<?php
declare(strict_types=1);

namespace WP_Rocket\Engine\Admin\RocketInsights\Recommendations;

use WP_Rocket\Admin\Options_Data;
use WP_Rocket\Engine\Admin\RocketInsights\GlobalMetrics\Calculator;
use WP_Rocket\Engine\Admin\RocketInsights\GlobalScore;
use WP_Rocket\Engine\Admin\RocketInsights\MetricFormatter;
use WP_Rocket\Engine\Tracking\TrackingTrait;
use WP_Rocket\Logger\LoggerAware;
use WP_Rocket\Logger\LoggerAwareInterface;

/**
 * Recommendations Data Manager.
 *
 * Centralized management for fetching, caching, and clearing recommendations.
 */
class DataManager implements LoggerAwareInterface {
	use LoggerAware;
	use TrackingTrait;

	/**
	 * Transient name for storing recommendations.
	 *
	 * @var string
	 */
	private const TRANSIENT_NAME = 'wpr_ri_recommendations';

	/**
	 * Cache expiration time in seconds (24 hours).
	 *
	 * @var int
	 */
	private const CACHE_EXPIRATION = DAY_IN_SECONDS;

	/**
	 * Map of WP Rocket option keys to their tab IDs in dashboard.
	 *
	 * These options affect recommendations and should trigger a refresh when changed.
	 *
	 * @var array<string, string>
	 */
	private const TRACKED_OPTIONS = [
		'image_dimensions'             => 'media',
		'defer_all_js'                 => 'file_optimization',
		'delay_js'                     => 'file_optimization',
		'lazyload_css_bg_img'          => 'media',
		'lazyload_iframes'             => 'media',
		'lazyload'                     => 'media',
		'minify_css'                   => 'file_optimization',
		'minify_js'                    => 'file_optimization',
		'manual_preload'               => 'preload',
		'auto_preload_fonts'           => 'media',
		'preload_links'                => 'preload',
		'remove_unused_css'            => 'file_optimization',
		'host_fonts_locally'           => 'media',

		'performance_monitoring'       => 'rocket_insights',
		'optimize_css_delivery'        => 'file_optimization',
		'delay_js_execution_safe_mode' => 'file_optimization',
		'lazyload_youtube'             => 'media',
		'database_revisions'           => 'database',
		'database_auto_drafts'         => 'database',
		'database_trashed_posts'       => 'database',
		'database_spam_comments'       => 'database',
		'database_trashed_comments'    => 'database',
		'database_optimize_tables'     => 'database',
		'schedule_automatic_cleanup'   => 'database',
		'cdn'                          => 'page_cdn',
		'control_heartbeat'            => 'heartbeat',
		'cache_logged_user'            => 'addons',
		'minify_concatenate_js'        => 'file_optimization',
		'database_all_transients'      => 'database',
		'sucury_waf_cache_sync'        => 'addons',
		'varnish_auto_purge'           => 'addons',
	];

	/**
	 * Mapping of average metric keys to API parameter keys.
	 */
	private const METRICS_MAPPING = [
		'largest_contentful_paint' => 'lcp',
		'time_to_first_byte'       => 'ttfb',
		'cumulative_layout_shift'  => 'cls',
		'total_blocking_time'      => 'tbt',
	];

	/**
	 * Recommendations API Client instance.
	 *
	 * @var APIClient
	 */
	private $api_client;

	/**
	 * Plugin options instance.
	 *
	 * @var Options_Data
	 */
	private $options;

	/**
	 * Global Score instance.
	 *
	 * @var GlobalScore
	 */
	private $global_score;

	/**
	 * Metric Formatter instance.
	 *
	 * @var MetricFormatter
	 */
	private $metric_formatter;

