<?php
namespace AdvancedAddons;

class BlocksToHtml {

	private static $text_tags = array(
		'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'span', 'p', 'a', 'button',
	);

	private static $self_closing = array( 'img', 'input', 'br' );

	/**
	 * Convert an array of block data to an HTML string.
	 *
	 * @param array $blocks Array of block data arrays.
	 * @return string HTML with Tailwind classes.
	 */
	public static function convert_blocks( $blocks ) {
		$html = '';
		foreach ( $blocks as $block ) {
			$html .= self::convert_block( $block );
		}
		return $html;
	}

	/**
	 * Convert a single block data array to an HTML string.
	 *
	 * @param array $block Block data with name, attributes, innerBlocks.
	 * @return string HTML fragment.
	 */
	public static function convert_block( $block ) {
		if ( ! is_array( $block ) || empty( $block['name'] ) ) {
			return '';
		}

		$name  = $block['name'];
		$attrs = $block['attributes'] ?? array();

		if ( 'core/html' === $name ) {
			return $attrs['content'] ?? '';
		}

		if ( 'tailwind/html' !== $name ) {
			// For native WordPress blocks, render server-side when possible.
			if ( function_exists( 'render_block' ) ) {
				return render_block( self::normalize_block( $block ) );
			}
			return '<!-- ' . esc_html( $name ) . ' -->';
		}

		$tag   = $attrs['tagName'] ?? 'div';
		$class = $attrs['className'] ?? '';

		$class_attr = $class ? ' class="' . htmlspecialchars( $class, ENT_QUOTES, 'UTF-8' ) . '"' : '';
		$extra_attrs = self::render_attrs( $attrs['attrs'] ?? array() );

		if ( in_array( $tag, self::$self_closing, true ) ) {
			$src   = self::decode_content( $attrs['src'] ?? '' );
			$alt   = self::decode_content( $attrs['alt'] ?? '' );
			$parts = array( '<' . $tag . $class_attr . $extra_attrs );
			if ( $src ) {
				$parts[] = ' src="' . htmlspecialchars( $src, ENT_QUOTES, 'UTF-8' ) . '"';
			}
			if ( $alt ) {
				$parts[] = ' alt="' . htmlspecialchars( $alt, ENT_QUOTES, 'UTF-8' ) . '"';
			}
			$parts[] = ' />';
			return implode( '', $parts );
		}

		$children_type = $attrs['children'] ?? '';
		$content       = self::decode_content( $attrs['content'] ?? '' );
		$inner         = isset( $block['innerBlocks'] )
			? self::convert_blocks( $block['innerBlocks'] )
			: '';

		if ( 'blocks' === $children_type ) {
			$inner_html = $inner;
		} elseif ( 'text' === $children_type ) {
			// Match the editor's RichText.Content serialization: escape &, <, >
			// but leave quotes untouched in text content.
			$inner_html = htmlspecialchars( $content, ENT_NOQUOTES, 'UTF-8' );
		} else {
			// 'html' or not set (backwards compat) — raw HTML content, fallback to innerBlocks.
			$inner_html = $content ?: $inner;
		}

		return '<' . $tag . $class_attr . $extra_attrs . '>' . $inner_html . '</' . $tag . '>';
	}

	/**
	 * Normalize block data from our format (name/attributes) to the
	 * WordPress parser format (blockName/attrs/innerHTML/innerContent)
	 * required by serialize_blocks().
	 *
	 * @param array $blocks Array of blocks in our format.
	 * @return array Array of blocks in WP parser format.
	 */
	public static function normalize_blocks( $blocks ) {
		$result = array();
		foreach ( $blocks as $block ) {
			$result[] = self::normalize_block( $block );
		}
		return $result;
	}

	/**
	 * Normalize a single block.
	 *
	 * @param array $block Block data in our format.
	 * @return array Block in WP parser format.
	 */
	private static function normalize_block( $block ) {
		$name  = $block['name'] ?? '';
		$attrs = $block['attributes'] ?? array();
		$inner = isset( $block['innerBlocks'] ) ? self::normalize_blocks( $block['innerBlocks'] ) : array();
		$tag   = $attrs['tagName'] ?? '';

		if ( 'core/html' === $name ) {
			$html = $attrs['content'] ?? '';
			return array(
				'blockName'    => $name,
				'attrs'        => array( 'content' => $html ),
				'innerBlocks'  => array(),
				'innerHTML'    => $html,
				'innerContent' => array( $html ),
			);
		}

		if ( 'tailwind/html' !== $name ) {
			$inner_html    = $block['innerHTML'] ?? '';
			$inner_content = $block['innerContent'] ?? array( $inner_html );
			return array(
				'blockName'    => $name,
				'attrs'        => $attrs,
				'innerBlocks'  => $inner,
				'innerHTML'    => $inner_html,
				'innerContent' => $inner_content,
			);
		}

