package v1

import (
	"errors"
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"

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

// AgentHandler handles agent CRUD + bulk_create endpoints.
// Reference: Chatwoot app/controllers/api/v1/accounts/agents_controller.rb
// An "agent" in Chatwoot is a User with an AccountUser membership in a specific account.
type AgentHandler struct {
	svc *service.AgentService
}

// NewAgentHandler creates a new AgentHandler.
func NewAgentHandler(svc *service.AgentService) *AgentHandler {
	return &AgentHandler{svc: svc}
}

// List returns all agents in the account.
// GET /api/v1/accounts/:account_id/agents
// Reference: Chatwoot agents_controller.rb#index
func (h *AgentHandler) List(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	agents, total, err := h.svc.List(c.Request.Context(), accountID, 0, 0)
	if err != nil {
		applogger.L().Errorf("List agents for account %d: %v", accountID, err)
		handleServiceError(c, err)
		return
	}

	_ = total
	c.JSON(http.StatusOK, serializeAgentDetails(agents, accountID))
}

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

	id, err := strconv.ParseUint(c.Param("agent_id"), 10, 32)
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid agent id")
		return
	}

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

	c.JSON(http.StatusOK, serializeAgentDetail(agent, accountID))
}

// Create adds an agent to the account.
// POST /api/v1/accounts/:account_id/agents
// Reference: Chatwoot agents_controller.rb#create → AgentBuilder.new.perform
func (h *AgentHandler) Create(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	userID := getUserID(c)
	if userID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "user not authenticated")
		return
	}

	var req service.CreateAgentRequest
	if err := bindJSONWrappedOrRaw(c, "agent", &req); err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}

	// Chatwoot: validate_limit → can_add_agent? — returns 402 if limit exceeded
	canAdd, err := h.svc.CanAddAgent(c.Request.Context(), accountID)
	if err != nil {
		applogger.L().Errorf("Check agent limit for account %d: %v", accountID, err)
		response.AbortWithStatusError(c, http.StatusInternalServerError, response.ErrInternal, err.Error())
		return
	}
	if !canAdd {
		response.AbortWithStatusError(c, http.StatusPaymentRequired, response.ErrPaymentRequired, "Account limit exceeded. Please purchase more licenses")
		return
	}

	agent, svcErr := h.svc.Create(c.Request.Context(), accountID, userID, req)
	if svcErr != nil {
		if errors.Is(svcErr, repository.ErrAlreadyMember) {
			c.JSON(http.StatusUnprocessableEntity, gin.H{
				"message":    "User has already been taken",
				"attributes": []string{"user_id"},
			})
			return
		}
		applogger.L().Errorf("Create agent for account %d: %v", accountID, svcErr)
		handleServiceError(c, svcErr)
		return
	}

	c.JSON(http.StatusOK, serializeAgentDetail(agent, accountID))
}

// Update modifies agent details (name on User, role/availability on AccountUser).
// PUT /api/v1/accounts/:account_id/agents/:id
// Reference: Chatwoot agents_controller.rb#update
func (h *AgentHandler) Update(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	id, err := strconv.ParseUint(c.Param("agent_id"), 10, 32)
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid agent id")
		return
	}

	var req service.UpdateAgentRequest
	if err := bindJSONWrappedOrRaw(c, "agent", &req); err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}

	agent, svcErr := h.svc.Update(c.Request.Context(), uint(id), accountID, req)
	if svcErr != nil {
		if errors.Is(svcErr, service.ErrAgentNameBlank) {
			c.JSON(http.StatusUnprocessableEntity, gin.H{
				"message":    "Name can't be blank",
				"attributes": []string{"name"},
			})
			return
		}
		applogger.L().Errorf("Update agent %d for account %d: %v", id, accountID, svcErr)
		handleServiceError(c, svcErr)
		return
	}

	c.JSON(http.StatusOK, serializeAgentDetail(agent, accountID))
}

// Delete removes an agent from the account.
// DELETE /api/v1/accounts/:account_id/agents/:id
// Reference: Chatwoot agents_controller.rb#destroy → current_account_user.destroy!
func (h *AgentHandler) Delete(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	id, err := strconv.ParseUint(c.Param("agent_id"), 10, 32)
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid agent id")
		return
	}

