<?php
/**
 * AI Search Quota Manager
 *
 * Handles quota data retrieval, caching, and display logic
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

class AI_Search_Quota_Manager {

    /**
     * @var AI_Search_Service
     */
    private $service_client;

    /**
     * Transient key for cached quota data
     */
    const QUOTA_CACHE_KEY = 'ai_search_quota_data';

    /**
     * Cache duration (6 hours)
     */
    const CACHE_DURATION = 6 * HOUR_IN_SECONDS;

    /**
     * Initialize quota manager
     */
    public function __construct() {
        $this->service_client = new AI_Search_Service();
    }

    /**
     * Get quota data (from cache or API)
     *
     * @param bool $force_refresh Force refresh from API
     * @return array|null Quota data or null if unavailable
     */
    public function get_quota_data( $force_refresh = false ) {
        // Check if using AI Service provider
        $provider = get_option( 'ai_search_provider', 'ai_service' );
        if ( $provider !== 'ai_service' ) {
            return null; // Not using AI Service
        }

        // Return cached data unless force refresh
        if ( ! $force_refresh ) {
            $cached_data = get_transient( self::QUOTA_CACHE_KEY );
            if ( $cached_data !== false ) {
                return $cached_data;
            }
        }

        // Fetch fresh data from API
        $quota_data = $this->fetch_quota_from_api();

        // Cache the data if valid
        if ( $quota_data && $this->validate_quota_data( $quota_data ) ) {
            set_transient( self::QUOTA_CACHE_KEY, $quota_data, self::CACHE_DURATION );
            return $quota_data;
        }

        return null;
    }

    /**
     * Fetch quota data from API
     *
     * @return array|null Raw quota data from API
     */
    private function fetch_quota_from_api() {
        $quota_data = $this->service_client->get_quota_info();

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

        return $quota_data;
    }

    /**
     * Validate quota data structure
     *
     * @param array $data Data to validate
     * @return bool True if valid
     */
    private function validate_quota_data( $data ) {
        if ( ! is_array( $data ) ) {
            return false;
        }

        $required_keys = [
            'total_embeddings_used',
            'total_embeddings_limit',
            'daily_usage',
            'daily_limit',
            'daily_quota_exceeded',
            'total_quota_exceeded',
        ];

        foreach ( $required_keys as $key ) {
            if ( ! isset( $data[ $key ] ) ) {
                return false;
            }
        }

        return true;
    }

    /**
     * Get default/placeholder quota data
     *
     * @return array Default quota structure
     */
    public function get_default_quota_data() {
        return [
            'total_embeddings_used' => 0,
            'total_embeddings_limit' => 10000,
            'daily_usage' => 0,
            'daily_limit' => 1000,
            'daily_quota_exceeded' => false,
            'total_quota_exceeded' => false,
        ];
    }

    /**
     * Calculate percentage for progress bars
     *
     * @param int $used Used amount
     * @param int $limit Total limit
     * @return float Percentage (0-100)
     */
    public function calculate_percentage( $used, $limit ) {
        if ( $limit <= 0 ) {
            return 0;
        }

        return ( $used / $limit ) * 100;
    }

    /**
     * Get status class for quota item
     *
     * @param bool $quota_exceeded Whether quota is exceeded
     * @return string CSS class name
     */
    public function get_status_class( $quota_exceeded ) {
        return $quota_exceeded ? 'quota-exceeded' : 'quota-ok';
    }

    /**
     * Clear quota cache
     *
     * @return bool True on success
     */
    public function clear_cache() {
        return delete_transient( self::QUOTA_CACHE_KEY );
    }

    /**
     * Check if quota data is available
     *
     * @return bool True if data exists in cache
     */
    public function has_cached_data() {
        return get_transient( self::QUOTA_CACHE_KEY ) !== false;
    }

    /**
     * Get last update timestamp
     *
     * @return int|null Timestamp or null if no cache
     */
    public function get_last_update_time() {
        $timeout_option = '_transient_timeout_' . self::QUOTA_CACHE_KEY;
        $timeout = get_option( $timeout_option );

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

        // Calculate when the cache was created
        return $timeout - self::CACHE_DURATION;
    }

    /**
     * Format last update time for display
     *
     * @return string Formatted time string
     */
    public function get_last_update_display() {
        $last_update = $this->get_last_update_time();

        if ( $last_update === null ) {
            return __( 'Never updated', 'ai-search' );
        }

        return sprintf(
            /* translators: %s: human-readable time difference */
            __( 'Last updated %s ago', 'ai-search' ),
            human_time_diff( $last_update, current_time( 'timestamp' ) )
        );
    }
}