Backend: implement alerting query (#847)

* Unit tests for backend

* minor change

* Implemented querNumericItems in backend

* Added query type

* Set alerting to true

* Return TimeSeries from History

* Updated alerting feature

* Fix params marshal error

* Fix params more

* Update zabbixAPIConnector.js

* Numbers, I guess

* Params Output Type

* Output marshaling

* Unmarshal and decoder error catch

* HistoryPoint and Unmarshal fixes

* Unmarshal to History

* Revert "Update zabbixAPIConnector.js"

This reverts commit e0ffdff859b6f920893a47a709493f8076e38ef4.

* Fix unmarshaling for real

* Time range integer

* Use more zabbix.Items

* Update response_models.go

* Update zabbix_api.go

* Update models.go

* Update zabbix_api.go

* Tests

* Adding more unit tests and cleaning up additional logging

* Make history request param a pointer

* Actually store datasource in cache

* Debug logs and timings

* Handle panics gracefully

* Updated Regex filter parsing

* Removed must compile

* Clean up regex filter

pkg/models_test.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_zabbixParamOutput(t *testing.T) {
+	tests := []struct {
+		name  string
+		input zabbixParams
+		want  string
+	}{
+		{
+			name: "Mode extend",
+			input: zabbixParams{
+				Output: &zabbixParamOutput{
+					Mode: "extend",
+				},
+				GroupIDs: []string{"test1", "test2"},
+			},
+			want: `{ "output": "extend", "groupids": ["test1", "test2"] }`,
+		},
+		{
+			name: "Fields",
+			input: zabbixParams{
+				Output: &zabbixParamOutput{
+					Fields: []string{"name", "key_", "hostid"},
+				},
+				GroupIDs: []string{"test1", "test2"},
+			},
+			want: `{ "output": ["name", "key_", "hostid"], "groupids": ["test1", "test2"] }`,
+		},
+		{
+			name: "No Output",
+			input: zabbixParams{
+				GroupIDs: []string{"test1", "test2"},
+			},
+			want: `{ "groupids": ["test1", "test2"] }`,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			jsonOut, err := json.Marshal(tt.input)
+			fmt.Printf("Output: %s\n", jsonOut)
+			assert.NoError(t, err)
+			if !assert.JSONEq(t, tt.want, string(jsonOut)) {
+				return
+			}
+
+			objOut := zabbixParams{}
+			err = json.Unmarshal(jsonOut, &objOut)
+			assert.NoError(t, err)
+			assert.Equal(t, tt.input, objOut)
+		})
+	}
+}