furnacecheck/main.go

package main

import (
	"bufio"
	"bytes"
	"database/sql"
	"encoding/json"
	"fmt"
	"image"
	"image/jpeg"
	"log"
	_ "modernc.org/sqlite"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"
)

func getEnv(key, fallback string) string {
	if val, ok := os.LookupEnv(key); ok {
		return val
	}
	return fallback
}

func getEnvInt(key string, fallback int) int {
	if val, ok := os.LookupEnv(key); ok {
		if i, err := strconv.Atoi(val); err == nil {
			return i
		}
	}
	return fallback
}

func getEnvDuration(key string, fallback time.Duration) time.Duration {
	if val, ok := os.LookupEnv(key); ok {
		if d, err := time.ParseDuration(val); err == nil {
			return d
		}
	}
	return fallback
}

type Light struct {
	Name            string `json:"name"`
	X, Y            int    `json:"x","y"`
	Priority        string `json:"priority"`
	MinOnDurationMS int64  `json:"min_on_duration_ms"`
}

var defaultLights = map[string]Light{
	"living_room_stat": {"Living Room Thermostat", 775, 251, "low", 100},
	"living_room_heat": {"Living Room Heating", 1320, 263, "low", 100},
	"dining_room_stat": {"Dining Room Thermostat", 779, 290, "low", 100},
	"dining_room_heat": {"Dining Room Heating", 1317, 305, "low", 100},
	"hot_water_stat":   {"Hot Water Thermostat", 773, 488, "low", 100},
	"hot_water_heat":   {"Hot Water Heating", 1313, 501, "low", 100},
	"first_bed_stat":   {"First Bedroom Thermostat", 769, 526, "low", 100},
	"first_bed_heat":   {"First Bedroom Heating", 1309, 540, "low", 100},
	"master_bed_stat":  {"Master Bedroom Thermostat", 773, 570, "low", 100},
	"master_bed_heat":  {"Master Bedroom Heating", 1309, 588, "low", 100},
	"basement_stat":    {"Basement Thermostat", 769, 614, "low", 100},
	"basement_heat":    {"Basement Heating", 1309, 630, "low", 100},
	"second_bed_stat":  {"Second Bedroom Thermostat", 764, 657, "low", 100},
	"second_bed_heat":  {"Second Bedroom Heating", 1307, 672, "low", 100},
	"inducer":          {"Inducer", 1307, 711, "low", 100},
	"burner":           {"Burner", 1307, 760, "low", 100},
	"circulator":       {"Circulator", 1307, 799, "low", 100},
	"furnace_power":    {"Furnace Power", 1038, 837, "urgent", 100},
}

func main() {
	fmt.Println("Starting multi-light monitor")

	dbPath := getEnv("LIGHT_DB_PATH", "lightlog.db")
	webcamURL := getEnv("WEBCAM_URL", "http://furnace.service:8081/stream")
	minBrightness := getEnvInt("MIN_BRIGHTNESS", 170)
	checkInterval := getEnvDuration("CHECK_INTERVAL", 2*time.Second)
	webPort := getEnv("FURNACE_WEB_PORT", "8090")
	lights, err := loadLightsFromEnv()
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Using DB:", dbPath)
	fmt.Println("Using webcam:", webcamURL)
	fmt.Println("Min Brightness:", minBrightness)
	fmt.Println("Check Interval:", checkInterval)

	db, err := sql.Open("sqlite", dbPath)

	go startWebServer(db, getEnv("HTTP_PORT", webPort))
	fmt.Println("Starting json data server on port ", webPort)

	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	_, err = db.Exec(`CREATE TABLE IF NOT EXISTS light_checks (
		id INTEGER PRIMARY KEY AUTOINCREMENT,
		name TEXT,
		state TEXT,
		timestamp DATETIME
	)`)
	_, err = db.Exec(`CREATE INDEX IF NOT EXISTS idx_light_checks_name_ts
       ON light_checks(name, timestamp DESC
    );`)

	if err != nil {
		log.Fatal(err)
	}

	prevStates := make(map[string]bool)

	for {
		img, err := grabFrame(webcamURL)
		if err != nil {
			log.Println("Error grabbing frame:", err)
			time.Sleep(time.Second)
			continue
		}

		now := time.Now()

		for key, light := range lights {
			on := isLightOn(img, light, minBrightness)

