var MEngine = {
    params: {},

    setParams: function (params) {
        if (typeof params !== 'object') {
            return;
        }

        MEngine.params = params;
        if (typeof MEngine.params.url === 'string') {
            if (!MEngine.params.url.endsWith('/')) {
                MEngine.params.url += '/';
            }

            MEngine.params.url += 'api/v3/';
        }

        if (MEngine.params.on_premise.toLowerCase() !== 'true'
                && typeof MEngine.params.on_demand_url_auth === 'string') {
            if (!MEngine.params.on_demand_url_auth.endsWith('/')) {
                MEngine.params.on_demand_url_auth += '/';
            }

            MEngine.params.on_demand_url_auth += 'oauth/v2/token?';
        }
    },

    setProxy: function (HTTPProxy) {
        MEngine.HTTPProxy = HTTPProxy;
    },

    createLink: function (id, url) {
        return url + (url.endsWith('/') ? '' : '/') +
            ((MEngine.params.on_premise.toLowerCase() === 'true')
                ? ('WorkOrder.do?woMode=viewWO&woID=' + id)
                : ('app/itdesk/ui/requests/' + id + '/details')
            );
    },

    refreshAccessToken: function () {
        [
            'on_demand_url_auth',
            'on_demand_refresh_token',
            'on_demand_client_id',
            'on_demand_client_secret'
        ].forEach(function (field) {
            if (typeof MEngine.params !== 'object' || typeof MEngine.params[field] === 'undefined'
                    || MEngine.params[field].trim() === '' ) {
                throw 'Required MEngine param is not set: "sd_' + field + '".';
            }
        });

        var response,
            request = new HttpRequest(),
            url = MEngine.params.on_demand_url_auth +
                'refresh_token=' + encodeURIComponent(MEngine.params.on_demand_refresh_token) +
                '&grant_type=refresh_token&client_id=' + encodeURIComponent(MEngine.params.on_demand_client_id) +
                '&client_secret=' + encodeURIComponent(MEngine.params.on_demand_client_secret) +
                '&redirect_uri=https://www.zoho.com&scope=SDPOnDemand.requests.ALL';

        if (MEngine.HTTPProxy) {
            request.setProxy(MEngine.HTTPProxy);
        }

        Zabbix.log(4, '[ ManageEngine Webhook ] Refreshing access token. Request: ' + url);

        response = request.post(url);

        Zabbix.log(4, '[ ManageEngine Webhook ] Received response with status code ' +
        request.getStatus() + '\n' + response);

        try {
            response = JSON.parse(response);
        }
        catch (error) {
            Zabbix.log(4, '[ ManageEngine Webhook ] Failed to parse response received from Zoho Accounts');
        }

        if ((request.getStatus() < 200 || request.getStatus() >= 300) && !response.access_token) {
            throw 'Access token refresh failed with HTTP status code ' + request.getStatus() +
                '. Check debug log for more information.';
        }
        else {
            MEngine.params.on_demand_auth_token = response.access_token;
        }
    },

    request: function (method, query, data) {
        var response,
            url = MEngine.params.url + query,
            input,
            request = new HttpRequest(),
            message;

        if (MEngine.params.on_premise.toLowerCase() === 'true') {
            request.addHeader('TECHNICIAN_KEY: ' + MEngine.params.on_premise_auth_token);
        }
        else {
            request.addHeader('Authorization: Zoho-oauthtoken ' + MEngine.params.on_demand_auth_token);
            request.addHeader('Accept: application/v3+json');
        }

        if (MEngine.HTTPProxy) {
            request.setProxy(MEngine.HTTPProxy);
        }

        if (typeof data !== 'undefined') {
            data = JSON.stringify(data);
        }

        input = 'input_data=' + encodeURIComponent(data);
        Zabbix.log(4, '[ ManageEngine Webhook ] Sending request: ' + url + '?' + input);

        switch (method) {
            case 'post':
                response = request.post(url, input);
                break;

            case 'put':
                response = request.put(url, input);
                break;

            default:
                throw 'Unsupported HTTP request method: ' + method;
        }

        Zabbix.log(4, '[ ManageEngine Webhook ] Received response with status code ' +
            request.getStatus() + '\n' + response);

        try {
            response = JSON.parse(response);
        }
        catch (error) {
            Zabbix.log(4, '[ ManageEngine Webhook ] Failed to parse response received from ManageEngine');
        }

        if ((request.getStatus() < 200 || request.getStatus() >= 300)
                && typeof response.response_status !== 'object') {
            throw 'Request failed with HTTP status code ' + request.getStatus() +
                '. Check debug log for more information.';
        }
        else if (typeof response.response_status === 'object' && response.response_status.status === 'failed') {
            message = 'Request failed with status_code ';

            if (typeof response.response_status.messages === 'object'
                    && response.response_status.messages[0]
                    && response.response_status.messages[0].message) {
                message += response.response_status.messages[0].status_code +
                    '. Message: ' + response.response_status.messages[0].message;
            }
            else {
                message += response.response_status.status_code;
            }

            message += '. Check debug log for more information.';
            throw message;
        }
        else if (response.request) {
            return response.request.id;
        }
    },

    createPaylaod: function (fields, isNote) {
        var data = {},
            result;

        if (isNote) {
            data.description = fields['field_string:description'].replace(/(?:\r\n|\r|\n)/g, '<br>');
            result = {request_note: data};
        }
        else {
            Object.keys(fields)
                .forEach(function(field) {
                    if (fields[field].trim() === '') {
                        Zabbix.log(4, '[ ManageEngine Webhook ] Field "' + field +
                            '" can\'t be empty. The field ignored.');
                    }
                    else {
                        try {
                            var prefix = field.split(':')[0],
                                root;

