<?php
namespace DayTidy\Modules\Notifications;

use DayTidy\Entities\Booking;
use WP_User;

class RecipientResolver
{
    /**
     * @param mixed[] $template
     * @return mixed[]
     */
    public function resolve(Booking $booking, string $context, array $template = []): array
    {
        if ($context === Registry::CONTEXT_ADMIN)
        {
            $recipients = $this->admin();
        }
        else if ($context === Registry::CONTEXT_OFFERING_HOST)
        {
            $recipients = $this->hosts($booking);
        }
        else if ($context === Registry::CONTEXT_PRIMARY_BOOKER)
        {
            $recipients = $this->primaryBooker($booking);
        }
        else if ($context === Registry::CONTEXT_REGISTRANT)
        {
            $recipients = $this->registrants($booking);
        }
        else if ($context === Registry::CONTEXT_CUSTOM)
        {
            $recipients = $this->picker((array) ($template['to'] ?? []));
        }
        else
        {
            $recipients = [];
        }

        $recipients = $this->dedupe($recipients, $context);

        return apply_filters(
            'DayTidy/F__DayTidy/Notifications/RecipientResolver__resolve/recipients',
            $recipients,
            $booking,
            $context,
            $template
        );
    }

    /**
     * @param mixed[] $picker
     * @return mixed[]
     */
    public function picker(array $picker): array
    {
        $recipients = [];

        $users = isset($picker['users']) && is_array($picker['users']) ? array_map('absint', $picker['users']) : [];
        foreach ($this->users($users) as $recipient) $recipients[] = $recipient;

        $roles = isset($picker['roles']) && is_array($picker['roles']) ? array_map('sanitize_key', $picker['roles']) : [];
        foreach ($this->roles($roles) as $recipient) $recipients[] = $recipient;

        $emails = isset($picker['emails']) ? (string) $picker['emails'] : '';
        foreach ($this->emails($emails) as $recipient) $recipients[] = $recipient;

        return $this->dedupe($recipients, Registry::CONTEXT_CUSTOM);
    }

    /**
     * @return mixed[]
     */
    private function admin(): array
    {
        $email = get_option('admin_email');
        $name = get_bloginfo('name');

        $recipient = $this->recipient((string) $email, (string) $name);

        return $recipient ? [$recipient] : [];
    }

    /**
     * @return mixed[]
     */
    private function hosts(Booking $booking): array
    {
        $offering = $booking->offering();
        if (!$offering) return [];

        $recipients = [];
        foreach ($offering->getHosts() as $host)
        {
            if (!is_object($host) || !method_exists($host, 'email')) continue;

            $email = (string) $host->email();
            $name = method_exists($host, 'name') ? (string) $host->name() : '';

            $recipient = $this->recipient($email, $name);
            if ($recipient) $recipients[] = $recipient;
        }

        return $recipients;
    }

    /**
     * @return mixed[]
     */
    private function primaryBooker(Booking $booking): array
    {
        $form = $booking->getData()->getMappedForm();

        $email = $this->field($form['email'] ?? []);
        $first = $this->field($form['first_name'] ?? []);
        $last = $this->field($form['last_name'] ?? []);
        $name = trim($first . ' ' . $last);

        $recipient = $this->recipient($email, $name);

        return $recipient ? [$recipient] : [];
    }

    /**
     * @return mixed[]
     */
    private function registrants(Booking $booking): array
    {
        $recipients = [];
        foreach ($booking->getData()->getMappedParticipants() as $participant)
        {
            if (!is_array($participant)) continue;

            $email = $this->participantEmail($participant);
            $first = $this->field($participant['first_name'] ?? []);
            $last = $this->field($participant['last_name'] ?? []);
            $name = trim($first . ' ' . $last);

            $recipient = $this->recipient($email, $name, ['participant' => $participant]);
            if ($recipient) $recipients[] = $recipient;
        }

        return $recipients;
    }

    /**
     * @param int[] $ids
     * @return mixed[]
     */
    private function users(array $ids): array
    {
        if (!count($ids)) return [];

        $recipients = [];
        $users = get_users([
            'include' => $ids,
            'fields' => ['ID', 'display_name', 'user_email'],
        ]);

        foreach ($users as $user)
        {
            if (!$user instanceof WP_User && !is_object($user)) continue;

            $recipient = $this->recipient(
                (string) $user->user_email,
                (string) $user->display_name,
                ['user_id' => (int) $user->ID]
            );

            if ($recipient) $recipients[] = $recipient;
        }

        return $recipients;
    }

    /**
     * @param string[] $roles
     * @return mixed[]
     */
    private function roles(array $roles): array
    {
        $roles = array_values(array_filter($roles));
        if (!count($roles)) return [];

        $recipients = [];
        $users = get_users([
            'role__in' => $roles,
            'fields' => ['ID', 'display_name', 'user_email'],
        ]);

        foreach ($users as $user)
        {
            if (!$user instanceof WP_User && !is_object($user)) continue;

            $recipient = $this->recipient(
                (string) $user->user_email,
                (string) $user->display_name,
                ['user_id' => (int) $user->ID]
            );

            if ($recipient) $recipients[] = $recipient;
        }

        return $recipients;
    }

    /**
     * @return mixed[]
     */
    private function emails(string $emails): array
    {
        $recipients = [];
        $items = preg_split('/[\s,;]+/', $emails);
        if (!$items) return [];

        foreach ($items as $email)
        {
            $recipient = $this->recipient((string) $email);
            if ($recipient) $recipients[] = $recipient;
        }

        return $recipients;
    }

    /**
     * @param mixed[] $field
     */
    private function field(array $field): string
    {
        return $this->stringify($field['value'] ?? '');
    }

    /**
     * @param mixed[] $participant
     */
    private function participantEmail(array $participant): string
    {
        if (isset($participant['email']) && is_array($participant['email']))
        {
            return $this->field($participant['email']);
        }

        foreach ($participant as $field)
        {
            if (!is_array($field)) continue;

            $value = $this->field($field);
            $type = (string) ($field['type'] ?? '');

            if ($type === 'email' && is_email($value)) return $value;
            if (is_email($value)) return $value;
        }

        return '';
    }

    /**
     * @param mixed $value
     */
    private function stringify($value): string
    {
        if (is_array($value))
        {
            $parts = [];
            foreach ($value as $item) $parts[] = $this->stringify($item);

            return implode(', ', array_filter($parts));
        }

        return trim(wp_strip_all_tags((string) $value));
    }

    /**
     * @param mixed[] $data
     * @return mixed[]|null
     */
    private function recipient(string $email, string $name = '', array $data = []): ?array
    {
        $email = sanitize_email($email);
        if (!is_email($email)) return null;

        return [
            'email' => $email,
            'name' => sanitize_text_field($name),
            'data' => $data,
        ];
    }

    /**
     * @param mixed[] $recipients
     * @return mixed[]
     */
    private function dedupe(array $recipients, string $context): array
    {
        $deduped = [];
        foreach ($recipients as $recipient)
        {
            if (!is_array($recipient) || empty($recipient['email'])) continue;

            $email = strtolower((string) $recipient['email']);
            if (isset($deduped[$email])) continue;

            $recipient['context'] = $context;
            $deduped[$email] = $recipient;
        }

        return array_values($deduped);
    }
}