feat: bootstrap foundation application

apps/server/internal/config/config.go

@@ -0,0 +1,99 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+type Config struct {
+	Server   ServerConfig   `json:"server"`
+	Database DatabaseConfig `json:"database"`
+	Content  ContentConfig  `json:"content"`
+	Web      WebConfig      `json:"web"`
+	LogLevel string         `json:"logLevel"`
+}
+
+type ServerConfig struct {
+	Addr string `json:"addr"`
+}
+
+type DatabaseConfig struct {
+	Path       string `json:"path"`
+	PrimaryURL string `json:"primaryUrl"`
+	AuthToken  string `json:"authToken"`
+}
+
+type ContentConfig struct {
+	SourceDir string `json:"sourceDir"`
+	StoreDir  string `json:"storeDir"`
+}
+
+type WebConfig struct {
+	DistDir string `json:"distDir"`
+}
+
+func Default() Config {
+	return Config{
+		Server: ServerConfig{
+			Addr: ":8080",
+		},
+		Database: DatabaseConfig{
+			Path: filepath.Join("..", "..", "data", "db.sqlite"),
+		},
+		Content: ContentConfig{
+			SourceDir: filepath.Join("..", "..", "content"),
+			StoreDir:  filepath.Join("..", "..", "data", "files"),
+		},
+		Web: WebConfig{
+			DistDir: filepath.Join("..", "web", "dist"),
+		},
+		LogLevel: "INFO",
+	}
+}
+
+func Load() (Config, error) {
+	cfg := Default()
+
+	if configPath := os.Getenv("MD_HUB_CONFIG"); configPath != "" {
+		if err := loadFile(configPath, &cfg); err != nil {
+			return Config{}, err
+		}
+	}
+
+	overrideString(&cfg.Server.Addr, "MD_HUB_SERVER_ADDR")
+	overrideString(&cfg.Database.Path, "MD_HUB_DATABASE_PATH")
+	overrideString(&cfg.Database.PrimaryURL, "MD_HUB_DATABASE_PRIMARY_URL")
+	overrideString(&cfg.Database.AuthToken, "MD_HUB_DATABASE_AUTH_TOKEN")
+	overrideString(&cfg.Content.SourceDir, "MD_HUB_CONTENT_SOURCE_DIR")
+	overrideString(&cfg.Content.StoreDir, "MD_HUB_CONTENT_STORE_DIR")
+	overrideString(&cfg.Web.DistDir, "MD_HUB_WEB_DIST_DIR")
+	overrideString(&cfg.LogLevel, "MD_HUB_LOG_LEVEL")
+
+	if cfg.Server.Addr == "" {
+		return Config{}, fmt.Errorf("server.addr must not be empty")
+	}
+
+	return cfg, nil
+}
+
+func loadFile(path string, cfg *Config) error {
+	file, err := os.Open(path)
+	if err != nil {
+		return fmt.Errorf("open config file %q: %w", path, err)
+	}
+	defer file.Close()
+
+	if err := json.NewDecoder(file).Decode(cfg); err != nil {
+		return fmt.Errorf("decode config file %q: %w", path, err)
+	}
+
+	return nil
+}
+
+func overrideString(target *string, key string) {
+	if value := os.Getenv(key); value != "" {
+		*target = value
+	}
+}