refactor terminal page controls and session helpers

ui/src/pages/terminal/sessionUtils.ts

@@ -0,0 +1,113 @@
+import type { Terminal as XTerm } from "@xterm/xterm";
+
+import type { TerminalSession } from "@/api";
+
+export type TerminalConnectionState =
+  | "idle"
+  | "connecting"
+  | "ready"
+  | "disconnected"
+  | "exited";
+
+export type TerminalModifiers = {
+  ctrl: boolean;
+  meta: boolean;
+};
+
+export const NO_TERMINAL_MODIFIERS: TerminalModifiers = {
+  ctrl: false,
+  meta: false,
+};
+
+export function mergeTerminalSession(
+  sessions: TerminalSession[],
+  next: TerminalSession,
+): TerminalSession[] {
+  const existingIndex = sessions.findIndex(
+    (item) => item.terminal_id === next.terminal_id,
+  );
+  if (existingIndex >= 0) {
+    // Attaching updates session state, not identity or tab position. Removing
+    // and re-inserting here made same-second sessions swap places on click.
+    return sessions.map((item, index) =>
+      index === existingIndex ? next : item,
+    );
+  }
+  return orderTerminalSessions([...sessions, next]);
+}
+
+function compareTerminalSessions(
+  left: TerminalSession,
+  right: TerminalSession,
+): number {
+  return (
+    left.created_at_unix - right.created_at_unix ||
+    left.terminal_id.localeCompare(right.terminal_id)
+  );
+}
+
+export function orderTerminalSessions(
+  sessions: TerminalSession[],
+): TerminalSession[] {
+  return [...sessions].sort(compareTerminalSessions);
+}
+
+export function reconcileTerminalSessions(
+  current: TerminalSession[],
+  listed: TerminalSession[],
+): TerminalSession[] {
+  const listedById = new Map(listed.map((item) => [item.terminal_id, item]));
+  const retained = current.flatMap((item) => {
+    const updated = listedById.get(item.terminal_id);
+    if (!updated) return [];
+    listedById.delete(item.terminal_id);
+    return [updated];
+  });
+  return [...retained, ...orderTerminalSessions([...listedById.values()])];
+}
+
+export function restoreCandidates(
+  sessions: TerminalSession[],
+  rememberedId: string | null,
+  selectedAgentId: string,
+): TerminalSession[] {
+  const remembered = sessions.find((item) => item.terminal_id === rememberedId);
+  const available = sessions.filter(
+    (item) => !item.operator_attached && item !== remembered,
+  );
+  available.sort((left, right) => {
+    const leftPreferred = left.agent_id === selectedAgentId ? 1 : 0;
+    const rightPreferred = right.agent_id === selectedAgentId ? 1 : 0;
+    return (
+      rightPreferred - leftPreferred ||
+      right.created_at_unix - left.created_at_unix
+    );
+  });
+  return remembered ? [remembered, ...available] : available;
+}
+
+export function applyTerminalModifiers(
+  data: string,
+  modifiers: TerminalModifiers,
+): string {
+  let modified = data;
+  if (modifiers.ctrl && modified.length === 1) {
+    const code = modified.toUpperCase().charCodeAt(0);
+    if (code >= 64 && code <= 95) {
+      modified = String.fromCharCode(code & 0x1f);
+    }
+  }
+  return modifiers.meta ? `\x1b${modified}` : modified;
+}
+
+export function visibleTerminalText(terminal: XTerm): string {
+  const buffer = terminal.buffer.active;
+  const firstLine = buffer.viewportY;
+  const lastLine = Math.min(buffer.length, firstLine + terminal.rows);
+  const lines: string[] = [];
+  for (let index = firstLine; index < lastLine; index += 1) {
+    lines.push(buffer.getLine(index)?.translateToString(true) ?? "");
+  }
+  while (lines.at(-1) === "") lines.pop();
+  return lines.join("\n");
+}