From ef1d23bd3d39a001281d35a48a611248680d6f25 Mon Sep 17 00:00:00 2001
From: Knut Ahlers <knut@ahlers.me>
Date: Sat, 20 Nov 2021 21:30:58 +0100
Subject: [PATCH] Add `fieldcollection` helper

Signed-off-by: Knut Ahlers <knut@ahlers.me>
---
 fieldcollection/fieldcollection.go      | 367 ++++++++++++++++++++++++
 fieldcollection/fieldcollection_test.go |  80 ++++++
 go.mod                                  |   1 +
 go.sum                                  |   2 +
 4 files changed, 450 insertions(+)
 create mode 100644 fieldcollection/fieldcollection.go
 create mode 100644 fieldcollection/fieldcollection_test.go

diff --git a/fieldcollection/fieldcollection.go b/fieldcollection/fieldcollection.go
new file mode 100644
index 0000000..3df3c2c
--- /dev/null
+++ b/fieldcollection/fieldcollection.go
@@ -0,0 +1,367 @@
+package fieldcollection
+
+import (
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	ErrValueNotSet   = errors.New("specified value not found")
+	ErrValueMismatch = errors.New("specified value has different format")
+)
+
+type FieldCollection struct {
+	data map[string]interface{}
+	lock sync.RWMutex
+}
+
+// NewFieldCollection creates a new FieldCollection with empty data store
+func NewFieldCollection() *FieldCollection {
+	return &FieldCollection{data: make(map[string]interface{})}
+}
+
+// FieldCollectionFromData is a wrapper around NewFieldCollection and SetFromData
+func FieldCollectionFromData(data map[string]interface{}) *FieldCollection {
+	o := NewFieldCollection()
+	o.SetFromData(data)
+	return o
+}
+
+// CanBool tries to read key name as bool and checks whether error is nil
+func (f *FieldCollection) CanBool(name string) bool {
+	_, err := f.Bool(name)
+	return err == nil
+}
+
+// CanDuration tries to read key name as time.Duration and checks whether error is nil
+func (f *FieldCollection) CanDuration(name string) bool {
+	_, err := f.Duration(name)
+	return err == nil
+}
+
+// CanInt64 tries to read key name as int64 and checks whether error is nil
+func (f *FieldCollection) CanInt64(name string) bool {
+	_, err := f.Int64(name)
+	return err == nil
+}
+
+// CanString tries to read key name as string and checks whether error is nil
+func (f *FieldCollection) CanString(name string) bool {
+	_, err := f.String(name)
+	return err == nil
+}
+
+// Clone is a wrapper around n.SetFromData(o.Data())
+func (f *FieldCollection) Clone() *FieldCollection {
+	out := new(FieldCollection)
+	out.SetFromData(f.Data())
+	return out
+}
+
+// Data creates a map-copy of the data stored inside the FieldCollection
+func (f *FieldCollection) Data() map[string]interface{} {
+	if f == nil {
+		return nil
+	}
+
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+
+	out := make(map[string]interface{})
+	for k := range f.data {
+		out[k] = f.data[k]
+	}
+
+	return out
+}
+
+// Expect takes a list of keys and returns an error with all non-found names
+func (f *FieldCollection) Expect(keys ...string) error {
+	if len(keys) == 0 {
+		return nil
+	}
+
+	if f == nil || f.data == nil {
+		return errors.New("uninitialized field collection")
+	}
+
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+
+	var missing []string
+
+	for _, k := range keys {
+		if _, ok := f.data[k]; !ok {
+			missing = append(missing, k)
+		}
+	}
+
+	if len(missing) > 0 {
+		return errors.Errorf("missing key(s) %s", strings.Join(missing, ", "))
+	}
+
+	return nil
+}
+
+// HasAll takes a list of keys and returns whether all of them exist inside the FieldCollection
+func (f *FieldCollection) HasAll(keys ...string) bool {
+	return f.Expect(keys...) == nil
+}
+
+// MustBool is a wrapper around Bool and panics if an error was returned
+func (f *FieldCollection) MustBool(name string, defVal *bool) bool {
+	v, err := f.Bool(name)
+	if err != nil {
+		if defVal != nil {
+			return *defVal
+		}
+		panic(err)
+	}
+	return v
+}
+
+// MustDuration is a wrapper around Duration and panics if an error was returned
+func (f *FieldCollection) MustDuration(name string, defVal *time.Duration) time.Duration {
