/**
 * 树莓派状态 JSON 数据接口
 */
require('dotenv').config()
const fs = require('fs')
const http = require('http')
const exec = require('child_process').exec
const port = process.env.PORT || 3000
const host = process.env.HOST || 'localhost'
const hostname = require('os').hostname()
const MEMINFO_FILE_PATH = '/proc/meminfo'
const TEMPERATURE_FILE_PATH = '/sys/class/thermal/thermal_zone0/temp'
const status = { hostname, cpu: { temperature: 0, load: 0 }, memory: { total: 0, available: 0 }, error: null }

const server = http.createServer(function (request, response) {
    // 如无必要，允许来自任意域名的跨域请求，只需要 `Access-Control-Allow-Origin:*` 一条就行了。
    response.setHeader('Access-Control-Allow-Origin', '*')
    // response.setHeader('Access-Control-Allow-Methods', 'HEAD,GET,POST,OPTIONS,PATCH,PUT,DELETE')
    // response.setHeader('Access-Control-Allow-Headers', 'Origin,X-Requested-With,Authorization,Content-Type,Accept,Z-Key')
    response.setHeader('Content-Type', 'application/json')
    response.end(JSON.stringify(status))
})
server.listen(port, host, () => console.log(`rpi status http server is running at http://${host}:${port}`))

const io = require('socket.io')(server, { cors: { origin: "*" } })
setInterval(() => { update_status() }, 1000)
function update_status() {
    try {
        const meminfo_string = String(fs.readFileSync(MEMINFO_FILE_PATH))
        const meminfo_total = meminfo_string.match(/MemTotal\:\s+(\d+) kB/)
        const meminfo_available = meminfo_string.match(/MemAvailable\:\s+(\d+) kB/)
        status.memory.total = Number(meminfo_total[1] * 1024)
        status.memory.available = Number(meminfo_available[1] * 1024)
        status.cpu.temperature = Number(fs.readFileSync(TEMPERATURE_FILE_PATH) / 1000)
        exec("cat /proc/stat |grep cpu |tail -1|awk '{print ($5*100)/($2+$3+$4+$5+$6+$7+$8+$9+$10)}'|awk '{print 100 - $1}'", (err, stdout, stderr) => {
            status.cpu.load = Number(stdout)
            status.error = null
            io.emit('status', status)
        })
    } catch (error) {
        status.error = error
        io.emit('status', status)
    }
}