task 400: add server session command scaffolding

1 files changed, 124 insertions, 0 deletions

diff --git a/internal/session/spec.go b/internal/session/spec.go
new file mode 100644
index 0000000..2d1b77d
--- /dev/null
+++ b/internal/session/spec.go
@@ -0,0 +1,124 @@
+package session
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/mimecast/dtail/internal/config"
+	"github.com/mimecast/dtail/internal/omode"
+	"github.com/mimecast/dtail/internal/regex"
+)
+
+// Spec captures the mutable, per-connection workload a DTail client wants to run.
+type Spec struct {
+	Mode        omode.Mode `json:"mode"`
+	Files       []string   `json:"files"`
+	Options     string     `json:"options,omitempty"`
+	Query       string     `json:"query,omitempty"`
+	Regex       string     `json:"regex,omitempty"`
+	RegexInvert bool       `json:"regex_invert,omitempty"`
+	Timeout     int        `json:"timeout,omitempty"`
+}
+
+// NewSpec returns a session specification from client args.
+func NewSpec(args config.Args) Spec {
+	return Spec{
+		Mode:        args.Mode,
+		Files:       splitFiles(args.What),
+		Options:     args.SerializeOptions(),
+		Query:       strings.TrimSpace(args.QueryStr),
+		Regex:       args.RegexStr,
+		RegexInvert: args.RegexInvert,
+		Timeout:     args.Timeout,
+	}
+}
+
+// Commands returns the legacy command stream for this session specification.
+func (s Spec) Commands() ([]string, error) {
+	switch {
+	case s.Mode == omode.HealthClient:
+		return []string{"health"}, nil
+	case s.Query != "":
+		return s.queryCommands()
+	default:
+		return s.readCommands(s.Mode.String())
+	}
+}
+
+func (s Spec) queryCommands() ([]string, error) {
+	if s.Mode != omode.MapClient && s.Mode != omode.TailClient {
+		return nil, fmt.Errorf("session spec query mode requires map or tail mode, got %s", s.Mode)
+	}
+
+	regexValue, err := s.serializedRegex()
+	if err != nil {
+		return nil, err
+	}
+
+	commands := []string{fmt.Sprintf("map:%s %s", s.Options, s.Query)}
+	readMode := "cat"
+	if s.Mode == omode.TailClient {
+		readMode = "tail"
+	}
+
+	for _, file := range s.Files {
+		if s.Timeout > 0 {
+			commands = append(commands, fmt.Sprintf("timeout %d %s %s %s", s.Timeout, readMode, file, regexValue))
+			continue
+		}
+		commands = append(commands, fmt.Sprintf("%s:%s %s %s", readMode, s.Options, file, regexValue))
+	}
+
+	return commands, nil
+}
+
+func (s Spec) readCommands(mode string) ([]string, error) {
+	switch s.Mode {
+	case omode.TailClient, omode.CatClient, omode.GrepClient:
+	default:
+		return nil, fmt.Errorf("unsupported session mode %s", s.Mode)
+	}
+
+	regexValue, err := s.serializedRegex()
+	if err != nil {
+		return nil, err
+	}
+
+	var commands []string
+	for _, file := range s.Files {
+		commands = append(commands, fmt.Sprintf("%s:%s %s %s", mode, s.Options, file, regexValue))
+	}
+
+	return commands, nil
+}
+
+func (s Spec) serializedRegex() (string, error) {
+	flag := regex.Default
+	if s.RegexInvert {
+		flag = regex.Invert
+	}
+
+	re, err := regex.New(s.Regex, flag)
+	if err != nil {
+		return "", err
+	}
+
+	return re.Serialize()
+}
+
+func splitFiles(what string) []string {
+	if strings.TrimSpace(what) == "" {
+		return nil
+	}
+
+	rawFiles := strings.Split(what, ",")
+	files := make([]string, 0, len(rawFiles))
+	for _, file := range rawFiles {
+		file = strings.TrimSpace(file)
+		if file == "" {
+			continue
+		}
+		files = append(files, file)
+	}
+	return files
+}