package v1

import (
	"encoding/json"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/gochat/gochat/internal/model"

	"github.com/gochat/gochat/internal/service"
	applogger "github.com/gochat/gochat/pkg/logger"
	"github.com/gochat/gochat/pkg/response"
)

// AgentCapacityHandler handles AgentCapacityPolicy CRUD operations.
// Reference: Chatwoot enterprise/app/controllers/api/v1/agent_capacity_policies_controller.rb
type AgentCapacityHandler struct {
	svc      *service.AgentCapacityPolicyService
	auditSvc *service.AuditService
}

// NewAgentCapacityHandler creates a new AgentCapacityPolicy handler.
func NewAgentCapacityHandler(svc *service.AgentCapacityPolicyService) *AgentCapacityHandler {
	return &AgentCapacityHandler{svc: svc}
}

func (h *AgentCapacityHandler) WithAuditService(auditSvc *service.AuditService) *AgentCapacityHandler {
	h.auditSvc = auditSvc
	return h
}

// List returns all agent capacity policies for an account.
// GET /api/v1/accounts/:account_id/agent_capacity_policies
func (h *AgentCapacityHandler) List(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	policies, _, err := h.svc.List(c.Request.Context(), accountID, 1, 1000)
	if err != nil {
		applogger.L().Errorf("List agent capacity policies for account %d: %v", accountID, err)
		handleServiceError(c, err)
		return
	}

	payload := make([]gin.H, 0, len(policies))
	for i := range policies {
		payload = append(payload, serializeAgentCapacityPolicy(&policies[i]))
	}
	c.JSON(http.StatusOK, payload)
}

// Create creates a new agent capacity policy for an account.
// POST /api/v1/accounts/:account_id/agent_capacity_policies
// Request body uses Chatwoot-style wrapper: { "agent_capacity_policy": { "name": "...", ... } }
func (h *AgentCapacityHandler) Create(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	req, err := bindAgentCapacityPolicyCreate(c)
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}

	policy, err := h.svc.Create(c.Request.Context(), accountID, req)
	if err != nil {
		applogger.L().Errorf("Create agent capacity policy for account %d: %v", accountID, err)
		handleAgentCapacityError(c, err)
		return
	}
	recordAuditMutation(c, h.auditSvc, auditMutation{
		AccountID:      accountID,
		AuditableType:  "AgentCapacityPolicy",
		AuditableID:    policy.ID,
		Action:         "create",
		AuditedChanges: serializeAgentCapacityPolicy(policy),
	})

	c.JSON(http.StatusOK, serializeAgentCapacityPolicy(policy))
}

// Get returns a single agent capacity policy by ID.
// GET /api/v1/accounts/:account_id/agent_capacity_policies/:id
func (h *AgentCapacityHandler) Get(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	id, err := parseUintParam(c, "id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid id")
		return
	}

	policy, svcErr := h.svc.GetByID(c.Request.Context(), id, accountID)
	if svcErr != nil {
		applogger.L().Errorf("Get agent capacity policy %d for account %d: %v", id, accountID, svcErr)
		handleServiceError(c, svcErr)
		return
	}

	c.JSON(http.StatusOK, serializeAgentCapacityPolicy(policy))
}

// Update updates an existing agent capacity policy.
// PUT /api/v1/accounts/:account_id/agent_capacity_policies/:id
func (h *AgentCapacityHandler) Update(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	id, err := parseUintParam(c, "id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid id")
		return
	}

	req, err := bindAgentCapacityPolicyUpdate(c)
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}

	policy, svcErr := h.svc.Update(c.Request.Context(), id, accountID, req)
	if svcErr != nil {
		applogger.L().Errorf("Update agent capacity policy %d for account %d: %v", id, accountID, svcErr)
		handleAgentCapacityError(c, svcErr)
		return
	}
	recordAuditMutation(c, h.auditSvc, auditMutation{
		AccountID:      accountID,
		AuditableType:  "AgentCapacityPolicy",
		AuditableID:    policy.ID,
		Action:         "update",
		AuditedChanges: serializeAgentCapacityPolicy(policy),
	})

	c.JSON(http.StatusOK, serializeAgentCapacityPolicy(policy))
}

// Delete deletes an agent capacity policy.
// DELETE /api/v1/accounts/:account_id/agent_capacity_policies/:id
func (h *AgentCapacityHandler) Delete(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	id, err := parseUintParam(c, "id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid id")
		return
	}

	if svcErr := h.svc.Delete(c.Request.Context(), id, accountID); svcErr != nil {
		applogger.L().Errorf("Delete agent capacity policy %d for account %d: %v", id, accountID, svcErr)
		handleServiceError(c, svcErr)
		return
	}
	recordAuditMutation(c, h.auditSvc, auditMutation{
		AccountID:      accountID,
		AuditableType:  "AgentCapacityPolicy",
		AuditableID:    id,
		Action:         "destroy",
		AuditedChanges: gin.H{"id": id},
	})