	/**
	 * Constructor.
	 *
	 * @param APIClient       $api_client   API Client instance.
	 * @param Options_Data    $options      Options instance.
	 * @param GlobalScore     $global_score Global Score instance.
	 * @param MetricFormatter $metric_formatter Metric Formatter instance.
	 */
	public function __construct( APIClient $api_client, Options_Data $options, GlobalScore $global_score, MetricFormatter $metric_formatter ) {
		$this->api_client       = $api_client;
		$this->options          = $options;
		$this->global_score     = $global_score;
		$this->metric_formatter = $metric_formatter;
	}

	/**
	 * Get cached recommendations.
	 *
	 * @return array|false Recommendations data or false if not cached.
	 */
	public function get_recommendations() {
		$data = get_transient( self::TRANSIENT_NAME );

		if ( false === $data ) {
			$this->logger::debug( 'Recommendations: No cached data found' );
			return false;
		}

		// Validate structure.
		if ( ! isset( $data['status'] ) || ! isset( $data['timestamp'] ) ) {
			$this->logger::warning( 'Recommendations: Invalid cached data structure, clearing cache' );
			$this->clear_recommendations();
			return false;
		}

		$this->logger::debug(
			'Recommendations: Retrieved from cache',
			[
				'status'    => $data['status'],
				'timestamp' => $data['timestamp'],
			]
		);

		return $data;
	}

	/**
	 * Fetch recommendations from API and store in transient.
	 *
	 * @param array $options New settings to consider when fetching recommendations if available.
	 * @return bool True on success, false on failure.
	 */
	public function fetch_recommendations( array $options = [] ): bool {
		// Set loading status immediately.
		$this->set_loading_status();

		// Track start time for performance measurement.
		$start_time = microtime( true );

		$this->logger::debug( 'Recommendations: Starting fetch from API' );

		// Get enabled WP Rocket options.
		$enabled_options = $this->get_enabled_options( $options );

		// Build API parameters.
		$params = [
			'email'           => $this->options->get( 'consumer_email', '' ),
			'language'        => $this->get_language(),
			'limit'           => 20, // Get all recommendations.
			'version'         => rocket_get_constant( 'WP_ROCKET_VERSION' ),
			'enabled_options' => $enabled_options,
		];

		// Add metrics to parameters.
		$metrics_params = $this->prepare_metrics_to_api();
		if ( ! empty( $metrics_params ) ) {
			$params = array_merge( $params, $metrics_params );
		}

		/**
		 * Filters the parameters sent to the Recommendations API.
		 *
		 * @param array $params API parameters.
		 * @return array Modified API parameters.
		 */
		$params = wpm_apply_filters_typed( 'array', 'rocket_insights_api_recommendations_params', $params );

		// Call API.
		$response = $this->api_client->get_recommendations( $params );

		// Handle error response.
		if ( is_wp_error( $response ) ) {
			// Calculate duration in milliseconds.
			$duration = round( ( microtime( true ) - $start_time ) * 1000 );

			$this->logger::error(
				'Recommendations: API request failed',
				[
					'code'    => $response->get_error_code(),
					'message' => $response->get_error_message(),
					'params'  => $params,
				]
			);

			$this->set_recommendations_failed( $response->get_error_message(), $duration );

			return false;
		}

		// Handle success response.
		if ( isset( $response['code'] ) && 200 === $response['code'] && isset( $response['data'] ) ) {
			// Calculate duration in milliseconds.
			$duration = round( ( microtime( true ) - $start_time ) * 1000 );
			$quantity = count( $response['data']['recommendations'] ?? [] );

			$this->logger::info(
				'Recommendations: Successfully fetched from API',
				[
					'total' => $quantity,
				]
			);

			$this->save_recommendations(
				[
					'status'          => 'completed',
					'recommendations' => $response['data']['recommendations'] ?? [],
					'metadata'        => $response['data']['metadata'] ?? [],
					'timestamp'       => time(),
					'metrics_hash'    => $this->calculate_metrics_hash(),
					'tracking'        => [
						'status'   => 'success',
						'quantity' => $quantity,
						'duration' => $duration,
					],
				]
			);

