支持可配置的会话自动分配策略

- 租户可设置负载最低或轮询，以及每位坐席最大进行中会话数
- 自动分配按策略过滤在线一线客服，满并发则保持排队
- 系统设置「客服分配规则」页可保存上述配置

server/internal/handler/assignment.go

@@ -2,39 +2,123 @@ package handler
 
 import (
 	"fmt"
+	"strings"
 
 	"kefu-sys/server/internal/model"
 	"kefu-sys/server/internal/ws"
 )
 
-const offlineLeavePrompt = "当前无客服在线，请留言并留下联系方式，我们上线后会尽快回复您。"
+const (
+	assignStrategyLeastLoad  = "least_load"
+	assignStrategyRoundRobin = "round_robin"
+	offlineLeavePrompt       = "当前无客服在线，请留言并留下联系方式，我们上线后会尽快回复您。"
+)
 
-// pickLeastLoadedAgent 在在线一线客服中选择当前进行中会话最少的一位。
-func pickLeastLoadedAgent(tenantID uint) (*model.User, error) {
+func normalizeAssignStrategy(raw string) string {
+	switch strings.TrimSpace(raw) {
+	case assignStrategyRoundRobin:
+		return assignStrategyRoundRobin
+	default:
+		return assignStrategyLeastLoad
+	}
+}
+
+// listOnlineAgents 租户内可自动接待的一线客服（online + role=agent）。
+func listOnlineAgents(tenantID uint) ([]model.User, error) {
 	var agents []model.User
-	if err := model.DB.Where("tenant_id = ? AND role = ? AND status = ?", tenantID, "agent", "online").
-		Order("id asc").Find(&agents).Error; err != nil {
+	err := model.DB.Where("tenant_id = ? AND role = ? AND status = ?", tenantID, "agent", "online").
+		Order("id asc").Find(&agents).Error
+	return agents, err
+}
+
+func agentActiveSessionCount(tenantID, agentID uint) (int64, error) {
+	var count int64
+	err := model.DB.Model(&model.Session{}).
+		Where("tenant_id = ? AND agent_id = ? AND status = ?", tenantID, agentID, "active").
+		Count(&count).Error
+	return count, err
+}
+
+// filterAssignable 按最大并发过滤；maxActive<=0 表示不限制。
+func filterAssignable(tenantID uint, agents []model.User, maxActive int) ([]model.User, map[uint]int64, error) {
+	counts := make(map[uint]int64, len(agents))
+	out := make([]model.User, 0, len(agents))
+	for i := range agents {
+		n, err := agentActiveSessionCount(tenantID, agents[i].ID)
+		if err != nil {
+			return nil, nil, err
+		}
+		counts[agents[i].ID] = n
+		if maxActive > 0 && int(n) >= maxActive {
+			continue
+		}
+		out = append(out, agents[i])
+	}
+	return out, counts, nil
+}
+
+// pickLeastLoadedAgent 在候选中选 active 会话最少者；平局取 id 更小。
+func pickLeastLoadedAgent(candidates []model.User, counts map[uint]int64) *model.User {
+	if len(candidates) == 0 {
+		return nil
+	}
+	best := &candidates[0]
+	bestCount := counts[best.ID]
+	for i := 1; i < len(candidates); i++ {
+		c := counts[candidates[i].ID]
+		if c < bestCount || (c == bestCount && candidates[i].ID < best.ID) {
+			bestCount = c
+			best = &candidates[i]
+		}
+	}
+	return best
+}
+
+// pickRoundRobinAgent 在按 id 排序的候选中，从 lastAgentID 之后轮转下一位。
+func pickRoundRobinAgent(candidates []model.User, lastAgentID *uint) *model.User {
+	if len(candidates) == 0 {
+		return nil
+	}
+	if lastAgentID == nil || *lastAgentID == 0 {
+		return &candidates[0]
+	}
+	// 找到 last 在全序中的位置，取其后第一个仍在候选中的
+	start := 0
+	for i, a := range candidates {
+		if a.ID > *lastAgentID {
+			start = i
+			return &candidates[start]
+		}
+		if a.ID == *lastAgentID {
+			start = (i + 1) % len(candidates)
+			return &candidates[start]
+		}
+	}
+	// last 已不在列表（离线/满载），从头开始
+	return &candidates[0]
+}
+
+// pickAgent 按租户策略选择可分配坐席。
+func pickAgent(tenantID uint, strategy string, maxActive int, rrLast *uint) (*model.User, error) {
+	agents, err := listOnlineAgents(tenantID)
+	if err != nil {
 		return nil, err
 	}
 	if len(agents) == 0 {
 		return nil, nil
 	}
-
-	best := &agents[0]
-	bestCount := int64(-1)
-	for i := range agents {
-		var count int64
-		if err := model.DB.Model(&model.Session{}).
-			Where("tenant_id = ? AND agent_id = ? AND status = ?", tenantID, agents[i].ID, "active").
-			Count(&count).Error; err != nil {
-			return nil, err
-		}
-		if bestCount < 0 || count < bestCount {
-			bestCount = count
-			best = &agents[i]
-		}
+	candidates, counts, err := filterAssignable(tenantID, agents, maxActive)
+	if err != nil {
+		return nil, err
 	}
-	return best, nil
+	if len(candidates) == 0 {
+		return nil, nil
+	}
+	strategy = normalizeAssignStrategy(strategy)
+	if strategy == assignStrategyRoundRobin {
+		return pickRoundRobinAgent(candidates, rrLast), nil
+	}
+	return pickLeastLoadedAgent(candidates, counts), nil
 }
 
