* @access private
 *
 * @param array $args {
 *     Optional. An associative array of values to calculate a fluid formula
 *     for font size. Default is empty array.
 *
 *     @type string $maximum_viewport_width Maximum size up to which type will have fluidity.
 *     @type string $minimum_viewport_width Minimum viewport size from which type will have fluidity.
 *     @type string $maximum_font_size      Maximum font size for any clamp() calculation.
 *     @type string $minimum_font_size      Minimum font size for any clamp() calculation.
 *     @type int    $scale_factor           A scale factor to determine how fast a font scales within boundaries.
 * }
 * @return string|null A font-size value using clamp() on success, otherwise null.
 */
function wp_get_computed_fluid_typography_value( $args = array() ) {
	$maximum_viewport_width_raw = isset( $args['maximum_viewport_width'] ) ? $args['maximum_viewport_width'] : null;
	$minimum_viewport_width_raw = isset( $args['minimum_viewport_width'] ) ? $args['minimum_viewport_width'] : null;
	$maximum_font_size_raw      = isset( $args['maximum_font_size'] ) ? $args['maximum_font_size'] : null;
	$minimum_font_size_raw      = isset( $args['minimum_font_size'] ) ? $args['minimum_font_size'] : null;
	$scale_factor               = isset( $args['scale_factor'] ) ? $args['scale_factor'] : null;

	// Normalizes the minimum font size in order to use the value for calculations.
	$minimum_font_size = wp_get_typography_value_and_unit( $minimum_font_size_raw );

	/*
	 * We get a 'preferred' unit to keep units consistent when calculating,
	 * otherwise the result will not be accurate.
	 */
	$font_size_unit = isset( $minimum_font_size['unit'] ) ? $minimum_font_size['unit'] : 'rem';

	// Normalizes the maximum font size in order to use the value for calculations.
	$maximum_font_size = wp_get_typography_value_and_unit(
		$maximum_font_size_raw,
		array(
			'coerce_to' => $font_size_unit,
		)
	);

	// Checks for mandatory min and max sizes, and protects against unsupported units.
	if ( ! $maximum_font_size || ! $minimum_font_size ) {
		return null;
	}

	// Uses rem for accessible fluid target font scaling.
	$minimum_font_size_rem = wp_get_typography_value_and_unit(
		$minimum_font_size_raw,
		array(
			'coerce_to' => 'rem',
		)
	);

	// Viewport widths defined for fluid typography. Normalize units.
	$maximum_viewport_width = wp_get_typography_value_and_unit(
		$maximum_viewport_width_raw,
		array(
			'coerce_to' => $font_size_unit,
		)
	);
	$minimum_viewport_width = wp_get_typography_value_and_unit(
		$minimum_viewport_width_raw,
		array(
			'coerce_to' => $font_size_unit,
		)
	);

	// Protects against unsupported units in min and max viewport widths.
	if ( ! $minimum_viewport_width || ! $maximum_viewport_width ) {
		return null;
	}

	/*
	 * Build CSS rule.
	 * Borrowed from https://websemantics.uk/tools/responsive-font-calculator/.
	 */
	$view_port_width_offset = round( $minimum_viewport_width['value'] / 100, 3 ) . $font_size_unit;
	$linear_factor          = 100 * ( ( $maximum_font_size['value'] - $minimum_font_size['value'] ) / ( $maximum_viewport_width['value'] - $minimum_viewport_width['value'] ) );
	$linear_factor_scaled   = round( $linear_factor * $scale_factor, 3 );
	$linear_factor_scaled   = empty( $linear_factor_scaled ) ? 1 : $linear_factor_scaled;
	$fluid_target_font_size = implode( '', $minimum_font_size_rem ) . " + ((1vw - $view_port_width_offset) * $linear_factor_scaled)";

	return "clamp($minimum_font_size_raw, $fluid_target_font_size, $maximum_font_size_raw)";
}

/**
 * Returns a font-size value based on a given font-size preset.
 * Takes into account fluid typography parameters and attempts to return a CSS
 * formula depending on available, valid values.
 *
 * @since 6.1.0
 * @since 6.1.1 Adjusted rules for min and max font sizes.
 * @since 6.2.0 Added 'settings.typography.fluid.minFontSize' support.
 * @since 6.3.0 Using layout.wideSize as max viewport width, and logarithmic scale factor to calculate minimum font scale.
 * @since 6.4.0 Added configurable min and max viewport width values to the typography.fluid theme.json schema.
 *
 * @param array $preset                     {
 *     Required. fontSizes preset value as seen in theme.json.
 *
 *     @type string           $name Name of the font size preset.
 *     @type string           $slug Kebab-case, unique identifier for the font size preset.
 *     @type string|int|float $size CSS font-size value, including units if applicable.
 * }
 * @param bool  $should_use_fluid_typography An override to switch fluid typography "on". Can be used for unit testing.
 *                                           Default is false.
 * @return string|null Font-size value or null if a size is not passed in $preset.
 */
function wp_get_typography_font_size_value( $preset, $should_use_fluid_typography = false ) {
	if ( ! isset( $preset['size'] ) ) {
		return null;
	}

	/*
	 * Catches empty values and 0/'0'.
	 * Fluid calculations cannot be performed on 0.
	 */
	if ( empty( $preset['size'] ) ) {
		return $preset['size'];
	}

