FadeIn

import React, {Children, type CSSProperties, type ReactNode} from "react";
import {useCurrentFrame, useVideoConfig} from "remotion";
import {finite, lerp, nonNegative, phase, positive, reveal, staggerAt, swapState, type MotionTiming, type Point} from "./core.js";

export type MotionProps = MotionTiming & {children: ReactNode; style?: CSSProperties};

export function FadeIn({children, at = 0, duration = 0.6, style}: MotionProps) {
  const p = reveal(useCurrentFrame(), useVideoConfig().fps, at, duration);
  return <div style={{...style, opacity: p}}>{children}</div>;
}

export type SlideInProps = MotionProps & {from?: "up" | "down" | "left" | "right"; distance?: number; fade?: boolean};
export function SlideIn({children, at = 0, duration = 0.6, from = "up", distance = 40, fade = true, style}: SlideInProps) {
  const p = reveal(useCurrentFrame(), useVideoConfig().fps, at, duration);
  nonNegative(distance, "distance");
  if (!["up", "down", "left", "right"].includes(from)) throw new TypeError("from must be up, down, left, or right.");
  const axis = from === "left" || from === "right" ? "X" : "Y";
  const sign = from === "left" || from === "up" ? -1 : 1;
  return <div style={{...style, opacity: fade ? p : 1, transform: `translate${axis}(${sign * distance * (1 - p)}px)`}}>{children}</div>;
}

export type ScaleInProps = MotionProps & {from?: number; origin?: string};
export function ScaleIn({children, at = 0, duration = 0.6, from = 0.88, origin = "50% 50%", style}: ScaleInProps) {
  const p = reveal(useCurrentFrame(), useVideoConfig().fps, at, duration);
  nonNegative(from, "from");
  return <div style={{...style, opacity: p, transform: `scale(${lerp(from, 1, p)})`, transformOrigin: origin}}>{children}</div>;
}

export type AnchoredRevealProps = MotionProps & {anchor: Point; from?: number};
export function AnchoredReveal({children, anchor, from = 0.75, at = 0, duration = 0.6, style}: AnchoredRevealProps) {
  finite(anchor.x, "anchor.x"); finite(anchor.y, "anchor.y");
  return <ScaleIn at={at} duration={duration} from={from} origin={`${anchor.x}px ${anchor.y}px`} style={style}>{children}</ScaleIn>;
}

export type StaggerCascadeProps = MotionProps & {stagger?: number; distance?: number; itemStyle?: CSSProperties};
export function StaggerCascade({children, at = 0, duration = 0.55, stagger = 0.09, distance = 24, style, itemStyle}: StaggerCascadeProps) {
  nonNegative(stagger, "stagger"); nonNegative(distance, "distance"); positive(duration, "duration"); finite(at, "at");
  return <div style={style}>{Children.map(children, (child, i) => <SlideIn key={i} at={staggerAt(at, i, stagger)} duration={duration} from="down" distance={distance} style={itemStyle}>{child}</SlideIn>)}</div>;
}

export type ValueSwapProps = MotionTiming & {from: ReactNode; to: ReactNode; style?: CSSProperties};
/** Both values occupy the same grid cell, reserving the larger value's geometry. */
export function ValueSwap({from, to, at = 0, duration = 0.5, style}: ValueSwapProps) {
  const state = swapState(phase(useCurrentFrame(), useVideoConfig().fps, at, duration));
  return <span style={{display: "inline-grid", ...style}}>
    <span aria-hidden={state.side !== "from"} style={{gridArea: "1 / 1", opacity: state.side === "from" ? state.opacity : 0}}>{from}</span>
    <span aria-hidden={state.side !== "to"} style={{gridArea: "1 / 1", opacity: state.side === "to" ? state.opacity : 0}}>{to}</span>
  </span>;
}

import {Easing} from "remotion";

/** All motion is evaluated from the local Remotion frame, including frames before a Sequence. */
export type MotionTiming = {at?: number; duration?: number};
export type Point = {x: number; y: number};
export type CameraPose = Point & {zoom: number};
export const out = Easing.bezier(0.16, 1, 0.3, 1);
export const inOut = Easing.bezier(0.65, 0, 0.35, 1);

export function finite(value: number, name: string): number {
  if (!Number.isFinite(value)) throw new TypeError(`${name} must be finite.`);
  return value;
}
export function positive(value: number, name: string): number {
  if (finite(value, name) <= 0) throw new RangeError(`${name} must be greater than zero.`);
  return value;
}
export function nonNegative(value: number, name: string): number {
  if (finite(value, name) < 0) throw new RangeError(`${name} must be zero or greater.`);
  return value;
}
export function unit(value: number, name = "progress"): number {
  return Math.min(1, Math.max(0, finite(value, name)));
}
export function lerp(from: number, to: number, p: number): number {
  finite(from, "from"); finite(to, "to");
  const t = unit(p);
  return finite(from * (1 - t) + to * t, "interpolated value");
}
export function phase(frame: number, fps: number, at = 0, duration = 0.6): number {
  finite(frame, "frame"); positive(fps, "fps"); finite(at, "at"); positive(duration, "duration");
  return unit((frame / fps - at) / duration);
}
export function reveal(frame: number, fps: number, at = 0, duration = 0.6): number {
  return out(phase(frame, fps, at, duration));
}
export function staggerAt(at: number, index: number, interval: number): number {
  finite(at, "at"); nonNegative(index, "index"); nonNegative(interval, "stagger");
  return at + index * interval;
}
export function swapState(progress: number): {side: "from" | "to"; opacity: number} {
  const p = unit(progress);
  return {side: p < 0.5 ? "from" : "to", opacity: Math.min(1, Math.abs(p - 0.5) * 4)};
}
export function cameraTransform(from: CameraPose, to: CameraPose, p: number, width: number, height: number): string {
  positive(from.zoom, "from.zoom"); positive(to.zoom, "to.zoom");
  positive(width, "width"); positive(height, "height");
  const x = lerp(from.x, to.x, p), y = lerp(from.y, to.y, p), zoom = lerp(from.zoom, to.zoom, p);
  const tx = finite(width / 2 - x * zoom, "camera translation x");
  const ty = finite(height / 2 - y * zoom, "camera translation y");
  return `translate(${tx}px, ${ty}px) scale(${zoom})`;
}
export function focusStyle(progress: number, blur: number, dim: number): {filter: string; opacity: number} {
  nonNegative(blur, "blur");
  if (finite(dim, "dim") < 0 || dim > 1) throw new RangeError("dim must be between zero and one.");
  const p = unit(progress);
  return {filter: `blur(${blur * p}px)`, opacity: lerp(1, dim, p)};
}
export function connectorGeometry(from: Point, to: Point, bend: number): {path: string; point: (p: number) => Point} {
  finite(from.x, "from.x"); finite(from.y, "from.y"); finite(to.x, "to.x"); finite(to.y, "to.y"); finite(bend, "bend");
  const middle = {x: lerp(from.x, to.x, 0.5), y: finite(lerp(from.y, to.y, 0.5) - bend, "curve midpoint")};
  return {
    path: `M ${from.x} ${from.y} Q ${middle.x} ${middle.y} ${to.x} ${to.y}`,
    point(p) { const t = unit(p); return {x: lerp(lerp(from.x, middle.x, t), lerp(middle.x, to.x, t), t), y: lerp(lerp(from.y, middle.y, t), lerp(middle.y, to.y, t), t)}; },
  };
}