feat: Refactor of Go backend code

app_system.go

@@ -0,0 +1,146 @@
+// Package main provides system-level utilities for EMLy.
+// This file contains methods for Windows registry access, character encoding
+// conversion, and file system operations.
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"unicode/utf8"
+
+	"golang.org/x/sys/windows/registry"
+	"golang.org/x/text/encoding/charmap"
+	"golang.org/x/text/transform"
+)
+
+// =============================================================================
+// Windows Default App Handler
+// =============================================================================
+
+// CheckIsDefaultEMLHandler checks if EMLy is registered as the default handler
+// for .eml files in Windows.
+//
+// This works by:
+//  1. Getting the current executable path
+//  2. Reading the UserChoice registry key for .eml files
+//  3. Finding the command associated with the chosen ProgId
+//  4. Comparing the command with our executable
+//
+// Returns:
+//   - bool: True if EMLy is the default handler
+//   - error: Error if registry access fails
+func (a *App) CheckIsDefaultEMLHandler() (bool, error) {
+	// Get current executable path for comparison
+	exePath, err := os.Executable()
+	if err != nil {
+		return false, err
+	}
+	exePath = strings.ToLower(exePath)
+
+	// Open the UserChoice key for .eml extension
+	// This is where Windows stores the user's chosen default app
+	k, err := registry.OpenKey(
+		registry.CURRENT_USER,
+		`Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.eml\UserChoice`,
+		registry.QUERY_VALUE,
+	)
+	if err != nil {
+		// Key doesn't exist - user hasn't made a specific choice
+		// or system default is active (which is usually not us)
+		return false, nil
+	}
+	defer k.Close()
+
+	// Get the ProgId (program identifier) for the chosen app
+	progId, _, err := k.GetStringValue("ProgId")
+	if err != nil {
+		return false, err
+	}
+
+	// Find the command associated with this ProgId
+	classKeyPath := fmt.Sprintf(`%s\shell\open\command`, progId)
+	classKey, err := registry.OpenKey(registry.CLASSES_ROOT, classKeyPath, registry.QUERY_VALUE)
+	if err != nil {
+		return false, fmt.Errorf("unable to find command for ProgId %s", progId)
+	}
+	defer classKey.Close()
+
+	// Get the command string
+	cmd, _, err := classKey.GetStringValue("")
+	if err != nil {
+		return false, err
+	}
+
+	// Compare command with our executable
+	// Check if the command contains our executable name
+	cmdLower := strings.ToLower(cmd)
+	if strings.Contains(cmdLower, strings.ToLower(filepath.Base(exePath))) {
+		return true, nil
+	}
+
+	return false, nil
+}
+
+// OpenDefaultAppsSettings opens the Windows Settings app to the Default Apps page.
+// This allows users to easily set EMLy as the default handler for email files.
+//
+// Returns:
+//   - error: Error if launching settings fails
+func (a *App) OpenDefaultAppsSettings() error {
+	cmd := exec.Command("cmd", "/c", "start", "ms-settings:defaultapps")
+	return cmd.Start()
+}
+
+// =============================================================================
+// Character Encoding
+// =============================================================================
+
+// ConvertToUTF8 attempts to convert a string to valid UTF-8.
+// If the string is already valid UTF-8, it's returned as-is.
+// Otherwise, it assumes Windows-1252 encoding (common for legacy emails)
+// and attempts to decode it.
+//
+// This is particularly useful for email body content that may have been
+// encoded with legacy Western European character sets.
+//
+// Parameters:
+//   - s: The string to convert
+//
+// Returns:
+//   - string: UTF-8 encoded string
+func (a *App) ConvertToUTF8(s string) string {
+	// If already valid UTF-8, return as-is
+	if utf8.ValidString(s) {
+		return s
+	}
+
+	// Assume Windows-1252 (superset of ISO-8859-1)
+	// This is the most common encoding for legacy Western European text
+	decoder := charmap.Windows1252.NewDecoder()
+	decoded, _, err := transform.String(decoder, s)
+	if err != nil {
+		// Return original if decoding fails
+		return s
+	}
+	return decoded
+}
+
+// =============================================================================
+// File System Operations
+// =============================================================================
+
+// OpenFolderInExplorer opens the specified folder in Windows Explorer.
+// This is used to show the user where bug report files are saved.
+//
+// Parameters:
+//   - folderPath: The path to the folder to open
+//
+// Returns:
+//   - error: Error if launching explorer fails
+func (a *App) OpenFolderInExplorer(folderPath string) error {
+	cmd := exec.Command("explorer", folderPath)
+	return cmd.Start()
+}