+	v, err := f.Duration(name)
+	if err != nil {
+		if defVal != nil {
+			return *defVal
+		}
+		panic(err)
+	}
+	return v
+}
+
+// MustInt64 is a wrapper around Int64 and panics if an error was returned
+func (f *FieldCollection) MustInt64(name string, defVal *int64) int64 {
+	v, err := f.Int64(name)
+	if err != nil {
+		if defVal != nil {
+			return *defVal
+		}
+		panic(err)
+	}
+	return v
+}
+
+// MustString is a wrapper around String and panics if an error was returned
+func (f *FieldCollection) MustString(name string, defVal *string) string {
+	v, err := f.String(name)
+	if err != nil {
+		if defVal != nil {
+			return *defVal
+		}
+		panic(err)
+	}
+	return v
+}
+
+// Bool tries to read key name as bool
+func (f *FieldCollection) Bool(name string) (bool, error) {
+	if f == nil || f.data == nil {
+		return false, errors.New("uninitialized field collection")
+	}
+
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+
+	v, ok := f.data[name]
+	if !ok {
+		return false, ErrValueNotSet
+	}
+
+	switch v := v.(type) {
+	case bool:
+		return v, nil
+	case string:
+		bv, err := strconv.ParseBool(v)
+		return bv, errors.Wrap(err, "parsing string to bool")
+	}
+
+	return false, ErrValueMismatch
+}
+
+// Duration tries to read key name as time.Duration
+func (f *FieldCollection) Duration(name string) (time.Duration, error) {
+	if f == nil || f.data == nil {
+		return 0, errors.New("uninitialized field collection")
+	}
+
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+
+	v, err := f.String(name)
+	if err != nil {
+		return 0, errors.Wrap(err, "getting string value")
+	}
+
+	d, err := time.ParseDuration(v)
+	return d, errors.Wrap(err, "parsing value")
+}
+
+// Int64 tries to read key name as int64
+func (f *FieldCollection) Int64(name string) (int64, error) {
+	if f == nil || f.data == nil {
+		return 0, errors.New("uninitialized field collection")
+	}
+
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+
+	v, ok := f.data[name]
+	if !ok {
+		return 0, ErrValueNotSet
+	}
+
+	switch v := v.(type) {
+	case int:
+		return int64(v), nil
+	case int16:
+		return int64(v), nil
+	case int32:
+		return int64(v), nil
+	case int64:
+		return v, nil
+	}
+
+	return 0, ErrValueMismatch
+}
+
+// Set sets a single key to specified value
+func (f *FieldCollection) Set(key string, value interface{}) {
+	if f == nil {
+		f = NewFieldCollection()
+	}
+
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	if f.data == nil {
+		f.data = make(map[string]interface{})
+	}
+
+	f.data[key] = value
+}
+
+// SetFromData takes a map of data and copies all data into the FieldCollection
+func (f *FieldCollection) SetFromData(data map[string]interface{}) {
+	if f == nil {
+		f = NewFieldCollection()
+	}
+
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	if f.data == nil {
+		f.data = make(map[string]interface{})
+	}
+
+	for key, value := range data {
+		f.data[key] = value
+	}
+}
+
+// String tries to read key name as string
+func (f *FieldCollection) String(name string) (string, error) {
+	if f == nil || f.data == nil {
+		return "", errors.New("uninitialized field collection")
+	}
+
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+
+	v, ok := f.data[name]
+	if !ok {
+		return "", ErrValueNotSet
+	}
+
+	if sv, ok := v.(string); ok {
+		return sv, nil
+	}
+
+	if iv, ok := v.(fmt.Stringer); ok {
+		return iv.String(), nil
+	}
+
+	return "", ErrValueMismatch
+}
+
+// StringSlice tries to read key name as []string
+func (f *FieldCollection) StringSlice(name string) ([]string, error) {
+	if f == nil || f.data == nil {
+		return nil, errors.New("uninitialized field collection")
+	}
+
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+
+	v, ok := f.data[name]
+	if !ok {
+		return nil, ErrValueNotSet
+	}
+
+	switch v := v.(type) {
+	case []string:
+		return v, nil
+
+	case []interface{}:
+		var out []string
+
+		for _, iv := range v {
+			sv, ok := iv.(string)
+			if !ok {
+				return nil, errors.New("value in slice was not string")
