Production state

internal/app/dotenv.go

@@ -0,0 +1,65 @@
+package app
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+)
+
+// LoadDotEnv loads simple KEY=VALUE entries without replacing variables that
+// are already present in the process environment. A missing file is allowed.
+func LoadDotEnv(path string) error {
+	file, err := os.Open(path)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil
+	}
+	if err != nil {
+		return fmt.Errorf("open dotenv file: %w", err)
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for lineNumber := 1; scanner.Scan(); lineNumber++ {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		line = strings.TrimSpace(strings.TrimPrefix(line, "export "))
+		key, value, found := strings.Cut(line, "=")
+		key = strings.TrimSpace(key)
+		if !found || !validEnvironmentKey(key) {
+			return fmt.Errorf("%s:%d: invalid environment assignment", path, lineNumber)
+		}
+		value = strings.TrimSpace(value)
+		if len(value) >= 2 && ((value[0] == '\'' && value[len(value)-1] == '\'') || (value[0] == '"' && value[len(value)-1] == '"')) {
+			value = value[1 : len(value)-1]
+		}
+		if _, exists := os.LookupEnv(key); !exists {
+			if err := os.Setenv(key, value); err != nil {
+				return fmt.Errorf("%s:%d: set environment: %w", path, lineNumber, err)
+			}
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return fmt.Errorf("read dotenv file: %w", err)
+	}
+	return nil
+}
+
+func validEnvironmentKey(key string) bool {
+	if key == "" || !isEnvironmentKeyStart(key[0]) {
+		return false
+	}
+	for i := 1; i < len(key); i++ {
+		if !isEnvironmentKeyStart(key[i]) && (key[i] < '0' || key[i] > '9') {
+			return false
+		}
+	}
+	return true
+}
+
+func isEnvironmentKeyStart(char byte) bool {
+	return char == '_' || char >= 'A' && char <= 'Z' || char >= 'a' && char <= 'z'
+}