Allow customizing companion commands

cmd/companion/commands.go

@@ -0,0 +1,96 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os/exec"
+	"runtime"
+	"strings"
+)
+
+// commandDefaults holds the per-OS open-command templates used when the user
+// hasn't overridden them in the config.
+type commandDefaults struct {
+	OpenFile   string
+	OpenFolder string
+}
+
+func defaultCommands() commandDefaults {
+	if runtime.GOOS == "windows" {
+		return commandDefaults{
+			OpenFile:   `cmd /c start "" "{path}"`,
+			OpenFolder: `explorer.exe "{path}"`,
+		}
+	}
+	return commandDefaults{
+		OpenFile:   `xdg-open "{path}"`,
+		OpenFolder: `xdg-open "{path}"`,
+	}
+}
+
+// resolveOpenCommand returns the user-configured command if non-blank, else
+// the platform default.
+func resolveOpenCommand(configured, fallback string) string {
+	if strings.TrimSpace(configured) != "" {
+		return configured
+	}
+	return fallback
+}
+
+// runOpenCommand tokenizes template, substitutes {path} with the resolved
+// path (appending it if the placeholder is missing), and starts the command.
+func runOpenCommand(template, path string) error {
+	tokens, err := tokenizeCommand(template)
+	if err != nil {
+		return fmt.Errorf("parse command: %w", err)
+	}
+	if len(tokens) == 0 {
+		return errors.New("command is empty")
+	}
+	sawPath := false
+	for i, t := range tokens {
+		if strings.Contains(t, "{path}") {
+			tokens[i] = strings.ReplaceAll(t, "{path}", path)
+			sawPath = true
+		}
+	}
+	if !sawPath {
+		tokens = append(tokens, path)
+	}
+	return exec.Command(tokens[0], tokens[1:]...).Start()
+}
+
+// tokenizeCommand splits a command-line string into argv tokens, honouring
+// double-quoted segments. An empty pair "" yields an empty argument — needed
+// for Windows `cmd /c start "" file`, where the empty quotes are the title.
+func tokenizeCommand(s string) ([]string, error) {
+	var tokens []string
+	var cur strings.Builder
+	inQuote := false
+	inToken := false
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if c == '"' {
+			inQuote = !inQuote
+			inToken = true
+			continue
+		}
+		if !inQuote && (c == ' ' || c == '\t') {
+			if inToken {
+				tokens = append(tokens, cur.String())
+				cur.Reset()
+				inToken = false
+			}
+			continue
+		}
+		cur.WriteByte(c)
+		inToken = true
+	}
+	if inQuote {
+		return nil, errors.New("unclosed quote")
+	}
+	if inToken {
+		tokens = append(tokens, cur.String())
+	}
+	return tokens, nil
+}