		$save_class = self::save_class( $attrs['className'] ?? '' );

		if ( in_array( $tag, self::$self_closing, true ) ) {
			$inner_html = self::render_block_for_save( $tag, $save_class, $attrs );
			return array(
				'blockName'    => $name,
				'attrs'        => $attrs,
				'innerBlocks'  => array(),
				'innerHTML'    => $inner_html,
				'innerContent' => array( $inner_html ),
			);
		}

		// Determine if this is a leaf block (text/html children) or container (blocks children).
		$children_type = $attrs['children'] ?? '';
		$is_leaf = ( 'text' === $children_type || 'html' === $children_type )
			|| ( '' === $children_type && in_array( $tag, self::$text_tags, true ) && empty( $inner ) );

		if ( $is_leaf ) {
			$inner_html = self::render_block_for_save( $tag, $save_class, $attrs );
			return array(
				'blockName'    => $name,
				'attrs'        => $attrs,
				'innerBlocks'  => array(),
				'innerHTML'    => $inner_html,
				'innerContent' => array( $inner_html ),
			);
		}

		// Container: build innerContent with null placeholders for inner blocks.
		$class_attr = $save_class ? ' class="' . htmlspecialchars( $save_class, ENT_QUOTES, 'UTF-8' ) . '"' : '';
		$extra_attrs   = self::render_attrs( $attrs['attrs'] ?? array() );
		$inner_content = array( '<' . $tag . $class_attr . $extra_attrs . '>' );
		foreach ( $inner as $child ) {
			$inner_content[] = null;
		}
		$inner_content[] = '</' . $tag . '>';

		$inner_html = self::render_block_for_save( $tag, $save_class, $attrs );

		return array(
			'blockName'    => $name,
			'attrs'        => $attrs,
			'innerBlocks'  => $inner,
			'innerHTML'    => $inner_html,
			'innerContent' => $inner_content,
		);
	}

	/**
	 * Prepend wp-block-tailwind-html class for save() validation.
	 */
	private static function save_class( $class ) {
		$classes = array_filter( explode( ' ', $class ) );
		array_unshift( $classes, 'wp-block-tailwind-html' );
		return implode( ' ', $classes );
	}

	/**
	 * Render a single tailwind/html block as HTML with save() classes.
	 */
	private static function render_block_for_save( $tag, $save_class, $attrs ) {
		$class_attr  = $save_class ? ' class="' . htmlspecialchars( $save_class, ENT_QUOTES, 'UTF-8' ) . '"' : '';
		$extra_attrs = self::render_attrs( $attrs['attrs'] ?? array() );

		if ( in_array( $tag, self::$self_closing, true ) ) {
			$src   = self::decode_content( $attrs['src'] ?? '' );
			$alt   = self::decode_content( $attrs['alt'] ?? '' );
			$parts = array( '<' . $tag . $class_attr . $extra_attrs );
			if ( $src ) {
				$parts[] = ' src="' . htmlspecialchars( $src, ENT_QUOTES, 'UTF-8' ) . '"';
			}
			if ( $alt ) {
				$parts[] = ' alt="' . htmlspecialchars( $alt, ENT_QUOTES, 'UTF-8' ) . '"';
			}
			$parts[] = ' />';
			return implode( '', $parts );
		}

		$children_type = $attrs['children'] ?? '';
		$content       = self::decode_content( $attrs['content'] ?? '' );

		// RichText.Content escapes HTML; dangerouslySetInnerHTML keeps it raw.
		if ( 'text' === $children_type ) {
			$content = htmlspecialchars( $content, ENT_NOQUOTES, 'UTF-8' );
		}

		return '<' . $tag . $class_attr . $extra_attrs . '>' . $content . '</' . $tag . '>';
	}

	/**
	 * Render extra HTML attributes stored in the `attrs` block attribute.
	 *
	 * @param array $attrs Key-value attribute pairs.
	 * @return string HTML attribute string.
	 */
	private static function render_attrs( $attrs ) {
		if ( empty( $attrs ) || ! is_array( $attrs ) ) {
			return '';
		}
		$html = '';
		foreach ( $attrs as $key => $value ) {
			if ( null === $value || ( '' === $value && 0 !== strpos( strtolower( $key ), 'data-' ) ) ) {
				continue;
			}
			$html .= ' ' . $key . '="' . htmlspecialchars( $value, ENT_QUOTES, 'UTF-8' ) . '"';
		}
		return $html;
	}

	/**
	 * Decode a block content value if it is prefixed with "base64:".
	 *
	 * SVG content is base64-encoded before being stored as a block attribute
	 * to avoid JSON/HTML serialization issues with the "<" character.
	 *
	 * @param string $content Block content value.
	 * @return string Decoded content.
	 */
	private static function decode_content( $content ) {
		if ( is_string( $content ) && 0 === strpos( $content, 'base64:' ) ) {
			$decoded = base64_decode( substr( $content, 7 ), true );
			if ( false !== $decoded ) {
				return $decoded;
			}
		}
		return $content;
	}
}