/**
 * @file PetSprite.tsx
 * @description The mascot wearing a custom pet (`/api/pets`). A Codex pet is
 * a spritesheet of 192×208 frames, 8 columns wide: 9 rows (v1, 1536×1872),
 * one per animation state (idle, run right, run left, waving, jumping, failed,
 * waiting, running, review), or 11 (v2, 1536×2288), whose rows 9–10 are 16
 * gaze poses. The sprite plays the row of Sagi's mood at Codex's own frame
 * timings; a moment (waving, jumping, failed, review) plays three times and
 * settles into idle, a condition loops. An `action` (dragged left/right,
 * hovered) plays the run-left/run-right or waving row over the mood's, like
 * Codex's own pet; a `moment` (a new session waves, a finish jumps, an error
 * fails, a wait waits, a new subagent reviews — `useSagiBrain`) plays its row
 * over the mood's, under the action; a v2 pet at idle holds the gaze pose `gaze` names. An
 * uploaded image is shown still and bobs with the same `data-mood` CSS as
 * Sagi. Reduced motion holds the row's first frame. A sprite that fails to
 * load (deleted from another browser) calls `onBroken`, so the mascot falls
 * back to Sagi instead of an empty box.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { useEffect, useState } from "react";
import { api } from "../../lib/api";
import type { Mood, PetMoment } from "./brain";

const CELL = { w: 192, h: 208 };
const COLS = 8;
/** `n` frames of `step` ms, the last one `last` ms. */
const frames = (n: number, step: number, last: number) =>
  Array.from({ length: n }, (_, i) => (i === n - 1 ? last : step));
/** Per row, each frame's ms: Codex's own table (codex-rs/tui/src/pets/model.rs).
 *  Idle is the pace the pets are drawn at; Codex plays it 6× slower, which is
 *  how a sleeping pet breathes here. */
const DURATIONS = [
  [280, 110, 110, 140, 140, 320], // idle
  frames(8, 120, 220), // run right
  frames(8, 120, 220), // run left
  frames(4, 140, 280), // waving
  frames(5, 140, 280), // jumping
  frames(8, 140, 240), // failed
  frames(6, 150, 260), // waiting
  frames(6, 120, 220), // running (working)
  frames(6, 150, 280), // review
];
const SLEEP_SLOWDOWN = 6;
/** Rows that play three times and settle into idle; the others loop. */
const MOMENTS = new Set([3, 4, 5, 8]);
/** v2 only: 16 gaze poses, 22.5° apart clockwise from straight up. */
const GAZE_ROW = 9;
/** Which row plays for each mood. */
const ROW: Record<Mood, number> = {
  idle: 0,
  sleeping: 0,
  thinking: 7, // running — an agent is working
  watching: 8, // review
  happy: 4, // jumping
  stuck: 6, // waiting — for the user
  worried: 5, // failed
  disconnected: 5,
};
/** What the user is doing to the pet, which outranks its mood. */
export type PetAction = "run-left" | "run-right" | "wave";
const ACTION_ROW: Record<PetAction, number> = { "run-right": 1, "run-left": 2, wave: 3 };
/** A moment's row: wave, jump, failed, waiting, review. It outranks the mood,
 *  and the user's own action outranks it. */
const MOMENT_ROW: Record<PetMoment, number> = { wave: 3, jump: 4, fail: 5, wait: 6, review: 8 };

export function PetSprite({
  id,
  kind,
  mood,
  action,
  moment,
  gaze,
  size,
  reducedMotion,
  onBroken,
}: {
  id: string;
  kind: "codex" | "image";
  mood: Mood;
  action?: PetAction | null;
  moment?: PetMoment | null;
  /** Gaze pose 0–15 (0 = up, clockwise), or none. Only a v2 sheet has them. */
  gaze?: number | null;
  size: number;
  reducedMotion: boolean;
  onBroken: () => void;
}) {
  const url = api.pets.spriteUrl(id);
  const row = action ? ACTION_ROW[action] : moment ? MOMENT_ROW[moment] : (ROW[mood] ?? 0);
  const sleeping = !action && !moment && mood === "sleeping";
  // The cell on show, tagged with the row it was played for: a cell left over
  // from the previous row (say column 7 of a run) is never drawn on the next.
  const [cell, setCell] = useState({ of: row, row, col: 0 });
  const [rows, setRows] = useState(9);

  useEffect(() => {
    setCell({ of: row, row, col: 0 });
    if (kind !== "codex" || reducedMotion) return;
    const play = (r: number, slow = 1) =>
      (DURATIONS[r] ?? [200]).map((ms, col) => ({ of: row, row: r, col, ms: ms * slow }));
    const own = play(row, sleeping ? SLEEP_SLOWDOWN : 1);
    let list = MOMENTS.has(row) ? [...own, ...own, ...own] : own;
    let i = 0;
    let timer = 0;
    // `i` always indexes `list`: it wraps at its end.
    const tick = () => {
      timer = window.setTimeout(() => {
        if (++i === list.length) {
          i = 0;
          if (MOMENTS.has(row)) list = play(0);
        }
        setCell(list[i]!);
        tick();
      }, list[i]!.ms);
    };
    tick();
    return () => window.clearTimeout(timer);
  }, [kind, row, sleeping, reducedMotion]);

  // A background image reports no error of its own: probe it once.
  useEffect(() => {
    if (kind !== "codex") return;
    // It also tells a v2 sheet (11 rows) from a v1 (9).
    const probe = new Image();
    probe.onload = () => setRows(Math.round(probe.naturalHeight / CELL.h) || 9);
    probe.onerror = onBroken;
    probe.src = url;
    return () => {
      probe.onload = null;
      probe.onerror = null;
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [url, kind]);

  if (kind === "image") {
    return (
      <img
        src={url}
        alt=""
        data-mood={mood}
        data-moment={moment ?? undefined}
        className="sagi-pet-image"
        width={size}
        height={size}
        draggable={false}
        onError={onBroken}
        style={{ width: size, height: size, objectFit: "contain" }}
      />
    );
  }
  const pose =
    gaze != null && rows > GAZE_ROW && !action && !moment && mood === "idle" ? gaze : null;
  const shown =
    pose != null
      ? { row: GAZE_ROW + Math.floor(pose / COLS), col: pose % COLS }
      : cell.of === row
        ? cell
        : { row, col: 0 };
  const scale = size / CELL.h;
  return (
    <div
      data-testid="pet-sprite"
      data-row={shown.row}
      aria-hidden
      style={{
        width: Math.round(CELL.w * scale),
        height: size,
        margin: "0 auto",
        backgroundImage: `url("${url}")`,
        backgroundRepeat: "no-repeat",
        backgroundSize: `${COLS * CELL.w * scale}px ${rows * CELL.h * scale}px`,
        backgroundPosition: `${-shown.col * CELL.w * scale}px ${-shown.row * CELL.h * scale}px`,
      }}
    />
  );
}