/**
 * OpenTUI React bindings for the Zesdex TUI.
 *
 * Renders `AppStateRest` as a polished OpenTUI layout and routes keyboard
 * input through the existing `handleKey` → `applyAction` pipeline.
 *
 * Layout (column flex over the full terminal):
 *   1. Header bar    — logo · model · session · live turn spinner
 *   2. Transcript    — role-coloured chat scrollbox (markdown-lite, flex-grow)
 *   3. Activity bar  — collapsed breadcrumb of the running turn's tools/agents
 *   4. Input row     — `❯` prompt + buffer + cursor
 *   5. Status bar    — turn state · token usage · uptime · toast · hints
 *
 * The logic layer (`state.ts`, `action.ts`, `command.ts`, `controller.ts`)
 * stays logic-pure and unit-tested; this file only reads it for display.
 */
import { useEffect, useState } from "react";
import { createCliRenderer } from "@opentui/core";
import {
  createRoot,
  useKeyboard,
  useTerminalDimensions as useTerminalDimensionsHook,
} from "@opentui/react";
import type { KeyEvent as OpenTuiKey, CliRenderer } from "@opentui/core";
import type { ReactNode } from "react";

import type { AppStateRest, ChatMessageDisplay } from "./state.ts";
import { pushTranscript, makeChatMessage, appendToLastTranscript } from "./state.ts";
import { Roles } from "@zesdex/domain";
import { handleKey, KeyCode } from "./controller.ts";
import type { KeyEvent as ZelKeyEvent } from "./controller.ts";
import { applyAction } from "./action.ts";
import type { Action } from "./action.ts";

/** Minimal key-shape accepted by toControllerKey (avoids depending on OpenTUI internals). */
export interface MinimalKey {
  name?: string;
  ctrl?: boolean;
  meta?: boolean;
  option?: boolean;
  shift?: boolean;
  eventType?: string;
}

/** Map an OpenTUI KeyEvent to the controller's KeyEvent shape. */
export function toControllerKey(key: MinimalKey): ZelKeyEvent {
  const name = (key.name ?? "").toLowerCase();
  const ctrl = key.ctrl ?? false;
  const alt = key.meta ?? key.option ?? false;
  const shift = key.shift ?? false;

  switch (name) {
    case "return":
    case "enter":
      return { code: KeyCode.Enter, ctrl, alt };
    case "backspace":
      return { code: KeyCode.Backspace, ctrl, alt };
    case "delete":
    case "del":
      return { code: KeyCode.Delete, ctrl, alt };
    case "up":
      return { code: KeyCode.Up, ctrl, alt };
    case "down":
      return { code: KeyCode.Down, ctrl, alt };
    case "left":
      return { code: KeyCode.Left, ctrl, alt };
    case "right":
      return { code: KeyCode.Right, ctrl, alt };
    case "pageup":
    case "pgup":
      return { code: KeyCode.PageUp, ctrl, alt };
    case "pagedown":
    case "pgdn":
      return { code: KeyCode.PageDown, ctrl, alt };
    case "home":
      return { code: KeyCode.Home, ctrl, alt };
    case "end":
      return { code: KeyCode.End, ctrl, alt };
    case "escape":
    case "esc":
      return { code: KeyCode.Esc, ctrl, alt };
    case "tab":
      return { code: KeyCode.Tab, ctrl, alt };
    case "space":
      return { code: KeyCode.Char, value: " ", ctrl, alt, shift };
    default:
      // Printable character (name is the char itself).
      return { code: KeyCode.Char, value: name, ctrl, alt, shift };
  }
}

/* ── Palette ──────────────────────────────────────────────────────── */

/** Zesdex brand colours — a calm, readable "deep ocean" scheme. */
const C = {
  bg: "#0d1117", // deep off-navy transcript ground
  surface: "#161b22", // panel / secondary background
  border: "#2a3340", // dim hairline separators
  fg: "#c9d1d9", // primary foreground
  dim: "#6e7681", // muted text
  cyan: "#58a6ff", // user / accents
  green: "#3fb950", // assistant
  yellow: "#d29922", // system
  magenta: "#bc8cff", // agent / tools
  red: "#f85149", // errors
  headerA: "#0d47a1", // header gradient start (deep blue)
  headerB: "#1f3a5f", // header gradient end
  accent: "#58a6ff", // prompt / highlight
} as const;