                            if  (prefix.startsWith('udf_') && !data.udf_fields) {
                                data.udf_fields = {};
                                root = data.udf_fields;
                            }
                            else if (prefix.startsWith('udf_')) {
                                root = data.udf_fields;
                            }
                            else {
                                root = data;
                            }

                            if (prefix.endsWith('string')) {
                                root[field.substring(field.indexOf(':') + 1)
                                    .toLowerCase()] = fields[field];
                            }
                            else {
                                root[field.substring(field.indexOf(':') + 1)
                                    .toLowerCase()] = {
                                    name: fields[field]
                                };
                            }
                        }
                        catch (error) {
                            Zabbix.log(4, '[ ManageEngine Webhook ] Can\'t parse field "' + field +
                                '". The field ignored.');
                        }
                    }
                });
            if (data.description) {
                data.description = data.description.replace(/(?:\r\n|\r|\n)/g, '<br>');
            }

            result = {request: data};
        }

        return result;
    }
};

try {
    var params = JSON.parse(value),
        fields = {},
        sd = {},
        result = {tags: {}},
        required_params = [
            'sd_on_premise', 'field_string:subject', 'field_string:description',
            'event_recovery_value', 'event_source', 'event_value', 'event_update_status'
        ],
        severities = [
            {name: 'not_classified', color: '#97AAB3'},
            {name: 'information', color: '#7499FF'},
            {name: 'warning', color: '#FFC859'},
            {name: 'average', color: '#FFA059'},
            {name: 'high', color: '#E97659'},
            {name: 'disaster', color: '#E45959'},
            {name: 'default', color: '#000000'}
        ];

    Object.keys(params)
        .forEach(function (key) {
            if (key.startsWith('sd_')) {
                sd[key.substring(3)] = params[key];
            }
            else if (key.startsWith('field_') || key.startsWith('udf_field_')) {
                fields[key] = params[key];
            }

            if (required_params.indexOf(key) !== -1 && params[key].trim() === '') {
                throw 'Parameter "' + key + '" can\'t be empty.';
            }
        });

    if ([0, 1, 2, 3].indexOf(parseInt(params.event_source)) === -1) {
        throw 'Incorrect "event_source" parameter given: ' + params.event_source + '\nMust be 0-3.';
    }

    // Check {EVENT.VALUE} for trigger-based and internal events.
    if (params.event_value !== '0' && params.event_value !== '1'
        && (params.event_source === '0' || params.event_source === '3')) {
        throw 'Incorrect "event_value" parameter given: ' + params.event_value + '\nMust be 0 or 1.';
    }

    // Check {EVENT.UPDATE.STATUS} only for trigger-based events.
    if (params.event_update_status !== '0' && params.event_update_status !== '1' && params.event_source === '0') {
        throw 'Incorrect "event_update_status" parameter given: ' + params.event_update_status + '\nMust be 0 or 1.';
    }

    if (params.event_source !== '0' && params.event_recovery_value === '0') {
        throw 'Recovery operations are supported only for trigger-based actions.';
    }

    if ([0, 1, 2, 3, 4, 5].indexOf(parseInt(params.event_nseverity)) === -1) {
        params.event_nseverity = '6';
    }

    if (params.event_update_status === '1' && (typeof params.sd_request_id === 'undefined'
            || params.sd_request_id.trim() === ''
            || params.sd_request_id === '{EVENT.TAGS.__zbx_sd_request_id}'
            || params.sd_request_id === '*UNKNOWN*')) {
        throw 'Parameter "sd_request_id" can\'t be empty for update operation.';
    }

    MEngine.setParams(sd);
    MEngine.setProxy(params.HTTPProxy);

    if (MEngine.params.on_premise.toLowerCase() !== 'true') {
        MEngine.refreshAccessToken();
    }

    // Create issue for non trigger-based events.
    if (params.event_source !== '0' && params.event_recovery_value !== '0') {
        fields['field_object:priority'] = params['priority_' + severities[params.event_nseverity].name]
        || 'Normal';

        MEngine.request('post', 'requests', MEngine.createPaylaod(fields));
    }
    // Create issue for trigger-based events.
    else if (params.event_value === '1' && params.event_update_status === '0') {
        fields['field_object:priority'] = params['priority_' + severities[params.event_nseverity].name]
        || 'Normal';

        var id = MEngine.request('post', 'requests', MEngine.createPaylaod(fields));

        result.tags.__zbx_sd_request_id = id;
        result.tags.__zbx_sd_request_link = MEngine.createLink(id, params.sd_url);
    }
    // Update created issue for trigger-based event.
    else {
        if (params.event_update_status === '1') {
            MEngine.request('post', 'requests/' + params.sd_request_id + '/notes',
                MEngine.createPaylaod(fields, true)
            );
        }
        delete fields['field_string:description'];
        MEngine.request('put', 'requests/' + params.sd_request_id, MEngine.createPaylaod(fields));
    }

    return JSON.stringify(result);
}
catch (error) {
    Zabbix.log(3, '[ ManageEngine Webhook ] ERROR: ' + error);
    throw 'Sending failed: ' + error;
}