refactor: Replace env config with atomic YAML

1 files changed, 120 insertions, 0 deletions

diff --git a/config/config.go b/config/config.go
new file mode 100644
index 0000000..98ccebc
--- /dev/null
+++ b/config/config.go
@@ -0,0 +1,120 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"gopkg.in/yaml.v3"
+)
+
+type Config struct {
+	Database DatabaseConfig `yaml:"database"`
+	Server   ServerConfig   `yaml:"server"`
+	Storage  StorageConfig  `yaml:"storage"`
+	Strava   StravaConfig   `yaml:"strava"`
+}
+
+type DatabaseConfig struct {
+	Path string `yaml:"path"`
+}
+
+type ServerConfig struct {
+	Address   string `yaml:"address"`
+	PublicURL string `yaml:"public_url"`
+}
+
+type StorageConfig struct {
+	GPXDir string `yaml:"gpx_dir"`
+}
+
+type StravaConfig struct {
+	ClientID     string `yaml:"client_id"`
+	ClientSecret string `yaml:"client_secret"`
+	AccessToken  string `yaml:"access_token"`
+	RefreshToken string `yaml:"refresh_token"`
+	ExpiresAt    int64  `yaml:"expires_at"`
+}
+
+func Default() Config {
+	return Config{
+		Database: DatabaseConfig{Path: "biking_home.db"},
+		Server: ServerConfig{
+			Address:   "127.0.0.1:8080",
+			PublicURL: "http://localhost:8080",
+		},
+		Storage: StorageConfig{GPXDir: "rides"},
+	}
+}
+
+func Load(filename string) (Config, error) {
+	data, err := os.ReadFile(filename)
+	if err != nil {
+		return Config{}, fmt.Errorf("read config %q: %w", filename, err)
+	}
+	config := Default()
+	if err := yaml.Unmarshal(data, &config); err != nil {
+		return Config{}, fmt.Errorf("parse config %q: %w", filename, err)
+	}
+	if config.Database.Path == "" {
+		return Config{}, fmt.Errorf("config %q: database.path is required", filename)
+	}
+	if config.Server.Address == "" || config.Server.PublicURL == "" {
+		return Config{}, fmt.Errorf("config %q: server.address and server.public_url are required", filename)
+	}
+	if config.Storage.GPXDir == "" {
+		return Config{}, fmt.Errorf("config %q: storage.gpx_dir is required", filename)
+	}
+	return config, nil
+}
+
+func Save(filename string, config Config) error {
+	data, err := yaml.Marshal(config)
+	if err != nil {
+		return fmt.Errorf("marshal config: %w", err)
+	}
+	directory := filepath.Dir(filename)
+	temporary, err := os.CreateTemp(directory, "."+filepath.Base(filename)+".tmp-*")
+	if err != nil {
+		return fmt.Errorf("create temporary config: %w", err)
+	}
+	temporaryName := temporary.Name()
+	removeTemporary := true
+	defer func() {
+		if removeTemporary {
+			_ = os.Remove(temporaryName)
+		}
+	}()
+	if err := temporary.Chmod(0o600); err != nil {
+		_ = temporary.Close()
+		return fmt.Errorf("set config permissions: %w", err)
+	}
+	if _, err := temporary.Write(data); err != nil {
+		_ = temporary.Close()
+		return fmt.Errorf("write temporary config: %w", err)
+	}
+	if err := temporary.Sync(); err != nil {
+		_ = temporary.Close()
+		return fmt.Errorf("sync temporary config: %w", err)
+	}
+	if err := temporary.Close(); err != nil {
+		return fmt.Errorf("close temporary config: %w", err)
+	}
+	if err := os.Rename(temporaryName, filename); err != nil {
+		return fmt.Errorf("replace config: %w", err)
+	}
+	removeTemporary = false
+	return syncDirectory(directory)
+}
+
+func syncDirectory(directory string) error {
+	dir, err := os.Open(directory)
+	if err != nil {
+		return fmt.Errorf("open config directory: %w", err)
+	}
+	defer dir.Close()
+	if err := dir.Sync(); err != nil {
+		return fmt.Errorf("sync config directory: %w", err)
+	}
+	return nil
+}