<?php
/**
 * Going through the new enquiries with drafts ready.
 *
 * @package Dealroot
 */

namespace Dealroot;

defined( 'ABSPATH' ) || exit;

/**
 * One button: spam goes to Spam, and the AI assistant writes a draft for each new enquiry that
 * waits for an answer. Then the owner goes through them one after the other, changes what does
 * not fit and sends each with one click. The drafts are written in the background, a few at a
 * time, with an allowance of their own, so the drafts written one by one stay available.
 *
 * phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
 */
class Inbox {

	const OPTION = 'dealroot_inbox';
	const HOOK   = 'dealroot_inbox_write';

	/**
	 * Enquiries in one go.
	 */
	const MAX = 20;

	/**
	 * Drafts written in one run of the background task.
	 */
	const PER_RUN = 4;

	/**
	 * Only enquiries of these last days still wait for a first answer.
	 */
	const DAYS = 14;

	/**
	 * Hooks.
	 */
	public function register() {
		add_action( 'admin_post_dealroot_inbox', array( __CLASS__, 'handle_start' ) );
		add_action( 'admin_post_dealroot_inbox_send', array( __CLASS__, 'handle_send' ) );
		add_action( 'admin_post_dealroot_inbox_skip', array( __CLASS__, 'handle_skip' ) );
		add_action( self::HOOK, array( __CLASS__, 'work' ) );
		add_action( 'dealroot_lead_status_changed', array( __CLASS__, 'status_changed' ), 10, 3 );
		add_filter( 'dealroot_attention_items', array( __CLASS__, 'attention' ), 20 );
	}

	/**
	 * Address of the screen.
	 *
	 * @param array $args More query arguments.
	 * @return string
	 */
	public static function url( array $args = array() ) {
		return add_query_arg( array_merge( array( 'inbox' => 1 ), $args ), admin_url( 'admin.php?page=' . Admin\Admin::LEADS_PAGE ) );
	}

	/**
	 * The sets of enquiries to go through: the new ones, and what other parts add, e.g. Pro.
	 *
	 * @return array<string, array{title: string, description: string, button: callable}>
	 */
	public static function sets() {
		$sets = array(
			'new' => array(
				'title'       => __( 'Go through new enquiries', 'dealroot' ),
				'description' => __( 'A draft for each new enquiry, written by the AI assistant in your style. Read it, change what does not fit, and send it.', 'dealroot' ),
				'button'      => static function ( $count ) {
					/* translators: %s: number of enquiries */
					$label = _n( 'Go through %s new enquiry', 'Go through %s new enquiries', $count, 'dealroot' );

					return $label;
				},
			),
		);

		/**
		 * Filters the sets of enquiries to go through with drafts ready.
		 *
		 * @param array $sets Key => title, description and the button: a function that gets the number of enquiries and returns the label, with %s for the number.
		 */
		return (array) apply_filters( 'dealroot_inbox_sets', $sets );
	}

	/**
	 * Enquiries of a set that wait for an answer and have no draft yet, oldest first.
	 *
	 * @param string $set Set; "new" for the new enquiries.
	 * @return object[]
	 */
	public static function waiting( $set = 'new' ) {
		/**
		 * Filters the enquiries of a set to write drafts for.
		 *
		 * @param object[] $leads Leads.
		 * @param string   $set   Set.
		 */
		return array_slice( (array) apply_filters( 'dealroot_inbox_waiting', 'new' === $set ? self::fresh() : array(), $set ), 0, self::MAX );
	}

	/**
	 * New enquiries that wait for a first answer and have no draft yet, oldest first.
	 *
	 * @return object[]
	 */
	private static function fresh() {
		global $wpdb;

		return (array) $wpdb->get_results(
			$wpdb->prepare(
				"SELECT * FROM %i
				WHERE status = 'new' AND contacted_at IS NULL AND form_plugin NOT IN ('manual', 'woocommerce')
					AND ai_kind NOT IN ('spam', 'job') AND ai_abusive = 0 AND privacy_request = ''
					AND email <> '' AND ( ai_draft IS NULL OR ai_draft = '' ) AND created_at >= %s
				ORDER BY created_at ASC LIMIT %d",
				Installer::table(),
				gmdate( 'Y-m-d H:i:s', time() - self::DAYS * DAY_IN_SECONDS ),
				self::MAX
			)
		);
	}

