<?php

/**
 * Helper class for dealing with common API requests.
 */
class MC4WP_MailChimp
{
    /**
     * @var string
     */
    public $error_code = '';

    /**
     * @var string
     */
    public $error_message = '';

    /**
     *
     * Sends a subscription request to the Mailchimp API
     *
     * @param string $list_id The list id to subscribe to
     * @param string $email_address The email address to subscribe
     * @param array $args
     * @param bool $update_existing Update information if this email is already on list?
     * @param bool $replace_interests Replace interest groupings, only if update_existing is true.
     *
     * @return object
     * @throws Exception
     */
    public function list_subscribe($list_id, $email_address, array $args = array(), $update_existing = false, $replace_interests = true)
    {
        $this->reset_error();
        $default_args         = array(
            'status'        => 'pending',
            'email_address' => $email_address,
        );
        $existing_member_data = null;

        // setup default args
        $args = array_merge($default_args, $args);
        $api  = $this->get_api();

        // first, check if subscriber is already on the given list
        try {
            $existing_member_data = $api->get_list_member($list_id, $email_address);
            if ($existing_member_data->status === 'subscribed') {
                // if we're not supposed to update, bail.
                if (! $update_existing) {
                    $this->error_code    = 214;
                    $this->error_message = 'That subscriber already exists.';

                    return null;
                }

                $args['status'] = 'subscribed';

                // this key only exists if list actually has interests
                if (isset($existing_member_data->interests)) {
                    $existing_interests = (array) $existing_member_data->interests;

                    // if replace, assume all existing interests disabled
                    if ($replace_interests) {
                        $existing_interests = array_fill_keys(array_keys($existing_interests), false);
                    }

                    $args['interests'] = array_replace($existing_interests, $args['interests']);
                }
            } elseif ($args['status'] === 'pending' && $existing_member_data->status === 'pending') {
                // this ensures that a new double opt-in email is send out
                $api->update_list_member(
                    $list_id,
                    $email_address,
                    array(
                        'status' => 'unsubscribed',
                    )
                );
            }
        } catch (MC4WP_API_Resource_Not_Found_Exception $e) {
            // subscriber does not exist (not an issue in this case)
        } catch (MC4WP_API_Exception $e) {
            // other errors.
            $this->error_code    = $e->getCode();
            $this->error_message = $e;
            return null;
        }

        try {
            if ($existing_member_data) {
                $data                      = $api->update_list_member($list_id, $email_address, $args);
                $data->was_already_on_list = $existing_member_data->status === 'subscribed';

                if (isset($args['tags']) && is_array($args['tags'])) {
                    $this->list_add_tags_to_subscriber($list_id, $data, $args['tags']);
                }
            } else {
                $data                      = $api->add_new_list_member($list_id, $args);
                $data->was_already_on_list = false;
            }
        } catch (MC4WP_API_Exception $e) {
            $this->error_code    = $e->getCode();
            $this->error_message = $e;
            return null;
        }

        return $data;
    }

    /**
     * Format tags to send to Mailchimp.
     *
     * @param $mailchimp_tags array existent user tags
     * @param $new_tags array new tags to add
     *
     * @return array
     * @since 4.7.9
     */
    private function merge_and_format_member_tags($mailchimp_tags, $new_tags)
    {
        $mailchimp_tags = array_map(
            function ($tag) {
                return $tag->name;
            },
            $mailchimp_tags
        );

        $tags = array_unique(array_merge($mailchimp_tags, $new_tags), SORT_REGULAR);

        return array_map(
            function ($tag) {
                return array(
                    'name'   => $tag,
                    'status' => 'active',
                );
            },
            $tags
        );
    }

    /**
     *  Post the tags on a list member.
     *
     * @param $mailchimp_list_id string The list id to subscribe to
     * @param $mailchimp_member stdClass mailchimp user informations
     * @param $new_tags array tags to add to the user
     *
     * @return bool
     * @throws Exception
     * @since 4.7.9
     */
    private function list_add_tags_to_subscriber($mailchimp_list_id, $mailchimp_member, array $new_tags)
    {
        // do nothing if no tags given
        if (count($new_tags) === 0) {
            return true;
        }

