package v1

// MicrosoftChannelHandler handles Microsoft (Azure AD/Teams) channel CRUD and OAuth flow.
// This is a gochat addition — Chatwoot does not have a native Microsoft channel.
//
// gochat maps these to:
//   - GET    /api/v1/accounts/:id/microsoft_channels/authorization    → OAuth authorize URL
//   - POST   /api/v1/accounts/:id/microsoft_channels/oauth_callback  → OAuth token exchange + inbox creation
//   - DELETE /api/v1/accounts/:id/microsoft_channels/:ms_id           → destroy Microsoft inbox
//   - POST   /api/v1/accounts/:id/microsoft_channels/reauthorize      → refresh token

import (
	"fmt"
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"

	microsoft "github.com/gochat/gochat/internal/channel/microsoft"
	"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"
)

// MicrosoftChannelHandler handles Microsoft/Azure AD channel management.
type MicrosoftChannelHandler struct {
	msService  *service.ChannelMicrosoftService
	msProvider *microsoft.MicrosoftProvider
	inboxSvc   *service.InboxService
	msRepo     *repository.ChannelMicrosoftRepo
}

// NewMicrosoftChannelHandler creates a new Microsoft channel handler.
func NewMicrosoftChannelHandler(
	msService *service.ChannelMicrosoftService,
	msProvider *microsoft.MicrosoftProvider,
	inboxSvc *service.InboxService,
	msRepo *repository.ChannelMicrosoftRepo,
) *MicrosoftChannelHandler {
	return &MicrosoftChannelHandler{
		msService:  msService,
		msProvider: msProvider,
		inboxSvc:   inboxSvc,
		msRepo:     msRepo,
	}
}

// === OAuth Authorization ===

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

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

	authURL, err := h.msProvider.BuildAuthURL(c.Request.Context(), uint(accountID), req.RedirectURL)
	if err != nil {
		applogger.L().Errorf("Failed to build Microsoft 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 Microsoft email OAuth authorization URL.
// POST /api/v1/accounts/:account_id/microsoft/authorization
func (h *MicrosoftChannelHandler) 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:     "AZURE_APP_ID",
		ClientSecretEnv: "AZURE_APP_SECRET",
		AuthorizeURL:    "https://login.microsoftonline.com/common/oauth2/v2.0/authorize",
		RedirectPath:    "/microsoft/callback",
		Scope:           "offline_access https://outlook.office.com/IMAP.AccessAsUser.All https://outlook.office.com/SMTP.Send openid profile email",
	})
	if err != nil {
		applogger.L().Errorf("Failed to build Microsoft 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 ===

// MicrosoftOAuthCallbackRequest is the DTO for Microsoft OAuth callback.
type MicrosoftOAuthCallbackRequest 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 Microsoft OAuth 2.0 code for tokens and creates a channel.
// POST /api/v1/accounts/:id/microsoft_channels/oauth_callback
func (h *MicrosoftChannelHandler) 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 MicrosoftOAuthCallbackRequest
	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 microsoft inbox"})
		return
	}

	// Exchange the code for tokens
	tokenResult, err := h.msProvider.ExchangeToken(ctx, req.Code, req.RedirectURL)
	if err != nil {
		applogger.L().Errorf("Microsoft 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.msProvider.ValidateAccessToken(ctx, tokenResult.AccessToken)
	if err != nil || !valid {
		applogger.L().Errorf("Microsoft token validation failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to validate Microsoft token"})
		return
	}

	// Create the Microsoft channel record
	msChannel := &channelmodel.ChannelMicrosoft{
		AccountID:    uint(accountID),
		AccessToken:  tokenResult.AccessToken,
		RefreshToken: tokenResult.RefreshToken,
		TenantID:     h.msProvider.GetTenantID(),
	}

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

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

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

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

	c.JSON(http.StatusCreated, gin.H{
		"inbox": gin.H{
			"id":           inbox.ID,
			"name":         inbox.Name,
			"channel_type": inbox.ChannelType,
		},
		"microsoft_channel": gin.H{
			"id":        msChannel.ID,
			"tenant_id": msChannel.TenantID,
		},
	})
}

