wp_save_image() WordPress Function

function wp_save_image( $post_id ) {
	$_wp_additional_image_sizes = wp_get_additional_image_sizes();

	$return  = new stdClass;
	$success = false;
	$delete  = false;
	$scaled  = false;
	$nocrop  = false;
	$post    = get_post( $post_id );

	$img = wp_get_image_editor( _load_image_to_edit_path( $post_id, 'full' ) );
	if ( is_wp_error( $img ) ) {
		$return->error = esc_js( __( 'Unable to create new image.' ) );
		return $return;
	}

	$fwidth  = ! empty( $_REQUEST['fwidth'] ) ? (int) $_REQUEST['fwidth'] : 0;
	$fheight = ! empty( $_REQUEST['fheight'] ) ? (int) $_REQUEST['fheight'] : 0;
	$target  = ! empty( $_REQUEST['target'] ) ? preg_replace( '/[^a-z0-9_-]+/i', '', $_REQUEST['target'] ) : '';
	$scale   = ! empty( $_REQUEST['do'] ) && 'scale' === $_REQUEST['do'];

	if ( $scale && $fwidth > 0 && $fheight > 0 ) {
		$size = $img->get_size();
		$sX   = $size['width'];
		$sY   = $size['height'];

		// Check if it has roughly the same w / h ratio.
		$diff = round( $sX / $sY, 2 ) - round( $fwidth / $fheight, 2 );
		if ( -0.1 < $diff && $diff < 0.1 ) {
			// Scale the full size image.
			if ( $img->resize( $fwidth, $fheight ) ) {
				$scaled = true;
			}
		}

		if ( ! $scaled ) {
			$return->error = esc_js( __( 'Error while saving the scaled image. Please reload the page and try again.' ) );
			return $return;
		}
	} elseif ( ! empty( $_REQUEST['history'] ) ) {
		$changes = json_decode( wp_unslash( $_REQUEST['history'] ) );
		if ( $changes ) {
			$img = image_edit_apply_changes( $img, $changes );
		}
	} else {
		$return->error = esc_js( __( 'Nothing to save, the image has not changed.' ) );
		return $return;
	}

	$meta         = wp_get_attachment_metadata( $post_id );
	$backup_sizes = get_post_meta( $post->ID, '_wp_attachment_backup_sizes', true );

	if ( ! is_array( $meta ) ) {
		$return->error = esc_js( __( 'Image data does not exist. Please re-upload the image.' ) );
		return $return;
	}

	if ( ! is_array( $backup_sizes ) ) {
		$backup_sizes = array();
	}

	// Generate new filename.
	$path = get_attached_file( $post_id );

	$basename = pathinfo( $path, PATHINFO_BASENAME );
	$dirname  = pathinfo( $path, PATHINFO_DIRNAME );
	$ext      = pathinfo( $path, PATHINFO_EXTENSION );
	$filename = pathinfo( $path, PATHINFO_FILENAME );
	$suffix   = time() . rand( 100, 999 );

	if ( defined( 'IMAGE_EDIT_OVERWRITE' ) && IMAGE_EDIT_OVERWRITE &&
		isset( $backup_sizes['full-orig'] ) && $backup_sizes['full-orig']['file'] != $basename ) {

		if ( 'thumbnail' === $target ) {
			$new_path = "{$dirname}/{$filename}-temp.{$ext}";
		} else {
			$new_path = $path;
		}
	} else {
		while ( true ) {
			$filename     = preg_replace( '/-e([0-9]+)$/', '', $filename );
			$filename    .= "-e{$suffix}";
			$new_filename = "{$filename}.{$ext}";
			$new_path     = "{$dirname}/$new_filename";
			if ( file_exists( $new_path ) ) {
				$suffix++;
			} else {
				break;
			}
		}
	}

	// Save the full-size file, also needed to create sub-sizes.
	if ( ! wp_save_image_file( $new_path, $img, $post->post_mime_type, $post_id ) ) {
		$return->error = esc_js( __( 'Unable to save the image.' ) );
		return $return;
	}

	if ( 'nothumb' === $target || 'all' === $target || 'full' === $target || $scaled ) {
		$tag = false;
		if ( isset( $backup_sizes['full-orig'] ) ) {
			if ( ( ! defined( 'IMAGE_EDIT_OVERWRITE' ) || ! IMAGE_EDIT_OVERWRITE ) && $backup_sizes['full-orig']['file'] !== $basename ) {
				$tag = "full-$suffix";
			}
		} else {
			$tag = 'full-orig';
		}

		if ( $tag ) {
			$backup_sizes[ $tag ] = array(
				'width'  => $meta['width'],
				'height' => $meta['height'],
				'file'   => $basename,
			);
		}
		$success = ( $path === $new_path ) || update_attached_file( $post_id, $new_path );

