package v1

// GoogleChannelHandler handles Google Chat channel CRUD and OAuth flow.
// This is a gochat addition — Chatwoot does not have a native Google Chat channel.
//
// gochat maps these to:
//   - GET    /api/v1/accounts/:id/google_channels/authorization     → OAuth authorize URL
//   - POST   /api/v1/accounts/:id/google_channels/oauth_callback   → OAuth token exchange + inbox creation
//   - DELETE /api/v1/accounts/:id/google_channels/:google_id        → destroy Google inbox
//   - POST   /api/v1/accounts/:id/google_channels/reauthorize       → refresh token

import (
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"

	googlechannel "github.com/gochat/gochat/internal/channel/google"
	"github.com/gochat/gochat/internal/model"
	channelmodel "github.com/gochat/gochat/internal/model/channel"
	"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"
)

// GoogleChannelHandler handles Google Chat channel management.
type GoogleChannelHandler struct {
	goService  *service.ChannelGoogleService
	goProvider *googlechannel.GoogleProvider
	inboxSvc   *service.InboxService
	goRepo     *repository.ChannelGoogleRepo
}

// NewGoogleChannelHandler creates a new Google channel handler.
func NewGoogleChannelHandler(
	goService *service.ChannelGoogleService,
	goProvider *googlechannel.GoogleProvider,
	inboxSvc *service.InboxService,
	goRepo *repository.ChannelGoogleRepo,
) *GoogleChannelHandler {
	return &GoogleChannelHandler{
		goService:  goService,
		goProvider: goProvider,
		inboxSvc:   inboxSvc,
		goRepo:     goRepo,
	}
}

// === OAuth Authorization ===

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

// Authorization generates a Google OAuth 2.0 authorize URL.
// GET /api/v1/accounts/:id/google_channels/authorization
func (h *GoogleChannelHandler) 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 GoogleAuthorizationRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	authURL, err := h.goProvider.BuildAuthURL(c.Request.Context(), uint(accountID), req.RedirectURL)
	if err != nil {
		applogger.L().Errorf("Failed to build Google 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})
}

// ChatwootAuthorization creates a Google email OAuth authorization URL.
// POST /api/v1/accounts/:account_id/google/authorization
func (h *GoogleChannelHandler) ChatwootAuthorization(c *gin.Context) {
	accountID, err := parseUintParam(c, "account_id")
	if err != nil {
		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrBadRequest, "invalid account_id")
		return
	}

	redirectURL, err := buildChatwootEmailOAuthAuthorizationURL(accountID, chatwootEmailOAuthAuthorizationConfig{
		ClientIDEnv:     "GOOGLE_OAUTH_CLIENT_ID",
		ClientSecretEnv: "GOOGLE_OAUTH_CLIENT_SECRET",
		AuthorizeURL:    "https://accounts.google.com/o/oauth2/auth",
		RedirectPath:    "/google/callback",
		Scope:           "email profile https://mail.google.com/",
		ExtraParams: map[string]string{
			"prompt":      "consent",
			"access_type": "offline",
		},
	})
	if err != nil {
		applogger.L().Errorf("Failed to build Google authorization URL: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"success": false})
		return
	}
	c.JSON(http.StatusOK, gin.H{"success": true, "url": redirectURL})
}

// === OAuth Callback ===

// GoogleOAuthCallbackRequest is the DTO for Google OAuth callback.
type GoogleOAuthCallbackRequest struct {
	Code        string `json:"code" validate:"required"`
	RedirectURL string `json:"redirect_url" validate:"required,url"`
	Name        string `json:"name" validate:"required,min=2"`
}

// OAuthCallback exchanges the Google OAuth 2.0 code for tokens and creates a channel.
// POST /api/v1/accounts/:id/google_channels/oauth_callback
func (h *GoogleChannelHandler) 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 GoogleOAuthCallbackRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	ctx := c.Request.Context()
	if err := h.inboxSvc.EnsureCanCreateInbox(ctx, uint(accountID)); err != nil {
		if renderInboxLimitExceeded(c, err) {
			return
		}
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to create google inbox"})
		return
	}

	// Exchange the code for tokens
	tokenResult, err := h.goProvider.ExchangeToken(ctx, req.Code, req.RedirectURL)
	if err != nil {
		applogger.L().Errorf("Google OAuth token exchange failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to exchange OAuth token"})
		return
	}

	// Validate the access token
	valid, err := h.goProvider.ValidateAccessToken(ctx, tokenResult.AccessToken)
	if err != nil || !valid {
		applogger.L().Errorf("Google token validation failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to validate Google token"})
		return
	}