			// Track Mixpanel event immediately.
			$this->track_event(
				'Rocket Insights Recommendation',
				[
					'status'   => 'success',
					'quantity' => $quantity,
					'duration' => $duration,
				]
			);

			return true;
		}

		// Unexpected response format.
		$this->logger::error(
			'Recommendations: Unexpected API response format',
			[ 'response' => $response ]
		);

		// Calculate duration for tracking.
		$duration = round( ( microtime( true ) - $start_time ) * 1000 );

		$this->save_recommendations(
			[
				'status'          => 'failed',
				'recommendations' => [],
				'metadata'        => [],
				'timestamp'       => time(),
				'error'           => 'Unexpected API response format',
				'tracking'        => [
					'status'   => 'error',
					'quantity' => 0,
					'duration' => $duration,
				],
			]
		);

		// Track Mixpanel event immediately.
		$this->track_event(
			'Rocket Insights Recommendation',
			[
				'status'   => 'error',
				'quantity' => 0,
				'duration' => $duration,
			]
		);

		return false;
	}

	/**
	 * Prepare average metrics for API parameters.
	 *
	 * @return array
	 */
	private function prepare_metrics_to_api(): array {
		$params = [];

		// Get average metrics from global score data.
		$average_metrics = $this->get_average_metrics( false );
		if ( ! is_array( $average_metrics ) || empty( $average_metrics ) ) {
			return [];
		}

		if ( isset( $average_metrics['global_score'] ) ) {
			$params['global_score'] = $average_metrics['global_score'];
			unset( $average_metrics['global_score'] );
		}

		foreach ( $average_metrics as $metric_key => $metric_value ) {
			if ( ! isset( self::METRICS_MAPPING[ $metric_key ] ) ) {
				continue;
			}
			$param_key            = self::METRICS_MAPPING[ $metric_key ];
			$params[ $param_key ] = in_array( $param_key, [ 'cls', 'tbt' ], true ) ? $metric_value : $metric_value / 1000;
		}

		return $params;
	}

	/**
	 * Clear cached recommendations.
	 *
	 * @return void
	 */
	public function clear_recommendations(): void {
		delete_transient( self::TRANSIENT_NAME );

		$this->logger::debug( 'Recommendations: Cache cleared' );
	}

	/**
	 * Get list of WP Rocket option keys that affect recommendations.
	 *
	 * @return array<string> Array of option keys.
	 */
	public static function get_tracked_option_keys(): array {
		return array_keys( self::TRACKED_OPTIONS );
	}

	/**
	 * Get current recommendation status.
	 *
	 * @return string Status: 'expired', 'pending', 'loading', 'completed', 'failed'.
	 */
	public function get_status(): string {
		$data = $this->get_recommendations();

		if ( false === $data ) {
			return 'expired';
		}

		return $data['status'];
	}


	/**
	 * Check if required metrics are available for recommendations.
	 *
	 * @return bool True if metrics exist, false otherwise.
	 */
	public function has_required_metrics(): bool {
		$average_metrics = $this->get_average_metrics();

		if ( null === $average_metrics ) {
			return false;
		}

		// Verify core metrics exist.
		$required = Calculator::METRIC_KEYS;
		foreach ( $required as $metric ) {
			if ( ! isset( $average_metrics[ $metric ] ) || 'N/A' === $average_metrics[ $metric ] ) {
				return false;
			}
		}

		return true;
	}

	/**
	 * Determine if recommendations should be fetched.
	 *
	 * Compares current metrics hash with cached hash.
	 *
	 * @return bool True if should fetch, false if cache is valid.
	 */
	public function should_fetch_recommendations(): bool {
		$recommendations = $this->get_recommendations();

		// No cache = should fetch.
		if ( false === $recommendations ) {
			return true;
		}

		// Calculate current hash.
		$current_hash = $this->calculate_metrics_hash();
		$cached_hash  = $recommendations['metrics_hash'] ?? '';