/** Short uppercase role tag shown before each message line. */
const roleTag: Record<string, string> = {
  [Roles.User]: "YOU",
  [Roles.Assistant]: "AI",
  [Roles.System]: "SYS",
  [Roles.Tool]: "TOOL",
};

/** Distinct colour per role — used for badges + body tint. */
const roleColor: Record<string, string> = {
  [Roles.User]: C.cyan,
  [Roles.Assistant]: C.green,
  [Roles.System]: C.yellow,
  [Roles.Tool]: C.magenta,
};

/** Column-align a pair of header cells across the full width. */
function spreadCenter(left: string, right: string, width: number): string {
  const gap = Math.max(1, width - left.length - right.length);
  return left + " ".repeat(gap) + right;
}

/** Pad a string to at least `n` chars, clipping if longer. */
function pad(s: string, n: number): string {
  return s.length >= n ? s : s + " ".repeat(n - s.length);
}

/* ── Spinner ──────────────────────────────────────────────────────── */

const SPINNER_FRAMES = ["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"];

/** Pick a spinner glyph that animates with the tick counter. */
function spinner(state: AppStateRest): string {
  const frame = Math.floor(state.misc.tickCount / 2) % SPINNER_FRAMES.length;
  return SPINNER_FRAMES[frame] ?? "⠋";
}

/* ── Markdown-lite rendering ──────────────────────────────────────── */

/** One styled run of text within a wrapped line. */
interface Run {
  text: string;
  fg?: string;
  bold?: boolean;
}

/**
 * Parse a modest Markdown subset into styled runs, then word-wrap them to a
 * fixed width with a left indent. Keeps layout fully under our control (vs the
 * self-drawing `<markdown>` node) so streaming + indent stay stable.
 *
 * Supported: **bold**, `inline code`, #headers, - bullets, > quotes, tables
 * are untouched (rare in agent output). Code fences are rendered as
 * single-colour blocks.
 */
function renderMarkdown(text: string, indent: number, width: number): Run[][] {
  const rows: Run[][] = [];
  const bodyWidth = Math.max(10, width - indent);
  const wrap = new Wrap(bodyWidth);

  for (const raw of stripFences(text).split("\n")) {
    const line = raw.replace(/\s+$/, "");
    if (line.trim().length === 0) {
      wrap.break();
      continue;
    }
    if (/^#{1,6}\s+/.test(line)) {
      const seg: Run = { text: line.replace(/^#{1,6}\s+/, "").trim(), bold: true, fg: C.cyan };
      wrap.add([seg]);
      continue;
    }
    if (/^[-*]\s+/.test(line)) {
      // Bullet: prefix glyph, then inline-parse the body so **bold**/`code`
      // inside list items render too.
      wrap.add([{ text: "• ", fg: C.fg }, ...inlineRuns(line.replace(/^[-*]\s+/, ""))]);
      continue;
    }
    if (/^>\s?/.test(line)) {
      wrap.add([{ text: "▍ ", fg: C.dim }, ...inlineRuns(line.replace(/^>\s?/, ""))]);
      continue;
    }
    const runs = inlineRuns(line);
    wrap.add(runs);
  }
  // Flatten wrapped rows into the output.
  for (const row of wrap.rows()) {
    rows.push(row);
  }
  return rows;
}

/** Render plain text (user / system / tool bodies) with wrapping + indent. */
function renderPlain(text: string, indent: number, width: number): Run[][] {
  const bodyWidth = Math.max(10, width - indent);
  const wrap = new Wrap(bodyWidth);
  for (const raw of text.split("\n")) {
    wrap.add([{ text: raw.replace(/\s+$/, "") }]);
  }
  return wrap.rows();
}

