feat: add content package schema validator

src/Package/PackageValidationResult.php

@@ -0,0 +1,42 @@
+<?php
+/**
+ * Package validation result.
+ *
+ * @package WPContentSync
+ */
+
+namespace WPContentSync\Package;
+
+final class PackageValidationResult {
+	/** @var array<int, string> */
+	private array $errors;
+
+	/**
+	 * @param array<int, string> $errors Validation errors.
+	 */
+	private function __construct( array $errors ) {
+		$this->errors = array_values( $errors );
+	}
+
+	public static function valid(): self {
+		return new self( array() );
+	}
+
+	/**
+	 * @param array<int, string> $errors Validation errors.
+	 */
+	public static function invalid( array $errors ): self {
+		return new self( $errors );
+	}
+
+	public function isValid(): bool {
+		return array() === $this->errors;
+	}
+
+	/**
+	 * @return array<int, string>
+	 */
+	public function errors(): array {
+		return $this->errors;
+	}
+}

src/Package/PackageValidator.php

@@ -0,0 +1,88 @@
+<?php
+/**
+ * Versioned package schema validator.
+ *
+ * @package WPContentSync
+ */
+
+namespace WPContentSync\Package;
+
+final class PackageValidator {
+	private const RECORD_BUCKETS = array(
+		'posts',
+		'terms',
+		'media',
+		'custom_post_types',
+	);
+
+	/**
+	 * @param array<string, mixed> $data Decoded package data.
+	 */
+	public function validate( array $data ): PackageValidationResult {
+		$errors = array();
+
+		foreach ( array( 'schema_version', 'generated_at', 'source', 'destination', 'manifest', 'records', 'checksums' ) as $field ) {
+			if ( ! array_key_exists( $field, $data ) ) {
+				$errors[] = $field . ' is required.';
+			}
+		}
+
+		if ( isset( $data['schema_version'] ) && ContentPackage::SCHEMA_VERSION !== $data['schema_version'] ) {
+			$errors[] = 'schema_version must be ' . ContentPackage::SCHEMA_VERSION . '.';
+		}
+
+		if ( isset( $data['source'] ) && ! is_array( $data['source'] ) ) {
+			$errors[] = 'source must be an object.';
+		}
+
+		if ( isset( $data['destination'] ) && ! is_array( $data['destination'] ) ) {
+			$errors[] = 'destination must be an object.';
+		}
+
+		if ( isset( $data['manifest'] ) && ! is_array( $data['manifest'] ) ) {
+			$errors[] = 'manifest must be an object.';
+		}
+
+		if ( isset( $data['records'] ) && ! is_array( $data['records'] ) ) {
+			$errors[] = 'records must be an object.';
+		}
+
+		if ( isset( $data['checksums'] ) && ! is_array( $data['checksums'] ) ) {
+			$errors[] = 'checksums must be an object.';
+		}
+
+		if ( isset( $data['manifest'], $data['records'] ) && is_array( $data['manifest'] ) && is_array( $data['records'] ) ) {
+			$errors = array_merge( $errors, $this->validateRecordBuckets( $data['manifest'], $data['records'] ) );
+		}
+
+		return array() === $errors ? PackageValidationResult::valid() : PackageValidationResult::invalid( $errors );
+	}
+
+	/**
+	 * @param array<string, mixed> $manifest Package manifest.
+	 * @param array<string, mixed> $records  Package records.
+	 *
+	 * @return array<int, string>
+	 */
+	private function validateRecordBuckets( array $manifest, array $records ): array {
+		$errors = array();
+
+		foreach ( self::RECORD_BUCKETS as $bucket ) {
+			if ( ! isset( $records[ $bucket ] ) || ! is_array( $records[ $bucket ] ) ) {
+				$errors[] = 'records.' . $bucket . ' is required and must be an array.';
+				continue;
+			}
+
+			if ( ! isset( $manifest[ $bucket ] ) || ! is_int( $manifest[ $bucket ] ) ) {
+				$errors[] = 'manifest.' . $bucket . ' is required and must be an integer.';
+				continue;
+			}
+
+			if ( count( $records[ $bucket ] ) !== $manifest[ $bucket ] ) {
+				$errors[] = 'manifest.' . $bucket . ' must match records.' . $bucket . ' count.';
+			}
+		}
+
+		return $errors;
+	}
+}