// === Delete ===

// Delete removes a Microsoft channel and its associated inbox.
// DELETE /api/v1/accounts/:id/microsoft_channels/:ms_id
func (h *MicrosoftChannelHandler) Delete(c *gin.Context) {
	msIDStr := c.Param("ms_id")
	msID, err := strconv.ParseUint(msIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid microsoft_id"})
		return
	}

	ctx := c.Request.Context()

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

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

// === Webhook Validation ===

// MicrosoftWebhookValidation handles Microsoft Graph API webhook validation request.
// Microsoft sends a validation request when creating a subscription.
// POST /api/v1/microsoft_webhook/validation
func (h *MicrosoftChannelHandler) WebhookValidation(c *gin.Context) {
	var validationReq struct {
		Value []struct {
			State           string `json:"state"`
			ClientState     string `json:"clientState"`
			ValidationToken string `json:"validationToken"`
		} `json:"value"`
	}

	if err := c.ShouldBindJSON(&validationReq); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	if len(validationReq.Value) > 0 {
		c.JSON(http.StatusOK, gin.H{"validationToken": validationReq.Value[0].ValidationToken})
		return
	}

	c.JSON(http.StatusBadRequest, gin.H{"error": "no validation token provided"})
}

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

// OAuthCallbackGET handles the OAuth redirect callback from Microsoft.
// GET /api/v1/accounts/:id/microsoft/callback?code=...&state=...
// This is the redirect endpoint that the Microsoft OAuth provider calls back to.
func (h *MicrosoftChannelHandler) 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 Microsoft provider
	redirectURL := h.msProvider.GetOAuthRedirectURL()

	tokenResult, err := h.msProvider.ExchangeToken(ctx, code, redirectURL)
	if err != nil {
		applogger.L().Errorf("Microsoft 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.msProvider.ValidateAccessToken(ctx, tokenResult.AccessToken)
	if err != nil || !valid {
		applogger.L().Errorf("Microsoft token validation failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to validate Microsoft token"})
		return
	}

	// Create the Microsoft channel record
	msChannel := &channelmodel.ChannelMicrosoft{
		AccountID:    uint(accountID),
		AccessToken:  tokenResult.AccessToken,
		RefreshToken: tokenResult.RefreshToken,
		TenantID:     h.msProvider.GetTenantID(),
	}

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

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

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

// RegisterWebhook creates a Microsoft Graph API webhook subscription.
// POST /api/v1/accounts/:id/microsoft/webhooks
// This uses the Microsoft Graph API subscriptions endpoint.
func (h *MicrosoftChannelHandler) 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"`
		Resource        string `json:"resource" binding:"required"`
		NotificationURL string `json:"notification_url" binding:"required"`
		ClientState     string `json:"client_state"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	clientState := req.ClientState
	if clientState == "" {
		clientState = fmt.Sprintf("gochat_ms_%d", accountID)
	}

	ctx := c.Request.Context()

	subscriptionID, err := h.msProvider.CreateSubscription(ctx, req.AccessToken, req.Resource, req.NotificationURL, clientState)
	if err != nil {
		applogger.L().Errorf("Microsoft webhook registration failed: %v", err)
		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to register Microsoft webhook"})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"subscription_id": subscriptionID,
		"account_id":      accountID,
		"resource":        req.Resource,
	})
}

// ListWebhooks lists all Microsoft Graph API webhook subscriptions.
// GET /api/v1/accounts/:id/microsoft/webhooks
func (h *MicrosoftChannelHandler) 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()

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

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

// === Webhook Event Processing ===

// MicrosoftWebhookEvent processes incoming Microsoft Graph API notifications.
// POST /api/v1/microsoft_webhook/events
func (h *MicrosoftChannelHandler) WebhookEvent(c *gin.Context) {
	var payload map[string]interface{}
	if err := c.ShouldBindJSON(&payload); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	applogger.L().Infof("Microsoft webhook event received")
	// Event processing will be handled by the Microsoft incoming message service
	// (to be implemented in a future milestone)

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