Change themes in random order once a day/hour (#62)

CHANGELOG.md

@@ -4,6 +4,14 @@ All notable changes to this package will be documented in this file.
 
 The format is based on [Keep a Changelog][keepachangelog] and this project adheres to [Semantic Versioning][semver].
 
+## UNRELEASED
+
+### Added
+
+- Possibility to change the template to the random once a day using "special" template name `random-daily` (or hourly, using `random-hourly`) [#48]
+
+[#48]:https://github.com/tarampampam/error-pages/issues/48
+
 ## v2.5.0
 
 ### Changed

internal/cli/serve/command.go

@@ -69,7 +69,7 @@ func run(parentCtx context.Context, log *zap.Logger, f flags, cfg *config.Config
 
 	var (
 		templateNames = cfg.TemplateNames()
-		picker        *pick.StringsSlice
+		picker        interface{ Pick() string }
 	)
 
 	switch f.template.name {
@@ -83,6 +83,16 @@ func run(parentCtx context.Context, log *zap.Logger, f flags, cfg *config.Config
 
 		picker = pick.NewStringsSlice(templateNames, pick.RandomEveryTime)
 
+	case useRandomTemplateDaily:
+		log.Info("A random template will be used and changed once a day")
+
+		picker = pick.NewStringsSliceWithInterval(templateNames, pick.RandomEveryTime, time.Hour*24) //nolint:gomnd
+
+	case useRandomTemplateHourly:
+		log.Info("A random template will be used and changed hourly")
+
+		picker = pick.NewStringsSliceWithInterval(templateNames, pick.RandomEveryTime, time.Hour)
+
 	case "":
 		log.Info("The first template (ordered by name) will be used")
 
@@ -132,6 +142,12 @@ func run(parentCtx context.Context, log *zap.Logger, f flags, cfg *config.Config
 	case <-ctx.Done(): // ..or context cancellation
 		log.Info("Gracefully server stopping", zap.Duration("uptime", time.Since(startedAt)))
 
+		if p, ok := picker.(interface{ Close() error }); ok {
+			if err := p.Close(); err != nil {
+				return err
+			}
+		}
+
 		// stop the server using created context above
 		if err := server.Stop(); err != nil {
 			return err

internal/cli/serve/flags.go

@@ -35,6 +35,8 @@ const (
 const (
 	useRandomTemplate              = "random"
 	useRandomTemplateOnEachRequest = "i-said-random"
+	useRandomTemplateDaily         = "random-daily"
+	useRandomTemplateHourly        = "random-hourly"
 )
 
 func (f *flags) init(flagSet *pflag.FlagSet) {
@@ -55,8 +57,13 @@ func (f *flags) init(flagSet *pflag.FlagSet) {
 		templateNameFlagName, "t",
 		"",
 		fmt.Sprintf(
-			"template name (set \"%s\" to use a randomized or \"%s\" to use a randomized template on each request) [$%s]", //nolint:lll
-			useRandomTemplate, useRandomTemplateOnEachRequest, env.TemplateName,
+			"template name (set \"%s\" to use a randomized or \"%s\" to use a randomized template on each request "+
+				"or \"%s/%s\" daily/hourly randomized) [$%s]",
+			useRandomTemplate,
+			useRandomTemplateOnEachRequest,
+			useRandomTemplateDaily,
+			useRandomTemplateHourly,
+			env.TemplateName,
 		),
 	)
 	flagSet.StringVarP(

internal/pick/picker.go

@@ -51,33 +51,38 @@ func (p *picker) NextIndex() uint32 {
 
 	case RandomOnce:
 		if p.lastIdx == unsetIdx {
-			p.mu.Lock()
-			defer p.mu.Unlock()
-
-			p.lastIdx = uint32(p.rand.Intn(int(p.maxIdx)))
+			return p.randomizeNext()
 		}
 
