////////////////////////////////////////////////
// Gradient slider demo
.range-slider.grad {
    --progress-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2) inset;
    --progress-flll-shadow: var(--progress-shadow);
    --fill-color: linear-gradient(to right, LightCyan, var(--primary-color));
    --thumb-shadow: 0 0 4px rgba(0, 0, 0, 0.3),
        -3px 9px 9px rgba(255, 255, 255, 0.33) inset,
        -1px 3px 2px rgba(255, 255, 255, 0.33) inset,
        0 0 0 99px var(--primary-color) inset;

    input {
        &:hover {
            --thumb-transform: scale(1.2);
        }

        &:active {
            --thumb-shadow: inherit;
            --thumb-transform: scale(1);
        }
    }
}

////////////////////////////////////////////////
// Flat double-range slider demo

.range-slider.flat {
    --thumb-size: 25px;
    --track-height: calc(var(--thumb-size) / 3);
    --progress-shadow: none;
    --progress-flll-shadow: none;
    --thumb-shadow: 0 0 0 7px var(--primary-color) inset, 0 0 0 99px white inset;
    --thumb-shadow-hover: 0 0 0 9px var(--primary-color) inset,
        0 0 0 99px white inset;
    --thumb-shadow-active: 0 0 0 13px var(--primary-color) inset;
}

////////////////////////////////////////////////
// Double-range slider demo

.range-slider.overlay {
    --primary-color: #d6e9ff;
    --track-height: 50px;
    --thumb-size: var(--track-height);
    --thumb-color: var(--primary-color);
    --thumb-shadow: none;
    --progress-flll-shadow: none;
    --progress-shadow: none;
    --progress-background: none;
    --progress-radius: 0px;
    --ticks-color: var(--primary-color);
    --ticks-height: 0;
    --ticks-thickness: 0;
    --ticks-gap: 0px; // must specify units
    --min-max-font: 700 18px Arial;
    --min-max-opacity: 1;
    --show-min-max: none;

    color: #0366d6;

    input {
        &:hover {
            // cannot use "--thumb-shadow-hover" because the "--is-left-most" variable is needed (which is declared per-input)
            // "--is-left-most" is either "0" or "1"
            --thumb-shadow: calc(25px - (50px * var(--is-left-most))) 0 0 -15px #0366d6
                inset;
        }

        &:active {
            --thumb-color: inherit;
        }
    }

    .range-slider {
        &__values {
            width: calc(100% - 50% / (var(--max) - var(--min)));
        }
    }
}

////////////////////////////////////////////////
// The main styles

.range-slider {
    --primary-color: #0366d6;

    --value-offset-y: var(--ticks-gap);
    --value-active-color: white;
    --value-background: transparent;
    --value-background-hover: var(--primary-color);
    --value-font: 700 12px/1 Arial;

    --fill-color: var(--primary-color);
    --progress-background: #eee;
    --progress-radius: 20px;
    --track-height: calc(var(--thumb-size) / 2);

    --min-max-font: 12px Arial;
    --min-max-opacity: 0.5;
    --min-max-x-offset: 10%; // 50% to center

    --thumb-size: 22px;
    --thumb-color: white;
    --thumb-shadow: 0 0 3px rgba(0, 0, 0, 0.4), 0 0 1px rgba(0, 0, 0, 0.5) inset,
        0 0 0 99px var(--thumb-color) inset;

    --thumb-shadow-active: 0 0 0 calc(var(--thumb-size) / 4) inset
            var(--thumb-color),
        0 0 0 99px var(--primary-color) inset, 0 0 3px rgba(0, 0, 0, 0.4);

    --thumb-shadow-hover: var(--thumb-shadow);

    --ticks-thickness: 1px;
    --ticks-height: 5px;
    --ticks-gap: var(
        --ticks-height,
        0
    ); // vertical space between the ticks and the progress bar
    --ticks-color: silver;

    // ⚠️ BELOW VARIABLES SHOULD NOT BE CHANGED
    --step: 1;
    --ticks-count: calc(var(--max) - var(--min)) / var(--step);
    --maxTicksAllowed: 30;
    --too-many-ticks: ~"min(1, max(var(--ticks-count) - var(--maxTicksAllowed), 0))";
    --x-step: ~"max(var(--step),var(--too-many-ticks) * (var(--max) - var(--min)))"; // manipulate the number of steps if too many ticks exist, so there would only be 2
    --tickInterval: 100/ ((var(--max) - var(--min)) / var(--step)) * var(--tickEvery, 1);
    --tickIntervalPerc: calc(
        (100% - var(--thumb-size)) / ((var(--max) - var(--min)) / var(--x-step)) *
            var(--tickEvery, 1)
    );

