Add chat history

shared/history.go

@@ -0,0 +1,85 @@
+/*
+* @Author: Bartuccio Antoine
+* @Date:   2018-07-24 01:27:11
+* @Last Modified by:   klmp200
+* @Last Modified time: 2018-07-24 02:09:53
+ */
+
+package shared
+
+import (
+	"sync"
+)
+
+type history struct {
+	mutex sync.Mutex
+	size  int
+	data  map[int64][]string
+}
+
+var History history
+
+func InitHistory(size int) {
+	History = history{}
+	History.mutex.Lock()
+	defer History.mutex.Unlock()
+	History.size = size
+	History.data = make(map[int64][]string)
+}
+
+func (h history) Size() int {
+	h.mutex.Lock()
+	defer h.mutex.Unlock()
+	return h.size
+}
+
+func (h history) Message(chatID int64, n int) string {
+	h.mutex.Lock()
+	defer h.mutex.Unlock()
+	array, exists := h.data[chatID]
+	if exists && n >= 0 && n < len(array) {
+		return array[n]
+	}
+	return ""
+}
+
+func (h history) AddMessage(chatID int64, m string) {
+	h.mutex.Lock()
+	defer h.mutex.Unlock()
+	if _, exists := h.data[chatID]; !exists {
+		h.data[chatID] = make([]string, h.size, h.size)
+	}
+	h.append(chatID, m)
+}
+
+func (h history) LastMessage(chatID int64) string {
+	h.mutex.Lock()
+	defer h.mutex.Unlock()
+	if _, exists := h.data[chatID]; exists {
+		return h.data[chatID][h.size-1]
+	}
+	return ""
+}
+
+func (h history) ChatHistory(chatID int64) []string {
+	h.mutex.Lock()
+	defer h.mutex.Unlock()
+	array, exists := h.data[chatID]
+	if exists {
+		c := make([]string, h.size, h.size)
+		copy(c, array)
+		return c
+	}
+	return nil
+}
+
+// Assert that the slice exists and mutex already locked
+func (h history) append(chatID int64, m string) {
+	c := make([]string, h.size-1, h.size-1)
+	array, _ := h.data[chatID]
+	copy(c, array[1:])
+	for i, val := range c {
+		array[i] = val
+	}
+	array[h.size-1] = m
+}