<?php
/**
 * Design presets and theme sanitizing.
 *
 * @package Fillaro
 */

namespace Fillaro\Forms;

defined( 'ABSPATH' ) || exit;

/**
 * A theme is a flat set of design tokens rendered as CSS custom properties.
 */
class Theme {

	/**
	 * Built-in presets.
	 *
	 * @return array<string,array>
	 */
	public static function presets() {
		$presets = array(
			'clean'    => array(
				'label'       => __( 'Clean', 'fillaro' ),
				'primary'     => '#4f46e5',
				'background'  => '#ffffff',
				'field'       => '#ffffff',
				'text'        => '#111827',
				'border'      => '#d1d5db',
				'radius'      => 8,
				'inputStyle'  => 'outlined',
				'buttonStyle' => 'solid',
				'font'        => 'inherit',
				'container'   => 'card',
			),
			'soft'     => array(
				'label'       => __( 'Soft', 'fillaro' ),
				'primary'     => '#db2777',
				'background'  => '#fff1f5',
				'field'       => '#ffffff',
				'text'        => '#3f3f46',
				'border'      => '#fbcfe8',
				'radius'      => 16,
				'inputStyle'  => 'filled',
				'buttonStyle' => 'pill',
				'font'        => 'rounded',
				'container'   => 'card',
			),
			'forest'   => array(
				'label'       => __( 'Forest', 'fillaro' ),
				'primary'     => '#15803d',
				'background'  => '#f3faf5',
				'field'       => '#ffffff',
				'text'        => '#14281d',
				'border'      => '#bfdcc8',
				'radius'      => 10,
				'inputStyle'  => 'outlined',
				'buttonStyle' => 'solid',
				'font'        => 'serif',
				'container'   => 'card',
			),
			'minimal'  => array(
				'label'       => __( 'Minimal', 'fillaro' ),
				'primary'     => '#111111',
				'background'  => '#ffffff',
				'field'       => '#ffffff',
				'text'        => '#111111',
				'border'      => '#bdbdbd',
				'radius'      => 0,
				'inputStyle'  => 'underline',
				'buttonStyle' => 'solid',
				'font'        => 'inherit',
				'container'   => 'plain',
			),
			'sunset'   => array(
				'label'       => __( 'Sunset', 'fillaro' ),
				'primary'     => '#ea580c',
				'background'  => '#fff8f1',
				'field'       => '#fffdfa',
				'text'        => '#431407',
				'border'      => '#fed7aa',
				'radius'      => 12,
				'inputStyle'  => 'outlined',
				'buttonStyle' => 'pill',
				'font'        => 'system',
				'container'   => 'card',
			),
			'midnight' => array(
				'label'       => __( 'Midnight', 'fillaro' ),
				'primary'     => '#38bdf8',
				'background'  => '#0f172a',
				'field'       => '#1e293b',
				'text'        => '#e2e8f0',
				'border'      => '#334155',
				'radius'      => 10,
				'inputStyle'  => 'filled',
				'buttonStyle' => 'solid',
				'font'        => 'system',
				'container'   => 'card',
			),
		);

		/**
		 * Filters the design presets.
		 *
		 * @param array $presets Presets keyed by id.
		 */
		return apply_filters( 'fillaro/theme_presets', $presets );
	}

	/**
	 * Default theme tokens.
	 *
	 * @return array
	 */
	public static function defaults() {
		$clean = self::presets()['clean'];
		unset( $clean['label'] );
		return array_merge(
			array(
				'preset'   => 'clean',
				'fontSize' => 16,
				'spacing'  => 'comfortable',
				'maxWidth' => 640,
			),
			$clean
		);
	}

