skyview/internal/config/config.go

package config

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

type Config struct {
	Server   ServerConfig   `json:"server"`
	Dump1090 Dump1090Config `json:"dump1090"`
	Origin   OriginConfig   `json:"origin"`
}

type ServerConfig struct {
	Address string `json:"address"`
	Port    int    `json:"port"`
}

type Dump1090Config struct {
	Host     string `json:"host"`
	DataPort int    `json:"data_port"`
}

type OriginConfig struct {
	Latitude  float64 `json:"latitude"`
	Longitude float64 `json:"longitude"`
	Name      string  `json:"name"`
}

func Load() (*Config, error) {
	cfg := &Config{
		Server: ServerConfig{
			Address: ":8080",
			Port:    8080,
		},
		Dump1090: Dump1090Config{
			Host:     "localhost",
			DataPort: 30003,
		},
		Origin: OriginConfig{
			Latitude:  37.7749,
			Longitude: -122.4194,
			Name:      "Default Location",
		},
	}

	configFile := os.Getenv("SKYVIEW_CONFIG")
	if configFile == "" {
		// Check for config files in common locations
		candidates := []string{"config.json", "./config.json", "skyview.json"}
		for _, candidate := range candidates {
			if _, err := os.Stat(candidate); err == nil {
				configFile = candidate
				break
			}
		}
	}

	if configFile != "" {
		if err := loadFromFile(cfg, configFile); err != nil {
			return nil, fmt.Errorf("failed to load config file %s: %w", configFile, err)
		}
	}

	loadFromEnv(cfg)

	return cfg, nil
}

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

	return json.Unmarshal(data, cfg)
}

func loadFromEnv(cfg *Config) {
	if addr := os.Getenv("SKYVIEW_ADDRESS"); addr != "" {
		cfg.Server.Address = addr
	}

	if portStr := os.Getenv("SKYVIEW_PORT"); portStr != "" {
		if port, err := strconv.Atoi(portStr); err == nil {
			cfg.Server.Port = port
			cfg.Server.Address = fmt.Sprintf(":%d", port)
		}
	}

	if host := os.Getenv("DUMP1090_HOST"); host != "" {
		cfg.Dump1090.Host = host
	}

	if dataPortStr := os.Getenv("DUMP1090_DATA_PORT"); dataPortStr != "" {
		if port, err := strconv.Atoi(dataPortStr); err == nil {
			cfg.Dump1090.DataPort = port
		}
	}

	if latStr := os.Getenv("ORIGIN_LATITUDE"); latStr != "" {
		if lat, err := strconv.ParseFloat(latStr, 64); err == nil {
			cfg.Origin.Latitude = lat
		}
	}

	if lonStr := os.Getenv("ORIGIN_LONGITUDE"); lonStr != "" {
		if lon, err := strconv.ParseFloat(lonStr, 64); err == nil {
			cfg.Origin.Longitude = lon
		}
	}

	if name := os.Getenv("ORIGIN_NAME"); name != "" {
		cfg.Origin.Name = name
	}
}