		// Fetch if hash changed.
		return $current_hash !== $cached_hash;
	}

	/**
	 * Extend transient expiration without fetching.
	 *
	 * Used when data hasn't changed but transient is expiring.
	 *
	 * @return void
	 */
	public function extend_transient(): void {
		$data = $this->get_recommendations();

		if ( false === $data ) {
			return;
		}

		set_transient( self::TRANSIENT_NAME, $data, self::CACHE_EXPIRATION );

		$this->logger::debug( 'Recommendations: Transient extended (no changes detected)' );
	}

	/**
	 * Set loading status in transient.
	 *
	 * @return void
	 */
	private function set_loading_status(): void {
		$data = [
			'status'          => 'loading',
			'recommendations' => [],
			'metadata'        => [],
			'timestamp'       => time(),
		];

		set_transient( self::TRANSIENT_NAME, $data, self::CACHE_EXPIRATION );

		$this->logger::debug( 'Recommendations: Status set to loading' );
	}

	/**
	 * Save recommendations to transient.
	 *
	 * @param array $data Recommendations data.
	 * @return void
	 */
	private function save_recommendations( array $data ): void {
		set_transient( self::TRANSIENT_NAME, $data, self::CACHE_EXPIRATION );

		$this->logger::debug(
			'Recommendations: Saved to cache',
			[ 'status' => $data['status'] ]
		);
	}

	/**
	 * Calculate hash of current metrics and settings.
	 *
	 * @return string MD5 hash.
	 */
	private function calculate_metrics_hash(): string {
		$global_score_data = $this->global_score->get_global_score_data();
		$enabled_options   = $this->get_enabled_options();

		$data = [
			'score'           => $global_score_data['score'] ?? 0,
			'average_metrics' => $global_score_data['average_metrics'] ?? [],
			'enabled_options' => $enabled_options,
		];

		return md5( (string) wp_json_encode( $data ) );
	}

	/**
	 * Get average metrics from global score data.
	 *
	 * @param bool $formatted Whether to return formatted metrics (default: true).
	 * @return array|null Average metrics or null if not available.
	 */
	private function get_average_metrics( bool $formatted = true ): ?array {
		$global_score_data = $this->global_score->get_global_score_data();

		if ( empty( $global_score_data['average_metrics'] ) ) {
			$this->logger::debug( 'Recommendations: No average metrics available' );
			return null;
		}

		foreach ( $global_score_data['average_metrics'] as $metric_key => $metric ) {
			if ( empty( $metric ) || ! isset( $metric['value'] ) ) {
				continue;
			}

			$global_score_data['average_metrics'][ $metric_key ] = $formatted ? $this->metric_formatter->format_metric( $metric_key, $metric['value'] ) : $metric['value'];
		}

		$global_score_data['average_metrics']['global_score'] = $global_score_data['score'];
		return $global_score_data['average_metrics'];
	}

	/**
	 * Get enabled WP Rocket options.
	 *
	 * Returns array of option slugs that are currently enabled.
	 *
	 * @param array $options Optional array of new settings to check instead of current options.
	 * @return array Enabled option slugs.
	 */
	private function get_enabled_options( array $options = [] ): array {
		$enabled = [];

		foreach ( self::TRACKED_OPTIONS as $option_key => $option_tab ) {
			$value = $this->get_option_value( $option_key, $options );

			// Check if option is enabled.
			if ( $this->is_option_enabled( $option_key, $value ) ) {
				$enabled[] = $option_key;
			}
		}

		$this->logger::debug(
			'Recommendations: Enabled options',
			[ 'enabled' => $enabled ]
		);

		return $enabled;
	}

	/**
	 * Check if a specific option is enabled.
	 *
	 * @param string $option_key Option key.
	 * @param mixed  $value      Option value.
	 * @return bool True if enabled, false otherwise.
	 */
	private function is_option_enabled( string $option_key, $value ): bool {
		// Boolean options.
		return ! empty( $value ) && 1 === (int) $value;
	}