        $api  = $this->get_api();
        $data = array(
            'tags' => $this->merge_and_format_member_tags($mailchimp_member->tags, $new_tags),
        );

        try {
            $api->update_list_member_tags($mailchimp_list_id, $mailchimp_member->email_address, $data);
        } catch (MC4WP_API_Exception $ex) {
            // fail silently
            return false;
        }

        return true;
    }

    /**
     * Changes the subscriber status to "unsubscribed"
     *
     * @param string $list_id
     * @param string $email_address
     *
     * @return boolean
     */
    public function list_unsubscribe($list_id, $email_address)
    {
        $this->reset_error();

        try {
            $this->get_api()->update_list_member($list_id, $email_address, array( 'status' => 'unsubscribed' ));
        } catch (MC4WP_API_Resource_Not_Found_Exception $e) {
            // if email wasn't even on the list: great.
            return true;
        } catch (MC4WP_API_Exception $e) {
            $this->error_code    = $e->getCode();
            $this->error_message = $e;

            return false;
        }

        return true;
    }

    /**
     * Checks if an email address is on a given list with status "subscribed"
     *
     * @param string $list_id
     * @param string $email_address
     *
     * @return boolean
     * @throws Exception
     */
    public function list_has_subscriber($list_id, $email_address)
    {
        try {
            $data = $this->get_api()->get_list_member($list_id, $email_address);
        } catch (MC4WP_API_Resource_Not_Found_Exception $e) {
            return false;
        }

        return ! empty($data->id) && $data->status === 'subscribed';
    }

    /**
     * @param string $list_id
     *
     * @return array
     * @throws Exception
     */
    public function get_list_merge_fields($list_id)
    {
        $transient_key = sprintf('mc4wp_list_%s_mf', $list_id);
        $cached        = get_transient($transient_key);
        if (is_array($cached)) {
            return $cached;
        }

        $api = $this->get_api();

        try {
            // fetch list merge fields
            $merge_fields = $api->get_list_merge_fields(
                $list_id,
                array(
                    'count'  => 100,
                    'fields' => 'merge_fields.name,merge_fields.tag,merge_fields.type,merge_fields.required,merge_fields.default_value,merge_fields.options,merge_fields.public',
                )
            );
        } catch (MC4WP_API_Exception $e) {
            return array();
        }

        // add EMAIL field
        array_unshift(
            $merge_fields,
            (object) array(
                'tag'      => 'EMAIL',
                'name'     => __('Email address', 'mailchimp-for-wp'),
                'required' => true,
                'type'     => 'email',
                'options'  => array(),
                'public'   => true,
            )
        );

        set_transient($transient_key, $merge_fields, HOUR_IN_SECONDS * 24);

        return $merge_fields;
    }

    /**
     * @param string $list_id
     *
     * @return array
     * @throws Exception
     */
    public function get_list_interest_categories($list_id)
    {
        $transient_key = sprintf('mc4wp_list_%s_ic', $list_id);
        $cached        = get_transient($transient_key);
        if (is_array($cached)) {
            return $cached;
        }

        $api = $this->get_api();

        try {
            // fetch list interest categories
            $interest_categories = $api->get_list_interest_categories(
                $list_id,
                array(
                    'count'  => 100,
                    'fields' => 'categories.id,categories.title,categories.type',
                )
            );
        } catch (MC4WP_API_Exception $e) {
            return array();
        }

        foreach ($interest_categories as $interest_category) {
            $interest_category->interests = array();

            try {
                // fetch groups for this interest
                $interests_data = $api->get_list_interest_category_interests(
                    $list_id,
                    $interest_category->id,
                    array(
                        'count'  => 100,
                        'fields' => 'interests.id,interests.name',
                    )
                );
                foreach ($interests_data as $interest_data) {
                    $interest_category->interests[ (string) $interest_data->id ] = $interest_data->name;
                }
            } catch (MC4WP_API_Exception $e) {
                // ignore
            }
        }

        set_transient($transient_key, $interest_categories, HOUR_IN_SECONDS * 24);

        return $interest_categories;
    }

    /**
     * Gets marketing permissions from a Mailchimp list.
     * The list needs to have at least 1 member for this to work.
     *
     * @param string $list_id
     *
     * @return array
     * @throws Exception
     */
    public function get_list_marketing_permissions($list_id)
    {
        $transient_key = sprintf('mc4wp_list_%s_mp', $list_id);
        $cached        = get_transient($transient_key);
        if (is_array($cached)) {
            return $cached;
        }

        try {
            $api  = $this->get_api();
            $data = $api->get_list_members(
                $list_id,
                array(
                    'fields' => array( 'members.marketing_permissions' ),
                    'count'  => 1,
                )
            );

            $marketing_permissions = array();
            if (count($data->members) > 0 && $data->members[0]->marketing_permissions) {
                foreach ($data->members[0]->marketing_permissions as $mp) {
                    $marketing_permissions[] = (object) array(
                        'marketing_permission_id' => $mp->marketing_permission_id,
                        'text'                    => $mp->text,
                    );
                }
            }
        } catch (MC4WP_API_Exception $e) {
            return array();
        }

        set_transient($transient_key, $marketing_permissions, HOUR_IN_SECONDS * 24);
        return $marketing_permissions;
    }

