add processor to pull field out of struct

internal/processor/struct-field-get.go

@@ -0,0 +1,49 @@
+package processor
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"reflect"
+
+	"github.com/jwetzell/showbridge-go/internal/config"
+)
+
+type StructFieldGet struct {
+	config config.ProcessorConfig
+	Name   string
+}
+
+func (sf *StructFieldGet) Process(ctx context.Context, payload any) (any, error) {
+	s := reflect.ValueOf(payload)
+
+	if s.Kind() != reflect.Struct {
+		return nil, errors.New("struct.field.get processor only accepts a struct payload")
+	}
+
+	field := s.FieldByName(sf.Name)
+	if !field.IsValid() {
+		return nil, fmt.Errorf("struct.field.get field '%s' does not exist", sf.Name)
+	}
+
+	return field.Interface(), nil
+}
+
+func (sf *StructFieldGet) Type() string {
+	return sf.config.Type
+}
+
+func init() {
+	RegisterProcessor(ProcessorRegistration{
+		Type: "struct.field.get",
+		New: func(config config.ProcessorConfig) (Processor, error) {
+			params := config.Params
+			nameString, err := params.GetString("name")
+			if err != nil {
+				return nil, fmt.Errorf("struct.field.get name error: %w", err)
+			}
+
+			return &StructFieldGet{config: config, Name: nameString}, nil
+		},
+	})
+}

internal/processor/test/struct-field-get_test.go

@@ -0,0 +1,176 @@
+package processor_test
+
+import (
+	"testing"
+
+	"github.com/jwetzell/showbridge-go/internal/config"
+	"github.com/jwetzell/showbridge-go/internal/processor"
+)
+
+func TestStructFieldGetFromRegistry(t *testing.T) {
+	registration, ok := processor.ProcessorRegistry["struct.field.get"]
+	if !ok {
+		t.Fatalf("struct.field.get processor not registered")
+	}
+
+	processorInstance, err := registration.New(config.ProcessorConfig{
+		Type: "struct.field.get",
+		Params: map[string]any{
+			"name": "Data",
+		},
+	})
+	if err != nil {
+		t.Fatalf("failed to create struct.field.get processor: %s", err)
+	}
+
+	if processorInstance.Type() != "struct.field.get" {
+		t.Fatalf("struct.field.get processor has wrong type: %s", processorInstance.Type())
+	}
+
+	payload := TestStruct{Data: "hello"}
+	expected := "hello"
+
+	got, err := processorInstance.Process(t.Context(), payload)
+	if err != nil {
+		t.Fatalf("struct.field.get processing failed: %s", err)
+	}
+
+	if got != expected {
+		t.Fatalf("struct.field.get got %+v, expected %+v", got, expected)
+	}
+}
+
+func TestGoodStructFieldGet(t *testing.T) {
+
+	tests := []struct {
+		name     string
+		params   map[string]any
+		payload  any
+		expected any
+	}{
+		{
+			name:     "string field",
+			params:   map[string]any{"name": "String"},
+			payload:  TestStruct{String: "hello"},
+			expected: "hello",
+		},
+		{
+			name:     "int field",
+			params:   map[string]any{"name": "Int"},
+			payload:  TestStruct{Int: 42},
+			expected: 42,
+		},
+		{
+			name:     "float field",
+			params:   map[string]any{"name": "Float"},
+			payload:  TestStruct{Float: 3.14},
+			expected: 3.14,
+		},
+		{
+			name:     "bool field",
+			params:   map[string]any{"name": "Bool"},
+			payload:  TestStruct{Bool: true},
+			expected: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			registration, ok := processor.ProcessorRegistry["struct.field.get"]
+			if !ok {
+				t.Fatalf("struct.field.get processor not registered")
+			}
+
+			processorInstance, err := registration.New(config.ProcessorConfig{
+				Type:   "struct.field.get",
+				Params: test.params,
+			})
+
+			if err != nil {
+				t.Fatalf("struct.field.get failed to create processor: %s", err)
+			}
+
+			got, err := processorInstance.Process(t.Context(), test.payload)
+
+			if err != nil {
+				t.Fatalf("struct.field.get failed: %s", err)
+			}
+
+			if got != test.expected {
+				t.Fatalf("struct.field.get got %s, expected %s", got, test.expected)
+			}
+		})
+	}
+}
+
+func TestBadStructFieldGet(t *testing.T) {
+	tests := []struct {
+		name        string
+		params      map[string]any
+		payload     any
+		errorString string
+	}{
+		{
+			name:        "no name param",
+			payload:     TestStruct{Data: "hello"},
+			params:      map[string]any{},
+			errorString: "struct.field.get name error: not found",
+		},
+		{
+			name:    "non string name",
+			payload: TestStruct{Data: "hello"},
+			params: map[string]any{
+				"name": 1,
+			},
+			errorString: "struct.field.get name error: not a string",
+		},
+		{
+			name:    "missing field",
+			payload: TestStruct{String: "hello"},
+			params: map[string]any{
+				"name": "NonExistentField",
+			},
+			errorString: "struct.field.get field 'NonExistentField' does not exist",
+		},
+		{
+			name:    "not a struct payload",
+			payload: "not a struct",
+			params: map[string]any{
+				"name": "NonExistentField",
+			},
+			errorString: "struct.field.get processor only accepts a struct payload",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+
+			registration, ok := processor.ProcessorRegistry["struct.field.get"]
+			if !ok {
+				t.Fatalf("struct.field.get processor not registered")
+			}
+
+			processorInstance, err := registration.New(config.ProcessorConfig{
+				Type:   "struct.field.get",
+				Params: test.params,
+			})
+
+			if err != nil {
+				if test.errorString != err.Error() {
+					t.Fatalf("struct.field.get got error '%s', expected '%s'", err.Error(), test.errorString)
+				}
+				return
+			}
+
+			got, err := processorInstance.Process(t.Context(), test.payload)
+
+			if err == nil {
+				t.Fatalf("struct.field.get expected to fail but got payload: %s", got)
+			}
+
+			if err.Error() != test.errorString {
+				t.Fatalf("struct.field.get got error '%s', expected '%s'", err.Error(), test.errorString)
+			}
+		})
+	}
+}