///
$breakpoints: (
    "phone": 380px,
    "phone-tab": 500px,
    "tablet": 835px,
    "desktop": 1024px,
) !default;

///
/// Creates a list of static expressions or media types
///
/// @example scss - Creates a single media type (screen)
///  $media-expressions: ('screen': 'screen');
///
/// @example scss - Creates a static expression with logical disjunction (OR operator)
///  $media-expressions: (
///    'retina2x': '(-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi)'
///  );
///
$media-expressions: (
    "screen": "screen",
    "print": "print",
    "handheld": "handheld",
    "landscape": "(orientation: landscape)",
    "portrait": "(orientation: portrait)",
    "retina2x": "(-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi), (min-resolution: 2dppx)",
    "retina3x": "(-webkit-min-device-pixel-ratio: 3), (min-resolution: 350dpi), (min-resolution: 3dppx)",
) !default;

///
/// Defines a number to be added or subtracted from each unit when declaring breakpoints with exclusive intervals
///
/// @example scss - Interval for pixels is defined as `1` by default
///  @include media('>128px') {}
///
///  /* Generates: */
///  @media (min-width: 129px) {}
///
/// @example scss - Interval for ems is defined as `0.01` by default
///  @include media('>20em') {}
///
///  /* Generates: */
///  @media (min-width: 20.01em) {}
///
/// @example scss - Interval for rems is defined as `0.1` by default, to be used with `font-size: 62.5%;`
///  @include media('>2.0rem') {}
///
///  /* Generates: */
///  @media (min-width: 2.1rem) {}
///
$unit-intervals: (
    "px": 1,
    "em": 0.01,
    "rem": 0.1,
    "": 0,
) !default;

///
/// Defines whether support for media queries is available, useful for creating separate stylesheets
/// for browsers that don't support media queries.
///
/// @example scss - Disables support for media queries
///  $im-media-support: false;
///  @include media('>=tablet') {
///    .foo {
///      color: tomato;
///    }
///  }
///
///  /* Generates: */
///  .foo {
///    color: tomato;
///  }
///
$im-media-support: true !default;

///
/// Selects which breakpoint to emulate when support for media queries is disabled. Media queries that start at or
/// intercept the breakpoint will be displayed, any others will be ignored.
///
/// @example scss - This media query will show because it intercepts the static breakpoint
///  $im-media-support: false;
///  $im-no-media-breakpoint: 'desktop';
///  @include media('>=tablet') {
///    .foo {
///      color: tomato;
///    }
///  }
///
///  /* Generates: */
///  .foo {
///    color: tomato;
///  }
///
/// @example scss - This media query will NOT show because it does not intercept the desktop breakpoint
///  $im-media-support: false;
///  $im-no-media-breakpoint: 'tablet';
///  @include media('>=desktop') {
///    .foo {
///      color: tomato;
///    }
///  }
///
///  /* No output */
///
$im-no-media-breakpoint: "desktop" !default;

///
/// Selects which media expressions are allowed in an expression for it to be used when media queries
/// are not supported.
///
/// @example scss - This media query will show because it intercepts the static breakpoint and contains only accepted media expressions
///  $im-media-support: false;
///  $im-no-media-breakpoint: 'desktop';
///  $im-no-media-expressions: ('screen');
///  @include media('>=tablet', 'screen') {
///    .foo {
///      color: tomato;
///    }
///  }
///
///   /* Generates: */
///   .foo {
///     color: tomato;
///   }
///
/// @example scss - This media query will NOT show because it intercepts the static breakpoint but contains a media expression that is not accepted
///  $im-media-support: false;
///  $im-no-media-breakpoint: 'desktop';
///  $im-no-media-expressions: ('screen');
///  @include media('>=tablet', 'retina2x') {
///    .foo {
///      color: tomato;
///    }
///  }
///
///  /* No output */
///
$im-no-media-expressions: ("screen", "portrait", "landscape") !default;

////
/// Cross-engine logging engine
/// @author Kitty Giraudel
/// @access private
////

///
/// Log a message either with `@error` if supported
/// else with `@warn`, using `feature-exists('at-error')`
/// to detect support.
///
/// @param {String} $message - Message to log
///
@function im-log($message) {
    @if feature-exists("at-error") {
        @error $message;
    } @else {
        @warn $message;
        $_: noop();
    }

    @return $message;
}

///
/// Wrapper mixin for the log function so it can be used with a more friendly
/// API than `@if im-log('..') {}` or `$_: im-log('..')`. Basically, use the function
/// within functions because it is not possible to include a mixin in a function
/// and use the mixin everywhere else because it's much more elegant.
///
/// @param {String} $message - Message to log
///
@mixin log($message) {
    @if im-log($message) {
    }
}

///
/// Function with no `@return` called next to `@warn` in Sass 3.3
/// to trigger a compiling error and stop the process.
///
@function noop() {
}