    --value-a: Clamp(
        var(--min),
        var(--value, 0),
        var(--max)
    ); // default value ("--value" is used in single-range markup)
    --value-b: var(--value, 0); // default value
    --text-value-a: var(--text-value, "");

    --completed-a: calc(
        (var(--value-a) - var(--min)) / (var(--max) - var(--min)) * 100
    );
    --completed-b: calc(
        (var(--value-b) - var(--min)) / (var(--max) - var(--min)) * 100
    );
    --ca: ~"Min(var(--completed-a), var(--completed-b))";
    --cb: ~"Max(var(--completed-a), var(--completed-b))";

    // breakdown of the below super-complex brain-breaking CSS math:
    // "clamp" is used to ensure either "-1" or "1"
    // "calc" is used to inflat the outcome into a huge number, to get rid of any value between -1 & 1
    // if absolute diff of both completed % is above "5" (%)
    // ".001" bumps the value just a bit, to avoid a scenario where calc resulted in "0" (then clamp will also be "0")
    --thumbs-too-close: ~"Clamp( -1,1000 * (Min(1, Max(var(--cb) - var(--ca) - 5, -1)) + 0.001),  1)";
    --thumb-close-to-min: ~"Min(1, Max(var(--ca) - 2, 0))"; // 2% threshold
    --thumb-close-to-max: ~"Min(1, Max(98 - var(--cb), 0))"; // 2% threshold

    @mixin thumb {
        appearance: none;
        height: var(--thumb-size);
        width: var(--thumb-size);
        transform: var(--thumb-transform);
        border-radius: var(--thumb-radius, 50%);
        background: var(--thumb-color);
        box-shadow: var(--thumb-shadow);
        border: none;
        pointer-events: auto;
        transition: 0.1s;
    }

    display: inline-block;
    height: ~"Max(var(--track-height), var(--thumb-size))";
    // margin: calc((var(--thumb-size) - var(--track-height)) * -.25) var(--thumb-size) 0;
    background: linear-gradient(
            to right,
            var(--ticks-color) var(--ticks-thickness),
            transparent 1px
        )
        repeat-x;
    background-size: var(--tickIntervalPerc) var(--ticks-height);
    background-position-x: calc(
        var(--thumb-size) / 2 - var(--ticks-thickness) / 2
    );
    background-position-y: var(--flip-y, bottom);

    padding-bottom: var(--flip-y, var(--ticks-gap));
    padding-top: calc(var(--flip-y) * var(--ticks-gap));

    position: relative;
    z-index: 1;

    &[data-ticks-position="top"] {
        --flip-y: 1;
    }

    // mix/max texts
    &::before,
    &::after {
        --offset: calc(var(--thumb-size) / 2);
        content: counter(x);
        display: var(--show-min-max, block);
        font: var(--min-max-font);
        position: absolute;
        bottom: var(--flip-y, -2.5ch);
        top: calc(-2.5ch * var(--flip-y));
        opacity: Clamp(0, var(--at-edge), var(--min-max-opacity));
        transform: translateX(
                calc(var(--min-max-x-offset) * var(--before, -1) * -1)
            )
            scale(var(--at-edge));
        pointer-events: none;
    }

    &::before {
        --before: 1;
        --at-edge: var(--thumb-close-to-min);
        counter-reset: x var(--min);
        left: var(--offset);
    }

    &::after {
        --at-edge: var(--thumb-close-to-max);
        counter-reset: x var(--max);
        right: var(--offset);
    }

    &__values {
        position: relative;
        top: 50%;
        line-height: 0;
        text-align: center;
        width: 100%;
        pointer-events: none;
        margin: 0 auto;
        z-index: 5;

        
        &::after {
            content: "";
            width: 100%;
            display: inline-block;
            height: 0;
            background: red;
        }
    }

    &__progress {
        --start-end: calc(var(--thumb-size) / 2);
        --clip-end: calc(100% - (var(--cb)) * 1%);
        --clip-start: calc(var(--ca) * 1%);
        --clip: inset(-20px var(--clip-end) -20px var(--clip-start));
        position: absolute;
        left: var(--start-end);
        right: var(--start-end);
        top: calc(
            var(--ticks-gap) * var(--flip-y, 0) + var(--thumb-size) / 2 -
                var(--track-height) / 2
        );
        //  transform: var(--flip-y, translateY(-50%) translateZ(0));
        height: calc(var(--track-height));
        background: var(--progress-background, #eee);
        pointer-events: none;
        z-index: -1;
        border-radius: var(--progress-radius);