	/**
	 * New enquiries with a draft ready, oldest first.
	 *
	 * @return object[]
	 */
	public static function ready() {
		global $wpdb;

		return (array) $wpdb->get_results(
			$wpdb->prepare(
				"SELECT * FROM %i WHERE status IN ('new', 'contacted', 'qualified', 'won') AND ai_draft IS NOT NULL AND ai_draft <> '' ORDER BY created_at ASC LIMIT %d",
				Installer::table(),
				self::MAX
			)
		);
	}

	/**
	 * Where the drafts in the background are.
	 *
	 * @return array{queue: int[], total: int, done: int, failed: int, error: string, user: int, set: string}
	 */
	public static function state() {
		$state = get_option( self::OPTION, array() );
		$state = is_array( $state ) ? $state : array();

		return array(
			'queue'  => array_map( 'absint', (array) ( $state['queue'] ?? array() ) ),
			'total'  => (int) ( $state['total'] ?? 0 ),
			'done'   => (int) ( $state['done'] ?? 0 ),
			'failed' => (int) ( $state['failed'] ?? 0 ),
			'error'  => (string) ( $state['error'] ?? '' ),
			'user'   => (int) ( $state['user'] ?? 0 ),
			'set'    => (string) ( $state['set'] ?? 'new' ),
		);
	}

	/**
	 * Sorts out spam and starts writing the drafts.
	 *
	 * @param int    $user_id Who answers.
	 * @param string $set     Set of enquiries.
	 * @return int Drafts to write.
	 */
	public static function start( $user_id, $set = 'new' ) {
		global $wpdb;

		// What the assistant read as spam goes where it belongs first.
		$spam = 'new' !== $set ? array() : $wpdb->get_col(
			$wpdb->prepare(
				"SELECT id FROM %i WHERE status = 'new' AND ai_kind = 'spam' AND created_at >= %s",
				Installer::table(),
				gmdate( 'Y-m-d H:i:s', time() - self::DAYS * DAY_IN_SECONDS )
			)
		);

		foreach ( $spam as $id ) {
			Leads::update( (int) $id, array( 'status' => 'spam' ) );
		}

		$queue = array_map(
			static function ( $lead ) {
				return (int) $lead->id;
			},
			self::waiting( $set )
		);

		update_option(
			self::OPTION,
			array(
				'queue'  => $queue,
				'total'  => count( $queue ),
				'done'   => 0,
				'failed' => 0,
				'error'  => '',
				'user'   => (int) $user_id,
				'set'    => $set,
				'spam'   => count( $spam ),
			),
			false
		);

		if ( $queue && ! wp_next_scheduled( self::HOOK ) ) {
			wp_schedule_single_event( time(), self::HOOK );
		}

		return count( $queue );
	}

	/**
	 * Writes the next few drafts, and schedules the rest.
	 */
	public static function work() {
		$state = self::state();
		$user  = get_user_by( 'id', $state['user'] );
		$begin = microtime( true );
		$count = 0;

		while ( $state['queue'] && $count < self::PER_RUN && microtime( true ) - $begin < 40 ) {
			$lead = Leads::get( array_shift( $state['queue'] ) );
			++$count;

			if ( ! $lead || ! in_array( $lead->status, array( 'new', 'contacted', 'qualified', 'won' ), true ) ) {
				--$state['total'];
				continue;
			}

			$draft = Ai::draft( $lead, '', $user ? $user : null, true );

			if ( is_wp_error( $draft ) ) {
				++$state['failed'];

