<?php
// Don't load directly
defined( 'WPINC' ) or die;

/**
 * A color utility that helps manipulate HEX colors
 *
 * @package Common
 * @since 4.3
 *
 * @since 4.14.2 Added get_hex_with_hash function.
 */

/**
 * Author: Arlo Carreon <http://arlocarreon.com>
 * Info: http://mexitek.github.io/phpColors/
 */

/**
 * PHP 5.2 Compatibility
 * Author: Gustavo Bordoni <http://twitter.com/webord>
 */

class Tribe__Utils__Color {

	private $_hex;
	private $_hsl;
	private $_rgb;

	/**
	 * Auto darkens/lightens by 10% for sexily-subtle gradients.
	 * Set this to FALSE to adjust automatic shade to be between given color
	 * and black (for darken) or white (for lighten)
	 */
	const DEFAULT_ADJUST = 10;

	/**
	 * Instantiates the class with a HEX value
	 * @param string $hex
	 * @throws Exception "Bad color format"
	 */
	public function __construct( $hex ) {
		// Strip # sign is present
		$color = str_replace( '#', '', $hex );

		// Make sure it's 6 digits
		if ( strlen( $color ) === 3 ) {
			$color = preg_replace( '/(.)(.)(.)/', '$1$1$2$2$3$3', $color );
		} elseif ( strlen( $color ) != 6 ) {
			throw new Exception( 'HEX color needs to be 6 or 3 digits long' );
		}

		$this->_hsl = self::hexToHsl( $color );
		$this->_hex = $color;
		$this->_rgb = self::hexToRgb( $color );
	}

	// ====================
	// = Public Interface =
	// ====================

	/**
	 * Given a HEX string returns a HSL array equivalent.
	 * @param string $color
	 * @return array HSL associative array
	 */
	public static function hexToHsl( $color ) {

		// Sanity check
		$color = self::_checkHex( $color );

		// Convert HEX to DEC
		$R = hexdec( $color[0] . $color[1] );
		$G = hexdec( $color[2] . $color[3] );
		$B = hexdec( $color[4] . $color[5] );

		$HSL = [];

		$var_R = ( $R / 255 );
		$var_G = ( $G / 255 );
		$var_B = ( $B / 255 );

		$var_Min = min( $var_R, $var_G, $var_B );
		$var_Max = max( $var_R, $var_G, $var_B );
		$del_Max = $var_Max - $var_Min;

		$L = ( $var_Max + $var_Min ) / 2;

		if ( 0 == $del_Max ) {
			$H = 0;
			$S = 0;
		} else {
			if ( $L < 0.5 ) {
				$S = $del_Max / ( $var_Max + $var_Min );
			} else {
				$S = $del_Max / ( 2 - $var_Max - $var_Min );
			}

			$del_R = ( ( ( $var_Max - $var_R ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
			$del_G = ( ( ( $var_Max - $var_G ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
			$del_B = ( ( ( $var_Max - $var_B ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;

			if ( $var_R == $var_Max ) {
				$H = $del_B - $del_G;
			} elseif ( $var_G == $var_Max ) {
				$H = ( 1 / 3 ) + $del_R - $del_B;
			} elseif ( $var_B == $var_Max ) {
				$H = ( 2 / 3 ) + $del_G - $del_R;
			}

			if ( $H < 0 ) {
				$H++;
			}
			if ( $H > 1 ) {
				$H--;
			}
		}

		$HSL['H'] = ( $H * 360 );
		$HSL['S'] = $S;
		$HSL['L'] = $L;

		return $HSL;
	}

	/**
	 *  Given a HSL associative array returns the equivalent HEX string
	 * @param array $hsl
	 * @return string HEX string
	 * @throws Exception "Bad HSL Array"
	 */
	public static function hslToHex( $hsl = [] ) {
		// Make sure it's HSL
		if ( empty( $hsl ) || ! isset( $hsl['H'] ) || ! isset( $hsl['S'] ) || ! isset( $hsl['L'] ) ) {
			throw new Exception( 'Param was not an HSL array' );
		}

		list( $H, $S, $L ) = [ $hsl['H'] / 360, $hsl['S'], $hsl['L'] ];

		if ( 0 == $S ) {
			$r = $L * 255;
			$g = $L * 255;
			$b = $L * 255;
		} else {
			if ( $L < 0.5 ) {
				$var_2 = $L * ( 1 + $S );
			} else {
				$var_2 = ( $L + $S ) - ( $S * $L );
			}