        // fill area
        &::before {
            content: "";
            position: absolute;
            // left: Clamp(0%, calc(var(--ca) * 1%), 100%); // confine to 0 or above
            // width: Min(100%, calc((var(--cb) - var(--ca)) * 1%)); // confine to maximum 100%
            left: 0;
            right: 0;
            clip-path: var(--clip);
            top: 0;
            bottom: 0;
            background: var(--fill-color, black);
            box-shadow: var(--progress-flll-shadow);
            z-index: 1;
            border-radius: inherit;
        }

        // shadow-effect
        &::after {
            content: "";
            position: absolute;
            top: 0;
            right: 0;
            bottom: 0;
            left: 0;
            box-shadow: var(--progress-shadow);
            pointer-events: none;
            border-radius: inherit;
        }
    }

    & > input {
        -webkit-appearance: none;
        width: 100%;
        height: var(--thumb-size);
        margin: 0;
        position: absolute;
        left: 0;
        top: calc(
            ~"
        50% - Max(var(--track-height), var(--thumb-size)) / 2 +
          calc(var(--ticks-gap) / 2 * var(--flip-y, -1))"
        );
        cursor: -webkit-grab;
        cursor: grab;
        outline: none;
        background: none;

        &:not(:only-of-type) {
            pointer-events: none;
        }

        &::-webkit-slider-thumb {
            @include thumb;
        }
        &::-moz-range-thumb {
            @include thumb;
        }
        &::-ms-thumb {
            @include thumb;
        }

        &:hover {
            --thumb-shadow: var(--thumb-shadow-hover);
            & + output {
                --value-background: var(--value-background-hover);
                --y-offset: -5px;
                color: var(--value-active-color);
                box-shadow: 0 0 0 3px var(--value-background);
            }
        }

        &:active {
            --thumb-shadow: var(--thumb-shadow-active);
            cursor: grabbing;
            z-index: 2; // when sliding left thumb over the right or vice-versa, make sure the moved thumb is on top
            + output {
                transition: 0s;
            }
        }

        &:nth-of-type(1) {
            --is-left-most: ~"Clamp(0, (var(--value-a) - var(--value-b)) * 99999, 1)";
            & + output {
                &:not(:only-of-type) {
                    --flip: calc(var(--thumbs-too-close) * -1);
                }

                --value: var(--value-a);
                --x-offset: calc(var(--completed-a) * -1%);
                &::after {
                    content: var(--prefix, "") var(--text-value-a)
                        var(--suffix, "");
                }
            }
        }

        &:nth-of-type(2) {
            --is-left-most: ~"Clamp(0, (var(--value-b) - var(--value-a)) * 99999, 1)";
            & + output {
                --value: var(--value-b);
            }
        }

        // non-multiple range should not clip start of progress bar
        &:only-of-type {
            ~ .range-slider__progress {
                --clip-start: 0;
            }
        }

        & + output {
            --flip: -1;
            --x-offset: calc(var(--completed-b) * -1%);
            --pos: calc(
                ((var(--value) - var(--min)) / (var(--max) - var(--min))) * 100%
            );

            pointer-events: none;
            position: absolute;
            z-index: 5;
            background: var(--value-background);
            border-radius: 10px;
            padding: 2px 4px;
            left: var(--pos);
            transform: translate(
                var(--x-offset),
                calc(
                    150% * var(--flip) -
                        (var(--y-offset, 0px) + var(--value-offset-y)) *
                        var(--flip)
                )
            );
            transition:
                all 0.12s ease-out,
                left 0s;

            &::after {
                content: var(--prefix, "") var(--text-value-b) var(--suffix, "");
                font: var(--value-font);
            }
        }
    }
}

////////////////////////////////////////////////
// PAGE SETUP

body {
    height: 100vh;
    display: grid;
    place-content: space-evenly;
    place-items: center;
    gap: 10%;
    padding: 1em 0;

    @media screen and (max-width: 500px) {
        padding-top: 2em;
        gap: 8%;
    }
}

a {
    position: fixed;
    top: 1em;
    left: 1em;
    display: inline-block;
    height: 2em;

    @media screen and (max-width: 500px) {
        position: static;
        order: -1;
    }

    > img {
        display: inherit;
        height: 100%;
    }
}

body > .range-slider,
label[dir="rtl"] .range-slider {
    width: Clamp(300px, 50vw, 800px);
    min-width: 200px;
}