import { ooAvatarColor, screenPointInViewer } from "@rakazo/core";
import { Keyboard } from "lucide-react";
import { useEffect, useRef, useState } from "react";
import {
  agentPointerFeed,
  POINTER_IDLE_MS,
  type PointerPoint,
  type PointerScreen,
  type PointerSegment,
  planPointerTimeline,
  pointerFrameAt,
} from "../../lib/agent-pointer";

function prefersReducedMotion() {
  return (
    typeof window.matchMedia === "function" &&
    window.matchMedia("(prefers-reduced-motion: reduce)").matches
  );
}

/**
 * Draws a bot's announced pointer over its live screen: it glides to each target, ripples on
 * clicks and shows when it types. Frames are written straight to the DOM so the chat never
 * re-renders at animation rate.
 */
export function AgentCursor({
  botId,
  color,
  name,
}: {
  botId: string;
  color: string;
  name: string;
}) {
  const layerRef = useRef<HTMLDivElement>(null);
  const cursorRef = useRef<HTMLDivElement>(null);
  const rippleRef = useRef<HTMLSpanElement>(null);
  const [typing, setTyping] = useState(false);
  const tint = ooAvatarColor(color) || undefined;

  useEffect(() => {
    const layer = layerRef.current;
    const cursor = cursorRef.current;
    const ripple = rippleRef.current;
    if (!layer || !cursor || !ripple) return;
    const reducedMotion = prefersReducedMotion();
    let screen: PointerScreen | null = null;
    let segments: PointerSegment[] = [];
    let position: PointerPoint | null = null;
    let frame = 0;
    let idleTimer: ReturnType<typeof setTimeout> | undefined;
    let viewer = { width: layer.clientWidth, height: layer.clientHeight };
    let shownTyping = false;

    const place = (point: PointerPoint, action: string | null, progress: number) => {
      if (!screen) return;
      const projected = screenPointInViewer(point, viewer, screen);
      cursor.style.transform = `translate3d(${projected.x}px, ${projected.y}px, 0)`;
      cursor.dataset.action = action ?? "move";
      const pressing = action === "click" || action === "double_click" || action === "right_click";
      const pulse = action === "double_click" ? (progress * 2) % 1 : progress;
      ripple.style.opacity = pressing && !reducedMotion ? String(0.55 * (1 - pulse)) : "0";
      ripple.style.transform = `scale(${0.35 + pulse * 1.15})`;
      cursor.style.setProperty("--agent-cursor-press", pressing && pulse < 0.35 ? "0.86" : "1");
      const nextTyping = action === "type" || action === "key";
      if (nextTyping !== shownTyping) {
        shownTyping = nextTyping;
        setTyping(nextTyping);
      }
    };

    const rest = () => {
      clearTimeout(idleTimer);
      idleTimer = setTimeout(() => {
        cursor.style.opacity = "0";
      }, POINTER_IDLE_MS);
    };

    const tick = () => {
      frame = 0;
      const now = performance.now();
      const state = pointerFrameAt(segments, now, reducedMotion);
      if (!state) return;
      position = state.point;
      place(state.point, state.action?.kind ?? null, state.action?.progress ?? 0);
      if (state.done) {
        segments = [];
        rest();
        return;
      }
      frame = requestAnimationFrame(tick);
    };

    const unsubscribe = agentPointerFeed.subscribe(botId, (payload) => {
      const now = performance.now();
      const current = pointerFrameAt(segments, now, reducedMotion)?.point ?? position;
      const sameScreen =
        screen?.width === payload.screen.width && screen?.height === payload.screen.height;
      screen = payload.screen;
      // A first announcement starts at its target rather than flying in from a corner.
      const firstTarget = payload.steps.find((step) => typeof step.x === "number");
      const from =
        current && sameScreen
          ? current
          : firstTarget
            ? { x: firstTarget.x ?? 0, y: firstTarget.y ?? 0 }
            : { x: payload.screen.width / 2, y: payload.screen.height / 2 };
      segments = planPointerTimeline(from, payload.steps, now);
      clearTimeout(idleTimer);
      cursor.style.opacity = "1";
      if (!frame) frame = requestAnimationFrame(tick);
    });

    const resize = new ResizeObserver(() => {
      viewer = { width: layer.clientWidth, height: layer.clientHeight };
      if (position && !frame) place(position, null, 0);
    });
    resize.observe(layer);

    return () => {
      unsubscribe();
      resize.disconnect();
      cancelAnimationFrame(frame);
      clearTimeout(idleTimer);
    };
  }, [botId]);

  return (
    <div
      ref={layerRef}
      aria-hidden
      data-testid="agent-cursor-layer"
      className="pointer-events-none absolute inset-0 overflow-hidden"
    >
      <div
        ref={cursorRef}
        data-testid="agent-cursor"
        className="absolute top-0 left-0 opacity-0 transition-opacity duration-300 will-change-transform"
        style={{ color: tint }}
      >
        <span
          ref={rippleRef}
          className="absolute -top-5 -left-5 size-10 rounded-full border-2 border-current opacity-0"
        />
        <svg
          viewBox="0 0 20 22"
          className="relative block size-5 origin-top-left drop-shadow-md transition-transform duration-100"
          style={{ transform: "scale(var(--agent-cursor-press, 1))" }}
        >
          <path
            d="M1.5 1.5 L1.5 17.5 L6 13.2 L9.2 20.2 L12.4 18.8 L9.3 12 L15.5 12 Z"
            fill="currentColor"
            className="stroke-background"
            strokeWidth="1.6"
            strokeLinejoin="round"
          />
        </svg>
        <span className="absolute top-5 left-3.5 flex max-w-40 items-center gap-1 rounded-full bg-popover px-2 py-0.5 text-ui-label font-medium whitespace-nowrap text-popover-foreground shadow-sm ring-1 ring-border">
          <span className="size-1.5 shrink-0 rounded-full bg-current" style={{ color: tint }} />
          <span className="truncate">{name}</span>
          {typing ? <Keyboard strokeWidth={1.8} className="size-3 shrink-0" /> : null}
        </span>
      </div>
    </div>
  );
}