package widget

import (
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/service"
)

// WidgetHandler handles the public-facing widget API endpoints.
// These endpoints are accessed by the embedded JS widget on customer websites
// and do not require agent JWT authentication — they use a widget_token instead.
// Reference: Chatwoot app/controllers/api/v1/widget_messages_controller.rb
type WidgetHandler struct {
	widgetService *service.WidgetService
}

// NewHandler creates a new WidgetHandler with the WidgetService dependency.
func NewHandler(widgetService *service.WidgetService) *WidgetHandler {
	return &WidgetHandler{
		widgetService: widgetService,
	}
}

// Init handles widget initialization — authenticates/creates a contact
// and returns a widget_token (pubsub_token) for subsequent requests.
// POST /widget/init
// Reference: Chatwoot widget SDK init — website_token identifies the inbox,
// contact attributes are optional (anonymous visitor if not provided).
func (h *WidgetHandler) Init(c *gin.Context) {
	var req service.WidgetInitRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid request body", "details": err.Error()})
		return
	}

	// HMAC verification: if the client provides an identifier + identifier_hash,
	// verify the hash against the inbox's hmac_token. This mirrors Chatwoot's
	// WebWidget HMAC verification (identifier_hash is SHA-256 HMAC of the identifier
	// using the hmac_token from channel_config).
	// When HMAC is verified, the contact is treated as authenticated (not anonymous).
	identifierHash := c.GetHeader("X-Identifier-Hash")
	if identifierHash == "" {
		identifierHash = c.Query("identifier_hash")
	}
	if req.Identifier != "" && identifierHash != "" {
		// Resolve the inbox to get its hmac_token for verification
		inbox, err := h.widgetService.GetInboxByWebsiteToken(c.Request.Context(), req.WebsiteToken)
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": "invalid website_token for HMAC verification"})
			return
		}
		widgetConfig, err := service.ParseWebWidgetConfig(inbox.ChannelConfig)
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": "invalid widget config"})
			return
		}
		if service.VerifyHMAC(widgetConfig.HMACToken, req.Identifier, identifierHash) {
			req.HMACVerified = true
		}
	}

	resp, err := h.widgetService.Init(c.Request.Context(), req)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, resp)
}

// SendMessage sends a message from the widget contact to the conversation.
// POST /widget/messages
// Reference: Chatwoot widget SDK — send message endpoint
func (h *WidgetHandler) SendMessage(c *gin.Context) {
	widgetToken := c.GetHeader("X-Widget-Token")
	if widgetToken == "" {
		widgetToken = c.Query("widget_token")
	}
	if widgetToken == "" {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "widget_token required"})
		return
	}

	var req service.WidgetSendMessageRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid request body", "details": err.Error()})
		return
	}

	req.WidgetToken = widgetToken
	resp, err := h.widgetService.SendMessage(c.Request.Context(), req)
	if err != nil {
		status := http.StatusBadRequest
		if err.Error() == "invalid widget_token" || err.Error() == "widget_token required" {
			status = http.StatusUnauthorized
		}
		c.JSON(status, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, resp)
}

// GetConversations returns the conversation list for a widget contact.
// GET /widget/conversations
// Reference: Chatwoot widget SDK — fetch conversation list
func (h *WidgetHandler) GetConversations(c *gin.Context) {
	widgetToken := c.GetHeader("X-Widget-Token")
	if widgetToken == "" {
		widgetToken = c.Query("widget_token")
	}
	if widgetToken == "" {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "widget_token required"})
		return
	}

	conversations, err := h.widgetService.GetConversations(c.Request.Context(), widgetToken)
	if err != nil {
		status := http.StatusBadRequest
		if err.Error() == "invalid widget_token" {
			status = http.StatusUnauthorized
		}
		c.JSON(status, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{"conversations": conversations})
}

// GetMessages retrieves messages for a specific conversation.
// GET /widget/conversations/:id/messages
// Reference: Chatwoot widget SDK — fetch messages for a conversation
func (h *WidgetHandler) GetMessages(c *gin.Context) {
	widgetToken := c.GetHeader("X-Widget-Token")
	if widgetToken == "" {
		widgetToken = c.Query("widget_token")
	}
	if widgetToken == "" {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "widget_token required"})
		return
	}

	conversationIDStr := c.Param("id")
	conversationID, err := strconv.ParseUint(conversationIDStr, 10, 32)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid conversation id"})
		return
	}

	offset, _ := strconv.Atoi(c.DefaultQuery("offset", "0"))
	limit, _ := strconv.Atoi(c.DefaultQuery("limit", "25"))
	if limit <= 0 || limit > 100 {
		limit = 25
	}

	messages, total, err := h.widgetService.GetMessages(
		c.Request.Context(), widgetToken, uint(conversationID), offset, limit)
	if err != nil {
		status := http.StatusBadRequest
		if err.Error() == "invalid widget_token" {
			status = http.StatusUnauthorized
		}
		c.JSON(status, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"messages": messages,
		"meta": gin.H{
			"total":  total,
			"offset": offset,
			"limit":  limit,
		},
	})
}