+			}
+			out = append(out, sv)
+		}
+
+		return out, nil
+	}
+
+	return nil, ErrValueMismatch
+}
+
+// Implement JSON marshalling to plain underlying map[string]interface{}
+
+func (f *FieldCollection) MarshalJSON() ([]byte, error) {
+	if f == nil || f.data == nil {
+		return []byte("{}"), nil
+	}
+
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+
+	return json.Marshal(f.data)
+}
+
+func (f *FieldCollection) UnmarshalJSON(raw []byte) error {
+	data := make(map[string]interface{})
+	if err := json.Unmarshal(raw, &data); err != nil {
+		return errors.Wrap(err, "unmarshalling from JSON")
+	}
+
+	f.SetFromData(data)
+	return nil
+}
+
+// Implement YAML marshalling to plain underlying map[string]interface{}
+
+func (f *FieldCollection) MarshalYAML() (interface{}, error) {
+	return f.Data(), nil
+}
+
+func (f *FieldCollection) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	data := make(map[string]interface{})
+	if err := unmarshal(&data); err != nil {
+		return errors.Wrap(err, "unmarshalling from YAML")
+	}
+
+	f.SetFromData(data)
+	return nil
+}
diff --git a/fieldcollection/fieldcollection_test.go b/fieldcollection/fieldcollection_test.go
new file mode 100644
index 0000000..c764707
--- /dev/null
+++ b/fieldcollection/fieldcollection_test.go
@@ -0,0 +1,80 @@
+package fieldcollection
+
+import (
+	"bytes"
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"gopkg.in/yaml.v2"
+)
+
+func TestFieldCollectionJSONMarshal(t *testing.T) {
+	var (
+		buf = new(bytes.Buffer)
+		raw = `{"key1":"test1","key2":"test2"}`
+		f   = NewFieldCollection()
+	)
+
+	if err := json.NewDecoder(strings.NewReader(raw)).Decode(f); err != nil {
+		t.Fatalf("Unable to unmarshal: %s", err)
+	}
+
+	if err := json.NewEncoder(buf).Encode(f); err != nil {
+		t.Fatalf("Unable to marshal: %s", err)
+	}
+
+	if raw != strings.TrimSpace(buf.String()) {
+		t.Errorf("Marshalled JSON does not match expectation: res=%s exp=%s", buf.String(), raw)
+	}
+}
+
+func TestFieldCollectionYAMLMarshal(t *testing.T) {
+	var (
+		buf = new(bytes.Buffer)
+		raw = "key1: test1\nkey2: test2"
+		f   = NewFieldCollection()
+	)
+
+	if err := yaml.NewDecoder(strings.NewReader(raw)).Decode(f); err != nil {
+		t.Fatalf("Unable to unmarshal: %s", err)
+	}
+
+	if err := yaml.NewEncoder(buf).Encode(f); err != nil {
+		t.Fatalf("Unable to marshal: %s", err)
+	}
+
+	if raw != strings.TrimSpace(buf.String()) {
+		t.Errorf("Marshalled YAML does not match expectation: res=%s exp=%s", buf.String(), raw)
+	}
+}
+
+func TestFieldCollectionNilModify(t *testing.T) {
+	var f *FieldCollection
+
+	f.Set("foo", "bar")
+
+	f = nil
+	f.SetFromData(map[string]interface{}{"foo": "bar"})
+}
+
+func TestFieldCollectionNilClone(t *testing.T) {
+	var f *FieldCollection
+
+	f.Clone()
+}
+
+func TestFieldCollectionNilDataGet(t *testing.T) {
+	var f *FieldCollection
+
+	for name, fn := range map[string]func(name string) bool{
+		"bool":     f.CanBool,
+		"duration": f.CanDuration,
+		"int64":    f.CanInt64,
+		"string":   f.CanString,
+	} {
+		if fn("foo") {
+			t.Errorf("%s key is available", name)
+		}
+	}
+}
diff --git a/go.mod b/go.mod
index 6238c92..d4da10f 100644
--- a/go.mod
+++ b/go.mod
@@ -11,6 +11,7 @@ require (
 	github.com/nxadm/tail v1.4.6 // indirect
 	github.com/onsi/ginkgo v1.15.0
 	github.com/onsi/gomega v1.10.5
+	github.com/pkg/errors v0.9.1
 	github.com/sirupsen/logrus v1.7.0
 	github.com/stretchr/testify v1.7.0 // indirect
 	golang.org/x/net v0.0.0-20210119194325-5f4716e94777 // indirect
diff --git a/go.sum b/go.sum
index 2b3a854..760e266 100644
--- a/go.sum
+++ b/go.sum
@@ -53,6 +53,8 @@ github.com/onsi/gomega v1.7.1/go.mod h1:XdKZgCCFLUoM/7CFJVPcG8C1xQ1AJ0vpAezJrB7J
 github.com/onsi/gomega v1.10.1/go.mod h1:iN09h71vgCQne3DLsj+A5owkum+a2tYe+TOCB1ybHNo=
 github.com/onsi/gomega v1.10.5 h1:7n6FEkpFmfCoo2t+YYqXH0evK+a9ICQz0xcAy9dYcaQ=
 github.com/onsi/gomega v1.10.5/go.mod h1:gza4q3jKQJijlu05nKWRCW/GavJumGt8aNRxWg7mt48=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=