	c.Status(http.StatusOK)
}

func (h *AgentCapacityHandler) CreateInboxLimit(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}
	policyID, err := parseUintAnyParam(c, "agent_capacity_policy_id", "id")
	if err != nil || policyID == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid id")
		return
	}
	var req service.CreateInboxCapacityLimitRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}
	limit, svcErr := h.svc.CreateInboxCapacityLimit(c.Request.Context(), policyID, accountID, req)
	if svcErr != nil {
		handleAgentCapacityError(c, svcErr)
		return
	}
	recordAuditMutation(c, h.auditSvc, auditMutation{
		AccountID:      accountID,
		AuditableType:  "InboxCapacityLimit",
		AuditableID:    limit.ID,
		Action:         "create",
		AuditedChanges: serializeInboxCapacityLimit(limit, false),
	})
	c.JSON(http.StatusOK, serializeInboxCapacityLimit(limit, false))
}

func (h *AgentCapacityHandler) UpdateInboxLimit(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}
	policyID, err := parseUintAnyParam(c, "agent_capacity_policy_id", "id")
	if err != nil || policyID == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid id")
		return
	}
	limitID, err := parseUintAnyParam(c, "limit_id", "id")
	if err != nil || limitID == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid limit id")
		return
	}
	var req service.UpdateInboxCapacityLimitRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}
	limit, svcErr := h.svc.UpdateInboxCapacityLimit(c.Request.Context(), policyID, accountID, limitID, req)
	if svcErr != nil {
		handleAgentCapacityError(c, svcErr)
		return
	}
	recordAuditMutation(c, h.auditSvc, auditMutation{
		AccountID:      accountID,
		AuditableType:  "InboxCapacityLimit",
		AuditableID:    limit.ID,
		Action:         "update",
		AuditedChanges: serializeInboxCapacityLimit(limit, true),
	})
	c.JSON(http.StatusOK, serializeInboxCapacityLimit(limit, true))
}

func (h *AgentCapacityHandler) DeleteInboxLimit(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}
	policyID, err := parseUintAnyParam(c, "agent_capacity_policy_id", "id")
	if err != nil || policyID == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid id")
		return
	}
	limitID, err := parseUintAnyParam(c, "limit_id", "id")
	if err != nil || limitID == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid limit id")
		return
	}
	if svcErr := h.svc.DeleteInboxCapacityLimit(c.Request.Context(), policyID, accountID, limitID); svcErr != nil {
		handleAgentCapacityError(c, svcErr)
		return
	}
	recordAuditMutation(c, h.auditSvc, auditMutation{
		AccountID:      accountID,
		AuditableType:  "InboxCapacityLimit",
		AuditableID:    limitID,
		Action:         "destroy",
		AuditedChanges: gin.H{"id": limitID, "agent_capacity_policy_id": policyID},
	})
	c.Status(http.StatusNoContent)
}

func (h *AgentCapacityHandler) ListUsers(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}
	policyID, err := parseUintAnyParam(c, "agent_capacity_policy_id", "id")
	if err != nil || policyID == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid id")
		return
	}
	users, svcErr := h.svc.ListUsers(c.Request.Context(), policyID, accountID)
	if svcErr != nil {
		handleAgentCapacityError(c, svcErr)
		return
	}
	payload := make([]gin.H, 0, len(users))
	for i := range users {
		payload = append(payload, serializeAgentCapacityUser(&users[i], accountID))
	}
	c.JSON(http.StatusOK, payload)
}

func (h *AgentCapacityHandler) CreateUser(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}
	policyID, err := parseUintAnyParam(c, "agent_capacity_policy_id", "id")
	if err != nil || policyID == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid id")
		return
	}
	var req service.AssignCapacityPolicyUserRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}
	user, svcErr := h.svc.AssignUser(c.Request.Context(), policyID, accountID, req)
	if svcErr != nil {
		handleAgentCapacityError(c, svcErr)
		return
	}
	recordAuditMutation(c, h.auditSvc, auditMutation{
		AccountID:     accountID,
		AuditableType: "AgentCapacityPolicyUser",
		AuditableID:   user.ID,
		Action:        "create",
		AuditedChanges: gin.H{
			"agent_capacity_policy_id": policyID,
			"user_id":                  user.ID,
		},
	})
	c.JSON(http.StatusOK, serializeAgentCapacityUser(user, accountID))
}

func (h *AgentCapacityHandler) DeleteUser(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}
	policyID, err := parseUintAnyParam(c, "agent_capacity_policy_id", "id")
	if err != nil || policyID == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid id")
		return
	}
	userID, err := parseUintAnyParam(c, "user_id", "id")
	if err != nil || userID == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid user id")
		return
	}
	if svcErr := h.svc.RemoveUser(c.Request.Context(), policyID, accountID, userID); svcErr != nil {
		handleAgentCapacityError(c, svcErr)
		return
	}
	recordAuditMutation(c, h.auditSvc, auditMutation{
		AccountID:     accountID,
		AuditableType: "AgentCapacityPolicyUser",
		AuditableID:   userID,
		Action:        "destroy",
		AuditedChanges: gin.H{
			"agent_capacity_policy_id": policyID,
			"user_id":                  userID,
		},
	})
	c.Status(http.StatusOK)
}