			$var_1 = 2 * $L - $var_2;

			$r = round( 255 * self::_huetorgb( $var_1, $var_2, $H + ( 1 / 3 ) ) );
			$g = round( 255 * self::_huetorgb( $var_1, $var_2, $H ) );
			$b = round( 255 * self::_huetorgb( $var_1, $var_2, $H - ( 1 / 3 ) ) );

		}

		// Convert to hex
		$r = dechex( $r );
		$g = dechex( $g );
		$b = dechex( $b );

		// Make sure we get 2 digits for decimals
		$r = ( strlen( '' . $r ) === 1 ) ? '0' . $r : $r;
		$g = ( strlen( '' . $g ) === 1 ) ? '0' . $g : $g;
		$b = ( strlen( '' . $b ) === 1 ) ? '0' . $b : $b;

		return $r.$g.$b;
	}

	/**
	 * Given a HEX string returns a RGB array equivalent.
	 * @param string $color
	 * @return array RGB associative array
	 */
	public static function hexToRgb( $color ) {

		// Sanity check
		$color = self::_checkHex( $color );

		// Convert HEX to DEC
		$R = hexdec( $color[0] . $color[1] );
		$G = hexdec( $color[2] . $color[3] );
		$B = hexdec( $color[4] . $color[5] );

		$RGB['R'] = $R;
		$RGB['G'] = $G;
		$RGB['B'] = $B;

		return $RGB;
	}

	/**
	 *  Given an RGB associative array returns the equivalent HEX string
	 * @param array $rgb
	 * @return string RGB string
	 * @throws Exception "Bad RGB Array"
	 */
	public static function rgbToHex( $rgb = [] ) {
		// Make sure it's RGB
		if ( empty( $rgb ) || ! isset( $rgb['R'] ) || ! isset( $rgb['G'] ) || ! isset( $rgb['B'] ) ) {
			throw new Exception( 'Param was not an RGB array' );
		}

		// Convert RGB to HEX
		$hex[0] = dechex( $rgb['R'] );
		$hex[1] = dechex( $rgb['G'] );
		$hex[2] = dechex( $rgb['B'] );

		return implode( '', $hex );
	}

	/**
	 * Given a HEX value, returns a darker color. If no desired amount provided, then the color halfway between
	 * given HEX and black will be returned.
	 * @param int $amount
	 * @return string Darker HEX value
	 */
	public function darken( $amount = self::DEFAULT_ADJUST ) {
		// Darken
		$darkerHSL = $this->_darken( $this->_hsl, $amount );
		// Return as HEX
		return self::hslToHex( $darkerHSL );
	}

	/**
	 * Given a HEX value, returns a lighter color. If no desired amount provided, then the color halfway between
	 * given HEX and white will be returned.
	 * @param int $amount
	 * @return string Lighter HEX value
	 */
	public function lighten( $amount = self::DEFAULT_ADJUST ) {
		// Lighten
		$lighterHSL = $this->_lighten( $this->_hsl, $amount );
		// Return as HEX
		return self::hslToHex( $lighterHSL );
	}

	/**
	 * Given a HEX value, returns a mixed color. If no desired amount provided, then the color mixed by this ratio
	 * @param string $hex2 Secondary HEX value to mix with
	 * @param int $amount = -100..0..+100
	 * @return string mixed HEX value
	 */
	public function mix( $hex2, $amount = 0 ) {
		$rgb2 = self::hexToRgb( $hex2 );
		$mixed = $this->_mix( $this->_rgb, $rgb2, $amount );

		// Return as HEX
		return self::rgbToHex( $mixed );
	}

	/**
	 * Creates an array with two shades that can be used to make a gradient
	 * @param int $amount Optional percentage amount you want your contrast color
	 * @return array An array with a 'light' and 'dark' index
	 */
	public function makeGradient( $amount = self::DEFAULT_ADJUST ) {
		// Decide which color needs to be made
		if ( $this->isLight() ) {
			$lightColor = $this->_hex;
			$darkColor = $this->darken( $amount );
		} else {
			$lightColor = $this->lighten( $amount );
			$darkColor = $this->_hex;
		}