				// Without allowance or service, the others would fail the same way.
				if ( in_array( $draft->get_error_code(), array( 'ai_quota', 'ai_off', 'ai_unavailable' ), true ) ) {
					$state['error'] = $draft->get_error_message();
					$state['queue'] = array();
				}

				continue;
			}

			if ( '' !== trim( $draft ) ) {
				self::store_draft( (int) $lead->id, $draft );
				++$state['done'];
			} else {
				++$state['failed'];
			}
		}

		update_option( self::OPTION, array_merge( (array) get_option( self::OPTION, array() ), $state ), false );

		if ( $state['queue'] && ! wp_next_scheduled( self::HOOK ) ) {
			wp_schedule_single_event( time(), self::HOOK );
		}
	}

	/**
	 * Keeps the draft of a lead, or removes it.
	 *
	 * @param int         $lead_id Lead ID.
	 * @param string|null $draft   Text, or null to remove it.
	 */
	public static function store_draft( $lead_id, $draft ) {
		global $wpdb;

		$wpdb->update(
			Installer::table(),
			array(
				'ai_draft'    => null === $draft ? null : sanitize_textarea_field( $draft ),
				'ai_draft_at' => null === $draft ? null : current_time( 'mysql', true ),
			),
			array( 'id' => (int) $lead_id )
		);
	}

	/**
	 * A lead answered in another way, or closed, needs no draft any more.
	 *
	 * @param int    $lead_id Lead ID.
	 * @param string $status  New status.
	 * @param string $old     Status before.
	 */
	public static function status_changed( $lead_id, $status, $old = '' ) {
		if ( in_array( $status, array( 'won', 'lost', 'spam' ), true ) || ( 'new' === $old && 'new' !== $status ) ) {
			self::store_draft( (int) $lead_id, null );
		}
	}

	/**
	 * Sends one answer by email.
	 *
	 * @param object $lead    Lead.
	 * @param string $subject Subject.
	 * @param string $text    Text.
	 * @return true|\WP_Error
	 */
	public static function send( $lead, $subject, $text ) {
		$text = trim( (string) $text );

		if ( '' === $text ) {
			return new \WP_Error( 'dealroot_empty', __( 'The answer is empty.', 'dealroot' ) );
		}

		if ( ! is_email( $lead->email ) ) {
			return new \WP_Error( 'dealroot_no_email', __( 'This lead has no email address.', 'dealroot' ) );
		}

		$subject = trim( (string) $subject );

		$subject = '' !== $subject ? $subject : __( 'Your enquiry', 'dealroot' );

		if ( ! Ai::mail( $lead->email, $subject, $text ) ) {
			return new \WP_Error( 'dealroot_mail', __( 'The email could not be sent. Check the email settings of your site.', 'dealroot' ) );
		}

		Messages::add( (int) $lead->id, 'out', 'email', $text, array( 'subject' => $subject ) );

		self::store_draft( (int) $lead->id, null );

		if ( 'new' === $lead->status ) {
			Impact::answered( (int) $lead->id, 'ai' );
			Leads::update( (int) $lead->id, array( 'status' => 'contacted' ) );
		} else {
			// A follow-up: the lead was touched again.
			Leads::update( (int) $lead->id, array() );
		}

		/**
		 * Fires after an answer to a lead was sent through Dealroot.
		 *
		 * @param int    $lead_id Lead ID.
		 * @param string $text    Text sent.
		 */
		do_action( 'dealroot_answer_sent', (int) $lead->id, $text );

		return true;
	}

	/**
	 * Starts from the button.
	 */
	public static function handle_start() {
		check_admin_referer( 'dealroot_inbox' );

		if ( ! current_user_can( Admin\Admin::capability() ) ) {
			wp_die( esc_html__( 'You are not allowed to edit leads.', 'dealroot' ), 403 );
		}

		$set = isset( $_POST['set'] ) ? sanitize_key( wp_unslash( $_POST['set'] ) ) : 'new';
		$set = isset( self::sets()[ $set ] ) ? $set : 'new';

		self::start( get_current_user_id(), $set );

