@function sam-typography-level(
  $font-size,
  $line-height: $font-size,
  $font-weight: 400,
  $font-family: null,
  $letter-spacing: null
) {
  @return (
    font-size: $font-size,
    line-height: $line-height,
    font-weight: $font-weight,
    font-family: $font-family,
    letter-spacing: $letter-spacing
  );
}

// Defaults come from https://designsystem.digital.gov/components/typography/
@function sam-typography-config(
  $font-family: '"Source Sans Pro", "Helvetica Neue", "Helvetica", sans-serif',
  $heading-1: sam-typography-level(38px, 42px, 700, null, -1px),
  $heading-2: sam-typography-level(32px, 41px, 700, null, -0.8px),
  $heading-3: sam-typography-level(24px, 31px, 600),
  $heading-4: sam-typography-level(18px, 25px, 700),
  $lead: sam-typography-level(20px, 26px, 300, null, 0),
  $body: sam-typography-level(16px, 24px, 400),
  $body-strong: sam-typography-level(16px, 24px, 600),
  $small: sam-typography-level(15px, 22px, 400),
  $button: sam-typography-level(14px, 14px, 600),
  $input: sam-typography-level(inherit, 1.125, 400)
) {
  // Declare an initial map with all of the levels.
  $config: (
    heading-1: $heading-1,
    heading-2: $heading-2,
    heading-3: $heading-3,
    heading-4: $heading-4,
    lead: $lead,
    body: $body,
    body-strong: $body-strong,
    small: $small,
    button: $button,
    input: $input,
  );

  // Loop through the levels and set the `font-family` of the ones that don't have one to the base.
  // Note that Sass can't modify maps in place, which means that we need to merge and re-assign.
  @each $key, $level in $config {
    @if map-get($level, font-family) == null {
      $new-level: map-merge(
        $level,
        (
          font-family: $font-family,
        )
      );
      $config: map-merge(
        $config,
        (
          $key: $new-level,
        )
      );
    }
  }

  // Add the base font family to the config.
  @return map-merge(
    $config,
    (
      font-family: $font-family,
    )
  );
}

// Adds the base typography styles, based on a config.
@mixin sam-base-typography($config, $selector: ".sam-typography") {
  h1.sam.heading,
  .sam.h1,
  #{$selector} h1 {
    @include sam-typography-level-to-styles($config, heading-1);
    padding: 25px 0 20px;
    margin: 0;
    .intro {
      @include sam-typography-level-to-styles($config, body);
      letter-spacing: 0;
      text-transform: uppercase;
      display: block;
      margin-bottom: 5px;
    }
  }

  h2.sam.heading,
  .sam.h2,
  #{$selector} h2 {
    @include sam-typography-level-to-styles($config, heading-2);
    padding: 20px 0 15px;
    margin: 0;
  }

  h3.sam.heading,
  .sam.h3,
  #{$selector} h3 {
    @include sam-typography-level-to-styles($config, heading-3);
    padding: 15px 0 10px;
    margin: 0;
  }

  h4.sam.heading,
  .sam.h4,
  #{$selector} h4 {
    @include sam-typography-level-to-styles($config, heading-4);
    padding: 10px 0 5px;
    margin: 0;
  }

  .sam.lead {
    @include sam-typography-level-to-styles($config, lead);
    padding-bottom: 30px !important;
    margin: 0;
  }

  html {
    font-family: "Source Sans Pro";
  }

  body {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
  }

  p {
    @include sam-typography-level-to-styles($config, body);
    padding-bottom: 15px !important;
    margin: 0;
  }

  b,
  strong {
    font-weight: 600;
  }

  a {
    font-weight: 400;
    text-decoration: none;
    cursor: pointer;
  }

  a:hover {
    text-decoration: underline;
  }

  .sam.body,
  #{$selector} {
    @include sam-typography-level-to-styles($config, body);

    p {
      margin: 0 0 12px;
    }
  }

  .sam.small {
    @include sam-typography-level-to-styles($config, small);
  }
}