// https://codepen.io/GreenSock/pen/gOvvJee?editors=1010
// https://gsap.com/docs/v3/HelperFunctions/helpers/seamlessLoop/

// https://codepen.io/GreenSock/pen/gOvvJee?editors=1010
// https://gsap.com/docs/v3/HelperFunctions/helpers/seamlessLoop/

function horizontalLoop(items, config) {
  let timeline;
  items = gsap.utils.toArray(items);
  config = config || {};
  gsap.context(() => {
    // use a context so that if this is called from within another context or a gsap.matchMedia(), we can perform proper cleanup like the "resize" event handler on the window
    let onChange = config.onChange,
      lastIndex = 0,
      tl = gsap.timeline({
        repeat: config.repeat,
        onUpdate:
          onChange &&
          function () {
            let i = tl.closestIndex();
            if (lastIndex !== i) {
              lastIndex = i;
              onChange(items[i], i);
            }
          },
        paused: config.paused,
        defaults: { ease: "none" },
        onReverseComplete: () =>
          tl.totalTime(tl.rawTime() + tl.duration() * 100),
      }),
      length = items.length,
      startX = items[0].offsetLeft,
      times = [],
      widths = [],
      spaceBefore = [],
      xPercents = [],
      curIndex = 0,
      indexIsDirty = false,
      center = config.center,
      pixelsPerSecond = (config.speed || 1) * 100,
      snap =
        config.snap === false ? (v) => v : gsap.utils.snap(config.snap || 1), // some browsers shift by a pixel to accommodate flex layouts, so for example if width is 20% the first element's width might be 242px, and the next 243px, alternating back and forth. So we snap to 5 percentage points to make things look more natural
      timeOffset = 0,
      container =
        center === true
          ? items[0].parentNode
          : gsap.utils.toArray(center)[0] || items[0].parentNode,
      totalWidth,
      getTotalWidth = () =>
        items[length - 1].offsetLeft +
        (xPercents[length - 1] / 100) * widths[length - 1] -
        startX +
        spaceBefore[0] +
        items[length - 1].offsetWidth *
          gsap.getProperty(items[length - 1], "scaleX") +
        (parseFloat(config.paddingRight) || 0),
      populateWidths = () => {
        let b1 = container.getBoundingClientRect(),
          b2;

        // Reset all items to their natural position first
        gsap.set(items, {
          x: 0,
          xPercent: 0,
          clearProps: "transform",
        });

        // Force a reflow
        items[0].offsetWidth;

        // Get the container's new position after reset
        startX = items[0].offsetLeft;

        items.forEach((el, i) => {
          // Get the natural width without any transforms
          widths[i] = el.offsetWidth;

          // Calculate the space between items
          b2 = el.getBoundingClientRect();
          spaceBefore[i] = b2.left - (i ? b1.right : b1.left);
          b1 = b2;

          // Reset xPercent to 0 for accurate calculations
          xPercents[i] = 0;
        });

        // Set all items to their calculated positions
        gsap.set(items, {
          xPercent: (i) => xPercents[i],
        });

