<?php
/** Strict bounded CSV parser and explicit target-field mapping. */
namespace Abientot\Import;
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}
final class Csv {
	public const BYTES   = 262144;
	public const ROWS    = 100;
	public const COLUMNS = 30;
	public const CELL    = 2000;
	public static function parse( string $csv, string $delimiter = ',' ): array {
		if ( $csv === '' || strlen( $csv ) > self::BYTES || ! preg_match( '//u', $csv ) || strpos( $csv, "\0" ) !== false || ! in_array( $delimiter, array( ',', ';', '\t' ), true ) ) {
			throw new \DomainException( 'import_csv' );
		}
		$file_digest = hash( 'sha256', $csv );
		if ( $delimiter === '\t' ) {
			$delimiter = "\t";
		}
		if ( str_starts_with( $csv, "\xef\xbb\xbf" ) ) {
			$csv = substr( $csv, 3 );
		}
		// fgetcsv accepts unterminated quotes; reject that and trailing garbage explicitly.
		self::lex( $csv, $delimiter );
		$stream = fopen( 'php://temp', 'w+' ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fopen -- In-memory php://temp stream for fgetcsv(); no file is written.
		if ( ! $stream ) {
			throw new \RuntimeException( 'import_csv' );
		}
		try {
			if ( fwrite( $stream, $csv ) !== strlen( $csv ) || ! rewind( $stream ) ) { // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fwrite -- Writes to the in-memory php://temp stream.
					throw new \RuntimeException( 'import_csv' );
			}
			$rows = array();while ( ( $row = fgetcsv( $stream, self::BYTES + 1, $delimiter, '"', '' ) ) !== false ) {
				if ( count( $row ) > self::COLUMNS ) {
					throw new \DomainException( 'import_columns' );
				}
				foreach ( $row as $cell ) {
					if ( ! is_string( $cell ) || strlen( $cell ) > self::CELL || preg_match( '/[\x00-\x08\x0b\x0c\x0e-\x1f]/', $cell ) || ( preg_match( '/^\s*[=@]/u', $cell ) || ( preg_match( '/^\s*\+/u', $cell ) && ! preg_match( '/^\s*\+[0-9 ().-]+\s*$/D', $cell ) ) ) ) {
								throw new \DomainException( 'import_cell' );
					}
				}
				$rows[] = $row;
				if ( count( $rows ) > self::ROWS + 1 ) {
					throw new \DomainException( 'import_rows' );
				}
			}
			if ( count( $rows ) < 2 ) {
				throw new \DomainException( 'import_rows' );
			}
			$headers = array_shift( $rows );
			if ( in_array( '', array_map( 'trim', $headers ), true ) || count( array_unique( $headers ) ) !== count( $headers ) ) {
				throw new \DomainException( 'import_header' );
			}
			foreach ( $rows as $row ) {
				if ( count( $row ) !== count( $headers ) ) {
					throw new \DomainException( 'import_columns' );
				}
			}
			return array(
				'headers'     => $headers,
				'rows'        => $rows,
				'file_digest' => $file_digest
			);
		} finally {
			fclose( $stream ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose -- Closes the in-memory php://temp stream.
		}
	}
	private static function lex( string $csv, string $delimiter ): void {
		$state  = 'start';
		$length = strlen( $csv );for ( $i = 0;$i < $length;++$i ) {
			$char = $csv[ $i ];
			if ( $state === 'quoted' ) {
				if ( $char === '"' ) {
					if ( $i + 1 < $length && $csv[ $i + 1 ] === '"' ) {
						++$i;
					} else {
						$state = 'closed';
					}
				}
				continue;
			}
			if ( $char === $delimiter || $char === "\r" || $char === "\n" ) {
				$state = 'start';
				continue;
			}
			if ( $state === 'closed' ) {
				throw new \DomainException( 'import_csv' );
			}
			if ( $char === '"' ) {
				if ( $state !== 'start' ) {
					throw new \DomainException( 'import_csv' );
				}
				$state = 'quoted';
			} else {
				$state = 'plain';
			}
		}
		if ( $state === 'quoted' ) {
			throw new \DomainException( 'import_csv' );
		}
	}
	public static function fields( string $kind ): array {
		if ( $kind === 'customers' ) {
			return array( 'source_key', 'display_name', 'email', 'phone' );
		}
		if ( $kind === 'services' ) {
			return array( 'source_key', 'name', 'slug', 'duration_minutes', 'price_cents', 'currency', 'buffer_before_minutes', 'buffer_after_minutes' );
		}
		if ( $kind === 'appointments' ) {
			return array( 'source_key', 'display_name', 'email', 'phone', 'service_key', 'staff_key', 'location_key', 'start_utc', 'duration_minutes', 'price_cents', 'currency', 'timezone', 'status_slug' );
		}
		throw new \DomainException( 'import_kind' );
	}
	public static function map( array $parsed, string $kind, array $mapping ): array {
		$fields = self::fields( $kind );
		if ( count( $mapping ) !== count( $parsed['headers'] ) ) {
			throw new \DomainException( 'import_mapping' );
		}
		$used = array();
		foreach ( $mapping as $column => $field ) {
			if ( ! preg_match( '/^(0|[1-9][0-9]*)$/D', (string) $column ) || (int) $column >= count( $parsed['headers'] ) || ! is_string( $field ) || ( $field !== 'ignore' && ! in_array( $field, $fields, true ) ) || ( $field !== 'ignore' && isset( $used[ $field ] ) ) ) {
				throw new \DomainException( 'import_mapping' );
			}
			if ( $field !== 'ignore' ) {
				$used[ $field ] = true;
			}
		}
		$required = $kind === 'customers' ? array( 'source_key', 'display_name' ) : ( $kind === 'services' ? array( 'source_key', 'name', 'slug', 'duration_minutes', 'price_cents', 'currency' ) : array( 'source_key', 'display_name', 'service_key', 'staff_key', 'location_key', 'start_utc', 'duration_minutes', 'price_cents', 'currency', 'timezone', 'status_slug' ) );
		if ( array_diff( $required, array_keys( $used ) ) ) {
			throw new \DomainException( 'import_mapping' );
		}
		$out = array();
		foreach ( $parsed['rows'] as $row ) {
			$item = array_fill_keys( $fields, '' );
			foreach ( $mapping as $column => $field ) {
				if ( $field !== 'ignore' ) {
					$item[ $field ] = $row[ (int) $column ];
				}
			}
			$out[] = $item;
		}
		return $out;
	}
	/** Defense for any future exported cell. Imports never evaluate formulas. */
	public static function spreadsheet_cell( string $cell ): string {
		return preg_match( '/^\s*[=+\-@]/u', $cell ) ? "'" . $cell : $cell;
	}
}