From 13a6dd5695121f7240cdc6d0d11cef1089daf35d Mon Sep 17 00:00:00 2001
From: Knut Ahlers <knut@ahlers.me>
Date: Tue, 29 Jun 2021 14:08:26 +0200
Subject: [PATCH] Add support for dynamic variables

Signed-off-by: Knut Ahlers <knut@ahlers.me>
---
 action_setvar.go | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 functions.go     |  7 +++++++
 store.go         | 35 +++++++++++++++++++++++++++++++----
 wiki/Home.md     |  6 ++++++
 4 files changed, 91 insertions(+), 4 deletions(-)
 create mode 100644 action_setvar.go

diff --git a/action_setvar.go b/action_setvar.go
new file mode 100644
index 0000000..7b109a6
--- /dev/null
+++ b/action_setvar.go
@@ -0,0 +1,47 @@
+package main
+
+import (
+	"github.com/go-irc/irc"
+	"github.com/pkg/errors"
+)
+
+func init() {
+	registerAction(func() Actor { return &ActorSetVariable{} })
+}
+
+type ActorSetVariable struct {
+	Variable string `json:"variable" yaml:"variable"`
+	Clear    bool   `json:"clear" yaml:"clear"`
+	Set      string `json:"set" yaml:"set"`
+}
+
+func (a ActorSetVariable) Execute(c *irc.Client, m *irc.Message, r *Rule) error {
+	if a.Variable == "" {
+		return nil
+	}
+
+	varName, err := formatMessage(a.Variable, m, r, nil)
+	if err != nil {
+		return errors.Wrap(err, "preparing variable name")
+	}
+
+	if a.Clear {
+		return errors.Wrap(
+			store.RemoveVariable(varName),
+			"removing variable",
+		)
+	}
+
+	value, err := formatMessage(a.Set, m, r, nil)
+	if err != nil {
+		return errors.Wrap(err, "preparing value")
+	}
+
+	return errors.Wrap(
+		store.SetVariable(varName, value),
+		"setting variable",
+	)
+}
+
+func (a ActorSetVariable) IsAsync() bool { return false }
+func (a ActorSetVariable) Name() string  { return "setvariable" }
diff --git a/functions.go b/functions.go
index ad53fc3..9026475 100644
--- a/functions.go
+++ b/functions.go
@@ -62,4 +62,11 @@ func init() {
 	tplFuncs.Register("toUpper", genericTemplateFunctionGetter(strings.ToUpper))
 	tplFuncs.Register("followDate", genericTemplateFunctionGetter(twitch.GetFollowDate))
 	tplFuncs.Register("concat", genericTemplateFunctionGetter(func(delim string, parts ...string) string { return strings.Join(parts, delim) }))
+	tplFuncs.Register("variable", genericTemplateFunctionGetter(func(name string, defVal ...string) string {
+		value := store.GetVariable(name)
+		if value == "" && len(defVal) > 0 {
+			return defVal[0]
+		}
+		return value
+	}))
 }
diff --git a/store.go b/store.go
index 0ea8ec3..7e89d42 100644
--- a/store.go
+++ b/store.go
@@ -11,8 +11,9 @@ import (
 )
 
 type storageFile struct {
-	Counters map[string]int64      `json:"counters"`
-	Timers   map[string]timerEntry `json:"timers"`
+	Counters  map[string]int64      `json:"counters"`
+	Timers    map[string]timerEntry `json:"timers"`
+	Variables map[string]string     `json:"variables"`
 
 	inMem bool
 	lock  *sync.RWMutex
@@ -20,8 +21,9 @@ type storageFile struct {
 
 func newStorageFile(inMemStore bool) *storageFile {
 	return &storageFile{
-		Counters: map[string]int64{},
-		Timers:   map[string]timerEntry{},
+		Counters:  map[string]int64{},
+		Timers:    map[string]timerEntry{},
+		Variables: map[string]string{},
 
 		inMem: inMemStore,
 		lock:  new(sync.RWMutex),
@@ -35,6 +37,13 @@ func (s *storageFile) GetCounterValue(counter string) int64 {
 	return s.Counters[counter]
 }
 
+func (s *storageFile) GetVariable(key string) string {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
+
+	return s.Variables[key]
+}
+
 func (s *storageFile) HasTimer(id string) bool {
 	s.lock.RLock()
 	defer s.lock.RUnlock()
@@ -121,6 +130,24 @@ func (s *storageFile) SetTimer(kind timerType, id string, expiry time.Time) erro
 	return errors.Wrap(s.Save(), "saving store")
 }
 
+func (s *storageFile) SetVariable(key, value string) error {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	s.Variables[key] = value
+
+	return errors.Wrap(s.Save(), "saving store")
+}
+
+func (s *storageFile) RemoveVariable(key string) error {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	delete(s.Variables, key)
+
+	return errors.Wrap(s.Save(), "saving store")
+}
+
 func (s *storageFile) UpdateCounter(counter string, value int64, absolute bool) error {
 	s.lock.Lock()
 	defer s.lock.Unlock()
diff --git a/wiki/Home.md b/wiki/Home.md
index 295e183..f9dd6e4 100644
--- a/wiki/Home.md
+++ b/wiki/Home.md
@@ -69,6 +69,11 @@ rules: # See below for examples
     # Issue a timeout on the user who wrote the chat-line
     - timeout: 1s # Duration value: 1s / 1m / 1h
 
+    # Set a variable to value defined for later usage
+    - variable: myvar       # String, name of the variable to set (applies templating)
+      clear: false          # Boolean, clear the variable
+      set: '{{ .channel }}' # String, value to set the variable to (applies templating)
+
     # Send a whisper (ATTENTION: You need to have a known / verified bot for this!)
     # Without being known / verified your whisper will just silently get dropped by Twitch
     # Go here to get that verification: https://dev.twitch.tv/limit-increase
@@ -154,6 +159,7 @@ Additionally there are some functions available in the templates:
 - `tag <tagname>` - Takes the message sent to the channel, returns the value of the tag specified
 - `toLower <string>` - Converts the given string to lower-case
 - `toUpper <string>` - Converts the given string to upper-case
+- `variable <name> [default]` - Returns the variable value or default in case it is empty
 
 ## Command executions