<?php

namespace WPFormsSurveys\Reporting;

/**
 * Handles datepicker-related logic for addon admin area.
 *
 * Provides helpers to determine currently selected dates/ranges, active
 * timespan keys, and available date filter choices for UI controls.
 *
 * @since 1.18.0
 */
class Datepicker {

	/**
	 * Date range delimiter used when returning concatenated ranges.
	 *
	 * @since 1.18.0
	 */
	public const RANGE_DELIMITER = ' - ';

	/**
	 * Selected timespan key (e.g., 'today', 'week_ago', 'custom').
	 *
	 * @since 1.18.0
	 *
	 * @var string
	 */
	private $timespan;

	/**
	 * Selected date or date range string.
	 * Examples: "2025-09-12" or "2025-08-15 - 2025-09-12".
	 *
	 * @since 1.18.0
	 *
	 * @var string
	 */
	private $date;

	/**
	 * Datepicker constructor.
	 *
	 * @since 1.18.0
	 *
	 * @param array $filters Filters array that may contain 'timespan' and 'date' keys.
	 */
	public function __construct( array $filters ) {

		$this->timespan = $filters['timespan'] ?? '';
		$this->date     = $filters['date'] ?? '';
	}

	/**
	 * Get a currently active date or date range string for filtering.
	 *
	 * Returns an empty string for "all", a single date for shortcuts like
	 * "today" or "yesterday", a concatenated range for presets, or the
	 * custom date string provided by the user.
	 *
	 * @since 1.18.0
	 *
	 * @return string
	 */
	public function get_current_date(): string {

		$ranges          = $this->get_ranges();
		$active_timespan = $this->get_active_timespan();

		if ( $active_timespan !== 'custom' && isset( $ranges[ $active_timespan ] ) ) {
			// active timespan range.
			return $ranges[ $active_timespan ];
		}

		return (string) $this->date;
	}

	/**
	 * Build an array of predefined date values keyed by timespan.
	 *
	 * Keys include: all, today, yesterday, week_ago, month_ago, quarter_ago, year_ago.
	 * Values are empty string, a single date (Y-m-d), or a concatenated range
	 * of two dates using RANGE_DELIMITER.
	 *
	 * @since 1.18.0
	 *
	 * @return array
	 */
	public function get_ranges(): array {

		$timezone     = wp_timezone(); // Retrieve the timezone string for the site.
		$current_date = date_create_immutable( 'now', $timezone )->setTime( 23, 59, 59 );
		$today        = $current_date->format( 'Y-m-d' );

		return [
			'all'         => '',
			'today'       => $today,
			'yesterday'   => $current_date->modify( '-1 day' )->format( 'Y-m-d' ),
			'week_ago'    => $current_date->modify( '-7 days' )->format( 'Y-m-d' ) . self::RANGE_DELIMITER . $today,
			'month_ago'   => $current_date->modify( '-30 days' )->format( 'Y-m-d' ) . self::RANGE_DELIMITER . $today,
			'quarter_ago' => $current_date->modify( '-90 days' )->format( 'Y-m-d' ) . self::RANGE_DELIMITER . $today,
			'year_ago'    => $current_date->modify( '-365 days' )->format( 'Y-m-d' ) . self::RANGE_DELIMITER . $today,
			'custom'      => '',
		];
	}

	/**
	 * Determine the active timespan key based on the provided filters.
	 *
	 * @since 1.18.0
	 *
	 * @return string Timespan key such as 'all', 'today', 'week_ago', or 'custom'.
	 */
	public function get_active_timespan(): string {

		if ( $this->timespan ) {
			return (string) $this->timespan;
		}

		if ( empty( $this->date ) ) {
			return 'all';
		}

		foreach ( $this->get_ranges() as $key => $range ) {
			if ( ( isset( $range ) && $this->date === $range ) ) {
				return $key;
			}
		}

		return 'custom';
	}

	/**
	 * Get date choices.
	 *
	 * @since 1.18.0
	 *
	 * @return array
	 */
	public function get_date_choices(): array {

		return [
			'all'         => __( 'All Time', 'wpforms-surveys-polls' ),
			'today'       => __( 'Today', 'wpforms-surveys-polls' ),
			'yesterday'   => __( 'Yesterday', 'wpforms-surveys-polls' ),
			'week_ago'    => __( 'Last 7 days', 'wpforms-surveys-polls' ),
			'month_ago'   => __( 'Last 30 days', 'wpforms-surveys-polls' ),
			'quarter_ago' => __( 'Last 90 days', 'wpforms-surveys-polls' ),
			'year_ago'    => __( 'Last 1 year', 'wpforms-surveys-polls' ),
			'custom'      => __( 'Custom', 'wpforms-surveys-polls' ),
		];
	}
}