Feat/snapshot metrics

internal/ui/keys.go

@@ -0,0 +1,157 @@
+// Copyright 2026 Erst Users
+// SPDX-License-Identifier: Apache-2.0
+
+package ui
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+// Key represents a normalised keyboard event.
+type Key int
+
+const (
+	KeyUnknown Key = iota
+	KeyTab
+	KeyUp
+	KeyDown
+	KeyLeft
+	KeyRight
+	KeyEnter
+	KeyQuit
+	KeySlash
+	KeyEscape
+	KeyDiff
+)
+
+func (k Key) String() string {
+	switch k {
+	case KeyTab:
+		return "Tab"
+	case KeyUp:
+		return "↑/k"
+	case KeyDown:
+		return "↓/j"
+	case KeyLeft:
+		return "←/h"
+	case KeyRight:
+		return "→/l"
+	case KeyEnter:
+		return "Enter"
+	case KeyQuit:
+		return "q"
+	case KeySlash:
+		return "/"
+	case KeyEscape:
+		return "Esc"
+	default:
+		return "?"
+	}
+}
+
+func KeyHelp() string {
+	return "Tab:switch-pane  ↑↓:navigate  Enter:expand  q:quit  /:search"
+}
+
+type KeyReader struct {
+	r *bufio.Reader
+}
+
+func NewKeyReader() *KeyReader {
+	return &KeyReader{r: bufio.NewReader(os.Stdin)}
+}
+
+func (kr *KeyReader) Read() (Key, error) {
+	b, err := kr.r.ReadByte()
+	if err != nil {
+		return KeyUnknown, err
+	}
+
+	switch b {
+	case '\t':
+		return KeyTab, nil
+	case '\r', '\n':
+		return KeyEnter, nil
+	case 'q', 'Q':
+		return KeyQuit, nil
+	case 'd', 'D':
+		return KeyDiff, nil
+	case 'k':
+		return KeyUp, nil
+	case 'j':
+		return KeyDown, nil
+	case 'h':
+		return KeyLeft, nil
+	case 'l':
+		return KeyRight, nil
+	case '/':
+		return KeySlash, nil
+	case 0x1b:
+		return kr.readEscape()
+	case 0x03:
+		return KeyQuit, nil
+	}
+	return KeyUnknown, nil
+}
+
+func (kr *KeyReader) readEscape() (Key, error) {
+	next, err := kr.r.ReadByte()
+	if err != nil {
+		return KeyEscape, nil
+	}
+	if next != '[' {
+		return KeyEscape, nil
+	}
+
+	var seq []byte
+	for {
+		c, err := kr.r.ReadByte()
+		if err != nil {
+			break
+		}
+		seq = append(seq, c)
+		if c >= 0x40 && c <= 0x7E {
+			break
+		}
+	}
+
+	if len(seq) == 0 {
+		return KeyUnknown, nil
+	}
+
+	switch seq[len(seq)-1] {
+	case 'A': // ESC[A
+		return KeyUp, nil
+	case 'B': // ESC[B
+		return KeyDown, nil
+	case 'C': // ESC[C
+		return KeyRight, nil
+	case 'D': // ESC[D
+		return KeyLeft, nil
+	}
+
+	return KeyUnknown, nil
+}
+
+// TermSize returns the current terminal dimensions. It reads $COLUMNS and
+// $LINES first, falling back to 80×24 when neither is set. The split-screen
+// layout calls this on every resize signal to reflow the panes.
+func TermSize() (width, height int) {
+	width = readEnvInt("COLUMNS", 80)
+	height = readEnvInt("LINES", 24)
+	return width, height
+}
+
+func readEnvInt(name string, fallback int) int {
+	val := os.Getenv(name)
+	if val == "" {
+		return fallback
+	}
+	var n int
+	if _, err := fmt.Sscanf(val, "%d", &n); err == nil && n > 0 {
+		return n
+	}
+	return fallback
+}