package reactor

// file describes reactor level coordinator and associated implementation

import (
    "fmt"
    "sync"
    "time"
    "math"
    "FRMS/internal/pkg/system"
    "FRMS/internal/pkg/I2C"
    "FRMS/internal/pkg/sensor"
    "errors"
    "context"
    "google.golang.org/grpc"
    "google.golang.org/grpc/status"
    "google.golang.org/grpc/credentials/insecure"
    pb "FRMS/internal/pkg/grpc"
)

// Coordinator == Reactor Level Coordinator

type Coordinator struct {
    *server
    *hwinfo
    Devices *DeviceManagers // struct for fine grain locking
    Err chan error
    mu sync.Mutex
    Active active
    pb.UnimplementedMonitoringServer
}

type active struct {
    bool
    int
    sync.Mutex
}

type server struct {
    // store central server endpoint
    Ip string
    Port int
}

type hwinfo struct {
    // store reactor info
    Ip string
    Port int
    Model string
    Type string
    Bus int
    Id uint32
}

type DeviceManagers struct {
    Managers map[int]DeviceManager
    sync.Mutex
}
// basic devicemanager struct manipulations

type DeviceManager interface {
    Start()
    GetType() string
    GetStatus() string
    GetData() string
}

type I2CDev interface {
    GetAddr() int
    GetStatus() string
    GetType() string
}

func NewDeviceManager(i2c I2CDev) DeviceManager {
    return sensor.NewDeviceManager(i2c)
}

type I2CMonitor interface {
    Monitor()
    GetDevice(int) interface{ GetStatus() string; GetType() string;GetAddr() int }
}

func NewI2CMonitor(b int,ch chan int) I2CMonitor {
    return I2C.NewMonitor(b, ch)
}

func NewCoordinator(ip string,port int,ch chan error) *Coordinator {
    serv := &server{Ip:ip,Port:port}
    sen := new(DeviceManagers)
    sen.Managers = make(map[int]DeviceManager)
    c := &Coordinator{Err:ch,Devices:sen}
    c.server = serv
    c.hwinfo = &hwinfo{}
    c.Type = "reactor" // explicit for client stuff
    return c
}

type Hardware interface {
    GetId() uint32
    GetIp() string
    GetBus() int
    GetModel() string
    GetPort() int
}

func GetHWInfo() (Hardware, error) {
    return system.NewHWinfo()
}

func (c *Coordinator) Start() {
    // should discover hwinfo and sensors on its own
    // now setting up sensor managers
    hw, err := GetHWInfo() // locking provided by struct is only useful on init
    if err != nil {
        c.Err <-err
    }
    // setting up hw stuff
    c.hwinfo.Ip = hw.GetIp() //get should prevent empty data
    c.Id = hw.GetId()
    c.Model = hw.GetModel()
    c.Bus = hw.GetBus()
    c.Register()
    go c.Monitor()
    go c.Connect()
}

func (c *Coordinator) Monitor() {
    // function to automatically create and destroy sm
    ch := make(chan int)
    im := NewI2CMonitor(c.Bus,ch)
    go im.Monitor()
    for {
        d := <-ch
        i := im.GetDevice(d)
        go c.DeviceConnect(i)
    }
}

func (c *Coordinator) DeviceConnect(i2c I2CDev) {
    c.Devices.Lock()
    defer c.Devices.Unlock()
    addr := i2c.GetAddr()
    if dm, exists := c.Devices.Managers[addr]; !exists{
        dm := NewDeviceManager(i2c)
        c.Devices.Managers[addr] = dm
        go dm.Start()
    } else {
        go dm.Start()
    }
}

func (c *Coordinator) Connect() {
    // function connects to central server and passes hwinfo
    var opts []grpc.DialOption
    opts = append(opts,grpc.WithTransportCredentials(insecure.NewCredentials()))
    var conn *grpc.ClientConn
    var err error
    for {
        conn, err = grpc.Dial(fmt.Sprintf("%v:%v",c.server.Ip,c.server.Port),opts...)
        code := status.Code(err)
        if code != 0 { // != OK
            if code == (5 | 14) { // service temp down
                to := c.Timeout()
                if to == 0 {
                    err = errors.New("Failed to connect to central server")
                    c.Err <-err
                }
                fmt.Printf("Server currently unavailable, retrying in %v ms", to)
                time.Sleep(time.Duration(to) * time.Millisecond)
            } else {
                c.Err <-err
            }
        }
        break;
    }
    defer conn.Close()
    client := pb.NewHandshakeClient(conn)
    req := &pb.ClientDiscoveryRequest{Id:c.Id,Ip:c.hwinfo.Ip,Port:int32(c.hwinfo.Port),Model:c.Model,ClientType:c.Type}
    resp, err := client.ClientDiscoveryHandler(context.Background(), req)
    if err != nil {
        c.Err <-err
    }
    if resp.GetSuccess() {
        fmt.Println("Central server reached")
    } else {
        c.Err <-errors.New("Failed to reach central server!")
    }
}

func (c *Coordinator) Timeout() int {
    c.Active.Lock()
    defer c.Active.Unlock()
    if c.Active.int < 9 {
        v := int(5 * math.Pow(float64(2), float64(c.Active.int)))
        c.Active.int +=1
        return v
    } else {
        //excedded retries
        return 0
    }
}