 		return p.lastIdx
 
 	case RandomEveryTime:
-		var idx = uint32(p.rand.Intn(int(p.maxIdx + 1)))
-
-		p.mu.Lock()
-		defer p.mu.Unlock()
-
-		if idx == p.lastIdx {
-			p.lastIdx++
-		} else {
-			p.lastIdx = idx
-		}
-
-		if p.lastIdx > p.maxIdx { // overflow?
-			p.lastIdx = 0
-		}
-
-		return p.lastIdx
+		return p.randomizeNext()
 
 	default:
 		panic("picker.NextIndex(): unsupported mode")
 	}
 }
+
+func (p *picker) randomizeNext() uint32 {
+	var idx = uint32(p.rand.Intn(int(p.maxIdx + 1)))
+
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	if idx == p.lastIdx {
+		p.lastIdx++
+	} else {
+		p.lastIdx = idx
+	}
+
+	if p.lastIdx > p.maxIdx { // overflow?
+		p.lastIdx = 0
+	}
+
+	if p.lastIdx == unsetIdx {
+		p.lastIdx--
+	}
+
+	return p.lastIdx
+}

internal/pick/strings_slice.go

@@ -1,5 +1,11 @@
 package pick
 
+import (
+	"errors"
+	"sync"
+	"time"
+)
+
 type StringsSlice struct {
 	s []string
 	p *picker
@@ -7,7 +13,13 @@ type StringsSlice struct {
 
 // NewStringsSlice creates new StringsSlice.
 func NewStringsSlice(items []string, mode pickMode) *StringsSlice {
-	return &StringsSlice{s: items, p: NewPicker(uint32(len(items)-1), mode)}
+	maxIdx := len(items) - 1
+
+	if maxIdx < 0 {
+		maxIdx = 0
+	}
+
+	return &StringsSlice{s: items, p: NewPicker(uint32(maxIdx), mode)}
 }
 
 // Pick an element from the strings slice.
@@ -18,3 +30,106 @@ func (s *StringsSlice) Pick() string {
 
 	return s.s[s.p.NextIndex()]
 }
+
+type StringsSliceWithInterval struct {
+	s []string
+	p *picker
+	d time.Duration
+
+	idxMu sync.RWMutex
+	idx   uint32
+
+	close    chan struct{}
+	closedMu sync.RWMutex
+	closed   bool
+}
+
+// NewStringsSliceWithInterval creates new StringsSliceWithInterval.
+func NewStringsSliceWithInterval(items []string, mode pickMode, interval time.Duration) *StringsSliceWithInterval {
+	maxIdx := len(items) - 1
+
+	if maxIdx < 0 {
+		maxIdx = 0
+	}
+
+	if interval <= time.Duration(0) {
+		panic("NewStringsSliceWithInterval: wrong interval")
+	}
+
+	s := &StringsSliceWithInterval{
+		s:     items,
+		p:     NewPicker(uint32(maxIdx), mode),
+		d:     interval,
+		close: make(chan struct{}, 1),
+	}
+
+	s.next()
+
+	go s.rotate()
+
+	return s
+}
+
+func (s *StringsSliceWithInterval) rotate() {
+	defer close(s.close)
+
+	timer := time.NewTimer(s.d)
+	defer timer.Stop()
+
+	for {
+		select {
+		case <-s.close:
+			return
+
+		case <-timer.C:
+			s.next()
+			timer.Reset(s.d)
+		}
+	}
+}
+
+func (s *StringsSliceWithInterval) next() {
+	idx := s.p.NextIndex()
+
+	s.idxMu.Lock()
+	s.idx = idx
+	s.idxMu.Unlock()
+}
+
+// Pick an element from the strings slice.
+func (s *StringsSliceWithInterval) Pick() string {
+	if s.isClosed() {
+		panic("StringsSliceWithInterval.Pick(): closed")
+	}
+
+	if len(s.s) == 0 {
+		return ""
+	}
+
+	s.idxMu.RLock()
+	defer s.idxMu.RUnlock()
+
+	return s.s[s.idx]
+}
+
+func (s *StringsSliceWithInterval) isClosed() (closed bool) {
+	s.closedMu.RLock()
+	closed = s.closed
+	s.closedMu.RUnlock()
+
+	return
+}
+
+func (s *StringsSliceWithInterval) Close() error {
+	if s.isClosed() {
+		return errors.New("closed")
+	}
+
+	s.closedMu.Lock()
+	s.closed = true
+	s.closedMu.Unlock()
+
+	s.close <- struct{}{}
+
+	return nil
+}