		// Return our gradient array
		return [ 'light' => $lightColor, 'dark' => $darkColor ];
	}

	/**
	 * Returns whether or not given color is considered "light"
	 * @param string|Boolean $color
	 * @return boolean
	 */
	public function isLight( $color = false ) {
		// Get our color
		$color = ( $color ) ? $color : $this->_hex;

		// Calculate straight from rbg
		$r = hexdec( $color[0] . $color[1] );
		$g = hexdec( $color[2] . $color[3] );
		$b = hexdec( $color[4] . $color[5] );

		return ( ( $r * 299 + $g * 587 + $b * 114 ) / 1000 > 130 );
	}

	/**
	 * Returns whether or not a given color is considered "dark"
	 * @param string|Boolean $color
	 * @return boolean
	 */
	public function isDark( $color = false ) {
		// Get our color
		$color = ( $color ) ? $color:$this->_hex;

		// Calculate straight from rbg
		$r = hexdec( $color[0] . $color[1] );
		$g = hexdec( $color[2] . $color[3] );
		$b = hexdec( $color[4] . $color[5] );

		return ( ( $r * 299 + $g * 587 + $b * 114 ) / 1000 <= 130 );
	}

	/**
	 * Returns the complimentary color
	 * @return string Complementary hex color
	 *
	 */
	public function complementary() {
		// Get our HSL
		$hsl = $this->_hsl;

		// Adjust Hue 180 degrees
		$hsl['H'] += ( $hsl['H'] > 180 ) ? -180 : 180;

		// Return the new value in HEX
		return self::hslToHex( $hsl );
	}

	/**
	 * Returns your color's HSL array
	 */
	public function getHsl() {
		return $this->_hsl;
	}

	/**
	 * Returns your original color minus any hash mark.
	 */
	public function getHex() {
		return $this->_hex;
	}

	/**
	 * Returns your original color with the hash mark.
	 *
	 * @since 4.14.2
	 *
	 * @return string Hex color code with hash prefix.
	 */
	public function get_hex_with_hash() {
		return '#' . $this->_hex;
	}

	/**
	 * Returns your color's RGB array
	 */
	public function getRgb() {
		return $this->_rgb;
	}

	/**
	 * Returns the cross browser CSS3 gradient
	 * @param int $amount Optional: percentage amount to light/darken the gradient
	 * @param boolean $vintageBrowsers Optional: include vendor prefixes for browsers that almost died out already
	 * @param string $prefix Optional: prefix for every lines
	 * @param string $suffix Optional: suffix for every lines
	 * @link  http://caniuse.com/css-gradients Resource for the browser support
	 * @return string CSS3 gradient for chrome, safari, firefox, opera and IE10
	 */
	public function getCssGradient( $amount = self::DEFAULT_ADJUST, $vintageBrowsers = false, $suffix = '', $prefix = '' ) {

		// Get the recommended gradient
		$g = $this->makeGradient( $amount );

		$css = '';
		/* fallback/image non-cover color */
		$css .= "{$prefix}background-color: #".$this->_hex.";{$suffix}";

		/* IE Browsers */
		$css .= "{$prefix}filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#".$g['light']."', endColorstr='#".$g['dark']."');{$suffix}";

		/* Safari 4+, Chrome 1-9 */
		if ( $vintageBrowsers ) {
			$css .= "{$prefix}background-image: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#{$g['light']}), to(#{$g['dark']}));{$suffix}";
		}

		/* Safari 5.1+, Mobile Safari, Chrome 10+ */
		$css .= "{$prefix}background-image: -webkit-linear-gradient(top, #{$g['light']}, #{$g['dark']});{$suffix}";

		/* Firefox 3.6+ */
		if ( $vintageBrowsers ) {
			$css .= "{$prefix}background-image: -moz-linear-gradient(top, #{$g['light']}, #{$g['dark']});{$suffix}";
		}

