package I2C

import (
    "time"
    _ "fmt"
    "sync"
)

/*
    i2c monitor implements a long running monitor responsible for sending active devices to the rlc
*/

type I2CMonitor struct {
    *I2CBus
    Devices *devs
    DevChan chan int
}

type devs struct {
    sync.Mutex
    m map[int]*I2CDevice
}

func NewMonitor(bus int,ch chan int) *I2CMonitor {
    m := &I2CMonitor{}
    b := NewBus(bus)
    m.I2CBus = b
    d := make(map[int]*I2CDevice)
    m.Devices = &devs{m:d}
    m.DevChan = ch
    return m
}

func (m *I2CMonitor) Update() {
    /*
    scans bus and adds new active devices
    */
    devs := m.Scan()
    chng := m.Devices.Parse(m.I2CBus,devs)
    for _, d := range chng {
        go m.ConnectDevice(d)
    }
}

func (m *I2CMonitor) Monitor() {
    // functon that updates the device list and notifies rlc of any changes to sensor composition
    s := make(chan struct{})
    t := 5 * time.Second
    go func(signal chan struct{},to time.Duration) { // simple signal func to init scan
        for {
            signal <-struct{}{}
            time.Sleep(to)
        }
    }(s,t)

    for {
        <-s
        m.Update()
   }
}

func (m *I2CMonitor) ConnectDevice(addr int) {
    m.DevChan <-addr
}

func (m *I2CMonitor) GetDevice(addr int) interface{ GetAddr() int; GetData() string; GetStatus() string; GetType() string } {
    m.Devices.Lock()
    defer m.Devices.Unlock()
    return m.Devices.m[addr]
}

func (d *devs) Parse(bus *I2CBus,devices map[int]bool) []int {
    d.Lock()
    defer d.Unlock()
    newdevs := []int{}
    for addr, status := range devices {
        if dev, exists := d.m[addr]; exists {
            // device seen
            if status != dev.bool { // if device state changed
                dev.bool = status
                if status {
                    newdevs = append(newdevs,dev.GetAddr())
                }
            }
        } else {
            // device not seen yet
            if status {
                // active
                newd := NewDevice(addr,bus)
                newd.bool = status
                d.m[addr] = newd
                newdevs = append(newdevs,newd.GetAddr())
            }
        }
    }
    return newdevs
}