	// Checks if fluid font sizes are activated.
	$global_settings     = wp_get_global_settings();
	$typography_settings = isset( $global_settings['typography'] ) ? $global_settings['typography'] : array();
	$layout_settings     = isset( $global_settings['layout'] ) ? $global_settings['layout'] : array();

	if (
		isset( $typography_settings['fluid'] ) &&
		( true === $typography_settings['fluid'] || is_array( $typography_settings['fluid'] ) )
	) {
		$should_use_fluid_typography = true;
	}

	if ( ! $should_use_fluid_typography ) {
		return $preset['size'];
	}

	$fluid_settings = isset( $typography_settings['fluid'] ) && is_array( $typography_settings['fluid'] )
		? $typography_settings['fluid']
		: array();

	// Defaults.
	$default_maximum_viewport_width       = '1600px';
	$default_minimum_viewport_width       = '320px';
	$default_minimum_font_size_factor_max = 0.75;
	$default_minimum_font_size_factor_min = 0.25;
	$default_scale_factor                 = 1;
	$default_minimum_font_size_limit      = '14px';

	// Defaults overrides.
	$minimum_viewport_width = isset( $fluid_settings['minViewportWidth'] ) ? $fluid_settings['minViewportWidth'] : $default_minimum_viewport_width;
	$maximum_viewport_width = isset( $layout_settings['wideSize'] ) && ! empty( wp_get_typography_value_and_unit( $layout_settings['wideSize'] ) ) ? $layout_settings['wideSize'] : $default_maximum_viewport_width;
	if ( isset( $fluid_settings['maxViewportWidth'] ) ) {
		$maximum_viewport_width = $fluid_settings['maxViewportWidth'];
	}
	$has_min_font_size       = isset( $fluid_settings['minFontSize'] ) && ! empty( wp_get_typography_value_and_unit( $fluid_settings['minFontSize'] ) );
	$minimum_font_size_limit = $has_min_font_size ? $fluid_settings['minFontSize'] : $default_minimum_font_size_limit;

	// Font sizes.
	$fluid_font_size_settings = isset( $preset['fluid'] ) ? $preset['fluid'] : null;

	// A font size has explicitly bypassed fluid calculations.
	if ( false === $fluid_font_size_settings ) {
		return $preset['size'];
	}

	// Try to grab explicit min and max fluid font sizes.
	$minimum_font_size_raw = isset( $fluid_font_size_settings['min'] ) ? $fluid_font_size_settings['min'] : null;
	$maximum_font_size_raw = isset( $fluid_font_size_settings['max'] ) ? $fluid_font_size_settings['max'] : null;

	// Font sizes.
	$preferred_size = wp_get_typography_value_and_unit( $preset['size'] );

	// Protects against unsupported units.
	if ( empty( $preferred_size['unit'] ) ) {
		return $preset['size'];
	}

	/*
	 * Normalizes the minimum font size limit according to the incoming unit,
	 * in order to perform comparative checks.
	 */
	$minimum_font_size_limit = wp_get_typography_value_and_unit(
		$minimum_font_size_limit,
		array(
			'coerce_to' => $preferred_size['unit'],
		)
	);

	// Don't enforce minimum font size if a font size has explicitly set a min and max value.
	if ( ! empty( $minimum_font_size_limit ) && ( ! $minimum_font_size_raw && ! $maximum_font_size_raw ) ) {
		/*
		 * If a minimum size was not passed to this function
		 * and the user-defined font size is lower than $minimum_font_size_limit,
		 * do not calculate a fluid value.
		 */
		if ( $preferred_size['value'] <= $minimum_font_size_limit['value'] ) {
			return $preset['size'];
		}
	}

	// If no fluid max font size is available use the incoming value.
	if ( ! $maximum_font_size_raw ) {
		$maximum_font_size_raw = $preferred_size['value'] . $preferred_size['unit'];
	}

	/*
	 * If no minimumFontSize is provided, create one using
	 * the given font size multiplied by the min font size scale factor.
	 */
	if ( ! $minimum_font_size_raw ) {
		$preferred_font_size_in_px = 'px' === $preferred_size['unit'] ? $preferred_size['value'] : $preferred_size['value'] * 16;

		/*
		 * The scale factor is a multiplier that affects how quickly the curve will move towards the minimum,
		 * that is, how quickly the size factor reaches 0 given increasing font size values.
		 * For a - b * log2(), lower values of b will make the curve move towards the minimum faster.
		 * The scale factor is constrained between min and max values.
		 */
		$minimum_font_size_factor     = min( max( 1 - 0.075 * log( $preferred_font_size_in_px, 2 ), $default_minimum_font_size_factor_min ), $default_minimum_font_size_factor_max );
		$calculated_minimum_font_size = round( $preferred_size['value'] * $minimum_font_size_factor, 3 );

		// Only use calculated min font size if it's > $minimum_font_size_limit value.
		if ( ! empty( $minimum_font_size_limit ) && $calculated_minimum_font_size <= $minimum_font_size_limit['value'] ) {
			$minimum_font_size_raw = $minimum_font_size_limit['value'] . $minimum_font_size_limit['unit'];
		} else {
			$minimum_font_size_raw = $calculated_minimum_font_size . $preferred_size['unit'];
		}
	}

	$fluid_font_size_value = wp_get_computed_fluid_typography_value(
		array(
			'minimum_viewport_width' => $minimum_viewport_width,
			'maximum_viewport_width' => $maximum_viewport_width,
			'minimum_font_size'      => $minimum_font_size_raw,
			'maximum_font_size'      => $maximum_font_size_raw,
			'scale_factor'           => $default_scale_factor,
		)
	);

	if ( ! empty( $fluid_font_size_value ) ) {
		return $fluid_font_size_value;
	}

	return $preset['size'];
}

// Register the block support.
WP_Block_Supports::get_instance()->register(
	'typography',
	array(
		'register_attribute' => 'wp_register_typography_support',
		'apply'              => 'wp_apply_typography_support',
	)
);