<?php
/**
 * Stats Endpoint
 *
 * REST API endpoint for retrieving schema usage statistics and
 * daily usage breakdowns.
 *
 * @package    Schema_AI
 * @subpackage Schema_AI/includes/api/endpoints
 * @since      1.0.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class Schema_AI_Stats_Endpoint extends Schema_AI_REST_Controller {

	/**
	 * Route base.
	 *
	 * @var string
	 */
	protected $rest_base = 'stats';

	/**
	 * Register REST API routes.
	 */
	public function register_routes() {
		// GET /stats - Get overall usage statistics.
		register_rest_route(
			$this->namespace,
			'/' . $this->rest_base,
			array(
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'get_stats' ),
					'permission_callback' => array( $this, 'stats_permissions_check' ),
				),
			)
		);

		// GET /stats/usage - Get daily usage breakdown.
		register_rest_route(
			$this->namespace,
			'/' . $this->rest_base . '/usage',
			array(
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'get_usage' ),
					'permission_callback' => array( $this, 'stats_permissions_check' ),
					'args'                => array(
						'start_date' => array(
							'description'       => __( 'Start date in Y-m-d format. Defaults to 30 days ago.', 'ai-schema-gen' ),
							'type'              => 'string',
							'sanitize_callback' => 'sanitize_text_field',
						),
						'end_date' => array(
							'description'       => __( 'End date in Y-m-d format. Defaults to today.', 'ai-schema-gen' ),
							'type'              => 'string',
							'sanitize_callback' => 'sanitize_text_field',
						),
					),
				),
			)
		);
	}

	/**
	 * Get overall usage statistics.
	 *
	 * Returns aggregated counts of schemas by type and validation status,
	 * today's AI generation count, and recent generation history.
	 *
	 * @param WP_REST_Request $request Full details about the request.
	 * @return WP_REST_Response Response object.
	 */
	public function get_stats( $request ) {
		global $wpdb;

		error_log( 'AI Schema Gen: get_stats() called — user=' . get_current_user_id() );

		$schemas_table     = esc_sql( $wpdb->prefix . 'schema_ai_schemas' );
		$usage_table       = esc_sql( $wpdb->prefix . 'schema_ai_usage' );
		$generations_table = esc_sql( $wpdb->prefix . 'schema_ai_generations' );
		$today             = current_time( 'Y-m-d' );
		$user_id           = get_current_user_id();

		// Total schemas count.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; no WP API alternative exists.
		$total_schemas = (int) $wpdb->get_var(
			// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
			"SELECT COUNT(*) FROM {$schemas_table}"
		);

		// Schemas grouped by type.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; no WP API alternative exists.
		$schemas_by_type = $wpdb->get_results(
			// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
			"SELECT schema_type, COUNT(*) AS count FROM {$schemas_table} GROUP BY schema_type ORDER BY count DESC",
			ARRAY_A
		);

		// Schemas grouped by validation status.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; no WP API alternative exists.
		$schemas_by_status = $wpdb->get_results(
			// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
			"SELECT validation_status, COUNT(*) AS count FROM {$schemas_table} GROUP BY validation_status ORDER BY count DESC",
			ARRAY_A
		);

		// AI generations today for the current user.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; no WP API alternative exists.
		$generations_today = (int) $wpdb->get_var(
			$wpdb->prepare(
				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
				"SELECT COALESCE( SUM( ai_generations ), 0 ) FROM {$usage_table} WHERE user_id = %d AND date = %s",
				$user_id,
				$today
			)
		);

		// Recent generation history (last 10 entries).
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; no WP API alternative exists.
		$recent_generations = $wpdb->get_results(
			$wpdb->prepare(
				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
				"SELECT * FROM {$generations_table} WHERE user_id = %d ORDER BY created_at DESC LIMIT %d",
				$user_id,
				10
			),
			ARRAY_A
		);

		if ( ! $recent_generations ) {
			$recent_generations = array();
		}

		// Cast numeric fields and add post metadata for the recent generations.
		foreach ( $recent_generations as &$gen ) {
			$gen['id']         = isset( $gen['id'] ) ? (int) $gen['id'] : 0;
			$gen['user_id']    = isset( $gen['user_id'] ) ? (int) $gen['user_id'] : 0;
			$gen['post_id']    = isset( $gen['post_id'] ) ? (int) $gen['post_id'] : 0;
			$gen['confidence'] = isset( $gen['confidence'] ) ? (float) $gen['confidence'] : null;
			$gen['post_title'] = $gen['post_id'] ? get_the_title( $gen['post_id'] ) : '';
			$gen['post_url']   = $gen['post_id'] ? get_permalink( $gen['post_id'] ) : '';
		}
		unset( $gen );

		// Cast count values.
		if ( $schemas_by_type ) {
			foreach ( $schemas_by_type as &$row ) {
				$row['count'] = (int) $row['count'];
			}
			unset( $row );
		} else {
			$schemas_by_type = array();
		}

		if ( $schemas_by_status ) {
			foreach ( $schemas_by_status as &$row ) {
				$row['count'] = (int) $row['count'];
			}
			unset( $row );
		} else {
			$schemas_by_status = array();
		}

		// Recent schemas (last 10 for the dashboard table).
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; no WP API alternative exists.
		$recent_schemas = $wpdb->get_results(
			// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
			"SELECT id, post_id, schema_type, validation_status, updated_at AS created_at FROM {$schemas_table} ORDER BY updated_at DESC LIMIT 10",
			ARRAY_A
		);

		if ( ! $recent_schemas ) {
			$recent_schemas = array();
		}

		foreach ( $recent_schemas as &$schema ) {
			$schema['id']      = (int) $schema['id'];
			$schema['post_id'] = (int) $schema['post_id'];
			$schema['post_title'] = $schema['post_id'] ? get_the_title( $schema['post_id'] ) : '';
			$schema['post_url']   = $schema['post_id'] ? get_permalink( $schema['post_id'] ) : '';
		}
		unset( $schema );

