import React from "react";
import {
  AbsoluteFill,
  Interactive,
  interpolate,
  useCurrentFrame,
} from "remotion";
import { COLORS, monoFont, SNAP } from "../theme";

/**
 * Scene 4 — The AI Reveal (8.2–11.0s)
 * ------------------------------------------------------------
 * The narrative turn: S1–S3 were the problem and the promise.
 * Now the screen goes dark and the experience is revealed —
 * softly, in a pool of light, line by line, like a terminal
 * coming alive. This is the first "AI" mention (~9s, per the
 * late-reveal direction).
 *
 *   Your AI tutor.
 *   Built for CBSE.
 *   Grounded in your textbook.
 *
 * Strictly monochrome. The soft light is made of blurred white
 * ellipses (no gradients / no glassmorphism).
 */

export const THE_AI_REVEAL_FRAMES = 168; // 2.8s @ 60fps

type Line = { text: string; start: number; step: number; size: number; y: number };

const LINES: Line[] = [
  { text: "Your AI tutor.", start: 24, step: 2.1, size: 96, y: 700 },
  { text: "Built for CBSE.", start: 78, step: 2.0, size: 72, y: 952 },
  { text: "Grounded in your textbook.", start: 116, step: 1.5, size: 64, y: 1180 },
];

const X0 = 150; // left margin (gap between caret-block and glyphs)
const monoAdvance = 0.6; // JetBrains Mono advance ratio (~0.6em)

// ── Soft spotlight pool (blurred white ellipses, no gradients) ──
const SpotlightLayer: React.FC<{
  w: number;
  h: number;
  blur: number;
  opacity: number;
  breathe: number;
}> = ({ w, h, blur, opacity, breathe }) => (
  <div
    style={{
      position: "absolute",
      left: 540 - w / 2,
      top: 920 - h / 2,
      width: w,
      height: h,
      borderRadius: "50%",
      backgroundColor: COLORS.white,
      filter: `blur(${blur}px)`,
      opacity,
      scale: String((1 + 0.012 * breathe).toFixed(4)),
    }}
  />
);

// ── Terminal caret (blinks after the last typed line) ─────────
const Caret: React.FC<{ x: number; y: number; size: number; blink: boolean }> = ({
  x,
  y,
  size,
  blink,
}) => {
  const frame = useCurrentFrame();
  const on = !blink || (frame % 40) < 24;
  return (
    <div
      style={{
        position: "absolute",
        left: x,
        top: y,
        width: Math.max(10, size * 0.2),
        height: size * 0.86,
        backgroundColor: COLORS.white,
        opacity: on ? 1 : 0.06,
      }}
    />
  );
};

export const AiReveal: React.FC = () => {
  const frame = useCurrentFrame();

  // Spotlight breathing + ambient drift
  const breathe = Math.sin((frame / 60) * (2 * Math.PI) / 9);
  const driftX = Math.sin((frame / 60) * (2 * Math.PI) / 13) * 7;
  const driftY = Math.cos((frame / 60) * (2 * Math.PI) / 17) * 5;
  const push = interpolate(frame, [0, 120], [1, 1.03], {
    extrapolateLeft: "clamp",
    extrapolateRight: "clamp",
    easing: SNAP,
  });

  // White out at the end → clean seam into Scene 5 (white UI)
  const out = interpolate(frame, [158, 166], [0, 1], {
    extrapolateLeft: "clamp",
    extrapolateRight: "clamp",
    easing: SNAP,
  });

  // Active line (the one most recently typed)
  let active: Line | null = null;
  for (const l of LINES) {
    if (frame >= l.start) active = l;
  }
  const activeCount = active
    ? Math.min(active.text.length, Math.max(0, Math.floor((frame - active.start) / active.step) + 1))
    : 0;
  const activeDone = active ? activeCount >= active.text.length : false;
  const caretX = active ? X0 + activeCount * active.size * monoAdvance : X0;
  const caretY = active ? active.y : 700;

  return (
    <AbsoluteFill name="Scene" style={{ backgroundColor: COLORS.black }}>
      <Interactive.Div
        name="Drift"
        style={{
          position: "absolute",
          left: 0,
          top: 0,
          width: "100%",
          height: "100%",
          translate: `${driftX.toFixed(2)}px ${driftY.toFixed(2)}px`,
          scale: String(push),
        }}
      >
        {/* Spotlight pool */}
        <Interactive.Div name="Spotlight">
          <SpotlightLayer w={1650} h={1050} blur={120} opacity={0.05} breathe={breathe} />
          <SpotlightLayer w={1180} h={700} blur={72} opacity={0.06} breathe={breathe} />
          <SpotlightLayer w={800} h={440} blur={34} opacity={0.09} breathe={breathe} />
        </Interactive.Div>

        {/* Dust motes in the light */}
        <Interactive.Div name="Dust">
          {[
            { x: 300, y: 1180, r: 7, d: 90 },
            { x: 760, y: 940, r: 5, d: 120 },
            { x: 420, y: 1330, r: 4, d: 150 },
          ].map((m, i) => {
            const rise = ((frame + m.d) % 220) / 220;
            return (
              <div
                key={i}
                style={{
                  position: "absolute",
                  left: m.x + Math.sin((frame + i * 40) / 30) * 30,
                  top: m.y - rise * 420,
                  width: m.r * 2,
                  height: m.r * 2,
                  borderRadius: "50%",
                  backgroundColor: COLORS.white,
                  filter: "blur(3px)",
                  opacity: 0.16,
                }}
              />
            );
          })}
        </Interactive.Div>

        {/* Typewriter lines */}
        <Interactive.Div name="Typewriter">
          {LINES.map((line, li) => {
            const visible = Math.min(
              line.text.length,
              Math.max(0, Math.floor((frame - line.start) / line.step) + 1),
            );
            return (
              <Interactive.Div
                key={li}
                name={`Line-${li}`}
                style={{
                  position: "absolute",
                  left: X0 + 18,
                  top: line.y,
                  whiteSpace: "nowrap",
                  fontFamily: monoFont,
                  fontSize: line.size,
                  fontWeight: 500,
                  color: COLORS.white,
                  letterSpacing: "0.02em",
                }}
              >
                {line.text.split("").map((ch, i) => (
                  <span
                    key={i}
                    style={{
                      opacity: i < visible ? 1 : 0,
                    }}
                  >
                    {ch === " " ? "\u00A0" : ch}
                  </span>
                ))}
              </Interactive.Div>
            );
          })}

          <Caret
            x={caretX}
            y={caretY}
            size={active?.size ?? 96}
            blink={activeDone}
          />
        </Interactive.Div>
      </Interactive.Div>

      {/* White-out exit */}
      <Interactive.Div
        name="RevealOut"
        style={{
          position: "absolute",
          inset: 0,
          backgroundColor: COLORS.white,
          opacity: out,
        }}
      />
    </AbsoluteFill>
  );
};