        // Calculate total width after all items are positioned
        totalWidth = getTotalWidth();
      },
      timeWrap,
      populateOffsets = () => {
        timeOffset = center
          ? (tl.duration() * (container.offsetWidth / 2)) / totalWidth
          : 0;
        center &&
          times.forEach((t, i) => {
            times[i] = timeWrap(
              tl.labels["label" + i] +
                (tl.duration() * widths[i]) / 2 / totalWidth -
                timeOffset
            );
          });
      },
      getClosest = (values, value, wrap) => {
        let i = values.length,
          closest = 1e10,
          index = 0,
          d;
        while (i--) {
          d = Math.abs(values[i] - value);
          if (d > wrap / 2) {
            d = wrap - d;
          }
          if (d < closest) {
            closest = d;
            index = i;
          }
        }
        return index;
      },
      populateTimeline = () => {
        let i, item, curX, distanceToStart, distanceToLoop;
        tl.clear();
        for (i = 0; i < length; i++) {
          item = items[i];
          curX = (xPercents[i] / 100) * widths[i];
          distanceToStart = item.offsetLeft + curX - startX + spaceBefore[0];
          distanceToLoop =
            distanceToStart + widths[i] * gsap.getProperty(item, "scaleX");
          tl.to(
            item,
            {
              xPercent: snap(((curX - distanceToLoop) / widths[i]) * 100),
              duration: distanceToLoop / pixelsPerSecond,
            },
            0
          )
            .fromTo(
              item,
              {
                xPercent: snap(
                  ((curX - distanceToLoop + totalWidth) / widths[i]) * 100
                ),
              },
              {
                xPercent: xPercents[i],
                duration:
                  (curX - distanceToLoop + totalWidth - curX) / pixelsPerSecond,
                immediateRender: false,
              },
              distanceToLoop / pixelsPerSecond
            )
            .add("label" + i, distanceToStart / pixelsPerSecond);
          times[i] = distanceToStart / pixelsPerSecond;
        }
        timeWrap = gsap.utils.wrap(0, tl.duration());
      },
      refresh = (deep) => {
        let progress = tl.progress();
        tl.progress(0, true);

        // Reset only the x transforms while preserving other properties
        gsap.set(items, {
          x: 0,
          xPercent: 0,
        });

        // Force a reflow
        items[0].offsetWidth;

        populateWidths();
        deep && populateTimeline();
        populateOffsets();

        if (deep && tl.draggable && tl.paused()) {
          tl.time(times[curIndex], true);
        } else {
          tl.progress(progress, true);
        }
      },
      onResize = () => {
        if (window.resizeTimeout) clearTimeout(window.resizeTimeout);
        window.resizeTimeout = setTimeout(() => {
          refresh(true);
        }, 100);
      },
      proxy;
    gsap.set(items, { x: 0 });
    populateWidths();
    populateTimeline();
    populateOffsets();
    window.addEventListener("resize", onResize);
    function toIndex(index, vars) {
      vars = vars || {};
      Math.abs(index - curIndex) > length / 2 &&
        (index += index > curIndex ? -length : length); // always go in the shortest direction
      let newIndex = gsap.utils.wrap(0, length, index),
        time = times[newIndex];
      if (time > tl.time() !== index > curIndex && index !== curIndex) {
        // if we're wrapping the timeline's playhead, make the proper adjustments
        time += tl.duration() * (index > curIndex ? 1 : -1);
      }
      if (time < 0 || time > tl.duration()) {
        vars.modifiers = { time: timeWrap };
      }
      curIndex = newIndex;
      vars.overwrite = true;
      gsap.killTweensOf(proxy);
      return vars.duration === 0
        ? tl.time(timeWrap(time))
        : tl.tweenTo(time, vars);
    }
    tl.toIndex = (index, vars) => toIndex(index, vars);
    tl.closestIndex = (setCurrent) => {
      let index = getClosest(times, tl.time(), tl.duration());
      if (setCurrent) {
        curIndex = index;
        indexIsDirty = false;
      }
      return index;
    };
    tl.current = () => (indexIsDirty ? tl.closestIndex(true) : curIndex);
    tl.next = (vars) => toIndex(tl.current() + 1, vars);
    tl.previous = (vars) => toIndex(tl.current() - 1, vars);
    tl.times = times;
    tl.progress(1, true).progress(0, true); // pre-render for performance
    if (config.reversed) {
      tl.vars.onReverseComplete();
      tl.reverse();
    }
    if (config.draggable && typeof Draggable === "function") {
      proxy = document.createElement("div");
      let wrap = gsap.utils.wrap(0, 1),
        ratio,
        startProgress,
        draggable,
        dragSnap,
        lastSnap,
        initChangeX,
        wasPlaying,
        align = () =>
          tl.progress(
            wrap(startProgress + (draggable.startX - draggable.x) * ratio)
          ),
        syncIndex = () => tl.closestIndex(true);
      typeof InertiaPlugin === "undefined" &&
        console.warn(
          "InertiaPlugin required for momentum-based scrolling and snapping. https://greensock.com/club"
        );
      draggable = Draggable.create(proxy, {
        trigger: items[0].parentNode,
        type: "x",
        onPressInit() {
          let x = this.x;
          gsap.killTweensOf(tl);
          wasPlaying = !tl.paused();
          tl.pause();
          startProgress = tl.progress();
          refresh();
          ratio = 1 / totalWidth;
          initChangeX = startProgress / -ratio - x;
          gsap.set(proxy, { x: startProgress / -ratio });
        },
        onDrag: align,
        onThrowUpdate: align,
        overshootTolerance: 0,
        inertia: true,
        snap(value) {
          //note: if the user presses and releases in the middle of a throw, due to the sudden correction of proxy.x in the onPressInit(), the velocity could be very large, throwing off the snap. So sense that condition and adjust for it. We also need to set overshootTolerance to 0 to prevent the inertia from causing it to shoot past and come back
          if (Math.abs(startProgress / -ratio - this.x) < 10) {
            return lastSnap + initChangeX;
          }
          let time = -(value * ratio) * tl.duration(),
            wrappedTime = timeWrap(time),
            snapTime = times[getClosest(times, wrappedTime, tl.duration())],
            dif = snapTime - wrappedTime;
          Math.abs(dif) > tl.duration() / 2 &&
            (dif += dif < 0 ? tl.duration() : -tl.duration());
          lastSnap = (time + dif) / tl.duration() / -ratio;
          return lastSnap;
        },
        onRelease() {
          syncIndex();
          draggable.isThrowing && (indexIsDirty = true);
        },
        onThrowComplete: () => {
          syncIndex();
          wasPlaying && tl.play();
        },
      })[0];
      tl.draggable = draggable;
    }
    tl.closestIndex(true);
    lastIndex = curIndex;
    onChange && onChange(items[curIndex], curIndex);
    timeline = tl;
    return () => window.removeEventListener("resize", onResize); // cleanup
  });
  return timeline;
}