		$meta['file'] = _wp_relative_upload_path( $new_path );

		$size           = $img->get_size();
		$meta['width']  = $size['width'];
		$meta['height'] = $size['height'];

		if ( $success ) {
			$sizes = get_intermediate_image_sizes();
			if ( 'nothumb' === $target || 'all' === $target ) {
				if ( 'nothumb' === $target ) {
					$sizes = array_diff( $sizes, array( 'thumbnail' ) );
				}
			} elseif ( 'thumbnail' !== $target ) {
				$sizes = array_diff( $sizes, array( $target ) );
			}
		}

		$return->fw = $meta['width'];
		$return->fh = $meta['height'];
	} elseif ( 'thumbnail' === $target ) {
		$sizes   = array( 'thumbnail' );
		$success = true;
		$delete  = true;
		$nocrop  = true;
	} else {
		$sizes   = array( $target );
		$success = true;
		$delete  = true;
		$nocrop  = $_wp_additional_image_sizes[ $size ]['crop'];
	}

	/*
	 * We need to remove any existing resized image files because
	 * a new crop or rotate could generate different sizes (and hence, filenames),
	 * keeping the new resized images from overwriting the existing image files.
	 * https://core.trac.wordpress.org/ticket/32171
	 */
	if ( defined( 'IMAGE_EDIT_OVERWRITE' ) && IMAGE_EDIT_OVERWRITE && ! empty( $meta['sizes'] ) ) {
		foreach ( $meta['sizes'] as $size ) {
			if ( ! empty( $size['file'] ) && preg_match( '/-e[0-9]{13}-/', $size['file'] ) ) {
				$delete_file = path_join( $dirname, $size['file'] );
				wp_delete_file( $delete_file );
			}
		}
	}

	if ( isset( $sizes ) ) {
		$_sizes = array();

		foreach ( $sizes as $size ) {
			$tag = false;
			if ( isset( $meta['sizes'][ $size ] ) ) {
				if ( isset( $backup_sizes[ "$size-orig" ] ) ) {
					if ( ( ! defined( 'IMAGE_EDIT_OVERWRITE' ) || ! IMAGE_EDIT_OVERWRITE ) && $backup_sizes[ "$size-orig" ]['file'] != $meta['sizes'][ $size ]['file'] ) {
						$tag = "$size-$suffix";
					}
				} else {
					$tag = "$size-orig";
				}

				if ( $tag ) {
					$backup_sizes[ $tag ] = $meta['sizes'][ $size ];
				}
			}

			if ( isset( $_wp_additional_image_sizes[ $size ] ) ) {
				$width  = (int) $_wp_additional_image_sizes[ $size ]['width'];
				$height = (int) $_wp_additional_image_sizes[ $size ]['height'];
				$crop   = ( $nocrop ) ? false : $_wp_additional_image_sizes[ $size ]['crop'];
			} else {
				$height = get_option( "{$size}_size_h" );
				$width  = get_option( "{$size}_size_w" );
				$crop   = ( $nocrop ) ? false : get_option( "{$size}_crop" );
			}

			$_sizes[ $size ] = array(
				'width'  => $width,
				'height' => $height,
				'crop'   => $crop,
			);
		}

		$meta['sizes'] = array_merge( $meta['sizes'], $img->multi_resize( $_sizes ) );
	}

	unset( $img );

	if ( $success ) {
		wp_update_attachment_metadata( $post_id, $meta );
		update_post_meta( $post_id, '_wp_attachment_backup_sizes', $backup_sizes );

		if ( 'thumbnail' === $target || 'all' === $target || 'full' === $target ) {
			// Check if it's an image edit from attachment edit screen.
			if ( ! empty( $_REQUEST['context'] ) && 'edit-attachment' === $_REQUEST['context'] ) {
				$thumb_url         = wp_get_attachment_image_src( $post_id, array( 900, 600 ), true );
				$return->thumbnail = $thumb_url[0];
			} else {
				$file_url = wp_get_attachment_url( $post_id );
				if ( ! empty( $meta['sizes']['thumbnail'] ) ) {
					$thumb             = $meta['sizes']['thumbnail'];
					$return->thumbnail = path_join( dirname( $file_url ), $thumb['file'] );
				} else {
					$return->thumbnail = "$file_url?w=128&h=128";
				}
			}
		}
	} else {
		$delete = true;
	}

	if ( $delete ) {
		wp_delete_file( $new_path );
	}

	$return->msg = esc_js( __( 'Image saved' ) );
	return $return;
}