internal/pick/strings_slice_test.go

@@ -2,6 +2,7 @@ package pick_test
 
 import (
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/tarampampam/error-pages/internal/pick"
@@ -47,3 +48,83 @@ func TestStringsSlice_Pick(t *testing.T) {
 		}
 	})
 }
+
+func TestNewStringsSliceWithInterval_Pick(t *testing.T) {
+	t.Run("first", func(t *testing.T) {
+		for i := uint8(0); i < 50; i++ {
+			p := pick.NewStringsSliceWithInterval([]string{}, pick.First, time.Millisecond)
+			assert.Equal(t, "", p.Pick())
+			assert.NoError(t, p.Close())
+			assert.Panics(t, func() { p.Pick() })
+		}
+
+		p := pick.NewStringsSliceWithInterval([]string{"foo", "bar", "baz"}, pick.First, time.Millisecond)
+
+		for i := uint8(0); i < 50; i++ {
+			assert.Equal(t, "foo", p.Pick())
+
+			<-time.After(time.Millisecond * 2)
+		}
+
+		assert.NoError(t, p.Close())
+		assert.Error(t, p.Close())
+		assert.Panics(t, func() { p.Pick() })
+	})
+
+	t.Run("random once", func(t *testing.T) {
+		for i := uint8(0); i < 50; i++ {
+			p := pick.NewStringsSliceWithInterval([]string{}, pick.RandomOnce, time.Millisecond)
+			assert.Equal(t, "", p.Pick())
+			assert.NoError(t, p.Close())
+			assert.Panics(t, func() { p.Pick() })
+		}
+
+		var (
+			p      = pick.NewStringsSliceWithInterval([]string{"foo", "bar", "baz"}, pick.RandomOnce, time.Millisecond)
+			picked = p.Pick()
+		)
+
+		for i := uint8(0); i < 50; i++ {
+			assert.Equal(t, picked, p.Pick())
+
+			<-time.After(time.Millisecond * 2)
+		}
+
+		assert.NoError(t, p.Close())
+		assert.Error(t, p.Close())
+		assert.Panics(t, func() { p.Pick() })
+	})
+
+	t.Run("random every time", func(t *testing.T) {
+		for i := uint8(0); i < 50; i++ {
+			p := pick.NewStringsSliceWithInterval([]string{}, pick.RandomEveryTime, time.Millisecond)
+			assert.Equal(t, "", p.Pick())
+			assert.NoError(t, p.Close())
+			assert.Panics(t, func() { p.Pick() })
+		}
+
+		var changed int
+
+		for i := uint8(0); i < 50; i++ {
+			p := pick.NewStringsSliceWithInterval([]string{"foo", "bar", "baz"}, pick.RandomEveryTime, time.Millisecond) //nolint:lll
+
+			one, two := p.Pick(), p.Pick()
+			assert.Equal(t, one, two)
+
+			<-time.After(time.Millisecond * 2)
+
+			three, four := p.Pick(), p.Pick()
+			assert.Equal(t, three, four)
+
+			if one != three {
+				changed++
+			}
+
+			assert.NoError(t, p.Close())
+			assert.Error(t, p.Close())
+			assert.Panics(t, func() { p.Pick() })
+		}
+
+		assert.GreaterOrEqual(t, changed, 25)
+	})
+}