/** A line-oriented wrapper that accumulates runs and breaks on width. */
class Wrap {
  private out: Run[][] = [];
  private cur: Run[] = [];
  private curLen = 0;
  constructor(private width: number) {}
  add(runs: Run[]): void {
    for (const r of runs) this.pushRun(r);
    this.break();
  }
  private pushRun(r: Run): void {
    if (this.curLen + r.text.length > this.width && this.cur.length > 0) {
      this.break();
    }
    if (r.text.length === 0) return;
    this.cur.push(r);
    this.curLen += r.text.length;
  }
  break(): void {
    if (this.cur.length > 0) {
      this.out.push(this.cur);
      this.cur = [];
      this.curLen = 0;
    }
  }
  rows(): Run[][] {
    this.break();
    return this.out;
  }
}

/** Tokenise a line into bold / inline-code / plain runs. */
function inlineRuns(line: string): Run[] {
  const runs: Run[] = [];
  const re = /(\*\*[^*]+\*\*|`[^`]+`)/g;
  let last = 0;
  let m: RegExpExecArray | null;
  while ((m = re.exec(line)) !== null) {
    if (m.index > last) runs.push({ text: line.slice(last, m.index) });
    const tok = m[0];
    if (tok.startsWith("**")) {
      runs.push({ text: tok.slice(2, -2), bold: true, fg: C.fg });
    } else {
      runs.push({ text: tok.slice(1, -1), fg: C.magenta });
    }
    last = m.index + tok.length;
  }
  if (last < line.length) runs.push({ text: line.slice(last) });
  return runs.length ? runs : [{ text: line }];
}

/** Neutralise fenced code blocks so inline parsing stays clean (kept as plain). */
function stripFences(text: string): string {
  return text.replace(/```[a-zA-Z0-9]*\n?/g, "");
}

/* ── Transcript rendering ─────────────────────────────────────────── */

/** One chat message rendered in the transcript. */
function TranscriptMessage(props: {
  msg: ChatMessageDisplay;
  width: number;
}): ReactNode {
  const { msg, width } = props;
  const color = roleColor[msg.role] ?? C.fg;
  const tag = roleTag[msg.role] ?? msg.role?.toUpperCase() ?? "?";
  const isAssistant = msg.role === Roles.Assistant;
  // Assistant messages legitimately have no body while a tool call is being
  // made (or mid-stream) — don't fill that with a misleading placeholder.
  const content =
    isAssistant && !msg.content.trim() ? "" : msg.content || "(empty)";

  const rows: Run[][] =
    msg.role === Roles.Assistant && content.length > 0
      ? renderMarkdown(content, 5, width)
      : renderPlain(content, 5, width);

  return (
    <box flexDirection="column" width="100%">
      {/* Role badge header line */}
      <text fg={color}>
        <b>{`  ${pad(`[${tag}]`, 6)}`}</b>
      </text>
      {/* Body — each wrapped line is a <text> whose styled runs are <span>/<b> */}
      {rows.map((row, i) => (
        <text key={i} fg={C.fg}>
          {row.map((r, j) => {
            const text = r.text;
            if (r.bold) {
              return (
                <b key={j} fg={r.fg ?? color}>
                  {text}
                </b>
              );
            }
            return (
              <span key={j} fg={r.fg ?? color}>
                {text}
              </span>
            );
          })}
        </text>
      ))}
      {/* Live reasoning (dimmed, kept to one line) */}
      {msg.reasoning.length > 0 && (
        <text fg={C.dim}>{`    ⋯ ${oneLine(msg.reasoning)}`}</text>
      )}
      {/* Thin separator between messages */}
      <text fg={C.border}>{`  ${"─".repeat(Math.max(0, Math.min(60, width - 4)))}`}</text>
    </box>
  );
}

const oneLine = (s: string): string =>
  s.replace(/\s+$/g, "").replace(/\n+/g, "\n").trim();

