Add dmr sandbox config and launch command

cmd/dmr/main.go

@@ -2,10 +2,14 @@
 package main
 
 import (
+	"bufio"
 	"context"
 	"fmt"
 	"os"
+	"os/exec"
 	"os/signal"
+	"path/filepath"
+	"strings"
 	"syscall"
 
 	"github.com/docker/cli/cli/command"
@@ -27,6 +31,15 @@
 }
 
 func run() error {
+	if len(os.Args) > 1 {
+		switch os.Args[1] {
+		case "config":
+			return runConfig(os.Args[2:])
+		case "launch":
+			return runLaunch(os.Args[2:])
+		}
+	}
+
 	cli, err := command.NewDockerCli()
 	if err != nil {
 		return fmt.Errorf("unable to initialize CLI: %w", err)
@@ -67,3 +80,124 @@
 		},
 	}
 }
+
+func runConfig(args []string) error {
+	if len(args) != 2 {
+		return fmt.Errorf("usage: dmr config sandbox.tool <tool>")
+	}
+
+	key := args[0]
+	value := args[1]
+
+	if key != "sandbox.tool" {
+		return fmt.Errorf("unsupported config key %q", key)
+	}
+
+	return writeSandboxToolConfig(value)
+}
+
+func runLaunch(args []string) error {
+	if len(args) == 0 {
+		return fmt.Errorf("usage: dmr launch <tool> [args...]")
+	}
+
+	sandboxTool, err := readSandboxToolConfig()
+	if err != nil {
+		return err
+	}
+
+	if sandboxTool == "" {
+		return fmt.Errorf("sandbox.tool is not configured. Run: dmr config sandbox.tool <tool>")
+	}
+
+	cmd := exec.Command(sandboxTool, args...)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	return cmd.Run()
+}
+
+func dmrConfigPath() (string, error) {
+	configDir, err := os.UserConfigDir()
+	if err != nil {
+		return "", fmt.Errorf("unable to determine config directory: %w", err)
+	}
+
+	return filepath.Join(configDir, "dmr", "config.toml"), nil
+}
+
+func writeSandboxToolConfig(tool string) error {
+	path, err := dmrConfigPath()
+	if err != nil {
+		return err
+	}
+
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return fmt.Errorf("unable to create config directory: %w", err)
+	}
+
+	content := fmt.Sprintf("[sandbox]\ntool = %q\n", tool)
+
+	if err := os.WriteFile(path, []byte(content), 0o600); err != nil {
+		return fmt.Errorf("unable to write config: %w", err)
+	}
+	if err := os.Chmod(path, 0o600); err != nil {
+		return fmt.Errorf("unable to secure config permissions: %w", err)
+	}
+
+	return nil
+}
+
+func readSandboxToolConfig() (string, error) {
+	path, err := dmrConfigPath()
+	if err != nil {
+		return "", err
+	}
+
+	file, err := os.Open(path)
+	if os.IsNotExist(err) {
+		return "", nil
+	}
+	if err != nil {
+		return "", fmt.Errorf("unable to read config: %w", err)
+	}
+	defer file.Close()
+
+	inSandboxSection := false
+	scanner := bufio.NewScanner(file)
+
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+
+		if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
+			inSandboxSection = line == "[sandbox]"
+			continue
+		}
+
+		if !inSandboxSection {
+			continue
+		}
+
+		key, value, ok := strings.Cut(line, "=")
+		if !ok {
+			continue
+		}
+
+		if strings.TrimSpace(key) != "tool" {
+			continue
+		}
+
+		return strings.Trim(strings.TrimSpace(value), `"`), nil
+	}
+
+	if err := scanner.Err(); err != nil {
+		return "", fmt.Errorf("unable to parse config: %w", err)
+	}
+
+	return "", nil
+}