@use 'sass:list';
@use 'sass:map';
@use 'sass:meta';
////
/// @group modules.typography
////

@use '../utils' as *;
@use 'config' as *;
@use 'misc' as *;
@use 'rems' as *;

// ---------------------------------------------------------------------------
// API
// ---------------------------------------------------------------------------

/// Get a font-size by name from the default typescale
///
/// @param {String or Number} $name The name or offset of the size to lookup. Must be defined in the
/// config $typescale variable.
///
/// @example
/// config(typescale, (sm: 14px, base: 15px, lg: 18px, xl: 20px));
///
/// font-size: fs(base)   // => font-size: 15px
/// font-size: fs(sm)     // => font-size: 14px
/// font-size: fs(-1)     // => font-size: 14px
/// font-size: fs(2)      // => font-size: 20px

@function fs($lookup: 'base', $use-rems: null) {
    $sizes: get('typography.type-sizes');
    $use-rems-default: get('typography.use-rems');
    $use-rems: if-null($use-rems, $use-rems-default);

    // if lookup is a string, find the size by name

    @if (meta.type-of($lookup) == 'string') {
        $size: map.get($sizes, $lookup);

        @if ($size) {
            @if (is-list($size)) {
                // if size is a map, use it with scale-vw (use-rems is ignored)
                $from: list.nth($size, 1);

                $to: list.nth($size, 2);
                $at-width: nth-or-val($size, 3, null);

                @return scale-vw($from, $to, $at-width);
            }

            @if ($use-rems) {
                @return rems($size);
            }

            @return $size;
        }

        @error '[fs] Could not find a size named #{$lookup} in the typescale.';
    }

    // if lookup is a number, find the size as an offset from the 'base' size (e.g
    // fs(2) would return the size that is two larger than the base)

    @if (meta.type-of($lookup) == 'number') {
        $sizes: get('typography.type-sizes');

        $names: map.keys($sizes);
        $base-index: list.index($names, 'base');

        @if ($base-index == null) {
            @error '[fs] The typescale must contain a size named "base".';
        }

        $name-index: $base-index + $lookup;

        @if ($name-index < 1 or $name-index > list.length($names)) {
            @error '[fs] The requested lookup index exceeds the boundares of the typescale.';
        }

        @return fs(list.nth($names, $name-index));
    }

    @error '[fs] Argument is unusable. Must be a string or a number.';
}