		/* Opera 11.10+ */
		if ( $vintageBrowsers ) {
			$css .= "{$prefix}background-image: -o-linear-gradient(top, #{$g['light']}, #{$g['dark']});{$suffix}";
		}

		/* Unprefixed version (standards): FF 16+, IE10+, Chrome 26+, Safari 7+, Opera 12.1+ */
		$css .= "{$prefix}background-image: linear-gradient(to bottom, #{$g['light']}, #{$g['dark']});{$suffix}";

		// Return our CSS
		return $css;
	}

	// ===========================
	// = Private Functions Below =
	// ===========================


	/**
	 * Darkens a given HSL array
	 * @param array $hsl
	 * @param int $amount
	 * @return array $hsl
	 */
	private function _darken( $hsl, $amount = self::DEFAULT_ADJUST ) {
		// Check if we were provided a number
		if ( $amount ) {
			$hsl['L'] = ( $hsl['L'] * 100 ) - $amount;
			$hsl['L'] = ( $hsl['L'] < 0 ) ? 0 : $hsl['L'] / 100;
		} else {
			// We need to find out how much to darken
			$hsl['L'] = $hsl['L'] / 2 ;
		}

		return $hsl;
	}

	/**
	 * Lightens a given HSL array
	 * @param array $hsl
	 * @param int $amount
	 * @return array $hsl
	 */
	private function _lighten( $hsl, $amount = self::DEFAULT_ADJUST ) {
		// Check if we were provided a number
		if ( $amount ) {
			$hsl['L'] = ( $hsl['L'] * 100 ) + $amount;
			$hsl['L'] = ( $hsl['L'] > 100 ) ? 1 : $hsl['L'] / 100;
		} else {
			// We need to find out how much to lighten
			$hsl['L'] += ( 1 - $hsl['L'] ) / 2;
		}

		return $hsl;
	}

	/**
	 * Mix 2 rgb colors and return an rgb color
	 * @param array $rgb1
	 * @param array $rgb2
	 * @param int $amount ranged -100..0..+100
	 * @return array $rgb
	 *
	 * 	ported from http://phpxref.pagelines.com/nav.html?includes/class.colors.php.source.html
	 */
	private function _mix( $rgb1, $rgb2, $amount = 0 ) {

		 $r1 = ( $amount + 100 ) / 100;
		 $r2 = 2 - $r1;

		 $rmix = ( ( $rgb1['R'] * $r1 ) + ( $rgb2['R'] * $r2 ) ) / 2;
		 $gmix = ( ( $rgb1['G'] * $r1 ) + ( $rgb2['G'] * $r2 ) ) / 2;
		 $bmix = ( ( $rgb1['B'] * $r1 ) + ( $rgb2['B'] * $r2 ) ) / 2;

		return [ 'R' => $rmix, 'G' => $gmix, 'B' => $bmix ];
	}

	/**
	 * Given a Hue, returns corresponding RGB value
	 * @param int $v1
	 * @param int $v2
	 * @param int $vH
	 * @return int
	 */
	private static function _huetorgb( $v1, $v2, $vH ) {
		if ( $vH < 0 ) {
			$vH += 1;
		}

		if ( $vH > 1 ) {
			$vH -= 1;
		}

		if ( ( 6 * $vH ) < 1 ) {
			   return ( $v1 + ( $v2 - $v1 ) * 6 * $vH );
		}

		if ( ( 2 * $vH ) < 1 ) {
			return $v2;
		}

		if ( ( 3 * $vH ) < 2 ) {
			return ( $v1 + ( $v2 - $v1 ) * ( ( 2 / 3 ) - $vH ) * 6 );
		}

		return $v1;

	}

	/**
	 * You need to check if you were given a good hex string
	 * @param string $hex
	 * @return string Color
	 * @throws Exception "Bad color format"
	 */
	private static function _checkHex( $hex ) {
		// Strip # sign is present
		$color = str_replace( '#', '', $hex );

		// Make sure it's 6 digits
		if ( strlen( $color ) == 3 ) {
			$color = $color[0] . $color[0] . $color[1] . $color[1] . $color[2] . $color[2];
		} elseif ( strlen( $color ) != 6 ) {
			throw new Exception( 'HEX color needs to be 6 or 3 digits long' );
		}

		return $color;
	}
}
