2 files changed, 128 insertions, 6 deletions

diff --git a/go/cmd/gitlab-shell/command/command.go b/go/cmd/gitlab-shell/command/command.go
new file mode 100644
index 0000000..c35a685
--- /dev/null
+++ b/go/cmd/gitlab-shell/command/command.go
@@ -0,0 +1,92 @@
+package command
+
+import (
+	"os"
+	"regexp"
+	"strconv"
+)
+
+type CommandType string
+
+const (
+	Discover CommandType = "discover"
+)
+
+type Command struct {
+	GitlabUsername string
+	GitlabKeyId    int
+	SshConnection  bool
+	Command        string
+	Type           CommandType
+}
+
+func New(arguments []string) (*Command, error) {
+	_, sshConnection := os.LookupEnv("SSH_CONNECTION")
+
+	command := &Command{SshConnection: sshConnection}
+
+	if _, err := parseWho(arguments, command); err != nil {
+		return nil, err
+	}
+
+	originalCommand, _ := os.LookupEnv("SSH_ORIGINAL_COMMAND")
+	parseCommand(originalCommand, command)
+
+	return command, nil
+}
+
+func parseWho(arguments []string, command *Command) (*Command, error) {
+	var err error = nil
+
+	for _, argument := range arguments {
+		keyId, err := tryParseKeyId(argument)
+		if keyId > 0 && err != nil {
+			command.GitlabKeyId = keyId
+			break
+		}
+
+		username, err := tryParseUsername(argument)
+		if username != "" && err != nil {
+			command.GitlabUsername = username
+			break
+		}
+	}
+
+	return command, err
+}
+
+func tryParseKeyId(argument string) (int, error) {
+	whoKeyRegex, err := regexp.Compile(`\bkey-(?P<keyid>\d+)\b`)
+	if err != nil {
+		return 0, err
+	}
+
+	keyMatch := whoKeyRegex.FindString(argument)
+	if keyMatch != "" {
+		gitlabKeyId, err := strconv.Atoi(keyMatch)
+
+		return gitlabKeyId, err
+	}
+
+	return 0, nil
+}
+
+func tryParseUsername(argument string) (string, error) {
+	whoUsernameRegex, err := regexp.Compile(`\busername-(?P<username>\S+)\b`)
+	if err != nil {
+		return "", err
+	}
+
+	usernameMatch := whoUsernameRegex.FindString(argument)
+	return usernameMatch, nil
+}
+
+func parseCommand(commandString string, command *Command) *Command {
+	command.Command = commandString
+
+	if commandString == "" {
+		command.Type = Discover
+	}
+
+	return nil
+}
diff --git a/go/cmd/gitlab-shell/main.go b/go/cmd/gitlab-shell/main.go
index ae54151..331e93d 100644
--- a/go/cmd/gitlab-shell/main.go
+++ b/go/cmd/gitlab-shell/main.go
@@ -6,22 +6,36 @@ import (
 	"path/filepath"
 	"syscall"
 
+	"gitlab.com/gitlab-org/gitlab-shell/go/cmd/gitlab-shell/command"
 	"gitlab.com/gitlab-org/gitlab-shell/go/internal/config"
 )
 
 var (
-	binDir  string
-	rootDir string
+	binDir   string
+	rootDir  string
+	features map[command.CommandType]bool
 )
 
 func init() {
 	binDir = filepath.Dir(os.Args[0])
 	rootDir = filepath.Dir(binDir)
+	features = map[command.CommandType]bool{}
 }
 
-func migrate(*config.Config) (int, bool) {
-	// TODO: Dispatch appropriate requests to Go handlers and return
-	// <exitstatus, true> depending on how they fare
+func migrate(config *config.Config) (int, bool) {
+	if !config.Migration.Enabled {
+		return 0, false
+	}
+	command, err := command.New(os.Args)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to build command: %v\n", err)
+		return 0, false
+	}
+
+	if featureEnabled(config, command.Type) {
+
+	}
+
 	return 0, false
 }
 
@@ -42,7 +56,7 @@ func main() {
 	// warning as this isn't something we can sustain indefinitely
 	config, err := config.NewFromDir(rootDir)
 	if err != nil {
-		fmt.Fprintln(os.Stderr, "Failed to read config, falling back to gitlab-shell-ruby")
+		fmt.Fprintf(os.Stderr, "Failed to read config, falling back to gitlab-shell-ruby: %v", err)
 		execRuby()
 	}
 
@@ -54,3 +68,19 @@ func main() {
 	// Since a migration has not handled the command, fall back to Ruby to do so
 	execRuby()
 }
+
+func featureEnabled(config *config.Config, commandType command.CommandType) bool {
+	if features[commandType] {
+		return true
+	}
+
+	fmt.Fprintf(os.Stderr, "Config: %v", config.Migration)
+
+	for _, featureName := range config.Migration.Features {
+		fmt.Fprintf(os.Stderr, "Setting feature: %v to %v", featureName, command.CommandType(featureName))
+
+		features[command.CommandType(featureName)] = true
+	}
+
+	return features[commandType]
+}