package main

import (
	"encoding/hex"
	"encoding/json"
	"log"
	"sync"
	"time"

	"github.com/gorilla/websocket"
)

type MasterView struct {
	Version uint32 `json:"version"`
	GitHash string `json:"git_hash"`
	OK      bool   `json:"ok"`
	Error   string `json:"error,omitempty"`
}

type ClientView struct {
	ID              uint32 `json:"id"`
	MAC             string `json:"mac"`
	Version         uint32 `json:"version"`
	Available       bool   `json:"available"`
	Used            bool   `json:"used"`
	LastPing        uint32 `json:"last_ping"`
	LastSuccessPing uint32 `json:"last_success_ping"`
}

type DashboardState struct {
	UpdatedAt     string       `json:"updated_at"`
	SerialPort    string       `json:"serial_port"`
	UARTConnected bool         `json:"uart_connected"`
	SerialOK      bool         `json:"serial_ok"`
	SerialError   string       `json:"serial_error,omitempty"`
	Master        MasterView   `json:"master"`
	Clients       []ClientView `json:"clients"`
}

type wsHub struct {
	mu      sync.RWMutex
	clients map[*websocket.Conn]struct{}
	state   DashboardState
}

func newWSHub() *wsHub {
	return &wsHub{clients: make(map[*websocket.Conn]struct{})}
}

func (h *wsHub) setState(st DashboardState) {
	h.mu.Lock()
	h.state = st
	conns := make([]*websocket.Conn, 0, len(h.clients))
	for c := range h.clients {
		conns = append(conns, c)
	}
	h.mu.Unlock()

	data, err := json.Marshal(st)
	if err != nil {
		return
	}
	for _, c := range conns {
		_ = c.WriteMessage(websocket.TextMessage, data)
	}
}

func (h *wsHub) register(c *websocket.Conn) {
	h.mu.Lock()
	h.clients[c] = struct{}{}
	snap := h.state
	h.mu.Unlock()

	if data, err := json.Marshal(snap); err == nil {
		_ = c.WriteMessage(websocket.TextMessage, data)
	}
}

func (h *wsHub) unregister(c *websocket.Conn) {
	h.mu.Lock()
	delete(h.clients, c)
	h.mu.Unlock()
}

func pollDashboard(link *managedSerial, portName string) DashboardState {
	st := DashboardState{
		UpdatedAt:  time.Now().Format(time.RFC3339),
		SerialPort: portName,
		Clients:    []ClientView{},
	}

	ver, err := link.getVersion()
	if err != nil {
		return disconnectedState(portName, err)
	}
	st.UARTConnected = true
	st.SerialOK = true
	st.Master = MasterView{
		Version: ver.GetVersion(),
		GitHash: ver.GetGitHash(),
		OK:      true,
	}

	clients, err := link.listClients()
	if err != nil {
		st.SerialOK = false
		st.SerialError = err.Error()
		st.UARTConnected = link.IsConnected()
		return st
	}

	for _, c := range clients {
		st.Clients = append(st.Clients, ClientView{
			ID:              c.GetId(),
			MAC:             formatMAC(c.GetMac()),
			Version:         c.GetVersion(),
			Available:       c.GetAvailable(),
			Used:            c.GetUsed(),
			LastPing:        c.GetLastPing(),
			LastSuccessPing: c.GetLastSuccessPing(),
		})
	}
	return st
}

func formatMAC(mac []byte) string {
	if len(mac) == 0 {
		return ""
	}
	return hex.EncodeToString(mac)
}

func runPoller(link *managedSerial, portName string, hub *wsHub, interval time.Duration, stop <-chan struct{}) {
	ticker := time.NewTicker(interval)
	defer ticker.Stop()

	uartUp := false
	publish := func() {
		st := pollDashboard(link, portName)
		if st.UARTConnected && !uartUp {
			log.Printf("UART %s connected", portName)
		}
		uartUp = st.UARTConnected
		hub.setState(st)
	}

	publish()
	for {
		select {
		case <-stop:
			return
		case <-ticker.C:
			publish()
		}
	}
}