			// Only act if state changed
			if on != prevStates[key] {
				stateStr := onOff(on)

				fmt.Printf("%s: %s\n", light.Name, stateStr)

				insertLightEvent(db, key, on, now)

				sendNtfyNotification(light, on)

				prevStates[key] = on
			}
		}

		time.Sleep(checkInterval)
	}
}

func loadLightsFromEnv() (map[string]Light, error) {
	raw := os.Getenv("LIGHTS_JSON")
	if raw == "" {
		return defaultLights, nil
	}

	var lights map[string]Light
	if err := json.Unmarshal([]byte(raw), &lights); err != nil {
		return nil, fmt.Errorf("invalid LIGHTS_JSON: %w", err)
	}

	if len(lights) == 0 {
		return nil, fmt.Errorf("no lights defined")
	}

	return lights, nil
}

func grabFrame(url string) (image.Image, error) {
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	reader := bufio.NewReader(resp.Body)
	frame, err := readJPEGFrame(reader)
	if err != nil {
		return nil, err
	}

	return jpeg.Decode(bytes.NewReader(frame))
}

func readJPEGFrame(r *bufio.Reader) ([]byte, error) {
	var buf bytes.Buffer

	for {
		line, err := r.ReadString('\n')
		if err != nil {
			return nil, err
		}
		if strings.HasPrefix(line, "--") {
			break
		}
	}

	for {
		line, err := r.ReadString('\n')
		if err != nil {
			return nil, err
		}
		if line == "\r\n" {
			break
		}
	}

	for {
		b, err := r.ReadByte()
		if err != nil {
			return nil, err
		}
		buf.WriteByte(b)

		data := buf.Bytes()
		if len(data) > 2 && data[len(data)-2] == 0xFF && data[len(data)-1] == 0xD9 {
			return buf.Bytes(), nil
		}
	}
}

func isLightOn(img image.Image, light Light, minBrightness int) bool {
	bounds := img.Bounds()

	x := clamp(light.X, bounds.Min.X, bounds.Max.X)
	y := clamp(light.Y, bounds.Min.Y, bounds.Max.Y)

	r, g, bl, _ := img.At(x, y).RGBA()

	// Convert to 8-bit
	rr := float64(r >> 8)
	gg := float64(g >> 8)
	bb := float64(bl >> 8)

	// Perceived luminance (Rec. 709)
	brightness := 0.2126*rr + 0.7152*gg + 0.0722*bb

	return brightness >= float64(minBrightness)
}

func clamp(v, min, max int) int {
	if v < min {
		return min
	}
	if v > max {
		return max
	}
	return v
}

func onOff(on bool) string {
	if on {
		return "ON"
	}
	return "OFF"
}

func sendNtfyNotification(light Light, on bool) {
	state := onOff(on)
	url := "https://ntfy.unbl.ink/furnace"
	body := bytes.NewBufferString(fmt.Sprintf("%s: %s", light.Name, state))
	req, err := http.NewRequest("POST", url, body)
	if err != nil {
		log.Println("Failed to create request:", err)
		return
	}
	req.Header.Set("Title", "Furnace State Change")
	req.Header.Set("Priority", light.Priority)

	client := &http.Client{Timeout: 5 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		log.Println("Failed to send notification:", err)
		return
	}
	resp.Body.Close()
}

func startWebServer(db *sql.DB, port string) {
	lights, err := loadLightsFromEnv()
	if err != nil {
		log.Fatal(err)
	}

	http.HandleFunc("/lights", func(w http.ResponseWriter, r *http.Request) {
		rows, err := db.Query(`
            SELECT name, state, MAX(timestamp) 
            FROM light_checks 
            GROUP BY name
        `)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		defer rows.Close()

		resp := make(map[string]string)
		for rows.Next() {
			var key, state string
			var ts string
			if err := rows.Scan(&key, &state, &ts); err != nil {
				http.Error(w, err.Error(), http.StatusInternalServerError)
				return
			}
			resp[lights[key].Name] = state
		}

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(resp)
	})

	log.Println("HTTP server listening on", port)
	log.Fatal(http.ListenAndServe(":"+port, nil))
}

func insertLightEvent(db *sql.DB, name string, on bool, ts time.Time) {
	state := "off"
	if on {
		state = "on"
	}

	_, err := db.Exec(
		`INSERT INTO light_checks (name, state, timestamp)
		 VALUES (?, ?, ?)`,
		name,
		state,
		ts,
	)
	if err != nil {
		log.Println("DB insert failed:", err)
	}
}