const license = Buffer.from(
        `/**\n * ${packInfo.name} v${packInfo.version}\n * Copyright (c) 2024 Ram Amoncar <ramamonkar444@gmail.com>\n * @license ${packInfo.license}\n */\n`
    )
    if (
        packInfo !== undefined &&
        packInfo.version !== undefined &&
        packInfo.name !== undefined &&
        packInfo.license !== undefined
    ) {
        for (const file of filenames) {
            if (extname(file.name) !== '.map' && file.isFile()) {
                const data = readFileSync(resolve(outDir, file.name))
                const fd = openSync(resolve(outDir, file.name), 'w+')
                writeSync(fd, license, 0, license.length, 0)
                writeSync(fd, data, 0, data.length, license.length)
                close(fd, (err) => {
                    if (err !== null) throw err
                })
            }
        }
    }
}

export default defineConfig({
    entry: ['src/index.ts'],
    format: ['cjs', 'esm'], // Build for commonJS and ESmodules
    dts: true, // Generate declaration file (.d.ts)
    splitting: false,
    sourcemap: true,
    clean: true,
    minify: true,
    onSuccess: prependLicense
})