/**
 * Root OpenTUI component for the Zesdex TUI.
 * @param state       The mutable AppStateRest (mutated by applyAction).
 * @param onQuit      Called when the app should exit (Ctrl+C confirmed).
 */
export function ZesdexApp(props: { state: AppStateRest; onQuit: () => void }): ReactNode {
  const { state, onQuit } = props;
  const [, setTick] = useState(0);

  useKeyboard((key: OpenTuiKey) => {
    if (key.eventType === "release") return;
    const zk = toControllerKey(key);
    let consumedByModal = false;
    try {
      const actions: Action[] = handleKey(zk, state);
      for (const act of actions) {
        if (act.tag === "QuitConfirm") {
          state.quit = true;
          onQuit();
          consumedByModal = true;
          continue;
        }
        // A slash-command that opens a modal (overlay / menu) "consumes" the
        // input line — clear the buffer so `/model` doesn't linger. Autocomplete
        // selection and normal submit must NOT be cleared (they own the buffer).
        const opensModal =
          act.tag === "OpenOverlay" ||
          act.tag === "OpenMenuById" ||
          act.tag === "OpenEditor" ||
          act.tag === "ShowDiff" ||
          act.tag === "ModelList";
        if (opensModal && !state.input.autocompleteVisible) consumedByModal = true;
        applyAction(state, act);
      }
    } finally {
      // Clear the input line only when a modal command consumed it this press.
      if (consumedByModal) {
        state.input.clear();
      }
      // Force React to re-read the mutated `state` on the next frame.
      setTick((t: number) => t + 1);
    }
  });

  const dimensions = useTerminalDimensionsHook();
  const width = dimensions.width ?? 80;
  const height = dimensions.height ?? 24;
  const running = state.turnInFlightFlag.value;

  // Turn driver: when a turn is submitted, run it against the real agent and
  // stream every event into the transcript as it happens.
  useEffect(() => {
    let turnRunning = false;
    const poll = async () => {
      if (turnRunning) return;
      const text = state.pendingSubmit;
      if (text == null) return;
      if (state.turnRunner == null) {
        appendToLastTranscript(
          state,
          "\n(no agent runtime — run via `zesdex` on the CLI / ensure settings)",
          false,
        );
        state.pendingSubmit = null;
        return;
      }
      turnRunning = true;
      const captured = state.pendingSubmit;
      state.pendingSubmit = null;
      state.turnInFlightFlag.value = true;
      const abort = new AbortController();
      state.turnAbort = abort;

      // Open an assistant message we stream into.
      pushTranscript(state, makeChatMessage(Roles.Assistant, ""));

      try {
        await state.turnRunner(captured ?? text, () => {
          // The turn runner already streams into state via handleEvent;
          // re-render as new tokens arrive.
          setTick((t: number) => t + 1);
        });
      } finally {
        state.turnInFlightFlag.value = false;
        state.turnAbort = null;
        state.abortFlag.value = false;
        // Keep the last activity breadcrumb visible briefly, then clear it on
        // the next turn start (see the start of poll()).
        setTimeout(() => {
          state.misc.activity = [];
          turnRunning = false;
          setTick((x: number) => x + 1);
        }, 0);
      }
    };
    const timer = setInterval(() => poll(), 100);
    return () => clearInterval(timer);
  }, [state, setTick]);

  // Tick the spinner + uptime while idle too (so ● running animates and the
  // uptime clock in the status bar advances even between key presses).
  useEffect(() => {
    if (!running) return;
    const id = setInterval(() => {
      state.misc.tickCount += 1;
      state.dirty = true;
      setTick((t: number) => t + 1);
    }, 120);
    return () => clearInterval(id);
  }, [running, state, setTick]);

  const overlayActive = state.misc.overlay !== "none";
  const menuActive = state.misc.menuStack.length > 0;

  // Modal overlays and interactive menus take the full body (below the header,
  // above the status bar), replacing the transcript + input.
  const body = menuActive ? (
    <MenuView state={state} height={height} />
  ) : overlayActive ? (
    <OverlayView state={state} width={width} height={height} />
  ) : (
    <box flexDirection="column" flexGrow={1} flexShrink={1} minHeight={0}>
      <scrollbox
        flexGrow={1}
        flexShrink={1}
        flexBasis={0}
        minHeight={0}
        style={{ backgroundColor: C.bg }}
        stickyScroll
        stickyStart="bottom"
      >
        <TranscriptView state={state} width={width} />
      </scrollbox>
      {/* Dropdown (compact, sized to content) + activity + input, in order. The
          input row is flexShrink:0 so the transcript scrollbox absorbs overflow
          and the text area is never hidden. */}
      {state.input.autocompleteVisible && <AutocompleteView state={state} />}
      <ActivityBar state={state} running={running} />
      <InputView state={state} width={width} />
    </box>
  );

  return (
    <box flexDirection="column" width={width} height={height}>
      {/* Header */}
      <HeaderView state={state} running={running} width={width} />
      {body}
      {/* Status bar */}
      <StatusBar state={state} running={running} width={width} />
    </box>
  );
}

