Initial commit.

internal/env/env.go

@@ -0,0 +1,55 @@
+// Package env provides .env file loading and typed lookups using only the
+// standard library.
+package env
+
+import (
+	"bufio"
+	"os"
+	"strings"
+)
+
+// Load reads KEY=VALUE pairs from the given file into the process
+// environment. Existing environment variables win over file values. A
+// missing file is not an error, so .env stays optional.
+func Load(path string) error {
+	f, err := os.Open(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		key, value, ok := strings.Cut(line, "=")
+		if !ok {
+			continue
+		}
+		key = strings.TrimSpace(strings.TrimPrefix(key, "export "))
+		value = strings.TrimSpace(value)
+		if len(value) >= 2 {
+			if (value[0] == '"' && value[len(value)-1] == '"') ||
+				(value[0] == '\'' && value[len(value)-1] == '\'') {
+				value = value[1 : len(value)-1]
+			}
+		}
+		if _, exists := os.LookupEnv(key); !exists {
+			os.Setenv(key, value)
+		}
+	}
+	return scanner.Err()
+}
+
+// Get returns the environment variable or a default.
+func Get(key, fallback string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return fallback
+}