upload.js

const {URLSearchParams} = require('url')

, {buffer} = require('micro')

, {lookup} = require('mime-types')

, {use, upload} = require('./storage')

, getProperties = (...parameters) =>
	parameters.reduce((result, [name, value]) => {
		if (value)
			result[name] = value

		return result
	}, {})

module.exports = async (request, response) => {
	if (request.method == 'PATCH') {
		const fileFolder = request.headers['upload-name'] + '/'
		, firstPart = request.headers['upload-offset'] == 0

		if (firstPart) {
			var fileExists = true

			try {
				await use('headObject', fileFolder)
			} catch (error) {
				if (error.code == 'NotFound')
					fileExists = false
				else
					throw error
			}
		}

		if (firstPart && fileExists)
			response.statusCode = 403
		else {
			var uploads = []

			if (firstPart) {
				const {maximumDownloadCount, expiryDateAndTime} = Array.from(
					new URLSearchParams(request.url.replace('/?', '')).entries()
				).reduce((result, [name, value]) => ({
					...result, [name]: value
				}), {})

				uploads.push(
					upload(fileFolder, undefined, {
						...getProperties([
							'ContentType', lookup(request.headers['upload-name'])
						])
						, Metadata: {
							contentLength: request.headers['upload-length']

							, ...getProperties(
								['maximumDownloadCount', maximumDownloadCount]
								, ['expiryDateAndTime', expiryDateAndTime]
							)
						}
					})
					, upload(fileFolder + 'downloadCount' + '/')
				)
			}

			uploads.push(
				upload(
					fileFolder + 'part' + '/' + request.headers['upload-offset']
					, await buffer(request)
				)
			)
		}
	}

	[
		['Access-Control-Allow-Origin', '*']

		, ...(request.method == 'OPTIONS' ? [
			, ['Access-Control-Allow-Methods', 'PATCH']
			, ['Access-Control-Allow-Headers', [
				'Content-Type'
				, 'Upload-Length'
				, 'Upload-Name'
				, 'Upload-Offset'
			]]
			, ['Access-Control-Max-Age', 7200]
		] : [])
	].forEach(header =>
		header &&
			response.setHeader(...header)
	)

	if (uploads)
		await Promise.all(uploads)

	response.end()
}