    /**
     * Get Mailchimp lists, from cache or remote API.
     *
     * @param boolean $skip_cache Whether to force a result by hitting Mailchimp API
     *
     * @return array
     */
    public function get_lists($skip_cache = false)
    {
        $cache_key = 'mc4wp_mailchimp_lists';
        $cached    = get_transient($cache_key);

        if (is_array($cached) && ! $skip_cache) {
            return $cached;
        }

        $lists = $this->fetch_lists();

        /**
         * Filters the cache time for Mailchimp lists configuration, in seconds. Defaults to 24 hours.
         */
        $cache_ttl = (int) apply_filters('mc4wp_lists_count_cache_time', HOUR_IN_SECONDS * 24);

        // make sure cache ttl is not lower than 60 seconds
        $cache_ttl = max(60, $cache_ttl);
        set_transient($cache_key, $lists, $cache_ttl);

        return $lists;
    }

    private function fetch_lists()
    {
        $client             = $this->get_api()->get_client();
        $lists_data         = array();
        $offset             = 0;
        $count              = 10;
        $exceptions_skipped = 0;

        // increase total time limit to 3 minutes
        @set_time_limit(180);

        // increase HTTP timeout to 30s as MailChimp is super slow to calculate dynamic fields
        add_filter(
            'mc4wp_http_request_args',
            function ($args) {
                $args['timeout'] = 30;
                return $args;
            }
        );

        // collect all lists in separate HTTP requests
        do {
            try {
                $data = $client->get(
                    '/lists',
                    array(
                        'count'  => $count,
                        'offset' => $offset,
                        'fields' => 'total_items,lists.id,lists.name,lists.web_id,lists.stats.member_count,lists.marketing_permissions',
                    )
                );

                $lists_data = array_merge($lists_data, $data->lists);
                $offset    += $count;
            } catch (MC4WP_API_Connection_Exception $e) {
                // ignore timeout errors as this is likely due to mailchimp being slow to calculate the lists.stats.member_count property
                // keep going so we can at least pull-in all other lists
                $offset += $count;
                ++$exceptions_skipped;

                // failsafe against infinite loop
                // bail after 5 skipped exceptions
                if ($exceptions_skipped >= 5) {
                    break;
                }

                continue;
            } catch (MC4WP_API_Exception $e) {
                // break on other errors, like "API key missing"etc.
                break;
            }
        } while ($data->total_items >= $offset);

        // key by list ID
        $lists = array();
        foreach ($lists_data as $list_data) {
            $lists["$list_data->id"] = $list_data;
        }

        return $lists;
    }

    /**
     * @param string $list_id
     *
     * @return object|null
     */
    public function get_list($list_id)
    {
        $lists = $this->get_lists();

        return isset($lists["$list_id"]) ? $lists["$list_id"] : null;
    }

    /**
     * Fetch lists data from Mailchimp.
     */
    public function refresh_lists()
    {
        $lists = $this->get_lists(true);

        foreach ($lists as $list_id => $list) {
            // delete cached merge fields
            $transient_key = sprintf('mc4wp_list_%s_mf', $list_id);
            delete_transient($transient_key);

            // delete cached interest categories
            $transient_key = sprintf('mc4wp_list_%s_ic', $list_id);
            delete_transient($transient_key);

            // delete cached marketing permissions
            $transient_key = sprintf('mc4wp_list_%s_mp', $list_id);
            delete_transient($transient_key);
        }

        return ! empty($lists);
    }


    /**
     * Returns number of subscribers on given lists.
     *
     * @param array|string $list_ids Array of list ID's, or single string.
     *
     * @return int Total # subscribers for given lists.
     */
    public function get_subscriber_count($list_ids)
    {
        // make sure we're getting an array
        if (! is_array($list_ids)) {
            $list_ids = array( $list_ids );
        }

        // if we got an empty array, return 0
        if (empty($list_ids)) {
            return 0;
        }

        $lists = $this->get_lists();

        // start calculating subscribers count for all given list ID's combined
        $count = 0;
        foreach ($list_ids as $list_id) {
            if (! isset($lists["$list_id"])) {
                continue;
            }

            $list   = $lists["$list_id"];
            $count += $list->stats->member_count;
        }

        /**
         * Filters the total subscriber_count for the given List ID's.
         *
         * @param string $count
         * @param array $list_ids
         *
         * @since 2.0
         */
        return apply_filters('mc4wp_subscriber_count', $count, $list_ids);
    }

    /**
     * Resets error properties.
     */
    public function reset_error()
    {
        $this->error_message = '';
        $this->error_code    = '';
    }

    /**
     * @return bool
     */
    public function has_error()
    {
        return ! empty($this->error_code);
    }

    /**
     * @return string
     */
    public function get_error_message()
    {
        return $this->error_message;
    }

    /**
     * @return string
     */
    public function get_error_code()
    {
        return $this->error_code;
    }

    /**
     * @return MC4WP_API_V3
     * @throws Exception
     */
    private function get_api()
    {
        return mc4wp('api');
    }
}