		// The first drafts are written right away, the rest while the screen waits.
		self::work();

		wp_safe_redirect( self::url( 'new' !== $set ? array( 'set' => $set ) : array() ) );
		exit;
	}

	/**
	 * Sends the answer of one lead.
	 */
	public static function handle_send() {
		$lead_id = isset( $_POST['lead_id'] ) ? absint( $_POST['lead_id'] ) : 0;

		check_admin_referer( 'dealroot_inbox_' . $lead_id );

		if ( ! current_user_can( Admin\Admin::capability() ) ) {
			wp_die( esc_html__( 'You are not allowed to edit leads.', 'dealroot' ), 403 );
		}

		$lead = Leads::get( $lead_id );
		$sent = $lead ? self::send(
			$lead,
			isset( $_POST['subject'] ) ? sanitize_text_field( wp_unslash( $_POST['subject'] ) ) : '',
			isset( $_POST['text'] ) ? sanitize_textarea_field( wp_unslash( $_POST['text'] ) ) : ''
		) : new \WP_Error( 'dealroot_gone', __( 'This lead was deleted.', 'dealroot' ) );

		if ( is_wp_error( $sent ) ) {
			set_transient( 'dealroot_inbox_error_' . get_current_user_id(), $sent->get_error_message(), MINUTE_IN_SECONDS );
		}

		wp_safe_redirect( self::url( is_wp_error( $sent ) ? array() : array( 'sent' => $lead_id ) ) );
		exit;
	}

	/**
	 * Leaves one lead for later, without its draft.
	 */
	public static function handle_skip() {
		$lead_id = isset( $_POST['lead_id'] ) ? absint( $_POST['lead_id'] ) : 0;

		check_admin_referer( 'dealroot_inbox_' . $lead_id );

		if ( ! current_user_can( Admin\Admin::capability() ) ) {
			wp_die( esc_html__( 'You are not allowed to edit leads.', 'dealroot' ), 403 );
		}

		self::store_draft( $lead_id, null );

		wp_safe_redirect( self::url() );
		exit;
	}

	/**
	 * The button that starts it.
	 *
	 * @param string $classes More classes.
	 * @param string $set     Set of enquiries.
	 * @return string
	 */
	public static function button( $classes = '', $set = 'new' ) {
		$sets  = self::sets();
		$count = isset( $sets[ $set ] ) && Ai::enabled() ? count( self::waiting( $set ) ) : 0;

		if ( ! $count ) {
			return '';
		}

		return sprintf(
			'<form method="post" action="%1$s" class="dealroot-inbox-start %2$s"><input type="hidden" name="action" value="dealroot_inbox"><input type="hidden" name="set" value="%3$s">%4$s<button type="submit" class="dealroot-button dealroot-button--secondary">%5$s</button></form>',
			esc_url( admin_url( 'admin-post.php' ) ),
			esc_attr( $classes ),
			esc_attr( $set ),
			wp_nonce_field( 'dealroot_inbox', '_wpnonce', true, false ),
			esc_html( sprintf( self::label( $sets[ $set ]['button'], $count ), number_format_i18n( $count ) ) )
		);
	}

	/**
	 * The label of a button for a number of enquiries.
	 *
	 * @param callable|array $button A function that gets the number, or a plural made with _n_noop() by an older add-on.
	 * @param int            $count  Number of enquiries.
	 * @return string With %s for the number.
	 */
	private static function label( $button, $count ) {
		if ( is_callable( $button ) ) {
			return (string) call_user_func( $button, $count );
		}

		// An older add-on: its plural, untranslated, until it is updated.
		return isset( $button['singular'], $button['plural'] ) ? (string) $button[ 1 === (int) $count ? 'singular' : 'plural' ] : '%s';
	}

	/**
	 * New enquiries waiting under "Needs your attention".
	 *
	 * @param array[] $items Items.
	 * @return array[]
	 */
	public static function attention( $items ) {
		if ( ! Ai::enabled() ) {
			return $items;
		}

