initial working version

internal/config/config.go

@@ -0,0 +1,64 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/adrg/xdg"
+	toml "github.com/pelletier/go-toml/v2"
+)
+
+type Config struct {
+	Issuer       string `toml:"issuer"`
+	ClientID     string `toml:"client_id"`
+	ClientSecret string `toml:"client_secret,omitempty"`
+	CacheHost    string `toml:"cache_host"`
+	NetrcPath    string `toml:"netrc_path"`
+}
+
+// Load reads the config from the given path, or from the default XDG location.
+func Load(path string) (*Config, error) {
+	if path == "" {
+		path = filepath.Join(xdg.ConfigHome, "nix-cache-login", "config.toml")
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("reading config file: %w", err)
+	}
+
+	var cfg Config
+	if err := toml.Unmarshal(data, &cfg); err != nil {
+		return nil, fmt.Errorf("parsing config file: %w", err)
+	}
+
+	cfg.NetrcPath = os.ExpandEnv(cfg.NetrcPath)
+
+	if err := cfg.validate(); err != nil {
+		return nil, err
+	}
+
+	return &cfg, nil
+}
+
+func (c *Config) validate() error {
+	if c.Issuer == "" {
+		return fmt.Errorf("config: issuer is required")
+	}
+	if c.ClientID == "" {
+		return fmt.Errorf("config: client_id is required")
+	}
+	if c.CacheHost == "" {
+		return fmt.Errorf("config: cache_host is required")
+	}
+	if c.NetrcPath == "" {
+		return fmt.Errorf("config: netrc_path is required")
+	}
+	return nil
+}
+
+// RefreshTokenPath returns the path to the stored refresh token.
+func RefreshTokenPath() string {
+	return filepath.Join(xdg.ConfigHome, "nix-cache-login", "refresh-token")
+}

internal/config/config_test.go

@@ -0,0 +1,177 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLoadValidConfig(t *testing.T) {
+	dir := t.TempDir()
+	cfgFile := filepath.Join(dir, "config.toml")
+
+	content := `
+issuer = "https://id.example.com/realms/test"
+client_id = "nix-cache"
+cache_host = "cache.example.com"
+netrc_path = "/home/user/.config/nix/netrc"
+`
+	if err := os.WriteFile(cfgFile, []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	cfg, err := Load(cfgFile)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if cfg.Issuer != "https://id.example.com/realms/test" {
+		t.Errorf("issuer = %q, want %q", cfg.Issuer, "https://id.example.com/realms/test")
+	}
+	if cfg.ClientID != "nix-cache" {
+		t.Errorf("client_id = %q, want %q", cfg.ClientID, "nix-cache")
+	}
+	if cfg.CacheHost != "cache.example.com" {
+		t.Errorf("cache_host = %q, want %q", cfg.CacheHost, "cache.example.com")
+	}
+	if cfg.ClientSecret != "" {
+		t.Errorf("client_secret = %q, want empty", cfg.ClientSecret)
+	}
+}
+
+func TestLoadConfigWithClientSecret(t *testing.T) {
+	dir := t.TempDir()
+	cfgFile := filepath.Join(dir, "config.toml")
+
+	content := `
+issuer = "https://id.example.com/realms/test"
+client_id = "nix-cache-server"
+client_secret = "super-secret"
+cache_host = "cache.example.com"
+netrc_path = "/tmp/netrc"
+`
+	if err := os.WriteFile(cfgFile, []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	cfg, err := Load(cfgFile)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if cfg.ClientSecret != "super-secret" {
+		t.Errorf("client_secret = %q, want %q", cfg.ClientSecret, "super-secret")
+	}
+}
+
+func TestEnvVarExpansionInNetrcPath(t *testing.T) {
+	dir := t.TempDir()
+	cfgFile := filepath.Join(dir, "config.toml")
+
+	t.Setenv("TEST_CONFIG_DIR", "/custom/config")
+
+	content := `
+issuer = "https://id.example.com/realms/test"
+client_id = "nix-cache"
+cache_host = "cache.example.com"
+netrc_path = "$TEST_CONFIG_DIR/nix/netrc"
+`
+	if err := os.WriteFile(cfgFile, []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	cfg, err := Load(cfgFile)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if cfg.NetrcPath != "/custom/config/nix/netrc" {
+		t.Errorf("netrc_path = %q, want %q", cfg.NetrcPath, "/custom/config/nix/netrc")
+	}
+}
+
+func TestEnvVarExpansionBraces(t *testing.T) {
+	dir := t.TempDir()
+	cfgFile := filepath.Join(dir, "config.toml")
+
+	t.Setenv("MY_HOME", "/home/testuser")
+
+	content := `
+issuer = "https://id.example.com/realms/test"
+client_id = "nix-cache"
+cache_host = "cache.example.com"
+netrc_path = "${MY_HOME}/.config/nix/netrc"
+`
+	if err := os.WriteFile(cfgFile, []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	cfg, err := Load(cfgFile)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if cfg.NetrcPath != "/home/testuser/.config/nix/netrc" {
+		t.Errorf("netrc_path = %q, want %q", cfg.NetrcPath, "/home/testuser/.config/nix/netrc")
+	}
+}
+
+func TestMissingRequiredFields(t *testing.T) {
+	tests := []struct {
+		name    string
+		content string
+		errMsg  string
+	}{
+		{
+			name:    "missing issuer",
+			content: `client_id = "x"` + "\n" + `cache_host = "x"` + "\n" + `netrc_path = "/tmp/x"`,
+			errMsg:  "issuer is required",
+		},
+		{
+			name:    "missing client_id",
+			content: `issuer = "https://x"` + "\n" + `cache_host = "x"` + "\n" + `netrc_path = "/tmp/x"`,
+			errMsg:  "client_id is required",
+		},
+		{
+			name:    "missing cache_host",
+			content: `issuer = "https://x"` + "\n" + `client_id = "x"` + "\n" + `netrc_path = "/tmp/x"`,
+			errMsg:  "cache_host is required",
+		},
+		{
+			name:    "missing netrc_path",
+			content: `issuer = "https://x"` + "\n" + `client_id = "x"` + "\n" + `cache_host = "x"`,
+			errMsg:  "netrc_path is required",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dir := t.TempDir()
+			cfgFile := filepath.Join(dir, "config.toml")
+			if err := os.WriteFile(cfgFile, []byte(tt.content), 0644); err != nil {
+				t.Fatal(err)
+			}
+
+			_, err := Load(cfgFile)
+			if err == nil {
+				t.Fatal("expected error, got nil")
+			}
+			if !contains(err.Error(), tt.errMsg) {
+				t.Errorf("error = %q, want to contain %q", err.Error(), tt.errMsg)
+			}
+		})
+	}
+}
+
+func contains(s, substr string) bool {
+	return len(s) >= len(substr) && searchString(s, substr)
+}
+
+func searchString(s, substr string) bool {
+	for i := 0; i <= len(s)-len(substr); i++ {
+		if s[i:i+len(substr)] == substr {
+			return true
+		}
+	}
+	return false
+}