aliyun-function-compat/index.js

aliyun function computing compat

'use strict'

function isHttpFunction(req, res) {
    return typeof res.send === 'function'
}

module.exports = function (handler) {
    async function normal(events, context, callback) {
        if (events instanceof Buffer) {
            events = JSON.parse(events.toString())
        }
        try {
            let result = await handler(events, context)
            callback(null, result)
        } catch (err) {
            callback(err)
        }
    }

    async function http(req, res, context) {
        req.body = await receiveData(req)
        try {
            let result = await handler(req, context)
            const isObj = typeof result === 'object'
            res.setHeader('content-type', isObj ? 'application/json' : 'text/plain')
            res.send(isObj ? JSON.stringify(result) : result)
        } catch (err) {
            res.setStatusCode(500)
            res.setHeader('content-type', 'application/json')
            res.send(JSON.stringify({
                errcode: err.code || -1,
                message: typeof err === 'string' ? err : err.message
            }))
        }
    }

    return function (...args) {
        isHttpFunction(...args) ? http(...args) : normal(...args)
    }
}

function receiveData(req) {
    return new Promise(res => {
        const method = req.method
        if (method !== 'POST' && method !== 'PUT') {
            return res(null)
        }
        const arr = []
        req.on('data', buf => arr.push(buf))
        req.on('end', () => {
            let json = /json/i.test(req.headers['content-type'])
            let buf = Buffer.concat(arr)
            res(json ? JSON.parse(buf.toString('utf8')) : buf)
        })
        req.on('error', res)
    })
}