package v1

// FacebookChannelHandler handles Facebook channel-specific configuration CRUD and OAuth flow.
// Reference: Chatwoot app/controllers/api/v1/accounts/channels/facebook_pages_controller.rb
//
// Chatwoot's FacebookPagesController provides:
//   - create: authorize FB page → create inbox (via OmniAuth callback or direct page_access_token)
//   - destroy: remove FB page channel + unsubscribe webhook
//   - reauthorize: refresh expired page access tokens
//
// gochat maps these to:
//   - POST   /api/v1/accounts/:id/channels/facebook_channel           → create FB inbox
//   - DELETE /api/v1/accounts/:id/channels/facebook_channel/:fb_id   → destroy FB inbox
//   - POST   /api/v1/accounts/:id/channels/facebook_channel/reauthorize → refresh token
//   - GET    /api/v1/accounts/:id/channels/facebook_channel/authorization → OAuth authorize URL

import (
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"

	facebookchannel "github.com/gochat/gochat/internal/channel/facebook"
	"github.com/gochat/gochat/internal/repository"
	"github.com/gochat/gochat/internal/service"
	applogger "github.com/gochat/gochat/pkg/logger"
)

// FacebookChannelHandler handles Facebook Messenger channel management.
// Follows InstagramChannelHandler pattern: uses top-level ChannelFacebookService for CRUD,
// internal FacebookProvider for OAuth/authorization.
type FacebookChannelHandler struct {
	fbChannelSvc *service.ChannelFacebookService
	fbProvider   *facebookchannel.FacebookProvider
	inboxSvc     *service.InboxService
	fbRepo       *repository.ChannelFacebookRepo
}

// NewFacebookChannelHandler creates a new Facebook channel handler.
func NewFacebookChannelHandler(
	fbChannelSvc *service.ChannelFacebookService,
	fbProvider *facebookchannel.FacebookProvider,
	inboxSvc *service.InboxService,
	fbRepo *repository.ChannelFacebookRepo,
) *FacebookChannelHandler {
	return &FacebookChannelHandler{
		fbChannelSvc: fbChannelSvc,
		fbProvider:   fbProvider,
		inboxSvc:     inboxSvc,
		fbRepo:       fbRepo,
	}
}

// === OAuth Authorization ===

// FacebookAuthorizationRequest is the DTO for initiating FB OAuth flow.
type FacebookAuthorizationRequest struct {
	RedirectURL string `json:"redirect_url" validate:"required,url"`
}

// Authorization generates a Facebook OAuth authorize URL.
// GET /api/v1/accounts/:id/channels/facebook_channel/authorization
func (h *FacebookChannelHandler) Authorization(c *gin.Context) {
	accountIDStr := c.Param("id")
	accountID, err := strconv.ParseUint(accountIDStr, 10, 64)
	if err != nil {
		applogger.L().Errorf("Invalid account_id: %v", err)
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid account_id"})
		return
	}

	var req FacebookAuthorizationRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		redirectURL := c.Query("redirect_url")
		if redirectURL == "" {
			applogger.L().Errorf("Failed to bind authorization request: %v", err)
			c.JSON(http.StatusBadRequest, gin.H{"error": "redirect_url is required"})
			return
		}
		req.RedirectURL = redirectURL
	}

	authURL, err := h.fbProvider.BuildAuthURL(c.Request.Context(), uint(accountID), req.RedirectURL)
	if err != nil {
		applogger.L().Errorf("Failed to build Facebook auth URL: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to generate authorization URL"})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"authorization_url": authURL,
		"account_id":        accountID,
	})
}

// FacebookOAuthCallbackRequest is the DTO for the OAuth callback after FB redirects back.
type FacebookOAuthCallbackRequest struct {
	Code        string `json:"code" validate:"required"`
	RedirectURL string `json:"redirect_url" validate:"required,url"`
}

// OAuthCallback exchanges the Facebook OAuth code for a long-lived access token.
// POST /api/v1/accounts/:id/channels/facebook_channel/oauth_callback
func (h *FacebookChannelHandler) OAuthCallback(c *gin.Context) {
	accountIDStr := c.Param("id")
	accountID, err := strconv.ParseUint(accountIDStr, 10, 64)
	if err != nil {
		applogger.L().Errorf("Invalid account_id: %v", err)
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid account_id"})
		return
	}

	var req FacebookOAuthCallbackRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		applogger.L().Errorf("Failed to bind OAuth callback request: %v", err)
		c.JSON(http.StatusBadRequest, gin.H{"error": "code and redirect_url are required"})
		return
	}

	tokenResult, err := h.fbProvider.ExchangeToken(c.Request.Context(), req.Code, req.RedirectURL)
	if err != nil {
		applogger.L().Errorf("Facebook token exchange failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to exchange token"})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"access_token": tokenResult.AccessToken,
		"expires_at":   tokenResult.ExpiresAt,
		"account_id":   accountID,
		"message":      "token obtained; use CreateFacebookPage endpoint to create inbox with page_access_token",
	})
}