/* ── Header ───────────────────────────────────────────────────────── */

function HeaderView(props: {
  state: AppStateRest;
  running: boolean;
  width: number;
}): ReactNode {
  const { state, running, width } = props;
  const model = String(state.settings.model ?? state.settings.provider ?? "?");
  const sessionId = String(state.settings.sessionId ?? state.sessionId ?? "");
  const shortId = sessionId.length > 12 ? sessionId.slice(0, 11) : sessionId;
  const glyph = running ? spinner(state) : "◆";
  const left = ` ${glyph} zesdex  ·  ${model} `;
  const right = sessionId ? ` session:${shortId} ` : "  ";
  const header = spreadCenter(left, right, width);
  const bg = running ? C.headerA : C.headerB;
  return (
    <box backgroundColor={bg}>
      <text fg={running ? C.green : "white"}>
        <b>{header}</b>
      </text>
    </box>
  );
}

/* ── Transcript ───────────────────────────────────────────────────── */

function TranscriptView(props: { state: AppStateRest; width: number }): ReactNode {
  const { state, width } = props;
  const messages = state.transcriptCache.messages;
  const scrollFromEnd = messages.length - state.scroll.offset;
  const visible = messages.slice(
    Math.max(0, scrollFromEnd - 40),
    scrollFromEnd,
  );

  if (messages.length === 0) {
    return (
      <text fg={C.dim}>
        {`\n  ─  no messages yet. Type a message below  (or /help)  ─`}
      </text>
    );
  }
  return (
    <box flexDirection="column">
      {visible.map((m, i) => (
        <TranscriptMessage key={`${m.timestamp}-${i}`} msg={m} width={width} />
      ))}
    </box>
  );
}

/* ── Activity bar (running turn) ──────────────────────────────────── */

function ActivityBar(props: { state: AppStateRest; running: boolean }): ReactNode {
  const { state, running } = props;
  const activity = state.misc.activity;
  if (!running || activity.length === 0) return null;
  const line = ` ${spinner(state)} ${activity.map((a) => label(a)).join("  ·  ")} `;
  return (
    <box flexDirection="column" width="100%" style={{ backgroundColor: C.surface }}>
      <text fg={C.magenta}>
        {line}
      </text>
    </box>
  );

  function label(a: { label: string; kind: string; detail?: string; count?: number }): string {
    const sym = a.kind === "error" ? "✕" : a.kind === "agent" ? "⧉" : "⚙";
    const n = a.count && a.count > 1 ? `×${a.count}` : "";
    return `${sym} ${a.label}${n}`;
  }
}

/* ── Input row ────────────────────────────────────────────────────── */

function InputView(props: { state: AppStateRest; width: number }): ReactNode {
  const { state, width } = props;
  const buffer = state.input.buffer;
  const cursor = state.input.cursor;
  const shown = buffer.slice(
    Math.max(0, cursor - Math.max(10, width - 14)),
    cursor + 40,
  );
  const hasContent = buffer.length > 0;
  return (
    <box flexDirection="column" width="100%" flexShrink={0}>
      <text fg={C.border}>{`─`.repeat(Math.max(0, width))}</text>
      <box flexDirection="row" width="100%">
        <text fg={C.accent}>
          <b>{`  ❯ `}</b>
        </text>
        {hasContent ? (
          <text fg={C.fg}>{shown}</text>
        ) : (
          <text fg={C.dim}>Ask Zesdex to help…</text>
        )}
        <text fg={C.accent}>{` ▏`}</text>
      </box>
    </box>
  );
}

