package config

import (
	"encoding/json"
	"fmt"
	"os"
)

type Config struct {
	ScreenID       string `json:"screen_id"`
	ServerBaseURL  string `json:"server_base_url"`
	MQTTBroker     string `json:"mqtt_broker"`
	HeartbeatEvery int    `json:"heartbeat_every_seconds"`
}

const defaultConfigPath = "/etc/signage/config.json"

func Load() (Config, error) {
	cfg := defaultConfig()

	configPath := getenv("MORZ_INFOBOARD_CONFIG", defaultConfigPath)
	if err := loadFromFile(configPath, &cfg); err != nil {
		if !os.IsNotExist(err) {
			return Config{}, fmt.Errorf("load config file: %w", err)
		}
	}

	overrideFromEnv(&cfg)

	if cfg.ScreenID == "" {
		return Config{}, fmt.Errorf("screen id is required")
	}

	if cfg.HeartbeatEvery <= 0 {
		cfg.HeartbeatEvery = defaultConfig().HeartbeatEvery
	}

	return cfg, nil
}


func defaultConfig() Config {
	return Config{
		ScreenID:       "unset-screen",
		ServerBaseURL:  "http://127.0.0.1:8080",
		MQTTBroker:     "tcp://127.0.0.1:1883",
		HeartbeatEvery: 30,
	}
}

func loadFromFile(path string, cfg *Config) error {
	data, err := os.ReadFile(path)
	if err != nil {
		return err
	}

	return json.Unmarshal(data, cfg)
}

func overrideFromEnv(cfg *Config) {
	cfg.ScreenID = getenv("MORZ_INFOBOARD_SCREEN_ID", cfg.ScreenID)
	cfg.ServerBaseURL = getenv("MORZ_INFOBOARD_SERVER_URL", cfg.ServerBaseURL)
	cfg.MQTTBroker = getenv("MORZ_INFOBOARD_MQTT_BROKER", cfg.MQTTBroker)
}

func getenv(key, fallback string) string {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}

	return value
}