<?php
/**
 * Usage Tracker
 *
 * Tracks daily usage counters in the schema_ai_usage table for
 * AI generations, manual generations, and validations.
 *
 * @package    Schema_AI
 * @subpackage Schema_AI/includes/utilities
 * @since      1.0.0
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

class Schema_AI_Usage_Tracker {

    /**
     * Allowed counter field names.
     *
     * @var array
     */
    const ALLOWED_FIELDS = array( 'ai_generations', 'manual_generations', 'validations' );

    /**
     * Increment a counter field for a given user.
     *
     * Creates a new row for today if one does not exist, otherwise
     * increments the specified column by one.
     *
     * @param int    $user_id WordPress user ID.
     * @param string $field   One of: ai_generations, manual_generations, validations.
     * @return bool True on success, false on invalid field or database error.
     */
    public function increment( $user_id, $field ) {
        if ( ! in_array( $field, self::ALLOWED_FIELDS, true ) ) {
            return false;
        }

        global $wpdb;

        $table = esc_sql( $wpdb->prefix . 'schema_ai_usage' );
        $today = current_time( 'Y-m-d' );

        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; no WP API alternative exists.
        $existing = $wpdb->get_var(
            $wpdb->prepare(
                // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
                "SELECT id FROM {$table} WHERE user_id = %d AND date = %s",
                $user_id,
                $today
            )
        );

        if ( $existing ) {
            // Column name comes from ALLOWED_FIELDS whitelist above.
            // Each case is hardcoded to avoid any dynamic interpolation in SQL.
            if ( 'ai_generations' === $field ) {
                // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
                $sql = $wpdb->prepare( "UPDATE {$table} SET ai_generations = ai_generations + 1 WHERE id = %d", $existing );
            } elseif ( 'manual_generations' === $field ) {
                // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
                $sql = $wpdb->prepare( "UPDATE {$table} SET manual_generations = manual_generations + 1 WHERE id = %d", $existing );
            } else {
                // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
                $sql = $wpdb->prepare( "UPDATE {$table} SET validations = validations + 1 WHERE id = %d", $existing );
            }

            // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared -- Required for custom table; write/DDL operation, caching not applicable.
            $result = $wpdb->query( $sql );

            return false !== $result;
        }

        // Build the insert data with all fields defaulting to zero.
        $data = array(
            'user_id'            => $user_id,
            'date'               => $today,
            'ai_generations'     => 0,
            'manual_generations' => 0,
            'validations'        => 0,
        );

        // Set the requested field to 1.
        $data[ $field ] = 1;

        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; write operation (INSERT), caching not applicable.
        $result = $wpdb->insert(
            $table,
            $data,
            array( '%d', '%s', '%d', '%d', '%d' )
        );

        return false !== $result;
    }

    /**
     * Get today's usage row for a user.
     *
     * @param int $user_id WordPress user ID.
     * @return object|null Row object with ai_generations, manual_generations,
     *                     validations, date, and last_reset. Null if no row exists.
     */
    public function get_daily( $user_id ) {
        global $wpdb;

        $table = esc_sql( $wpdb->prefix . 'schema_ai_usage' );
        $today = current_time( 'Y-m-d' );

        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; no WP API alternative exists.
        $row = $wpdb->get_row(
            $wpdb->prepare(
                // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
                "SELECT * FROM {$table} WHERE user_id = %d AND date = %s",
                $user_id,
                $today
            )
        );

        return $row;
    }

    /**
     * Get usage rows for a user within a date range (inclusive).
     *
     * @param int    $user_id    WordPress user ID.
     * @param string $start_date Start date in Y-m-d format.
     * @param string $end_date   End date in Y-m-d format.
     * @return array Array of row objects.
     */
    public function get_range( $user_id, $start_date, $end_date ) {
        global $wpdb;

        $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(
            $wpdb->prepare(
                // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
                "SELECT * FROM {$table} WHERE user_id = %d AND date >= %s AND date <= %s ORDER BY date ASC",
                $user_id,
                $start_date,
                $end_date
            )
        );

        return $results ? $results : array();
    }

    /**
     * Get all-time aggregate totals for a user.
     *
     * @param int $user_id WordPress user ID.
     * @return object {
     *     @type int $ai_generations     Total AI generations.
     *     @type int $manual_generations  Total manual generations.
     *     @type int $validations         Total validations.
     *     @type int $total_days          Number of days with activity.
     * }
     */
    public function get_totals( $user_id ) {
        global $wpdb;

        $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.
        $row = $wpdb->get_row(
            $wpdb->prepare(
                // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
                "SELECT COALESCE( SUM( ai_generations ), 0 ) AS ai_generations, COALESCE( SUM( manual_generations ), 0 ) AS manual_generations, COALESCE( SUM( validations ), 0 ) AS validations, COUNT( * ) AS total_days FROM {$table} WHERE user_id = %d",
                $user_id
            )
        );

        if ( ! $row ) {
            return (object) array(
                'ai_generations'     => 0,
                'manual_generations' => 0,
                'validations'        => 0,
                'total_days'         => 0,
            );
        }

        return (object) array(
            'ai_generations'     => (int) $row->ai_generations,
            'manual_generations' => (int) $row->manual_generations,
            'validations'        => (int) $row->validations,
            'total_days'         => (int) $row->total_days,
        );
    }

    /**
     * Reset daily counters.
     *
     * Intended to be called by the schema_ai_usage_reset cron event.
     * It does not delete rows; instead it inserts fresh zero-count rows
     * for every user who had activity the previous day, ensuring a
     * clean slate. The actual reset is automatic because get_daily()
     * looks for today's date, and a new day means a new row.
     *
     * This method serves as a hook point for any additional reset logic
     * (e.g., firing notifications, syncing external services).
     */
    public function reset_daily() {
        /**
         * Fires when the daily usage counters are reset.
         *
         * @since 1.0.0
         */
        do_action( 'schema_ai_usage_daily_reset' );
    }

    /**
     * Delete usage records older than a specified number of days.
     *
     * @param int $days Number of days to keep. Records older than this are deleted. Default 30.
     * @return int Number of rows deleted.
     */
    public function cleanup( $days = 30 ) {
        global $wpdb;

        $table    = esc_sql( $wpdb->prefix . 'schema_ai_usage' );
        $cutoff   = gmdate( 'Y-m-d', strtotime( '-' . absint( $days ) . ' days' ) );

        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Required for custom table; write/DDL operation, caching not applicable.
        $deleted = $wpdb->query(
            $wpdb->prepare(
                // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name is sanitized via esc_sql() and not user input.
                "DELETE FROM {$table} WHERE date < %s",
                $cutoff
            )
        );

        return $deleted ? (int) $deleted : 0;
    }
}