Plugins: Refactor plugin dashboards (#44315)

Moves/refactor Grafana specific functionality related to plugin dashboards 
out to specific services for importing dashboards and keep app plugin dashboards
up-to-date.

Fixes #44257

pkg/services/dashboardimport/utils/dash_template_evaluator.go

@@ -0,0 +1,116 @@
+package utils
+
+import (
+	"encoding/json"
+	"fmt"
+	"regexp"
+
+	"github.com/grafana/grafana/pkg/components/simplejson"
+	"github.com/grafana/grafana/pkg/expr"
+	"github.com/grafana/grafana/pkg/services/dashboardimport"
+)
+
+var varRegex = regexp.MustCompile(`(\$\{.+?\})`)
+
+type DashboardInputMissingError struct {
+	VariableName string
+}
+
+func (e DashboardInputMissingError) Error() string {
+	return fmt.Sprintf("Dashboard input variable: %v missing from import command", e.VariableName)
+}
+
+type DashTemplateEvaluator struct {
+	template  *simplejson.Json
+	inputs    []dashboardimport.ImportDashboardInput
+	variables map[string]string
+	result    *simplejson.Json
+}
+
+func NewDashTemplateEvaluator(template *simplejson.Json, inputs []dashboardimport.ImportDashboardInput) *DashTemplateEvaluator {
+	return &DashTemplateEvaluator{
+		template: template,
+		inputs:   inputs,
+	}
+}
+
+func (e *DashTemplateEvaluator) findInput(varName string, varType string) *dashboardimport.ImportDashboardInput {
+	for _, input := range e.inputs {
+		if varType == input.Type && (input.Name == varName || input.Name == "*") {
+			return &input
+		}
+	}
+
+	return nil
+}
+
+func (e *DashTemplateEvaluator) Eval() (*simplejson.Json, error) {
+	e.result = simplejson.New()
+	e.variables = make(map[string]string)
+
+	// check that we have all inputs we need
+	for _, inputDef := range e.template.Get("__inputs").MustArray() {
+		inputDefJson := simplejson.NewFromAny(inputDef)
+		inputName := inputDefJson.Get("name").MustString()
+		inputType := inputDefJson.Get("type").MustString()
+		input := e.findInput(inputName, inputType)
+
+		// force expressions value to `__expr__`
+		if inputDefJson.Get("pluginId").MustString() == expr.DatasourceType {
+			input = &dashboardimport.ImportDashboardInput{
+				Value: expr.DatasourceType,
+			}
+		}
+
+		if input == nil {
+			return nil, &DashboardInputMissingError{VariableName: inputName}
+		}
+
+		e.variables["${"+inputName+"}"] = input.Value
+	}
+
+	return simplejson.NewFromAny(e.evalObject(e.template)), nil
+}
+
+func (e *DashTemplateEvaluator) evalValue(source *simplejson.Json) interface{} {
+	sourceValue := source.Interface()
+
+	switch v := sourceValue.(type) {
+	case string:
+		interpolated := varRegex.ReplaceAllStringFunc(v, func(match string) string {
+			replacement, exists := e.variables[match]
+			if exists {
+				return replacement
+			}
+			return match
+		})
+		return interpolated
+	case bool:
+		return v
+	case json.Number:
+		return v
+	case map[string]interface{}:
+		return e.evalObject(source)
+	case []interface{}:
+		array := make([]interface{}, 0)
+		for _, item := range v {
+			array = append(array, e.evalValue(simplejson.NewFromAny(item)))
+		}
+		return array
+	}
+
+	return nil
+}
+
+func (e *DashTemplateEvaluator) evalObject(source *simplejson.Json) interface{} {
+	result := make(map[string]interface{})
+
+	for key, value := range source.MustMap() {
+		if key == "__inputs" {
+			continue
+		}
+		result[key] = e.evalValue(simplejson.NewFromAny(value))
+	}
+
+	return result
+}

pkg/services/dashboardimport/utils/dash_template_evaluator_test.go

@@ -0,0 +1,39 @@
+package utils
+
+import (
+	"testing"
+
+	"github.com/grafana/grafana/pkg/components/simplejson"
+	"github.com/grafana/grafana/pkg/services/dashboardimport"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDashTemplateEvaluator(t *testing.T) {
+	template, err := simplejson.NewJson([]byte(`{
+		"__inputs": [
+			{
+				"name": "DS_NAME",
+				"type": "datasource"
+			}
+		],
+		"test": {
+			"prop": "${DS_NAME}_${DS_NAME}"
+		}
+	}`))
+	require.NoError(t, err)
+
+	evaluator := &DashTemplateEvaluator{
+		template: template,
+		inputs: []dashboardimport.ImportDashboardInput{
+			{Name: "*", Type: "datasource", Value: "my-server"},
+		},
+	}
+
+	res, err := evaluator.Eval()
+	require.NoError(t, err)
+
+	require.Equal(t, "my-server_my-server", res.GetPath("test", "prop").MustString())
+
+	inputs := res.Get("__inputs")
+	require.Nil(t, inputs.Interface())
+}