<?php

/**
 * Author: Arlo Carreon <http://arlocarreon.com>
 * Info: http://mexitek.github.io/phpColors/
 * License: http://arlo.mit-license.org/
 */


/**
 * A color utility that helps manipulate HEX colors
 */
class 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)
	 */
	public 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 = $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");
		}

		$this->_hsl = self::hexToHsl($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 ($del_Max == 0) {
			$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");
		}

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

		if ($S == 0) {
			$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;

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

		}

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

		// https://github.com/mexitek/phpColors/issues/25#issuecomment-88354815
		// Convert RGB to HEX
		$hex[0] = str_pad(dechex($rgb['R']), 2, '0', STR_PAD_LEFT);
		$hex[1] = str_pad(dechex($rgb['G']), 2, '0', STR_PAD_LEFT);
		$hex[2] = str_pad(dechex($rgb['B']), 2, '0', STR_PAD_LEFT);

		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
	 * @param int $lighterThan
	 * @return boolean
	 */
	public function isLight($color = false, $lighterThan = 130)
	{
		// Get our 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 > $lighterThan);
	}

	/**
	 * Returns whether or not a given color is considered "dark"
	 * @param string|Boolean $color
	 * @param int $darkerThan
	 * @return boolean
	 */
	public function isDark($color = false, $darkerThan = 130)
	{
		// Get our 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 <= $darkerThan);
	}

	/**
	 * 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
	 */
	public function getHex()
	{
		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;
	}

}