// RegisterAgentCapacityRoutes registers agent capacity policy routes on a gin.RouterGroup.
func RegisterAgentCapacityRoutes(rg *gin.RouterGroup, h *AgentCapacityHandler) {
	policies := rg.Group("/agent_capacity_policies")
	{
		policies.GET("/", h.List)
		policies.POST("/", h.Create)
		policies.GET("/:id", h.Get)
		policies.PUT("/:id", h.Update)
		policies.PATCH("/:id", h.Update)
		policies.DELETE("/:id", h.Delete)
		policies.GET("/:id/users", h.ListUsers)
		policies.POST("/:id/users", h.CreateUser)
		policies.DELETE("/:id/users/:user_id", h.DeleteUser)
		policies.POST("/:id/inbox_limits", h.CreateInboxLimit)
		policies.PUT("/:id/inbox_limits/:limit_id", h.UpdateInboxLimit)
		policies.PATCH("/:id/inbox_limits/:limit_id", h.UpdateInboxLimit)
		policies.DELETE("/:id/inbox_limits/:limit_id", h.DeleteInboxLimit)
	}
}

func bindAgentCapacityPolicyCreate(c *gin.Context) (service.CreateAgentCapacityPolicyRequest, error) {
	var raw map[string]json.RawMessage
	if err := c.ShouldBindJSON(&raw); err != nil {
		return service.CreateAgentCapacityPolicyRequest{}, err
	}
	var req service.CreateAgentCapacityPolicyRequest
	if wrapped, ok := raw["agent_capacity_policy"]; ok {
		return req, json.Unmarshal(wrapped, &req)
	}
	buf, err := json.Marshal(raw)
	if err != nil {
		return req, err
	}
	return req, json.Unmarshal(buf, &req)
}

func bindAgentCapacityPolicyUpdate(c *gin.Context) (service.UpdateAgentCapacityPolicyRequest, error) {
	var raw map[string]json.RawMessage
	if err := c.ShouldBindJSON(&raw); err != nil {
		return service.UpdateAgentCapacityPolicyRequest{}, err
	}
	var req service.UpdateAgentCapacityPolicyRequest
	if wrapped, ok := raw["agent_capacity_policy"]; ok {
		return req, json.Unmarshal(wrapped, &req)
	}
	buf, err := json.Marshal(raw)
	if err != nil {
		return req, err
	}
	return req, json.Unmarshal(buf, &req)
}

func serializeAgentCapacityPolicy(policy *model.AgentCapacityPolicy) gin.H {
	limits := make([]gin.H, 0, len(policy.InboxCapacityLimits))
	for i := range policy.InboxCapacityLimits {
		limit := policy.InboxCapacityLimits[i]
		limits = append(limits, gin.H{
			"id":                 limit.ID,
			"inbox_id":           limit.InboxID,
			"conversation_limit": limit.ConversationLimit,
		})
	}
	return gin.H{
		"id":                    policy.ID,
		"name":                  policy.Name,
		"description":           policy.Description,
		"exclusion_rules":       policy.ExclusionRules,
		"created_at":            policy.CreatedAt.Unix(),
		"updated_at":            policy.UpdatedAt.Unix(),
		"account_id":            policy.AccountID,
		"assigned_agent_count":  len(policy.AccountUsers),
		"inbox_capacity_limits": limits,
	}
}

func serializeInboxCapacityLimit(limit *model.InboxCapacityLimit, includeInboxName bool) gin.H {
	payload := gin.H{
		"id":                       limit.ID,
		"inbox_id":                 limit.InboxID,
		"agent_capacity_policy_id": limit.AgentCapacityPolicyID,
		"conversation_limit":       limit.ConversationLimit,
		"created_at":               limit.CreatedAt.Unix(),
		"updated_at":               limit.UpdatedAt.Unix(),
	}
	if includeInboxName {
		payload["inbox_name"] = limit.Inbox.Name
	}
	return payload
}

func serializeAgentCapacityUser(user *model.User, accountID uint) gin.H {
	availableName := user.DisplayName
	if availableName == "" {
		availableName = user.Name
	}
	if availableName == "" {
		availableName = user.Email
	}
	return gin.H{
		"access_token":      nil,
		"account_id":        accountID,
		"available_name":    availableName,
		"avatar_url":        user.AvatarURL,
		"confirmed":         user.ConfirmedAt != nil,
		"display_name":      user.DisplayName,
		"message_signature": user.MessageSignature,
		"email":             user.Email,
		"id":                user.ID,
		"inviter_id":        nil,
		"name":              user.Name,
		"provider":          user.Provider,
		"pubsub_token":      user.PubsubToken,
		"role":              user.Role,
		"ui_settings":       user.UISettings,
		"uid":               user.UID,
		"type":              user.Type,
	}
}

func handleAgentCapacityError(c *gin.Context, err error) {
	if err == nil {
		return
	}
	lower := strings.ToLower(err.Error())
	if strings.Contains(lower, "already been assigned") || strings.Contains(lower, "greater than or equal") {
		response.AbortWithStatusError(c, http.StatusUnprocessableEntity, response.ErrValidation, err.Error())
		return
	}
	handleServiceError(c, err)
}