/* ── Autocomplete ─────────────────────────────────────────────────── */

function AutocompleteView(props: { state: AppStateRest }): ReactNode {
  const { state } = props;
  const candidates = state.input.autocompleteCandidates;
  const kind = state.input.autocompleteKind;
  const title = kind === "command" ? "commands" : "files";
  const selected = Math.min(state.input.autocompleteIdx, candidates.length - 1);
  const visible = candidates.slice(0, 10);
  // Render the whole panel as ONE multiline <text> — this fixes the OpenTUI
  // quirk where sibling <text> children overlap. The box is sized to its
  // content (flexShrink 0, explicit height) so it never squashes the input row.
  const lines = [
    ` ${title}`,
    ...visible.map((c, i) => (i === selected ? `▸ ${c}` : `  ${c}`)),
    `  ↑/↓ navigate · Tab accept · Esc close`,
  ];
  const body = lines.join("\n");
  return (
    <box
      width="100%"
      flexDirection="column"
      flexGrow={0}
      flexShrink={0}
      style={{ border: true, borderColor: C.border, backgroundColor: C.surface, padding: 1 }}
    >
      <text fg={kind === "command" ? C.accent : C.magenta} height={lines.length}>
        {body}
      </text>
    </box>
  );
}

/* ── Overlays ─────────────────────────────────────────────────────── */

function OverlayView(props: {
  state: AppStateRest;
  width: number;
  height: number;
}): ReactNode {
  const { state } = props;
  const name = state.misc.overlay;

  switch (name) {
    case "quit_confirm":
      return (
        <ConfirmOverlay
          title="Quit Zesdex?"
          body="  Are you sure you want to quit?\n\n  Any in-flight turn will be aborted."
          hint="y=yes  n=no  Esc=cancel"
        />
      );
    case "clear_confirm":
      return (
        <ConfirmOverlay
          title="Clear transcript?"
          body="  This clears the visible conversation from the transcript view."
          hint="y=yes  n=no  Esc=cancel"
        />
      );
    case "help":
      return <HelpOverlay state={state} />;
    case "diff":
      return <DiffOverlay state={state} />;
    case "model_selector":
      return <ModelSelectorOverlay state={state} />;
    case "editor":
      return <EditorOverlay state={state} />;
    default:
      return <PlaceholderOverlay name={name} state={state} />;
  }
}

function ConfirmOverlay(props: { title: string; body: string; hint: string }): ReactNode {
  const { title, body, hint } = props;
  return (
    <OverlayFrame title={title}>
      <text fg={C.fg}>{body}</text>
      <text fg={C.dim}>{`  ${hint}`}</text>
    </OverlayFrame>
  );
}

function HelpOverlay(props: { state: AppStateRest }): ReactNode {
  const { state } = props;
  return (
    <OverlayFrame title="Keyboard Shortcuts">
      <text fg={C.fg}>{state.helpText}</text>
      <text fg={C.dim}>{"  Esc or /help to close"}</text>
    </OverlayFrame>
  );
}

function DiffOverlay(props: { state: AppStateRest }): ReactNode {
  const { state } = props;
  const lines = state.misc.diffContent.split("\n");
  const start = state.misc.diffScroll;
  const slice = lines.slice(start, start + 18);
  return (
    <OverlayFrame title="Git Diff">
      <scrollbox flexGrow={1} stickyScroll stickyStart="bottom">
        {slice.map((l, i) => {
          const fg = l.startsWith("+")
            ? C.green
            : l.startsWith("-")
              ? C.red
              : l.startsWith("@@")
                ? C.cyan
                : C.dim;
          return (
            <text key={i} fg={fg}>
              {l.length ? l : " "}
            </text>
          );
        })}
      </scrollbox>
      <text fg={C.dim}>
        {`  ↑/↓ / PgUp/PgDn scroll · Esc close  — ${Math.min(start + 1, lines.length)}/${lines.length}`}
      </text>
    </OverlayFrame>
  );
}