 // countOnlineAgents 统计租户当前可接待的在线客服数。
@@ -46,7 +130,7 @@ func countOnlineAgents(tenantID uint) (int64, error) {
 	return count, err
 }
 
-// tryAutoAssign 将会话自动分配给负载最低的在线客服；无可分配客服时返回 nil。
+// tryAutoAssign 按租户分配策略自动分配 waiting 会话；无可分配客服时返回 nil。
 func tryAutoAssign(session *model.Session) (*model.User, error) {
 	if session == nil || session.ID == 0 {
 		return nil, nil
@@ -55,7 +139,18 @@ func tryAutoAssign(session *model.Session) (*model.User, error) {
 		return nil, nil
 	}
 
-	agent, err := pickLeastLoadedAgent(session.TenantID)
+	setting, err := getOrCreateTenantSettings(session.TenantID)
+	if err != nil {
+		// 设置失败时回退默认 least_load、不限制并发
+		setting = &model.TenantSetting{AssignStrategy: assignStrategyLeastLoad}
+	}
+	strategy := normalizeAssignStrategy(setting.AssignStrategy)
+	maxActive := setting.MaxActivePerAgent
+	if maxActive < 0 {
+		maxActive = 0
+	}
+
+	agent, err := pickAgent(session.TenantID, strategy, maxActive, setting.RRLastAgentID)
 	if err != nil || agent == nil {
 		return nil, err
 	}
@@ -80,7 +175,24 @@ func tryAutoAssign(session *model.Session) (*model.User, error) {
 
 	session.AgentID = &agent.ID
 	session.Status = "active"
-	detail := fmt.Sprintf("系统自动分配给 %s", agent.Nickname)
+
+	// 推进轮询游标（仅 round_robin）
+	if strategy == assignStrategyRoundRobin && setting.ID > 0 {
+		aid := agent.ID
+		_ = model.DB.Model(&model.TenantSetting{}).
+			Where("id = ?", setting.ID).
+			Update("rr_last_agent_id", aid).Error
+		setting.RRLastAgentID = &aid
+	}
+
+	strategyLabel := "负载最低"
+	if strategy == assignStrategyRoundRobin {
+		strategyLabel = "轮询"
+	}
+	detail := fmt.Sprintf("系统自动分配给 %s（%s）", agent.Nickname, strategyLabel)
+	if agent.Nickname == "" {
+		detail = fmt.Sprintf("系统自动分配给 %s（%s）", agent.Username, strategyLabel)
+	}
 	model.DB.Create(&model.SessionEvent{
 		SessionID:  session.ID,
 		OperatorID: 0,

server/internal/handler/assignment_test.go

@@ -0,0 +1,49 @@
+package handler
+
+import (
+	"testing"
+
+	"kefu-sys/server/internal/model"
+)
+
+func TestPickLeastLoadedPrefersFewerSessions(t *testing.T) {
+	a := model.User{ID: 1}
+	b := model.User{ID: 2}
+	c := model.User{ID: 3}
+	candidates := []model.User{a, b, c}
+	counts := map[uint]int64{1: 3, 2: 1, 3: 1}
+	got := pickLeastLoadedAgent(candidates, counts)
+	if got == nil || got.ID != 2 {
+		t.Fatalf("期望 id=2（平局取更小 id），got=%v", got)
+	}
+}
+
+func TestPickRoundRobinAdvances(t *testing.T) {
+	candidates := []model.User{{ID: 10}, {ID: 20}, {ID: 30}}
+	last := uint(10)
+	got := pickRoundRobinAgent(candidates, &last)
+	if got == nil || got.ID != 20 {
+		t.Fatalf("期望下一位 20，got=%v", got)
+	}
+	last = 30
+	got = pickRoundRobinAgent(candidates, &last)
+	if got == nil || got.ID != 10 {
+		t.Fatalf("期望绕回 10，got=%v", got)
+	}
+	got = pickRoundRobinAgent(candidates, nil)
+	if got == nil || got.ID != 10 {
+		t.Fatalf("无游标时期望第一位 10，got=%v", got)
+	}
+}
+
+func TestNormalizeAssignStrategy(t *testing.T) {
+	if normalizeAssignStrategy("round_robin") != assignStrategyRoundRobin {
+		t.Fatal("round_robin")
+	}
+	if normalizeAssignStrategy("") != assignStrategyLeastLoad {
+		t.Fatal("default least_load")
+	}
+	if normalizeAssignStrategy("unknown") != assignStrategyLeastLoad {
+		t.Fatal("unknown -> least_load")
+	}
+}