	/**
	 * Get option value from either provided options array or current options instance.
	 *
	 * @param string         $option_key Option key to retrieve.
	 * @param array|string[] $options Optional array of new settings to check instead of current options. If empty, will use current options instance.
	 *
	 * @return mixed
	 */
	private function get_option_value( string $option_key, $options = [] ) {
		if ( ! empty( $options ) ) {
			return $options[ $option_key ] ?? false;
		}
		return $this->options->get( $option_key, false );
	}

	/**
	 * Get current language code.
	 *
	 * @return string ISO language code (e.g., 'en', 'fr').
	 */
	private function get_language(): string {
		// Get WordPress locale (e.g., 'en_US', 'fr_FR').
		$locale = get_locale();

		// Extract language code (first 2 characters).
		$language = substr( $locale, 0, 2 );

		return $language;
	}

	/**
	 * Maybe fetch recommendations with validation.
	 *
	 * Checks:
	 * 1. Average metrics are available
	 * 2. Hash has changed (data is different)
	 * 3. Not already loading
	 *
	 * @return void
	 */
	public function maybe_fetch_recommendations(): void {
		// Bail if already loading.
		if ( 'loading' === $this->get_status() ) {
			return;
		}

		// Get global score data to check for URLs.
		$global_score_data = $this->global_score->get_global_score_data();
		$status            = $global_score_data['status'];

		// If no URLs in Performance Monitoring, save failed state.
		// There's nothing to analyze yet, so show failed state.
		if ( 'no-url' === $status ) {
			$this->save_empty_recommendations();
			return;
		}

		// Save empty state if metrics not ready (e.g., all tests failed).
		if ( ! $this->has_required_metrics() ) {
			return;
		}

		// Bail if data hasn't changed.
		if ( ! $this->should_fetch_recommendations() ) {
			$this->extend_transient(); // Extend for another 24h.
			return;
		}

		// Fetch new recommendations.
		$this->fetch_recommendations();
	}

	/**
	 * Returns the section anchor corresponding to a given option slug.
	 *
	 * This method maps a provided option slug to its associated section anchor,
	 * which is used for navigation within the admin interface. If the option slug
	 * does not exist in the mapping, it defaults to 'dashboard'.
	 *
	 * @param string $option_slug The slug of the option to map.
	 * @return string
	 */
	public function get_section_from_option_slug( string $option_slug ): string {
		return self::TRACKED_OPTIONS[ $option_slug ] ?? 'dashboard';
	}

	/**
	 * Save empty recommendations state when metrics are not available.
	 *
	 * This displays the failed state when:
	 * - No URLs exist in Performance Monitoring yet
	 * - All tests have failed
	 * - Metrics are incomplete
	 *
	 * @return void
	 */
	private function save_empty_recommendations(): void {
		$this->save_recommendations(
			[
				'status'          => 'failed',
				'recommendations' => [],
				'metadata'        => [],
				'timestamp'       => time(),
				'error'           => 'Recommendations unavailable',
			]
		);

		$this->logger::debug( 'Recommendations: Saved failed state (no recommendations available)' );
	}

	/**
	 * Set recommendations to failed status with error message and tracking info.
	 *
	 * @param string $error_message Error message to store (default: 'Failed to fetch recommendations').
	 * @param float  $duration Duration of the failed fetch attempt in milliseconds (default: 0).
	 * @return void
	 */
	public function set_recommendations_failed( string $error_message = 'Failed to fetch recommendations', float $duration = 0 ): void {
		$this->save_recommendations(
			[
				'status'          => 'failed',
				'recommendations' => [],
				'metadata'        => [],
				'timestamp'       => time(),
				'error'           => $error_message,
				'tracking'        => [
					'status'   => 'error',
					'quantity' => 0,
					'duration' => $duration,
				],
			]
		);

		// Track Mixpanel event immediately.
		$this->track_event(
			'Rocket Insights Recommendation',
			[
				'status'   => 'error',
				'quantity' => 0,
				'duration' => $duration,
			]
		);
	}

	/**
	 * Forces the recalculation of global metrics.
	 *
	 * @return void
	 */
	public function force_global_metrics_recalculation(): void {
		$this->global_score->reset();
	}
}