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

	c.Status(http.StatusOK)
}

// BulkCreate adds multiple agents to the account by email.
// POST /api/v1/accounts/:account_id/agents/bulk_create
// Reference: Chatwoot agents_controller.rb#bulk_create
func (h *AgentHandler) BulkCreate(c *gin.Context) {
	accountID := getAccountID(c)
	if accountID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "account not identified")
		return
	}

	userID := getUserID(c)
	if userID == 0 {
		response.AbortWithStatusError(c, http.StatusUnauthorized, response.ErrUnauthorized, "user not authenticated")
		return
	}

	var req service.BulkCreateAgentRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}

	// Chatwoot: validate_limit_for_bulk_create — emails.count <= available_agent_count
	canAdd, err := h.svc.CanAddAgents(c.Request.Context(), accountID, len(req.Emails))
	if err != nil {
		applogger.L().Errorf("Check agent limit for account %d: %v", accountID, err)
		response.AbortWithStatusError(c, http.StatusInternalServerError, response.ErrInternal, err.Error())
		return
	}
	if !canAdd {
		response.AbortWithStatusError(c, http.StatusPaymentRequired, response.ErrPaymentRequired, "Account limit exceeded. Please purchase more licenses")
		return
	}

	_, svcErr := h.svc.BulkCreate(c.Request.Context(), accountID, userID, req)
	if svcErr != nil {
		applogger.L().Errorf("BulkCreate agents for account %d: %v", accountID, svcErr)
		handleServiceError(c, svcErr)
		return
	}

	c.Status(http.StatusOK)
}

func serializeAgentDetails(agents []repository.AgentDetail, accountID uint) []map[string]any {
	payload := make([]map[string]any, 0, len(agents))
	for i := range agents {
		payload = append(payload, serializeAgentDetail(&agents[i], accountID))
	}
	return payload
}

func serializeAgentDetail(agent *repository.AgentDetail, accountID uint) map[string]any {
	if agent == nil {
		return map[string]any{}
	}
	payload := serializeAgentUser(&agent.User, accountID, agent.Role, agent.Availability, agent.AutoOffline, agent.CustomRoleID)
	if agent.InvitedBy != 0 {
		payload["invited_by"] = agent.InvitedBy
	}
	if agent.AccountUserID != 0 {
		payload["account_user_id"] = agent.AccountUserID
	}
	return payload
}

func serializeAgentUser(user *model.User, accountID uint, role string, availability string, autoOffline bool, customRoleID uint) map[string]any {
	if user == nil {
		return map[string]any{}
	}
	availabilityStatus := nonEmpty(availability, availabilityStatus(user.Available))
	payload := map[string]any{
		"id":                  user.ID,
		"account_id":          accountID,
		"availability_status": availabilityStatus,
		"auto_offline":        autoOffline,
		"confirmed":           user.ConfirmedAt != nil,
		"email":               user.Email,
		"provider":            nonEmpty(user.Provider, "email"),
		"available_name":      nonEmpty(user.DisplayName, user.Name),
		"name":                user.Name,
		"role":                nonEmpty(role, user.Role),
		"thumbnail":           user.AvatarURL,
	}
	if attrs := jsonObject(user.CustomAttributes); len(attrs) > 0 {
		payload["custom_attributes"] = attrs
	}
	if customRoleID != 0 {
		payload["custom_role_id"] = customRoleID
	} else if user.CustomRoleID != nil && *user.CustomRoleID != 0 {
		payload["custom_role_id"] = *user.CustomRoleID
	}
	return payload
}