		$ready   = count( self::ready() );
		$waiting = count( self::waiting() );

		if ( $ready ) {
			$items[] = array(
				'tone'   => 'info',
				/* translators: %s: number of drafts */
				'title'  => sprintf( _n( '%s draft is ready to send', '%s drafts are ready to send', $ready, 'dealroot' ), number_format_i18n( $ready ) ),
				'text'   => __( 'Read each answer, change what does not fit and send it with one click.', 'dealroot' ),
				'url'    => self::url(),
				'action' => __( 'Go through them', 'dealroot' ),
			);
		} elseif ( $waiting >= 2 ) {
			$items[] = array(
				'tone'   => 'info',
				/* translators: %s: number of enquiries */
				'title'  => sprintf( _n( '%s new enquiry waits for an answer', '%s new enquiries wait for an answer', $waiting, 'dealroot' ), number_format_i18n( $waiting ) ),
				'text'   => __( 'The AI assistant writes a draft for each, and you go through them one after the other.', 'dealroot' ),
				'url'    => self::url(),
				'action' => __( 'Go through them', 'dealroot' ),
			);
		}

		return $items;
	}

	/**
	 * The screen.
	 */
	public static function render() {
		$state = self::state();
		$ready = self::ready();
		$error = get_transient( 'dealroot_inbox_error_' . get_current_user_id() );
		$sent  = isset( $_GET['sent'] ) ? absint( $_GET['sent'] ) : 0; // phpcs:ignore WordPress.Security.NonceVerification.Recommended
		$busy  = (bool) $state['queue'];
		$sets  = self::sets();
		$set   = isset( $_GET['set'] ) ? sanitize_key( wp_unslash( $_GET['set'] ) ) : 'new'; // phpcs:ignore WordPress.Security.NonceVerification.Recommended
		$set   = isset( $sets[ $set ] ) ? $set : 'new';

		if ( $error ) {
			delete_transient( 'dealroot_inbox_error_' . get_current_user_id() );
		}

		Admin\Shell::open(
			'leads',
			$sets[ $set ]['title'],
			array(
				'description' => $sets[ $set ]['description'],
				'actions'     => implode(
					'',
					array_map(
						static function ( $other ) {
							return self::button( '', $other );
						},
						array_diff( array_keys( $sets ), array( $set ) )
					)
				),
				'back'        => array(
					'url'   => admin_url( 'admin.php?page=' . Admin\Admin::LEADS_PAGE ),
					'label' => __( 'All leads', 'dealroot' ),
				),
			)
		);
		?>
		<div class="dealroot-inbox"<?php echo $busy ? ' data-inbox-busy' : ''; ?>>
			<?php if ( $busy ) : ?>
				<meta http-equiv="refresh" content="4">
				<p class="dealroot-inbox__progress" role="status">
					<?php
					/* translators: 1: drafts written, 2: drafts in all */
					echo esc_html( sprintf( __( 'The AI assistant is writing the drafts: %1$s of %2$s. This page refreshes by itself.', 'dealroot' ), number_format_i18n( $state['done'] ), number_format_i18n( $state['total'] ) ) );
					?>
				</p>
			<?php endif; ?>
			<?php if ( '' !== $state['error'] ) : ?>
				<p class="dealroot-geo-status is-error"><?php echo esc_html( $state['error'] ); ?></p>
			<?php endif; ?>
			<?php if ( $error ) : ?>
				<p class="dealroot-geo-status is-error"><?php echo esc_html( $error ); ?></p>
			<?php elseif ( $sent ) : ?>
				<p class="dealroot-geo-status is-ok" role="status"><?php esc_html_e( 'Sent. The lead is marked as contacted.', 'dealroot' ); ?></p>
			<?php endif; ?>

