<?php
/**
 * CSV import parsing and validation. Pure PHP apart from translation, so it is unit-tested.
 * Matching rows to products happens in LFQTY_Import, which passes a lookup callback.
 *
 * Columns: "sku" or "product_id" (one is required), then any of the field names in
 * LFQTY_Fields::definitions(). A blank cell clears that field. "enabled" defaults to "yes".
 *
 * @package LayoutFoundryQuantities
 */

defined( 'ABSPATH' ) || exit;

/**
 * CSV import.
 */
final class LFQTY_Csv {

	/** Most data rows in one file. */
	const MAX_ROWS = 2000;

	/** Largest file in bytes (1 MB). */
	const MAX_BYTES = 1048576;

	/**
	 * Parses and validates a CSV file.
	 *
	 * @param string   $text   File contents.
	 * @param callable $lookup fn( string $sku, int $id ): array{id:int,name:string}|null.
	 * @return array{errors:string[],rows:array<int,array{line:int,product_id:int,product_name:string,values:array,errors:string[]}>}
	 */
	public static function parse( $text, callable $lookup ) {
		$text = (string) $text;
		if ( strlen( $text ) > self::MAX_BYTES ) {
			return self::file_error( __( 'The file is larger than 1 MB. Split it into smaller files.', 'layout-foundry-quantities' ) );
		}
		// Excel adds a byte order mark; line endings may be Windows, Mac or Unix.
		$text  = preg_replace( '/^\xEF\xBB\xBF/', '', $text );
		$lines = self::read_rows( $text );
		if ( count( $lines ) < 2 ) {
			return self::file_error( __( 'The file needs a header row and at least one product row.', 'layout-foundry-quantities' ) );
		}
		if ( count( $lines ) - 1 > self::MAX_ROWS ) {
			/* translators: %d: most rows allowed. */
			return self::file_error( sprintf( __( 'The file has more than %d product rows. Split it into smaller files.', 'layout-foundry-quantities' ), self::MAX_ROWS ) );
		}

		$fields  = array_keys( LFQTY_Fields::definitions() );
		$headers = array_map(
			static function ( $header ) {
				return strtolower( trim( (string) $header ) );
			},
			$lines[0]
		);
		$unknown = array_diff( array_filter( $headers, 'strlen' ), array_merge( array( 'sku', 'product_id' ), $fields ) );
		if ( $unknown ) {
			/* translators: 1: unknown column names, 2: allowed column names. */
			return self::file_error( sprintf( __( 'Unknown columns: %1$s. Allowed columns: %2$s.', 'layout-foundry-quantities' ), implode( ', ', $unknown ), implode( ', ', array_merge( array( 'sku', 'product_id' ), $fields ) ) ) );
		}
		if ( ! in_array( 'sku', $headers, true ) && ! in_array( 'product_id', $headers, true ) ) {
			return self::file_error( __( 'The header row needs a sku or product_id column.', 'layout-foundry-quantities' ) );
		}
		if ( count( $headers ) !== count( array_unique( $headers ) ) ) {
			return self::file_error( __( 'A column name appears twice in the header row.', 'layout-foundry-quantities' ) );
		}

		$rows = array();
		$seen = array();
		foreach ( array_slice( $lines, 1 ) as $index => $cells ) {
			$line = $index + 2;
			if ( array( '' ) === array_map( 'trim', $cells ) || array() === array_filter( array_map( 'trim', $cells ), 'strlen' ) ) {
				continue; // Blank line.
			}
			$errors = array();
			if ( count( $cells ) !== count( $headers ) ) {
				/* translators: 1: cells found, 2: columns in the header. */
				$errors[] = sprintf( __( 'This row has %1$d cells; the header has %2$d.', 'layout-foundry-quantities' ), count( $cells ), count( $headers ) );
			}
			$cells = array_pad( array_slice( $cells, 0, count( $headers ) ), count( $headers ), '' );
			$data  = array_combine( $headers, array_map( 'trim', $cells ) );

			$sku     = isset( $data['sku'] ) ? $data['sku'] : '';
			$id_text = isset( $data['product_id'] ) ? $data['product_id'] : '';
			$product = null;
			if ( '' !== $id_text && ! preg_match( '/^\d{1,12}$/', $id_text ) ) {
				/* translators: %s: value given. */
				$errors[] = sprintf( __( 'product_id "%s" must be a whole number.', 'layout-foundry-quantities' ), $id_text );
			} elseif ( '' === $sku && '' === $id_text ) {
				$errors[] = __( 'The row has no sku or product_id.', 'layout-foundry-quantities' );
			} else {
				$product = call_user_func( $lookup, $sku, (int) $id_text );
				if ( ! $product ) {
					$errors[] = '' !== $sku
						/* translators: %s: SKU. */
						? sprintf( __( 'No simple product has the SKU "%s".', 'layout-foundry-quantities' ), $sku )
						/* translators: %s: product id. */
						: sprintf( __( 'No simple product has the ID %s.', 'layout-foundry-quantities' ), $id_text );
				}
			}
			if ( $product && isset( $seen[ $product['id'] ] ) ) {
				/* translators: %d: line number of the earlier row. */
				$errors[] = sprintf( __( 'This product is already on line %d.', 'layout-foundry-quantities' ), $seen[ $product['id'] ] );
			}
			if ( $product ) {
				$seen[ $product['id'] ] = $line;
			}

			$raw = array_intersect_key( $data, array_flip( $fields ) );
			if ( ! isset( $raw['enabled'] ) || '' === $raw['enabled'] ) {
				$raw['enabled'] = 'yes';
			}
			$checked = LFQTY_Fields::validate( $raw );

			$rows[] = array(
				'line'         => $line,
				'product_id'   => $product ? (int) $product['id'] : 0,
				'product_name' => $product ? (string) $product['name'] : '',
				'values'       => $checked['values'],
				'errors'       => array_merge( $errors, $checked['errors'] ),
			);
		}

		if ( ! $rows ) {
			return self::file_error( __( 'The file needs a header row and at least one product row.', 'layout-foundry-quantities' ) );
		}
		return array(
			'errors' => array(),
			'rows'   => $rows,
		);
	}

	/**
	 * Rows of cells. Handles quoted cells with commas, quotes and line breaks.
	 *
	 * @param string $text CSV text.
	 * @return array<int,string[]>
	 */
	private static function read_rows( $text ) {
		$file = new SplTempFileObject();
		$file->fwrite( $text );
		$file->rewind();
		$file->setFlags( SplFileObject::READ_CSV | SplFileObject::SKIP_EMPTY | SplFileObject::READ_AHEAD );
		$file->setCsvControl( ',', '"', '' );
		$rows = array();
		foreach ( $file as $cells ) {
			if ( is_array( $cells ) && array( null ) !== $cells ) {
				$rows[] = array_map( 'strval', $cells );
			}
			if ( count( $rows ) > self::MAX_ROWS + 1 ) {
				break;
			}
		}
		return $rows;
	}

	/**
	 * Result for a file that cannot be read at all.
	 *
	 * @param string $message Message.
	 * @return array
	 */
	private static function file_error( $message ) {
		return array(
			'errors' => array( $message ),
			'rows'   => array(),
		);
	}
}