		// Build by_type and by_status as keyed objects for frontend.
		$by_type = array();
		foreach ( $schemas_by_type as $row ) {
			$by_type[ $row['schema_type'] ] = $row['count'];
		}

		$by_status = array();
		foreach ( $schemas_by_status as $row ) {
			$by_status[ $row['validation_status'] ] = $row['count'];
		}

		error_log( 'AI Schema Gen: get_stats() returning — total_schemas=' . $total_schemas . ' today_generations=' . $generations_today . ' recent_count=' . count( $recent_schemas ) );

		return $this->success_response(
			array(
				'total_schemas'       => $total_schemas,
				'by_type'             => $by_type,
				'by_status'           => $by_status,
				'today_generations'   => $generations_today,
				'recent'              => $recent_schemas,
				'recent_generations'  => $recent_generations,
			)
		);
	}

	/**
	 * Get daily usage breakdown for a date range.
	 *
	 * Returns a row for each day with AI generation and validation
	 * counts from the usage table.
	 *
	 * @param WP_REST_Request $request Full details about the request.
	 * @return WP_REST_Response Response object.
	 */
	public function get_usage( $request ) {
		global $wpdb;

		$user_id    = get_current_user_id();
		$end_date   = sanitize_text_field( $request->get_param( 'end_date' ) );
		$start_date = sanitize_text_field( $request->get_param( 'start_date' ) );

		// Default to the last 30 days.
		if ( empty( $end_date ) ) {
			$end_date = current_time( 'Y-m-d' );
		}

		if ( empty( $start_date ) ) {
			$start_date = gmdate( 'Y-m-d', strtotime( '-30 days', strtotime( $end_date ) ) );
		}

		// Validate date formats.
		if ( ! preg_match( '/^\d{4}-\d{2}-\d{2}$/', $start_date ) || ! preg_match( '/^\d{4}-\d{2}-\d{2}$/', $end_date ) ) {
			return $this->error_response(
				'schema_ai_invalid_date',
				__( 'Dates must be in Y-m-d format.', 'ai-schema-gen' ),
				400
			);
		}

		$table = esc_sql( $wpdb->prefix . 'schema_ai_usage' );

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; no WP API alternative exists.
		$results = $wpdb->get_results(
			$wpdb->prepare(
				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
				"SELECT date, ai_generations, manual_generations, validations FROM {$table} WHERE user_id = %d AND date >= %s AND date <= %s ORDER BY date ASC",
				$user_id,
				$start_date,
				$end_date
			),
			ARRAY_A
		);

		if ( ! $results ) {
			$results = array();
		}

		// Cast numeric fields.
		foreach ( $results as &$row ) {
			$row['ai_generations']     = (int) $row['ai_generations'];
			$row['manual_generations'] = (int) $row['manual_generations'];
			$row['validations']        = (int) $row['validations'];
		}
		unset( $row );

		// Get limit/remaining from the backend — single source of truth.
		$settings = get_option( 'schema_ai_settings', array() );
		$api_key  = ! empty( $settings['api_key'] ) ? $settings['api_key'] : '';

		if ( empty( $api_key ) ) {
			return $this->error_response(
				'schema_ai_no_api_key',
				__( 'AI Schema Gen API key is not configured.', 'ai-schema-gen' ),
				400
			);
		}

		$backend_response = wp_remote_get(
			SCHEMA_AI_API_BASE . '/usage',
			array(
				'timeout' => 10,
				'headers' => array(
					'Content-Type' => 'application/json',
					'X-API-Key'    => $api_key,
				),
			)
		);

		if ( is_wp_error( $backend_response ) || 200 !== wp_remote_retrieve_response_code( $backend_response ) ) {
			return $this->error_response(
				'schema_ai_backend_error',
				__( 'Could not retrieve usage from AI Schema Gen server.', 'ai-schema-gen' ),
				502
			);
		}

		$backend_data = json_decode( wp_remote_retrieve_body( $backend_response ), true );

		if ( empty( $backend_data['success'] ) || ! isset( $backend_data['data']['rateLimit'] ) ) {
			return $this->error_response(
				'schema_ai_backend_error',
				__( 'Invalid response from AI Schema Gen server.', 'ai-schema-gen' ),
				502
			);
		}

		$rate_limit   = $backend_data['data']['rateLimit'];
		$remaining    = (int) $rate_limit['remaining'];
		$limit        = (int) $rate_limit['limit'];
		$monthly_used = (int) $rate_limit['used'];
		$plan         = isset( $backend_data['data']['plan'] ) ? $backend_data['data']['plan'] : 'free';

		return $this->success_response(
			array(
				'start_date' => $start_date,
				'end_date'   => $end_date,
				'days'       => count( $results ),
				'usage'      => $results,
				'remaining'  => $remaining,
				'limit'      => $limit,
				'used'       => $monthly_used,
				'plan'       => $plan,
			)
		);
	}

	/**
	 * Permission check for stats endpoints.
	 *
	 * @param WP_REST_Request $request Full details about the request.
	 * @return true|WP_Error True if allowed.
	 */
	public function stats_permissions_check( $request ) {
		if ( ! current_user_can( 'edit_posts' ) ) {
			return new WP_Error(
				'schema_ai_forbidden',
				__( 'You do not have permission to view statistics.', 'ai-schema-gen' ),
				array( 'status' => 403 )
			);
		}

		return true;
	}
}