function ModelSelectorOverlay(props: { state: AppStateRest }): ReactNode {
  const { state } = props;
  const names = Object.keys(state.appConfig.providers);
  const list = names.length ? names : ["claude", "zen", "router"];
  const idx = Math.min(Math.max(0, state.misc.selectedIndex), list.length - 1);
  const current = String(state.settings.provider ?? "");
  const selected = idx;
  const body = list
    .map((p, i) => {
      const isSel = i === selected;
      const active = p === current;
      const suffix = active ? "  (active)" : "";
      return `${isSel ? "▸ " : "  "}${pad(p, 15)}${suffix}`;
    })
    .join("\n");
  return (
    <OverlayFrame title="Select Model / Provider">
      <text fg={C.fg}>
        {body}
      </text>
      <text fg={C.dim}>{"  ↑/↓ select · Enter apply · Esc close"}</text>
    </OverlayFrame>
  );
}

function EditorOverlay(props: { state: AppStateRest }): ReactNode {
  const { state } = props;
  const ed = state.misc.editor;
  if (!ed) return <OverlayFrame title="Editor"><text fg={C.fg}>No buffer.</text></OverlayFrame>;
  const lines = ed.content.split("\n");
  const start = Math.max(0, ed.cursor - 5);
  const slice = lines.slice(start, start + 12);
  return (
    <OverlayFrame title={`Edit ${ed.path}`}>
      {slice.map((l, i) => (
        <text key={i} fg={C.fg}>
          {`${String(start + i + 1).padStart(3)} | ${l}`}
        </text>
      ))}
      <text fg={C.dim}>
        {"  type to edit · Enter newline · Esc save & close"}
      </text>
    </OverlayFrame>
  );
}

function PlaceholderOverlay(props: { name: string; state: AppStateRest }): ReactNode {
  const { name, state } = props;
  const content =
    name === "todo"
      ? state.misc.todoContent
      : name === "plan"
        ? state.misc.planContent
        : "";
  const summary =
    name === "todo" ? "todo list" :
    name === "plan" ? "plan outline" :
    name === "usage" ? "usage statistics" :
    name === "mcp" ? "MCP server management" :
    name === "settings" ? "settings" :
    name === "bash" ? "bash jobs" :
    name === "rewind" ? "rewind history" :
    name === "learning" ? "learned patterns" :
    "overlay";
  return (
    <OverlayFrame title={`${name} — ${summary}`}>
      {content ? (
        <text fg={C.fg}>{content}</text>
      ) : (
        <text fg={C.dim}>{`  ${summary}: nothing yet.`}</text>
      )}
      <text fg={C.dim}>{"  Esc to close"}</text>
    </OverlayFrame>
  );
}

function OverlayFrame(props: { title: string; children: ReactNode }): ReactNode {
  const { title, children } = props;
  return (
    <box
      width="100%"
      flexDirection="column"
      flexGrow={1}
      flexShrink={0}
      style={{
        border: true,
        borderColor: C.accent,
        padding: 1,
        backgroundColor: C.surface,
      }}
      title={title}
      titleAlignment="center"
    >
      {children}
    </box>
  );
}

/* ── Interactive menu ─────────────────────────────────────────────── */

/** Modal picker for the menu stack — like Claude Code / opencode selectors. */
function MenuView(props: { state: AppStateRest; height: number }): ReactNode {
  const { state, height } = props;
  const stack = state.misc.menuStack;
  const frame = stack[stack.length - 1];
  if (!frame) return null;
  const filter = (frame.filter ?? "").toLowerCase();
  // Rows that match the live filter (empty filter = all rows).
  const rawMatched = frame.items
    .map((it, i) => ({ it, i }))
    .filter((r) => !filter || r.it.toLowerCase().includes(filter));
  // Fit the visible rows to the modal height (top rows take priority so the
  // selected row stays anchored near the top).
  const maxRows = Math.max(4, height - 8);
  const visibleStart = Math.max(0, Math.min(rawMatched.length - maxRows, frame.selected));
  const matched = rawMatched.slice(visibleStart, visibleStart + maxRows);
  const detailOf = frame.details;