			<?php if ( ! $ready && ! $busy ) : ?>
				<div class="dealroot-panel dealroot-inbox__empty">
					<p><?php esc_html_e( 'No draft waits to be sent.', 'dealroot' ); ?></p>
					<?php echo wp_kses( self::button( '', $set ), Kses::screen() ); ?>
				</div>
			<?php endif; ?>

			<?php foreach ( $ready as $position => $lead ) : ?>
				<?php self::card( $lead, 0 === $position ); ?>
			<?php endforeach; ?>
		</div>
		<?php
		Admin\Shell::close();
	}

	/**
	 * One enquiry with its draft.
	 *
	 * @param object $lead  Lead.
	 * @param bool   $first Whether it is the one to answer now.
	 */
	private static function card( $lead, $first ) {
		$replies = Replies::all( $lead );
		$subject = '' !== (string) ( $replies[0]['subject'] ?? '' ) ? Replies::fill( $replies[0]['subject'], $lead ) : __( 'Your enquiry', 'dealroot' );
		$name    = '' !== trim( (string) $lead->name ) ? $lead->name : $lead->email;
		$id      = 'dealroot-inbox-' . (int) $lead->id;
		?>
		<article class="dealroot-panel dealroot-inbox__card<?php echo $first ? ' is-first' : ''; ?>" aria-labelledby="<?php echo esc_attr( $id ); ?>-name">
			<header class="dealroot-inbox__head">
				<h2 id="<?php echo esc_attr( $id ); ?>-name"><a href="<?php echo esc_url( admin_url( 'admin.php?page=' . Admin\Admin::PAGE . '&lead=' . (int) $lead->id ) ); ?>"><?php echo esc_html( $name ); ?></a></h2>
				<span class="dealroot-muted">
					<?php
					/* translators: %s: time, e.g. "3 hours" */
					echo esc_html( sprintf( __( '%s ago', 'dealroot' ), human_time_diff( (int) strtotime( $lead->created_at . ' UTC' ) ) ) );
					?>
				</span>
			</header>
			<?php if ( '' !== (string) $lead->ai_summary ) : ?>
				<p class="dealroot-inbox__summary"><?php echo esc_html( $lead->ai_summary ); ?></p>
			<?php endif; ?>
			<details class="dealroot-inbox__enquiry">
				<summary><?php esc_html_e( 'Show the enquiry', 'dealroot' ); ?></summary>
				<p><?php echo nl2br( esc_html( wp_html_excerpt( Ai::text( $lead ), 1200, '…' ) ) ); ?></p>
			</details>
			<form method="post" action="<?php echo esc_url( admin_url( 'admin-post.php' ) ); ?>" class="dealroot-inbox__form">
				<input type="hidden" name="lead_id" value="<?php echo (int) $lead->id; ?>">
				<?php wp_nonce_field( 'dealroot_inbox_' . $lead->id ); ?>
				<label for="<?php echo esc_attr( $id ); ?>-subject"><?php esc_html_e( 'Subject', 'dealroot' ); ?></label>
				<input type="text" id="<?php echo esc_attr( $id ); ?>-subject" name="subject" class="regular-text" value="<?php echo esc_attr( $subject ); ?>">
				<label for="<?php echo esc_attr( $id ); ?>-text">
					<?php
					/* translators: %s: email address */
					echo esc_html( sprintf( __( 'Answer to %s', 'dealroot' ), $lead->email ) );
					?>
				</label>
				<textarea id="<?php echo esc_attr( $id ); ?>-text" name="text" rows="9"><?php echo esc_textarea( (string) $lead->ai_draft ); ?></textarea>
				<div class="dealroot-inbox__actions">
					<button type="submit" name="action" value="dealroot_inbox_send" class="dealroot-button dealroot-button--primary"><?php esc_html_e( 'Send by email', 'dealroot' ); ?></button>
					<button type="submit" name="action" value="dealroot_inbox_skip" class="dealroot-button dealroot-button--quiet"><?php esc_html_e( 'Answer later', 'dealroot' ); ?></button>
				</div>
			</form>
		</article>
		<?php
	}
}