///
/// Determines whether a list of conditions is intercepted by the static breakpoint.
///
/// @param {Arglist}   $conditions  - Media query conditions
///
/// @return {Boolean} - Returns true if the conditions are intercepted by the static breakpoint
///
@function im-intercepts-static-breakpoint($conditions...) {
    $no-media-breakpoint-value: map-get($breakpoints, $im-no-media-breakpoint);

    @if not $no-media-breakpoint-value {
        @if im-log("`#{$im-no-media-breakpoint}` is not a valid breakpoint.") {
        }
    }

    @each $condition in $conditions {
        @if not map-has-key($media-expressions, $condition) {
            $operator: get-expression-operator($condition);
            $prefix: get-expression-prefix($operator);
            $value: get-expression-value($condition, $operator);

            @if ($prefix == "max" and $value <= $no-media-breakpoint-value) or ($prefix == "min" and $value > $no-media-breakpoint-value) {
                @return false;
            }
        } @else if not index($im-no-media-expressions, $condition) {
            @return false;
        }
    }

    @return true;
}

////
/// Parsing engine
/// @author Kitty Giraudel
/// @access private
////

///
/// Get operator of an expression
///
/// @param {String} $expression - Expression to extract operator from
///
/// @return {String} - Any of `>=`, `>`, `<=`, `<`, `≥`, `≤`
///
@function get-expression-operator($expression) {
    @each $operator in (">=", ">", "<=", "<", "≥", "≤") {
        @if str-index($expression, $operator) {
            @return $operator;
        }
    }

    // It is not possible to include a mixin inside a function, so we have to
    // rely on the `im-log(..)` function rather than the `log(..)` mixin. Because
    // functions cannot be called anywhere in Sass, we need to hack the call in
    // a dummy variable, such as `$_`. If anybody ever raise a scoping issue with
    // Sass 3.3, change this line in `@if im-log(..) {}` instead.
    $_: im-log("No operator found in `#{$expression}`.");
}

///
/// Get dimension of an expression, based on a found operator
///
/// @param {String} $expression - Expression to extract dimension from
/// @param {String} $operator - Operator from `$expression`
///
/// @return {String} - `width` or `height` (or potentially anything else)
///
@function get-expression-dimension($expression, $operator) {
    $operator-index: str-index($expression, $operator);
    $parsed-dimension: str-slice($expression, 0, $operator-index - 1);
    $dimension: "width";

    @if str-length($parsed-dimension) > 0 {
        $dimension: $parsed-dimension;
    }

    @return $dimension;
}

///
/// Get dimension prefix based on an operator
///
/// @param {String} $operator - Operator
///
/// @return {String} - `min` or `max`
///
@function get-expression-prefix($operator) {
    @return if(index(("<", "<=", "≤"), $operator), "max", "min");
}

///
/// Get value of an expression, based on a found operator
///
/// @param {String} $expression - Expression to extract value from
/// @param {String} $operator - Operator from `$expression`
///
/// @return {Number} - A numeric value
///
@function get-expression-value($expression, $operator) {
    $operator-index: str-index($expression, $operator);
    $value: str-slice($expression, $operator-index + str-length($operator));

    @if map-has-key($breakpoints, $value) {
        $value: map-get($breakpoints, $value);
    } @else {
        $value: to-number($value);
    }

    $interval: map-get($unit-intervals, unit($value));

    @if not $interval {
        // It is not possible to include a mixin inside a function, so we have to
        // rely on the `im-log(..)` function rather than the `log(..)` mixin. Because
        // functions cannot be called anywhere in Sass, we need to hack the call in
        // a dummy variable, such as `$_`. If anybody ever raise a scoping issue with
        // Sass 3.3, change this line in `@if im-log(..) {}` instead.
        $_: im-log("Unknown unit `#{unit($value)}`.");
    }

    @if $operator == ">" {
        $value: $value + $interval;
    } @else if $operator == "<" {
        $value: $value - $interval;
    }

    @return $value;
}

///
/// Parse an expression to return a valid media-query expression
///
/// @param {String} $expression - Expression to parse
///
/// @return {String} - Valid media query
///
@function parse-expression($expression) {
    // If it is part of $media-expressions, it has no operator
    // then there is no need to go any further, just return the value
    @if map-has-key($media-expressions, $expression) {
        @return map-get($media-expressions, $expression);
    }

    $operator: get-expression-operator($expression);
    $dimension: get-expression-dimension($expression, $operator);
    $prefix: get-expression-prefix($operator);
    $value: get-expression-value($expression, $operator);

    @return "(#{$prefix}-#{$dimension}: #{$value})";
}

///
/// Slice `$list` between `$start` and `$end` indexes
///
/// @access private
///
/// @param {List} $list - List to slice
/// @param {Number} $start [1] - Start index
/// @param {Number} $end [length($list)] - End index
///
/// @return {List} Sliced list
///
@function slice($list, $start: 1, $end: length($list)) {
    @if length($list) < 1 or $start > $end {
        @return ();
    }

    $result: ();

    @for $i from $start through $end {
        $result: append($result, nth($list, $i));
    }

    @return $result;
}

////
/// String to number converter
/// @author Kitty Giraudel
/// @access private
////