// === Facebook Channel CRUD ===

// CreateFacebookPageRequest is the DTO for creating a Facebook Messenger inbox.
type CreateFacebookPageRequest struct {
	Name                 string `json:"name" validate:"required,min=2"`
	PageID               string `json:"page_id" validate:"required"`
	PageAccessToken      string `json:"page_access_token" validate:"required"`
	WebhookVerifyToken   string `json:"webhook_verify_token,omitempty"` // auto-generated if empty
	EnableAutoAssignment bool   `json:"enable_auto_assignment,omitempty"`
}

// CreateFacebookPage creates a new Facebook Messenger inbox for a Facebook Page.
// POST /api/v1/accounts/:id/channels/facebook_channel
func (h *FacebookChannelHandler) CreateFacebookPage(c *gin.Context) {
	accountIDStr := c.Param("id")
	accountID, err := strconv.ParseUint(accountIDStr, 10, 64)
	if err != nil {
		applogger.L().Errorf("Invalid account_id: %v", err)
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid account_id"})
		return
	}

	var req CreateFacebookPageRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		applogger.L().Errorf("Failed to bind create facebook page request: %v", err)
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	ctx := c.Request.Context()

	// Delegate to InboxService.CreateFacebookInbox (matches Instagram pattern)
	inboxReq := service.CreateFacebookInboxRequest{
		Name:                 req.Name,
		PageID:               req.PageID,
		PageAccessToken:      req.PageAccessToken,
		PageName:             "", // populated after Graph API call or update
		WebhookVerifyToken:   req.WebhookVerifyToken,
		EnableAutoAssignment: req.EnableAutoAssignment,
	}

	inbox, err := h.inboxSvc.CreateFacebookInbox(ctx, uint(accountID), inboxReq, h.fbRepo)
	if err != nil {
		applogger.L().Errorf("Failed to create Facebook inbox: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to create Facebook inbox", "details": err.Error()})
		return
	}

	c.JSON(http.StatusCreated, gin.H{
		"inbox": gin.H{
			"id":                  inbox.ID,
			"name":                inbox.Name,
			"channel_type":        inbox.ChannelType,
			"channel_id":          inbox.ChannelID,
			"enabled":             inbox.Enabled,
			"enable_auto_assignment": inbox.EnableAutoAssignment,
		},
	})
}

// GetFacebookChannel retrieves a Facebook channel by ID.
// GET /api/v1/accounts/:id/channels/facebook_channel/:fb_id
func (h *FacebookChannelHandler) GetFacebookChannel(c *gin.Context) {
	accountIDStr := c.Param("id")
	accountID, err := strconv.ParseUint(accountIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid account_id"})
		return
	}

	fbIDStr := c.Param("fb_id")
	fbID, err := strconv.ParseUint(fbIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid fb_id"})
		return
	}

	ctx := c.Request.Context()

	ch, err := h.fbChannelSvc.GetByID(ctx, uint(fbID))
	if err != nil {
		applogger.L().Errorf("Failed to get Facebook channel: %v", err)
		c.JSON(http.StatusNotFound, gin.H{"error": "Facebook channel not found"})
		return
	}

	// Verify account ownership
	if ch.AccountID != uint(accountID) {
		c.JSON(http.StatusForbidden, gin.H{"error": "Facebook channel does not belong to this account"})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"id":                   ch.ID,
		"account_id":           ch.AccountID,
		"inbox_id":             ch.InboxID,
		"page_id":              ch.PageID,
		"page_name":            ch.PageName,
		"app_id":               ch.AppID,
		"reauthorization_required": ch.ReauthorizationRequired,
	})
}

// ListFacebookChannels retrieves all Facebook channels for an account.
// GET /api/v1/accounts/:id/channels/facebook_channel
func (h *FacebookChannelHandler) ListFacebookChannels(c *gin.Context) {
	accountIDStr := c.Param("id")
	accountID, err := strconv.ParseUint(accountIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid account_id"})
		return
	}

	ctx := c.Request.Context()

	channels, err := h.fbChannelSvc.ListByAccount(ctx, uint(accountID))
	if err != nil {
		applogger.L().Errorf("Failed to list Facebook channels: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to list Facebook channels"})
		return
	}

	result := make([]gin.H, 0, len(channels))
	for _, ch := range channels {
		result = append(result, gin.H{
			"id":                   ch.ID,
			"account_id":           ch.AccountID,
			"inbox_id":             ch.InboxID,
			"page_id":              ch.PageID,
			"page_name":            ch.PageName,
			"app_id":               ch.AppID,
			"reauthorization_required": ch.ReauthorizationRequired,
		})
	}

	c.JSON(http.StatusOK, gin.H{
		"channels": result,
		"count":    len(result),
	})
}

