package v1

import (
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/service"
	"github.com/gochat/gochat/pkg/response"
)

// ConversationParticipantHandler handles conversation participant API endpoints.
// Reference: Chatwoot app/controllers/api/v1/conversations/participants_controller.rb
type ConversationParticipantHandler struct {
	participantSvc *service.ConversationParticipantService
}

// NewConversationParticipantHandler creates a new ConversationParticipantHandler.
func NewConversationParticipantHandler(participantSvc *service.ConversationParticipantService) *ConversationParticipantHandler {
	return &ConversationParticipantHandler{participantSvc: participantSvc}
}

// List retrieves all participants for a conversation.
// GET /api/v1/accounts/:account_id/conversations/:conversation_id/participants
func (h *ConversationParticipantHandler) List(c *gin.Context) {
	accountID, err := parseUintParam(c, "account_id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid account_id")
		return
	}

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

	participants, svcErr := h.participantSvc.List(c.Request.Context(), accountID, conversationID)
	if svcErr != nil {
		handleServiceError(c, svcErr)
		return
	}

	c.JSON(http.StatusOK, serializeConversationParticipantAgents(accountID, participants))
}

// Add adds a participant to a conversation.
// POST /api/v1/accounts/:account_id/conversations/:conversation_id/participants
func (h *ConversationParticipantHandler) Add(c *gin.Context) {
	accountID, err := parseUintParam(c, "account_id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid account_id")
		return
	}

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

	var req struct {
		UserID  uint   `json:"user_id"`
		UserIDs []uint `json:"user_ids"`
		Role    string `json:"role"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}
	userIDs := participantRequestUserIDs(req.UserID, req.UserIDs)
	if len(userIDs) == 0 {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, "user_ids is required")
		return
	}

	participants, svcErr := h.participantSvc.AddMany(c.Request.Context(), accountID, conversationID, userIDs, req.Role)
	if svcErr != nil {
		handleServiceError(c, svcErr)
		return
	}

	c.JSON(http.StatusOK, serializeConversationParticipantAgents(accountID, participants))
}

// Update updates a participant's role in a conversation.
// PATCH /api/v1/accounts/:account_id/conversations/:conversation_id/participants/:user_id
func (h *ConversationParticipantHandler) Update(c *gin.Context) {
	accountID, err := parseUintParam(c, "account_id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid account_id")
		return
	}

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

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

	var req struct {
		Role string `json:"role" binding:"required"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}

	participant, svcErr := h.participantSvc.Update(c.Request.Context(), accountID, conversationID, userID, req.Role)
	if svcErr != nil {
		handleServiceError(c, svcErr)
		return
	}

	c.JSON(http.StatusOK, serializeConversationParticipantAgents(accountID, []model.ConversationParticipant{*participant}))
}

// Remove removes a participant from a conversation.
// DELETE /api/v1/accounts/:account_id/conversations/:conversation_id/participants/:user_id
func (h *ConversationParticipantHandler) Remove(c *gin.Context) {
	accountID, err := parseUintParam(c, "account_id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid account_id")
		return
	}

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

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

	if svcErr := h.participantSvc.Remove(c.Request.Context(), accountID, conversationID, userID); svcErr != nil {
		handleServiceError(c, svcErr)
		return
	}

	c.Status(http.StatusOK)
}

// Destroy removes multiple participants from a conversation.
// DELETE /api/v1/accounts/:account_id/conversations/:conversation_id/participants
func (h *ConversationParticipantHandler) Destroy(c *gin.Context) {
	accountID, err := parseUintParam(c, "account_id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid account_id")
		return
	}

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

	var req struct {
		UserIDs []uint `json:"user_ids"`
	}
	if c.Request.ContentLength != 0 {
		if err := c.ShouldBindJSON(&req); err != nil {
			response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
			return
		}
	}

	if svcErr := h.participantSvc.RemoveMany(c.Request.Context(), accountID, conversationID, req.UserIDs); svcErr != nil {
		handleServiceError(c, svcErr)
		return
	}

	c.Status(http.StatusOK)
}

// BatchUpdate adds and/or removes multiple participants in a single call.
// PATCH /api/v1/accounts/:account_id/conversations/:conversation_id/participants
// Accepts: { "user_ids": [1,2,3] } as the final participant set.
// Reference: Chatwoot app/controllers/api/v1/conversations/participants_controller.rb#update
func (h *ConversationParticipantHandler) BatchUpdate(c *gin.Context) {
	accountID, err := parseUintParam(c, "account_id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid account_id")
		return
	}

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

	var req struct {
		UserIDs []uint `json:"user_ids"`
		Role    string `json:"role"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
		return
	}

	participants, svcErr := h.participantSvc.Replace(c.Request.Context(), accountID, conversationID, req.UserIDs, req.Role)
	if svcErr != nil {
		handleServiceError(c, svcErr)
		return
	}

	c.JSON(http.StatusOK, serializeConversationParticipantAgents(accountID, participants))
}

func participantRequestUserIDs(userID uint, userIDs []uint) []uint {
	if len(userIDs) > 0 {
		return userIDs
	}
	if userID != 0 {
		return []uint{userID}
	}
	return nil
}

func serializeConversationParticipantAgents(accountID uint, participants []model.ConversationParticipant) []map[string]any {
	payload := make([]map[string]any, 0, len(participants))
	for i := range participants {
		payload = append(payload, serializeAgentUser(participants[i].User, accountID, "", "", false, 0))
	}
	return payload
}