///
/// Casts a string into a number
///
/// @param {String | Number} $value - Value to be parsed
///
/// @return {Number}
///
@function to-number($value) {
    @if type-of($value) == "number" {
        @return $value;
    } @else if type-of($value) != "string" {
        $_: im-log("Value for `to-number` should be a number or a string.");
    }

    $first-character: str-slice($value, 1, 1);
    $result: 0;
    $digits: 0;
    $minus: ($first-character == "-");
    $numbers: (
        "0": 0,
        "1": 1,
        "2": 2,
        "3": 3,
        "4": 4,
        "5": 5,
        "6": 6,
        "7": 7,
        "8": 8,
        "9": 9,
    );

    // Remove +/- sign if present at first character
    @if ($first-character == "+" or $first-character == "-") {
        $value: str-slice($value, 2);
    }

    @for $i from 1 through str-length($value) {
        $character: str-slice($value, $i, $i);

        @if not(index(map-keys($numbers), $character) or $character == ".") {
            @return to-length(if($minus, -$result, $result), str-slice($value, $i));
        }

        @if $character == "." {
            $digits: 1;
        } @else if $digits == 0 {
            $result: $result * 10 + map-get($numbers, $character);
        } @else {
            $digits: $digits * 10;
            $result: $result + map-get($numbers, $character) / $digits;
        }
    }

    @return if($minus, -$result, $result);
}

///
/// Add `$unit` to `$value`
///
/// @param {Number} $value - Value to add unit to
/// @param {String} $unit - String representation of the unit
///
/// @return {Number} - `$value` expressed in `$unit`
///
@function to-length($value, $unit) {
    $units: (
        "px": 1px,
        "cm": 1cm,
        "mm": 1mm,
        "%": 1%,
        "ch": 1ch,
        "pc": 1pc,
        "in": 1in,
        "em": 1em,
        "rem": 1rem,
        "pt": 1pt,
        "ex": 1ex,
        "vw": 1vw,
        "vh": 1vh,
        "vmin": 1vmin,
        "vmax": 1vmax,
    );

    @if not index(map-keys($units), $unit) {
        $_: im-log("Invalid unit `#{$unit}`.");
    }

    @return $value * map-get($units, $unit);
}

///
/// This mixin aims at redefining the configuration just for the scope of
/// the call. It is helpful when having a component needing an extended
/// configuration such as custom breakpoints (referred to as tweakpoints)
/// for instance.
///
/// @author Kitty Giraudel
///
/// @param {Map} $tweakpoints [()] - Map of tweakpoints to be merged with `$breakpoints`
/// @param {Map} $tweak-media-expressions [()] - Map of tweaked media expressions to be merged with `$media-expression`
///
/// @example scss - Extend the global breakpoints with a tweakpoint
///  @include media-context(('custom': 678px)) {
///    .foo {
///      @include media('>phone', '<=custom') {
///       // ...
///      }
///    }
///  }
///
/// @example scss - Extend the global media expressions with a custom one
///  @include media-context($tweak-media-expressions: ('all': 'all')) {
///    .foo {
///      @include media('all', '>phone') {
///       // ...
///      }
///    }
///  }
///
/// @example scss - Extend both configuration maps
///  @include media-context(('custom': 678px), ('all': 'all')) {
///    .foo {
///      @include media('all', '>phone', '<=custom') {
///       // ...
///      }
///    }
///  }
///
@mixin media-context($tweakpoints: (), $tweak-media-expressions: ()) {
    // Save global configuration
    $global-breakpoints: $breakpoints;
    $global-media-expressions: $media-expressions;

    // Update global configuration
    $breakpoints: map-merge($breakpoints, $tweakpoints) !global;
    $media-expressions: map-merge($media-expressions, $tweak-media-expressions) !global;

    @content;

    // Restore global configuration
    $breakpoints: $global-breakpoints !global;
    $media-expressions: $global-media-expressions !global;
}

////
/// include-media public exposed API
/// @author Eduardo Boucas
/// @access public
////

///
/// Generates a media query based on a list of conditions
///
/// @param {Arglist}   $conditions  - Media query conditions
///
/// @example scss - With a single set breakpoint
///  @include media('>phone') { }
///
/// @example scss - With two set breakpoints
///  @include media('>phone', '<=tablet') { }
///
/// @example scss - With custom values
///  @include media('>=358px', '<850px') { }
///
/// @example scss - With set breakpoints with custom values
///  @include media('>desktop', '<=1350px') { }
///
/// @example scss - With a static expression
///  @include media('retina2x') { }
///
/// @example scss - Mixing everything
///  @include media('>=350px', '<tablet', 'retina3x') { }
///
@mixin media($conditions...) {
    @if ($im-media-support and length($conditions) == 0) or (not $im-media-support and im-intercepts-static-breakpoint($conditions...)) {
        @content;
    } @else if ($im-media-support and length($conditions) > 0) {
        @media #{unquote(parse-expression(nth($conditions, 1)))} {
            // Recursive call
            @include media(slice($conditions, 2)...) {
                @content;
            }
        }
    }
}
