<?php

declare(strict_types=1);

namespace Pcm\IconBundle\Twig\Functions;

use Twig\Extension\AbstractExtension;
use Twig\TwigFunction;

final class IconExtension extends AbstractExtension
{
    public const DEFAULT_SIZE = 32;

    private const DEFAULT_OPTIONS = [
        'icon'    => null,
        'title'   => null,
        'size'    => self::DEFAULT_SIZE,
        'colour'  => 'primary',
        'hover'   => null,
        'classes' => [],
    ];

    public function __construct(private array $directories, private array $colours)
    {
        if (empty($this->colours)) {
            throw new \InvalidArgumentException('Colours array must contain at least one colour!');
        }

        $coloursContainsNonArray = array_reduce($this->colours,
            fn($notArray, $path) => $notArray || !is_array($path));

        if ($coloursContainsNonArray) {
            throw new \TypeError('Colours array must only contain arrays!');
        }

        foreach ($this->colours as $colour) {
            if (!(
                array_key_exists('stroke', $colour) &&
                array_key_exists('fill', $colour) &&
                array_key_exists('fill-hover', $colour) &&
                array_key_exists('stroke-hover', $colour) &&
                array_key_exists('fill-group-hover', $colour) &&
                array_key_exists('stroke-group-hover', $colour))
            ) {
                throw new \Exception('Colours must contain a "stroke" and "fill" key!');
            }
        }
    }

    /**
     * @inheritDoc
     */
    public function getFunctions(): array
    {
        return [
            new TwigFunction('icon', [$this, 'renderIcon'], [
                'is_safe' => ['html']
            ])
        ];
    }

    /**
     * @param array $options
     * ```
     * $options = [
     *     'icon'     => (string)  REQUIRED Which icon to use
     *     'title'    => (?string) Text to appear on mouse hover
     *     'size'     => (int)     Height and width in px
     *     'colour'   => (string)  Main colour
     *     'hover'    => (?string) Hover colour
     *     'classes'  => (array)   Additional classes to add to the icon.
     *                             Use with caution as this can potentially
     *                             cause Tailwind class conflicts!
     * ]
     * ```
     */
    public function renderIcon(array $userOptions): string
    {
        $options = $this->getMergedOptions($userOptions);
        $svg = $this->getSanitisedIconSvg($options['icon']);

        $colourClasses = $this->getColourClasses($options['colour'], $options['hover']);
        $extraClasses = $this->getExtraClasses($options['classes']);

        $svg = $this->addClassesToSvg($svg, trim($colourClasses.' '.$extraClasses));
        $svg = $this->addTitleToSvgIfNotNull($svg, $options['title']);
        $svg = $this->setSvgHeightAndWidth($svg, $options['size']);

        return $svg;
    }

    private function getExtraClasses(array $extraClasses): string
    {
        return implode(' ', $extraClasses);
    }

    private function getMergedOptions(array $userOptions): array
    {
        $this->throwIfUnrecognisedOptionExists($userOptions);
        return $this->mergeUserOptionsWithDefaults($userOptions);
    }

    private function mergeUserOptionsWithDefaults(array $userOptions): array
    {
        return array_merge(self::DEFAULT_OPTIONS, $userOptions);
    }

    private function throwIfUnrecognisedOptionExists(array $options): void
    {
        foreach (array_keys($options) as $key) {
            if (!key_exists($key, self::DEFAULT_OPTIONS)) {
                throw new \InvalidArgumentException("Unrecognised option '{$key}'!");
            }
        }
    }

    private function getSanitisedIconSvg(string $iconName): string
    {
        $iconFilepath = $this->findSvgFilepath($iconName);
        $rawSvgMarkup = $this->getSvgMarkup($iconFilepath);
        $cleanSvgMarkup = $this->removeExistingTitleElement($rawSvgMarkup);
        $cleanSvgMarkup = $this->removeBlackStrokeAttributes($cleanSvgMarkup);

