5 files changed, 122 insertions, 0 deletions
diff --git a/danmaku/dmmsg/danmu.go b/danmaku/dmmsg/danmu.go
new file mode 100644
index 0000000..2cc5dfa
--- /dev/null
+++ b/danmaku/dmmsg/danmu.go
@@ -0,0 +1,55 @@
+package dmmsg
+
+/*
+Decoder of raw danmaku messages.
+*/
+
+import (
+	"fmt"
+)
+
+type RawDanMuMessage = BaseRawMessage[[]interface{}, interface{}]
+
+type DanMuMessage struct {
+	Content    string
+	SourceUser struct {
+		Nickname string
+		UID      int64
+	}
+}
+
+func (dm DanMuMessage) String() string {
+	return fmt.Sprintf("(user: %v, uid: %v) %v",
+		dm.SourceUser.Nickname, dm.SourceUser.UID, dm.Content)
+}
+
+const kInvalidDanmakuJson = "invalid danmaku JSON document"
+
+func ParseDanmakuMessage(body RawDanMuMessage) (dmm DanMuMessage, err error) {
+	if len(body.Info) != 16 {
+		err = fmt.Errorf("%s: \"info\" length != 16", kInvalidDanmakuJson)
+		return
+	}
+
+	dmm.Content, err = castValue[string](body.Info[1])
+	if err != nil {
+		return
+	}
+
+	userInfo, err := castValue[[]interface{}](body.Info[2])
+
+	var ok bool
+	uid, ok := userInfo[0].(float64)
+	if !ok {
+		err = fmt.Errorf("%s: uid is not a float64: %v", kInvalidDanmakuJson, userInfo[0])
+		return
+	}
+	dmm.SourceUser.UID = int64(uid)
+
+	dmm.SourceUser.Nickname, ok = userInfo[1].(string)
+	if !ok {
+		err = fmt.Errorf("%s: nickname is not a string: %v", kInvalidDanmakuJson, userInfo[1])
+		return
+	}
+	return
+}
diff --git a/danmaku/dmmsg/interactword.go b/danmaku/dmmsg/interactword.go
new file mode 100644
index 0000000..d5dc315
--- /dev/null
+++ b/danmaku/dmmsg/interactword.go
@@ -0,0 +1,39 @@
+package dmmsg
+
+type InteractWordMessage struct {
+	Contribution struct {
+		Grade int `json:"grade"`
+	} `json:"contribution"`
+	DanMuScore int `json:"dmscore"`
+	FansMedal  struct {
+		AnchorRoomid int    `json:"anchor_roomid"`
+		GuardLevel   int    `json:"guard_level"`
+		IconID       int    `json:"icon_id"`
+		IsLighted    int    `json:"is_lighted"`
+		Color        int    `json:"medal_color"`
+		ColorBorder  int    `json:"medal_color_border"`
+		ColorEnd     int    `json:"medal_color_end"`
+		ColorStart   int    `json:"medal_color_start"`
+		Level        int    `json:"medal_level"`
+		Name         string `json:"medal_name"`
+		Score        int    `json:"score"`
+		Special      string `json:"special"`
+		TargetID     int    `json:"target_id"`
+	} `json:"fans_medal"`
+	Identities    []int  `json:"identities"`
+	IsSpread      int    `json:"is_spread"`
+	MsgType       int    `json:"msg_type"`
+	PrivilegeType int    `json:"privilege_type"`
+	RoomId        int    `json:"roomid"`
+	Score         int64  `json:"score"`
+	SpreadDesc    string `json:"spread_desc"`
+	SpreadInfo    string `json:"spread_info"`
+	TailIcon      int    `json:"tail_icon"`
+	Timestamp     int    `json:"timestamp"`
+	TriggerTime   int64  `json:"trigger_time"`
+	UID           int    `json:"uid"`
+	UserName      string `json:"uname"`
+	UserNameColor string `json:"uname_color"`
+}
+
+type RawInteractWordMessage = BaseRawMessage[interface{}, InteractWordMessage]
diff --git a/danmaku/dmmsg/messages.go b/danmaku/dmmsg/messages.go
new file mode 100644
index 0000000..d1480b7
--- /dev/null
+++ b/danmaku/dmmsg/messages.go
@@ -0,0 +1,7 @@
+package dmmsg
+
+type BaseRawMessage[I any, D any] struct {
+	Cmd  string `json:"cmd"`
+	Info I      `json:"info"`
+	Data D      `json:"data"`
+}
diff --git a/danmaku/dmmsg/msghandler.go b/danmaku/dmmsg/msghandler.go
new file mode 100644
index 0000000..32766aa
--- /dev/null
+++ b/danmaku/dmmsg/msghandler.go
@@ -0,0 +1,4 @@
+package dmmsg
+
+type DanmakuMessageHandler interface {
+}
diff --git a/danmaku/dmmsg/util.go b/danmaku/dmmsg/util.go
new file mode 100644
index 0000000..9d41ab9
--- /dev/null
+++ b/danmaku/dmmsg/util.go
@@ -0,0 +1,17 @@
+package dmmsg
+
+import (
+	"fmt"
+	"reflect"
+)
+
+func castValue[T any](obj interface{}) (thing T, err error) {
+	casted, ok := (obj).(T)
+	if !ok {
+		err = fmt.Errorf("%s: required value is not of type \"%v\": %v",
+			kInvalidDanmakuJson, reflect.TypeOf(thing).String(), obj)
+		return
+	}
+	thing = casted
+	return
+}