/* -- Global Params */
const sliderParams = {
  duration: 0.5,
  ease: "power2.out",
};

addEventListener("GSAPReady", (event) => {
  const wrapper = document.querySelector("[data-animate='slider']");
  const slides = [...wrapper.querySelector("[data-slider='slides']").children];

  /* -- Setup Slider UI */
  const progress = wrapper.querySelector("[data-slider='progress']");
  const next = wrapper.querySelector("[data-slider='next']");
  const prev = wrapper.querySelector("[data-slider='prev']");
  let currentIndex = 0;

  const dots = [...wrapper.querySelector("[data-slider='dots']").children].map(
    (item, index) => {
      const btn = item.children[0];
      btn.addEventListener("click", () => {
        loop.toIndex(index, sliderParams);
      });

      return btn;
    }
  );

  /* -- Helper Functions */
  const updateCurrent = (index) => {
    // handle dots
    dots[currentIndex].classList.remove("current");
    dots[index].classList.add("current");
    slides[currentIndex].classList.remove("current");
    slides[index].classList.add("current");
    // handle slides
    // ...
    gsap.to(progress.children[0], {
      width: `${(index / (slides.length - 1)) * 100}%`,
      duration: 0.6,
      ease: "expo.out",
    });

    // save the previous position
    currentIndex = index;
  };

  /* -- Setup Slider */
  let loop;
  setTimeout(() => {
    loop = horizontalLoop(slides, {
      paused: true,
      draggable: true,
      // draggableOptions: {
      //   dragResistance: 10,
      //   resistance: 10,
      // },
      center: true,
      onChange: (element, index) => {
        updateCurrent(index);
      },
    });
  }, 500);
  // (*) THIS IS JUST TO CHECK PLEASE REMOVE

  next.addEventListener("click", () => {
    loop.next(sliderParams);
  });

  prev.addEventListener("click", () => {
    loop.previous(sliderParams);
  });
});