Implement IP API daemon with GeoIP database support

- Create modular architecture with separate packages for config, database, HTTP, logging, and state management
- Implement Cobra CLI with daemon command
- Set up Uber FX dependency injection
- Add Chi router with health check and IP lookup endpoints
- Implement GeoIP database downloader with automatic updates
- Add state persistence for tracking database download times
- Include comprehensive test coverage for all components
- Configure structured logging with slog
- Add Makefile with test, lint, and build targets
- Support both IPv4 and IPv6 lookups
- Return country, city, ASN, and location data in JSON format

internal/config/config.go

@@ -0,0 +1,77 @@
+// Package config handles application configuration.
+package config
+
+import (
+	"os"
+	"strconv"
+
+	"git.eeqj.de/sneak/smartconfig"
+)
+
+// Config holds the application configuration.
+type Config struct {
+	Port     int
+	StateDir string
+	LogLevel string
+}
+
+// New creates a new configuration instance.
+func New(configFile string) (*Config, error) {
+	// Check if config file exists first
+	if _, err := os.Stat(configFile); os.IsNotExist(err) {
+		return newDefaultConfig(), nil
+	}
+
+	// Load smartconfig
+	sc, err := smartconfig.NewFromConfigPath(configFile)
+	if err != nil {
+		return nil, err
+	}
+
+	cfg := &Config{}
+
+	// Get port from smartconfig or environment or default
+	if port, err := sc.GetInt("port"); err == nil {
+		cfg.Port = port
+	} else {
+		cfg.Port = getPortFromEnv()
+	}
+
+	// Get state directory
+	if stateDir, err := sc.GetString("state_dir"); err == nil {
+		cfg.StateDir = stateDir
+	} else {
+		cfg.StateDir = "/var/lib/ipapi"
+	}
+
+	// Get log level
+	if logLevel, err := sc.GetString("log_level"); err == nil {
+		cfg.LogLevel = logLevel
+	} else {
+		cfg.LogLevel = "info"
+	}
+
+	return cfg, nil
+}
+
+func newDefaultConfig() *Config {
+	return &Config{
+		Port:     getPortFromEnv(),
+		StateDir: "/var/lib/ipapi",
+		LogLevel: "info",
+	}
+}
+
+func getPortFromEnv() int {
+	const defaultPort = 8080
+	portStr := os.Getenv("PORT")
+	if portStr == "" {
+		return defaultPort
+	}
+	port, err := strconv.Atoi(portStr)
+	if err != nil {
+		return defaultPort
+	}
+
+	return port
+}

internal/config/config_test.go

@@ -0,0 +1,64 @@
+package config
+
+import (
+	"os"
+	"testing"
+)
+
+func TestNewDefaultConfig(t *testing.T) {
+	// Clear PORT env var for test
+	oldPort := os.Getenv("PORT")
+	os.Unsetenv("PORT")
+	defer os.Setenv("PORT", oldPort)
+
+	cfg := newDefaultConfig()
+	if cfg.Port != 8080 {
+		t.Errorf("expected default port 8080, got %d", cfg.Port)
+	}
+	if cfg.StateDir != "/var/lib/ipapi" {
+		t.Errorf("expected default state dir /var/lib/ipapi, got %s", cfg.StateDir)
+	}
+	if cfg.LogLevel != "info" {
+		t.Errorf("expected default log level info, got %s", cfg.LogLevel)
+	}
+}
+
+func TestGetPortFromEnv(t *testing.T) {
+	tests := []struct {
+		name     string
+		envValue string
+		expected int
+	}{
+		{"no env", "", 8080},
+		{"valid port", "9090", 9090},
+		{"invalid port", "invalid", 8080},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			oldPort := os.Getenv("PORT")
+			if tt.envValue == "" {
+				os.Unsetenv("PORT")
+			} else {
+				os.Setenv("PORT", tt.envValue)
+			}
+			defer os.Setenv("PORT", oldPort)
+
+			port := getPortFromEnv()
+			if port != tt.expected {
+				t.Errorf("expected port %d, got %d", tt.expected, port)
+			}
+		})
+	}
+}
+
+func TestNew(t *testing.T) {
+	// Test with non-existent file (should use defaults)
+	cfg, err := New("/nonexistent/config.yml")
+	if err != nil {
+		t.Fatalf("expected no error for non-existent file, got %v", err)
+	}
+	if cfg == nil {
+		t.Fatal("expected config, got nil")
+	}
+}