	/**
	 * Sanitize theme tokens.
	 *
	 * @param mixed $raw Raw tokens.
	 * @return array
	 */
	public static function sanitize( $raw ) {
		$raw   = is_array( $raw ) ? $raw : array();
		$d     = self::defaults();
		$pick  = static function ( $key, array $allowed ) use ( $raw, $d ) {
			return ( isset( $raw[ $key ] ) && in_array( $raw[ $key ], $allowed, true ) ) ? $raw[ $key ] : $d[ $key ];
		};
		$color = static function ( $key ) use ( $raw, $d ) {
			$c = isset( $raw[ $key ] ) ? sanitize_hex_color( (string) $raw[ $key ] ) : '';
			return $c ? $c : $d[ $key ];
		};
		$int   = static function ( $key, $min, $max ) use ( $raw, $d ) {
			return isset( $raw[ $key ] ) && is_numeric( $raw[ $key ] ) ? max( $min, min( $max, (int) $raw[ $key ] ) ) : $d[ $key ];
		};

		return array(
			'preset'      => ( isset( $raw['preset'] ) && is_string( $raw['preset'] ) ) ? sanitize_key( $raw['preset'] ) : $d['preset'],
			'primary'     => $color( 'primary' ),
			'background'  => $color( 'background' ),
			'field'       => $color( 'field' ),
			'text'        => $color( 'text' ),
			'border'      => $color( 'border' ),
			'radius'      => $int( 'radius', 0, 32 ),
			'fontSize'    => $int( 'fontSize', 13, 22 ),
			'maxWidth'    => $int( 'maxWidth', 320, 1200 ),
			'spacing'     => $pick( 'spacing', array( 'compact', 'comfortable', 'spacious' ) ),
			'inputStyle'  => $pick( 'inputStyle', array( 'outlined', 'filled', 'underline' ) ),
			'buttonStyle' => $pick( 'buttonStyle', array( 'solid', 'outline', 'pill' ) ),
			'font'        => $pick( 'font', array( 'inherit', 'system', 'serif', 'rounded', 'mono' ) ),
			'container'   => $pick( 'container', array( 'card', 'plain' ) ),
		);
	}

	/**
	 * CSS custom properties for a theme.
	 *
	 * @param array $theme Clean theme.
	 * @return string Inline style value.
	 */
	public static function to_style( array $theme ) {
		$fonts = array(
			'inherit' => 'inherit',
			'system'  => 'system-ui, -apple-system, "Segoe UI", Roboto, sans-serif',
			'serif'   => 'Georgia, "Iowan Old Style", "Times New Roman", serif',
			'rounded' => 'ui-rounded, "SF Pro Rounded", "Nunito", system-ui, sans-serif',
			'mono'    => 'ui-monospace, "SF Mono", Menlo, Consolas, monospace',
		);
		$gaps  = array(
			'compact'     => '14px',
			'comfortable' => '20px',
			'spacious'    => '28px',
		);

		$vars = array(
			'--pf-primary'    => $theme['primary'],
			'--pf-on-primary' => self::readable_on( $theme['primary'] ),
			'--pf-bg'         => $theme['background'],
			'--pf-field'      => $theme['field'],
			'--pf-text'       => $theme['text'],
			'--pf-border'     => $theme['border'],
			'--pf-radius'     => $theme['radius'] . 'px',
			'--pf-font'       => $fonts[ $theme['font'] ],
			'--pf-font-size'  => $theme['fontSize'] . 'px',
			'--pf-gap'        => $gaps[ $theme['spacing'] ],
			'--pf-max-width'  => $theme['maxWidth'] . 'px',
		);

		$style = '';
		foreach ( $vars as $name => $value ) {
			$style .= $name . ':' . $value . ';';
		}
		return $style;
	}

	/**
	 * Black or white, whichever reads better on a background color.
	 *
	 * @param string $hex Hex color.
	 * @return string
	 */
	public static function readable_on( $hex ) {
		$hex = ltrim( $hex, '#' );
		if ( 3 === strlen( $hex ) ) {
			$hex = $hex[0] . $hex[0] . $hex[1] . $hex[1] . $hex[2] . $hex[2];
		}
		$channels = array();
		foreach ( array( 0, 2, 4 ) as $offset ) {
			$c          = hexdec( substr( $hex, $offset, 2 ) ) / 255;
			$channels[] = $c <= 0.03928 ? $c / 12.92 : pow( ( $c + 0.055 ) / 1.055, 2.4 );
		}
		$lum = 0.2126 * $channels[0] + 0.7152 * $channels[1] + 0.0722 * $channels[2];
		// White text reads well on saturated brand colors; switch to dark text
		// only when white falls below 3:1 (the WCAG ratio for bold UI text).
		return ( 1.05 / ( $lum + 0.05 ) ) >= 3 ? '#ffffff' : '#111111';
	}
}