        return $this->removeBlackFillAttributes($cleanSvgMarkup);
    }

    private function findSvgFilepath(string $iconName): string
    {
        foreach ($this->directories as $directory) {
            $potentialFilepath = sprintf('%s/%s.svg', $directory, $iconName);

            if (file_exists($potentialFilepath)) {
                return $potentialFilepath;
            }
        }

        throw new IconNotFound(sprintf('File "%s.svg" not found in %s', $iconName, implode(', ', $this->directories)));
    }

    private function getSvgMarkup(string $filepath): string
    {
        return file_get_contents($filepath);
    }

    private function removeExistingTitleElement(string $svg): string
    {
        return preg_replace('/<title>.*<\/title>/', '', $svg);
    }

    private function removeBlackStrokeAttributes(string $content): string
    {
        return preg_replace('/stroke(=|:)"?\s*(#0{6}|#000|rgb\(\s*0,\s*0,\s*0\s*\)|black)\s*"?/', '', $content);
    }

    private function removeBlackFillAttributes(string $content): string
    {
        return preg_replace('/fill(=|:)"?\s*(#0{6}|#000|rgb\(\s*0,\s*0,\s*0\s*\)|black)\s*"?/', '', $content);
    }

    private function getColourClasses(string $primaryColour, ?string $hoverColour): string
    {
        $mainColour = $this->getColour($primaryColour);
        $colourClasses = "{$mainColour['stroke']} {$mainColour['fill']}";

        if (null !== $hoverColour) {
            $hoverColour = $this->getColour($hoverColour);
            $colourClasses .= " cursor-pointer {$hoverColour['stroke-hover']} {$hoverColour['fill-hover']} {$hoverColour['stroke-group-hover']} {$hoverColour['fill-group-hover']}";
        }

        return $colourClasses;
    }

    private function getColour(string $colourName): array
    {
        if (array_key_exists($colourName, $this->colours)) {
            return $this->colours[$colourName];
        }

        throw new ColourNotFound("The colour \"$colourName\" was not found!");
    }

    private function addClassesToSvg(string $svg, string $classes): string
    {
        $xml = new \SimpleXMLElement($svg);
        $xml = $this->addAttributeToXmlElement($xml, 'class', $classes);
        return $this->removeXMLDeclaration($xml->saveXML());
    }

    private function addTitleToSvgIfNotNull(string $svg, ?string $title): string
    {
        if (null === $title) {
            return $svg;
        }

        $this->throwIfTitleIsEmpty($title);

        return preg_replace('/(<svg(.|\n)*?>\n?)/', "$1<title>$title</title>", $svg);
    }

    private function addAttributeToXmlElement(\SimpleXMLElement $xml, string $attrName, mixed $attrValue): \SimpleXMLElement
    {
        if (isset($xml->attributes()->$attrName)) {
            $xml->attributes()->$attrName = strval($attrValue);
        } else {
            $xml->addAttribute($attrName, strval($attrValue));
        }

        return $xml;
    }

    private function removeXMLDeclaration(string $content): string
    {
        return trim(preg_replace('/<\?xml.*\?>/', '', $content));
    }

    private function throwIfTitleIsEmpty(string $title): void
    {
        if ('' === $title) {
            throw new \InvalidArgumentException('Title string must not be empty!');
        }
    }

    private function setSvgHeightAndWidth(string $content, int $size): string
    {
        $this->throwIfSizeIsNegative($size);
        $svgAsXmlElement = new \SimpleXMLElement($content);
        $svgAsXmlElement = $this->addAttributeToXmlElement($svgAsXmlElement, 'width', $size);
        $svgAsXmlElement = $this->addAttributeToXmlElement($svgAsXmlElement, 'height', $size);
        return $this->removeXMLDeclaration($svgAsXmlElement->saveXML());
    }

    private function throwIfSizeIsNegative(int $size): void
    {
        if ($size < 0) {
            throw new \InvalidArgumentException('Size must not be negative');
        }
    }
}

class IconNotFound extends \Exception {};

class ColourNotFound extends \Exception {};