  // Breadcrumb: titles from the stack, e.g. "Model › pick a model (zen)".
  const crumb = stack.map((f) => f.title).join(" › ");

  return (
    <OverlayFrame title={crumb}>
      {/* Quick filter bar at the top */}
      <text fg={C.dim}>{filter ? `  filter: ${frame.filter}   ` : "  type to filter…"}</text>
      {matched.map(({ it, i }) => {
        const isSel = i === frame.selected;
        const detail = detailOf?.[i] ?? "";
        return (
          <box key={i} flexDirection="row" width="100%">
            <text fg={isSel ? C.accent : C.fg} flexGrow={1}>
              {isSel ? <b>{`${"▸ "}${it}`}</b> : `  ${it}`}
            </text>
            {detail && (
              <text fg={C.dim} flexShrink={0}>
                {detail}
              </text>
            )}
          </box>
        );
      })}
      {matched.length === 0 && (
        <text fg={C.red}>  no matches — type less or press Backspace.</text>
      )}
      <text fg={C.dim}>
        {`  ${frame.hint ?? ""}`}
      </text>
      {frame.items.length > 10 && (
        <text fg={C.dim}>
          {`  showing ${matched.length}/${frame.items.length} · PgUp/PgDn scroll`}
        </text>
      )}
    </OverlayFrame>
  );
}

/* ── Status bar ───────────────────────────────────────────────────── */

function StatusBar(props: {
  state: AppStateRest;
  running: boolean;
  width: number;
}): ReactNode {
  const { state, running, width } = props;
  const left = running ? "● running" : "● idle";
  const usage = state.lastUsage;
  const usageStr = usage
    ? `in:${usage.tokensIn} · out:${usage.tokensOut}`
    : "in:– · out:–";

  // Uptime since boot.
  const uptime = fmtUptime((Date.now() - state.bootedAt) / 1000);

  // Autocomplete hint for the active input.
  const ac =
    state.input.autocompleteVisible &&
    state.input.autocompleteCandidates[state.input.autocompleteIdx] != null
      ? ` [tab: ${state.input.autocompleteCandidates[state.input.autocompleteIdx]}]`
      : "";

  // Most recent live toast (expires via MiscState).
  const toasts = state.misc.toasts;
  const toast = toasts.length > 0 ? ` (${toasts[toasts.length - 1]?.message})` : "";

  const hints = running ? "Esc abort" : "/help · Ctrl+C quit · ↑ history";

  const statusColor = toast
    ? C.yellow
    : running
      ? C.green
      : C.dim;

  const activity = running ? ` ${spinner(state)}` : "";

  const cell = ` ${left}${activity}   ${usageStr}   ${uptime}${ac}${toast}   ${hints} `;
  return (
    <box backgroundColor={C.surface}>
      <text fg={statusColor}>{trimTo(cell, width)}</text>
    </box>
  );
}

/** Clip a status line to the available width (avoid overflow). */
function trimTo(s: string, width: number): string {
  if (s.length <= width) return s;
  return s.slice(0, Math.max(0, width - 1)) + "…";
}

/** Format seconds as a compact human uptime (e.g. 1m23s). */
function fmtUptime(sec: number): string {
  const s = Math.floor(sec);
  const m = Math.floor(s / 60);
  const h = Math.floor(m / 60);
  if (h > 0) return `${h}h${String(m % 60).padStart(2, "0")}m`;
  if (m > 0) return `${m}m${String(s % 60).padStart(2, "0")}s`;
  return `${s}s`;
}

/** Boot the OpenTUI renderer and mount the Zesdex app. */
export async function bootTui(state: AppStateRest): Promise<void> {
  pushTranscript(state, makeChatMessage(Roles.System, "Zesdex ready. Type a message or /help."));

  const renderer: CliRenderer = await createCliRenderer();
  const root = createRoot(renderer);

  root.render(<ZesdexApp state={state} onQuit={() => renderer.destroy()} />);

  return new Promise<void>((resolve) => {
    const check = setInterval(() => {
      if (state.quit) {
        clearInterval(check);
        try {
          root.unmount();
        } catch {
          /* already unmounted */
        }
        renderer.destroy();
        resolve();
      }
    }, 60);
  });
}