<?php
/**
 * SP Event featured-image generator.
 *
 * Auto-generates bisected team-color images for SP Events.
 *
 * @package Tonys_Sportspress_Enhancements
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Register the head-to-head rewrite endpoint.
 *
 * @return void
 */
function tony_sportspress_add_image_generator_endpoint() {
	add_rewrite_endpoint( 'head-to-head', EP_ROOT, true );
}
add_action( 'init', 'tony_sportspress_add_image_generator_endpoint' );

/**
 * Serve the generated matchup image on template_redirect.
 *
 * @return void
 */
function tony_sportspress_handle_image_request() {
	if ( ! isset( $_GET['post'] ) ) {
		return;
	}

	$post_id = absint( $_GET['post'] );
	if ( $post_id <= 0 ) {
		return;
	}

	$post = get_post( $post_id );
	if ( ! $post || $post->post_type !== 'sp_event' ) {
		return;
	}

	$team_ids = get_post_meta( $post_id, 'sp_team', false );
	if ( count( $team_ids ) < 2 ) {
		return;
	}

	$team1_id = (int) $team_ids[0];
	$team2_id = (int) $team_ids[1];

	$team1 = get_post( $team1_id );
	$team2 = get_post( $team2_id );

	if ( ! $team1 || ! $team2 ) {
		return;
	}

	$team1_modified = strtotime( $team1->post_modified );
	$team2_modified = strtotime( $team2->post_modified );
	$cache_key      = "team_image_{$team1_id}_{$team1_modified}-{$team2_id}_{$team2_modified}";

	$cached_path = get_transient( $cache_key );
	if ( $cached_path && file_exists( $cached_path ) ) {
		tony_sportspress_serve_image( $cached_path );
		exit;
	}

	$default_color = '#FFFFFF';
	$team1_colors  = get_post_meta( $team1_id, 'sp_colors', true );
	$team2_colors  = get_post_meta( $team2_id, 'sp_colors', true );
	$team1_color   = ! empty( $team1_colors['primary'] ) ? $team1_colors['primary'] : $default_color;
	$team2_color   = ! empty( $team2_colors['primary'] ) ? $team2_colors['primary'] : $default_color;

	// Validate hex colors.
	if ( ! preg_match( '/^#[a-fA-F0-9]{6}$/', $team1_color ) ) {
		$team1_color = $default_color;
	}
	if ( ! preg_match( '/^#[a-fA-F0-9]{6}$/', $team2_color ) ) {
		$team2_color = $default_color;
	}

	$team1_logo_url = get_the_post_thumbnail_url( $team1_id, 'full' );
	$team2_logo_url = get_the_post_thumbnail_url( $team2_id, 'full' );

	// Skip if both teams have no distinguishable color or logo.
	if ( $team1_color === $default_color && empty( $team1_logo_url )
		&& $team2_color === $default_color && empty( $team2_logo_url ) ) {
		return;
	}

	$team1_logo = get_attached_file( get_post_thumbnail_id( $team1_id ) );
	$team2_logo = get_attached_file( get_post_thumbnail_id( $team2_id ) );

	$image_data = tony_sportspress_generate_bisected_image( $team1_color, $team2_color, $team1_logo, $team2_logo );
	$image_path = tony_sportspress_save_image_to_cache( $image_data, $cache_key );
	set_transient( $cache_key, $image_path, DAY_IN_SECONDS * 30 );

	tony_sportspress_serve_image( $image_path );
	exit;
}
add_action( 'template_redirect', 'tony_sportspress_handle_image_request' );

/**
 * Send a cached PNG image file to the browser.
 *
 * @param string $image_path Absolute path to the image file.
 * @return void
 */
function tony_sportspress_serve_image( $image_path ) {
	header( 'Content-Type: image/png' );

	if ( file_exists( $image_path ) ) {
		status_header( 200 );
	} else {
		status_header( 404 );
		exit( 'Image not found.' );
	}

	while ( ob_get_level() ) {
		ob_end_clean();
	}

	readfile( $image_path ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_readfile
}

/**
 * Write raw image data to the uploads directory and return the file path.
 *
 * @param string $image_data Raw PNG data.
 * @param string $cache_key  Cache key used as the filename stem.
 * @return string
 */
function tony_sportspress_save_image_to_cache( $image_data, $cache_key ) {
	$upload_dir = wp_get_upload_dir();
	$file_path  = $upload_dir['path'] . '/' . $cache_key . '.png';

	file_put_contents( $file_path, $image_data ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents

	return $file_path;
}

/**
 * Generate a bisected two-color PNG with optional team logos.
 *
 * @param string $color1     Hex color for the left half (e.g. #FF0000).
 * @param string $color2     Hex color for the right half.
 * @param string $logo1_path Absolute path to team 1 PNG logo (or empty).
 * @param string $logo2_path Absolute path to team 2 PNG logo (or empty).
 * @return string Raw PNG image data.
 */
function tony_sportspress_generate_bisected_image( $color1, $color2, $logo1_path, $logo2_path ) {
	$width    = 1200;
	$height   = 628;
	$x_margin = 0.1 * ( $width / 2 );
	$y_margin = 0.1 * $height;
	$image    = imagecreatetruecolor( $width, $height );

	$rgb1         = sscanf( $color1, '#%02x%02x%02x' );
	$rgb2         = sscanf( $color2, '#%02x%02x%02x' );
	$color1_alloc = imagecolorallocate( $image, $rgb1[0], $rgb1[1], $rgb1[2] );
	$color2_alloc = imagecolorallocate( $image, $rgb2[0], $rgb2[1], $rgb2[2] );

	// Left trapezoid.
	imagefilledpolygon(
		$image,
		array( 0, 0, 0, $height, $width * 0.40, $height, $width * 0.60, 0 ),
		$color1_alloc
	);

	// Right trapezoid.
	imagefilledpolygon(
		$image,
		array( $width, 0, $width, $height, $width * 0.40, $height, $width * 0.60, 0 ),
		$color2_alloc
	);

	$max_logo_width  = ( $width / 2 ) - ( 2 * $x_margin );
	$max_logo_height = $height - ( 2 * $y_margin );

	foreach ( array(
		array( 'path' => $logo1_path, 'center_x' => $width / 4 ),
		array( 'path' => $logo2_path, 'center_x' => 3 * $width / 4 ),
	) as $logo ) {
		if ( empty( $logo['path'] ) ) {
			continue;
		}

		$src = imagecreatefrompng( $logo['path'] );
		if ( ! $src ) {
			continue;
		}

		$src_w = imagesx( $src );
		$src_h = imagesy( $src );

		$dst_w = $src_w;
		$dst_h = $src_h;

		if ( $src_w > $max_logo_width || $src_h > $max_logo_height ) {
			$ratio = $src_w / $src_h;
			if ( $src_w / $max_logo_width > $src_h / $max_logo_height ) {
				$dst_w = $max_logo_width;
				$dst_h = $max_logo_width / $ratio;
			} else {
				$dst_h = $max_logo_height;
				$dst_w = $max_logo_height * $ratio;
			}
		}

		$dst_x = (int) ( $logo['center_x'] - $dst_w / 2 );
		$dst_y = (int) ( $height / 2 - $dst_h / 2 );

		imagecopyresampled( $image, $src, $dst_x, $dst_y, 0, 0, (int) $dst_w, (int) $dst_h, $src_w, $src_h );
		imagedestroy( $src );
	}

	ob_start();
	imagepng( $image );
	$image_data = (string) ob_get_clean();
	imagedestroy( $image );

	return $image_data;
}