server/internal/handler/settings.go

@@ -60,6 +60,8 @@ func getOrCreateTenantSettings(tenantID uint) (*model.TenantSetting, error) {
 		NotifyNewSession:   true,
 		NotifyOfflineLeave: true,
 		NotifyDailyReport:  false,
+		AssignStrategy:     assignStrategyLeastLoad,
+		MaxActivePerAgent:  0,
 	}
 	if err := model.DB.Create(&setting).Error; err != nil {
 		return nil, err
@@ -135,18 +137,25 @@ func isWithinWorkHours(setting *model.TenantSetting, now time.Time) bool {
 }
 
 func settingsResponse(setting *model.TenantSetting) gin.H {
+	strategy := normalizeAssignStrategy(setting.AssignStrategy)
+	maxActive := setting.MaxActivePerAgent
+	if maxActive < 0 {
+		maxActive = 0
+	}
 	return gin.H{
-		"tenant_id":            setting.TenantID,
-		"display_name":         setting.DisplayName,
-		"agent_nickname":       setting.AgentNickname,
-		"timezone":             setting.Timezone,
-		"welcome_message":      setting.WelcomeMessage,
-		"offline_prompt":       setting.OfflinePrompt,
-		"work_hours":           parseWorkHours(setting.WorkHoursJSON),
-		"worktime_prompt":      setting.WorktimePrompt,
-		"notify_new_session":   setting.NotifyNewSession,
-		"notify_offline_leave": setting.NotifyOfflineLeave,
-		"notify_daily_report":  setting.NotifyDailyReport,
+		"tenant_id":             setting.TenantID,
+		"display_name":          setting.DisplayName,
+		"agent_nickname":        setting.AgentNickname,
+		"timezone":              setting.Timezone,
+		"welcome_message":       setting.WelcomeMessage,
+		"offline_prompt":        setting.OfflinePrompt,
+		"work_hours":            parseWorkHours(setting.WorkHoursJSON),
+		"worktime_prompt":       setting.WorktimePrompt,
+		"notify_new_session":    setting.NotifyNewSession,
+		"notify_offline_leave":  setting.NotifyOfflineLeave,
+		"notify_daily_report":   setting.NotifyDailyReport,
+		"assign_strategy":       strategy,
+		"max_active_per_agent":  maxActive,
 	}
 }
 
@@ -175,6 +184,8 @@ type updateSettingsReq struct {
 	NotifyNewSession   *bool             `json:"notify_new_session"`
 	NotifyOfflineLeave *bool             `json:"notify_offline_leave"`
 	NotifyDailyReport  *bool             `json:"notify_daily_report"`
+	AssignStrategy     *string           `json:"assign_strategy"`
+	MaxActivePerAgent  *int              `json:"max_active_per_agent"`
 }
 
 func (h *SettingsHandler) Update(c *gin.Context) {
@@ -284,6 +295,21 @@ func (h *SettingsHandler) Update(c *gin.Context) {
 	if req.NotifyDailyReport != nil {
 		updates["notify_daily_report"] = *req.NotifyDailyReport
 	}
+	if req.AssignStrategy != nil {
+		raw := strings.TrimSpace(*req.AssignStrategy)
+		if raw != assignStrategyLeastLoad && raw != assignStrategyRoundRobin {
+			c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "分配策略无效，可选 least_load / round_robin"})
+			return
+		}
+		updates["assign_strategy"] = raw
+	}
+	if req.MaxActivePerAgent != nil {
+		if *req.MaxActivePerAgent < 0 || *req.MaxActivePerAgent > 200 {
+			c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "最大并发需为 0–200（0 表示不限制）"})
+			return
+		}
+		updates["max_active_per_agent"] = *req.MaxActivePerAgent
+	}
 	if len(updates) == 0 {
 		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "没有可更新字段"})
 		return