// GetCableToken returns the pubsub_token for WebSocket/ActionCable connection.
// GET /widget/cable_token
// Reference: Chatwoot widget SDK — fetch token for ActionCable subscription
func (h *WidgetHandler) GetCableToken(c *gin.Context) {
	widgetToken := c.GetHeader("X-Widget-Token")
	if widgetToken == "" {
		widgetToken = c.Query("widget_token")
	}
	if widgetToken == "" {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "widget_token required"})
		return
	}

	resp, err := h.widgetService.GetCableToken(c.Request.Context(), widgetToken)
	if err != nil {
		status := http.StatusBadRequest
		if err.Error() == "invalid widget_token" {
			status = http.StatusUnauthorized
		}
		c.JSON(status, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, resp)
}

// UpdateContact updates the contact's profile from the widget.
// PATCH /widget/contact
// Reference: Chatwoot widget SDK — update contact name/email
func (h *WidgetHandler) UpdateContact(c *gin.Context) {
	widgetToken := c.GetHeader("X-Widget-Token")
	if widgetToken == "" {
		widgetToken = c.Query("widget_token")
	}
	if widgetToken == "" {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "widget_token required"})
		return
	}

	var req struct {
		Name  string `json:"name,omitempty"`
		Email string `json:"email,omitempty"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid request body", "details": err.Error()})
		return
	}

	contact, err := h.widgetService.UpdateContact(c.Request.Context(), widgetToken, req.Name, req.Email)
	if err != nil {
		status := http.StatusBadRequest
		if err.Error() == "invalid widget_token" {
			status = http.StatusUnauthorized
		}
		c.JSON(status, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, contact)
}

// ToggleTyping signals that the contact is typing or stopped typing.
// POST /widget/conversations/:id/toggle_typing
// Reference: Chatwoot widget SDK — typing indicator
func (h *WidgetHandler) ToggleTyping(c *gin.Context) {
	widgetToken := c.GetHeader("X-Widget-Token")
	if widgetToken == "" {
		widgetToken = c.Query("widget_token")
	}
	if widgetToken == "" {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "widget_token required"})
		return
	}

	conversationIDStr := c.Param("id")
	conversationID, err := strconv.ParseUint(conversationIDStr, 10, 32)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid conversation id"})
		return
	}

	var req struct {
		Typing bool `json:"typing"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		// Default to typing=true if no body provided
		req.Typing = true
	}

	err = h.widgetService.ToggleTyping(c.Request.Context(), widgetToken, uint(conversationID), req.Typing)
	if err != nil {
		status := http.StatusBadRequest
		if err.Error() == "invalid widget_token" {
			status = http.StatusUnauthorized
		}
		c.JSON(status, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{"status": "ok"})
}

// SubmitOfflineMessage handles a visitor submitting a message when agents are offline.
// POST /widget/offline_message
// Reference: Chatwoot widget SDK — when business_hours are disabled and no agents online,
// visitors can still leave their info + message which creates a pending conversation.
func (h *WidgetHandler) SubmitOfflineMessage(c *gin.Context) {
	websiteToken := c.Query("website_token")
	if websiteToken == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "website_token is required"})
		return
	}

	// Resolve inbox from website_token
	inbox, err := h.widgetService.GetInboxByWebsiteToken(c.Request.Context(), websiteToken)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "invalid website_token"})
		return
	}

	var submission model.WidgetOfflineMessageSubmission
	if err := c.ShouldBindJSON(&submission); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid request body", "details": err.Error()})
		return
	}

	referer := c.Request.Referer()
	browserInfo := c.GetHeader("User-Agent")

	msg, err := h.widgetService.SubmitOfflineMessage(
		c.Request.Context(),
		inbox.ID,
		inbox.AccountID,
		&submission,
		referer,
		browserInfo,
	)
	if err != nil {
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"offline_message": msg,
		"message":         "Your message has been recorded. An agent will respond when available.",
	})
}