// DeleteFacebookPage removes a Facebook Page channel and its inbox.
// DELETE /api/v1/accounts/:id/channels/facebook_channel/:fb_id
func (h *FacebookChannelHandler) DeleteFacebookPage(c *gin.Context) {
	accountIDStr := c.Param("id")
	accountID, err := strconv.ParseUint(accountIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid account_id"})
		return
	}

	fbIDStr := c.Param("fb_id")
	fbID, err := strconv.ParseUint(fbIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid fb_id"})
		return
	}

	ctx := c.Request.Context()

	ch, err := h.fbChannelSvc.GetByID(ctx, uint(fbID))
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "Facebook channel not found"})
		return
	}

	// Verify account ownership
	if ch.AccountID != uint(accountID) {
		c.JSON(http.StatusForbidden, gin.H{"error": "Facebook channel does not belong to this account"})
		return
	}

	// Delete the channel record
	if err := h.fbChannelSvc.Delete(ctx, uint(fbID)); err != nil {
		applogger.L().Errorf("Failed to delete Facebook channel: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to delete Facebook channel"})
		return
	}

	// Delete the associated inbox (if exists)
	if ch.InboxID > 0 {
		if delErr := h.inboxSvc.DeleteByAccount(ctx, uint(accountID), ch.InboxID); delErr != nil {
			applogger.L().Warnf("Failed to delete inbox for Facebook channel: %v", delErr)
		}
	}

	c.JSON(http.StatusOK, gin.H{"message": "Facebook page channel deleted successfully"})
}

// === Reauthorization ===

// ReauthorizeFacebookPageRequest is the DTO for refreshing a FB page access token.
type ReauthorizeFacebookPageRequest struct {
	PageAccessToken string `json:"page_access_token" validate:"required"`
}

// ReauthorizeFacebookPage refreshes an expired Facebook Page access token.
// POST /api/v1/accounts/:id/channels/facebook_channel/reauthorize
func (h *FacebookChannelHandler) ReauthorizeFacebookPage(c *gin.Context) {
	accountIDStr := c.Param("id")
	accountID, err := strconv.ParseUint(accountIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid account_id"})
		return
	}

	var req ReauthorizeFacebookPageRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		applogger.L().Errorf("Failed to bind reauthorize request: %v", err)
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	ctx := c.Request.Context()

	// Find all Facebook channels for this account and update their tokens
	channels, listErr := h.fbChannelSvc.ListByAccount(ctx, uint(accountID))
	if listErr != nil {
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to list Facebook channels"})
		return
	}

	for _, ch := range channels {
		ch.PageAccessToken = req.PageAccessToken
		ch.ReauthorizationRequired = false
		if updateErr := h.fbRepo.Update(ctx, &ch); updateErr != nil {
			applogger.L().Warnf("Failed to update token for channel %d: %v", ch.ID, updateErr)
		}
	}

	c.JSON(http.StatusOK, gin.H{"message": "Facebook page access token refreshed successfully"})
}

// GetFacebookPage retrieves a Facebook channel page by ID.
// GET /api/v1/accounts/:id/channels/facebook_channel/:fb_id
// Alias for GetFacebookChannel — router registers both names.
func (h *FacebookChannelHandler) GetFacebookPage(c *gin.Context) {
	h.GetFacebookChannel(c)
}

// UpdateFacebookPage updates a Facebook channel page configuration.
// PATCH /api/v1/accounts/:id/channels/facebook_channel/:fb_id
func (h *FacebookChannelHandler) UpdateFacebookPage(c *gin.Context) {
	accountIDStr := c.Param("id")
	accountID, err := strconv.ParseUint(accountIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid account_id"})
		return
	}

	fbIDStr := c.Param("fb_id")
	fbID, err := strconv.ParseUint(fbIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid fb_id"})
		return
	}

	ctx := c.Request.Context()

	ch, err := h.fbChannelSvc.GetByID(ctx, uint(fbID))
	if err != nil {
		applogger.L().Errorf("Failed to get Facebook channel for update: %v", err)
		c.JSON(http.StatusNotFound, gin.H{"error": "Facebook channel not found"})
		return
	}

	// Verify account ownership
	if ch.AccountID != uint(accountID) {
		c.JSON(http.StatusForbidden, gin.H{"error": "Facebook channel does not belong to this account"})
		return
	}

	var req struct {
		PageName              *string `json:"page_name"`
		ReauthorizationRequired *bool  `json:"reauthorization_required"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid request body", "details": err.Error()})
		return
	}

	updateReq := service.UpdateFacebookChannelRequest{
		PageName:              req.PageName,
		ReauthorizationRequired: req.ReauthorizationRequired,
	}

	updated, err := h.fbChannelSvc.Update(ctx, uint(accountID), ch.InboxID, updateReq)
	if err != nil {
		applogger.L().Errorf("Failed to update Facebook channel: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to update Facebook channel"})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"id":                     updated.ID,
		"account_id":             updated.AccountID,
		"inbox_id":               updated.InboxID,
		"page_id":                updated.PageID,
		"page_name":              updated.PageName,
		"reauthorization_required": updated.ReauthorizationRequired,
	})
}