	// Create the Google channel record
	goChannel := &channelmodel.ChannelGoogle{
		AccountID:    uint(accountID),
		AccessToken:  tokenResult.AccessToken,
		RefreshToken: tokenResult.RefreshToken,
	}

	if err := h.goService.Create(ctx, goChannel); err != nil {
		applogger.L().Errorf("Failed to create Google channel: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to create google channel"})
		return
	}

	// Create the inbox
	inboxReq := service.CreateInboxRequest{
		Name:        req.Name,
		ChannelType: string(model.InboxChannelTypeGoogle),
	}

	inbox, err := h.inboxSvc.Create(ctx, uint(accountID), inboxReq)
	if err != nil {
		applogger.L().Errorf("Failed to create Google inbox: %v", err)
		if delErr := h.goService.Delete(ctx, goChannel.ID); delErr != nil {
			applogger.L().Warnf("Failed to rollback Google channel after inbox creation failure: %v", delErr)
		}
		if renderInboxLimitExceeded(c, err) {
			return
		}
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to create google inbox"})
		return
	}

	// Link the channel to the inbox
	goChannel.InboxID = inbox.ID
	if err := h.goService.Update(ctx, goChannel); err != nil {
		applogger.L().Warnf("Failed to link Google channel to inbox: %v", err)
	}

	c.JSON(http.StatusCreated, gin.H{
		"inbox": gin.H{
			"id":           inbox.ID,
			"name":         inbox.Name,
			"channel_type": inbox.ChannelType,
		},
		"google_channel": gin.H{
			"id": goChannel.ID,
		},
	})
}

// === Chatwoot-style GET OAuth callback (G10) ===

// OAuthCallbackGET handles the OAuth redirect callback from Google.
// GET /api/v1/accounts/:id/google/callback?code=...&state=...
// This is the redirect endpoint that the Google OAuth provider calls back to.
func (h *GoogleChannelHandler) OAuthCallbackGET(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
	}

	code := c.Query("code")
	state := c.Query("state")
	if code == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "missing code parameter"})
		return
	}

	ctx := c.Request.Context()

	// Use the configured redirect URL from the Google provider
	redirectURL := h.goProvider.GetOAuthRedirectURL()

	tokenResult, err := h.goProvider.ExchangeToken(ctx, code, redirectURL)
	if err != nil {
		applogger.L().Errorf("Google OAuth GET callback token exchange failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to exchange OAuth token"})
		return
	}

	// Validate the access token
	valid, err := h.goProvider.ValidateAccessToken(ctx, tokenResult.AccessToken)
	if err != nil || !valid {
		applogger.L().Errorf("Google token validation failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to validate Google token"})
		return
	}

	// Create the Google channel record
	goChannel := &channelmodel.ChannelGoogle{
		AccountID:    uint(accountID),
		AccessToken:  tokenResult.AccessToken,
		RefreshToken: tokenResult.RefreshToken,
	}

	if err := h.goService.Create(ctx, goChannel); err != nil {
		applogger.L().Errorf("Failed to create Google channel: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to create google channel"})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"channel_id":    goChannel.ID,
		"access_token":  goChannel.AccessToken,
		"refresh_token": goChannel.RefreshToken,
		"state":         state,
	})
}

// === Delete ===

// Delete removes a Google channel and its associated inbox.
// DELETE /api/v1/accounts/:id/google_channels/:google_id
func (h *GoogleChannelHandler) Delete(c *gin.Context) {
	googleIDStr := c.Param("google_id")
	googleID, err := strconv.ParseUint(googleIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid google_id"})
		return
	}

	ctx := c.Request.Context()

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

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

// === Webhook Registration (G10) ===

// RegisterWebhook registers a webhook URL with the Google Chat API.
// POST /api/v1/accounts/:id/google/webhooks
func (h *GoogleChannelHandler) RegisterWebhook(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 struct {
		AccessToken string `json:"access_token" binding:"required"`
		WebhookURL  string `json:"webhook_url" binding:"required"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	ctx := c.Request.Context()

	webhookID, err := h.goProvider.RegisterWebhook(ctx, req.AccessToken, req.WebhookURL)
	if err != nil {
		applogger.L().Errorf("Google webhook registration failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to register Google webhook"})
		return
	}

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

// ListWebhooks lists all registered webhooks for Google Chat.
// GET /api/v1/accounts/:id/google/webhooks
func (h *GoogleChannelHandler) ListWebhooks(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
	}

	accessToken := c.Query("access_token")
	if accessToken == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "access_token query parameter is required"})
		return
	}

	ctx := c.Request.Context()

	webhooks, err := h.goProvider.ListWebhooks(ctx, accessToken)
	if err != nil {
		applogger.L().Errorf("Google webhook listing failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to list Google webhooks"})
		return
	}

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