package services

import (
	"context"
	"encoding/json"
	"time"

	"github.com/breakpilot/billing-service/internal/database"
	"github.com/breakpilot/billing-service/internal/models"
	"github.com/google/uuid"
)

// SubscriptionService handles subscription-related operations
type SubscriptionService struct {
	db *database.DB
}

// NewSubscriptionService creates a new SubscriptionService
func NewSubscriptionService(db *database.DB) *SubscriptionService {
	return &SubscriptionService{db: db}
}

// GetByUserID retrieves a subscription by user ID
func (s *SubscriptionService) GetByUserID(ctx context.Context, userID uuid.UUID) (*models.Subscription, error) {
	query := `
		SELECT id, user_id, stripe_customer_id, stripe_subscription_id, plan_id,
		       status, trial_end, current_period_end, cancel_at_period_end,
		       created_at, updated_at
		FROM subscriptions
		WHERE user_id = $1
	`

	var sub models.Subscription
	var stripeCustomerID, stripeSubID *string
	var trialEnd, periodEnd *time.Time

	err := s.db.Pool.QueryRow(ctx, query, userID).Scan(
		&sub.ID, &sub.UserID, &stripeCustomerID, &stripeSubID, &sub.PlanID,
		&sub.Status, &trialEnd, &periodEnd, &sub.CancelAtPeriodEnd,
		&sub.CreatedAt, &sub.UpdatedAt,
	)

	if err != nil {
		if err.Error() == "no rows in result set" {
			return nil, nil
		}
		return nil, err
	}

	if stripeCustomerID != nil {
		sub.StripeCustomerID = *stripeCustomerID
	}
	if stripeSubID != nil {
		sub.StripeSubscriptionID = *stripeSubID
	}
	sub.TrialEnd = trialEnd
	sub.CurrentPeriodEnd = periodEnd

	return &sub, nil
}

// GetByStripeSubscriptionID retrieves a subscription by Stripe subscription ID
func (s *SubscriptionService) GetByStripeSubscriptionID(ctx context.Context, stripeSubID string) (*models.Subscription, error) {
	query := `
		SELECT id, user_id, stripe_customer_id, stripe_subscription_id, plan_id,
		       status, trial_end, current_period_end, cancel_at_period_end,
		       created_at, updated_at
		FROM subscriptions
		WHERE stripe_subscription_id = $1
	`

	var sub models.Subscription
	var stripeCustomerID, subID *string
	var trialEnd, periodEnd *time.Time

	err := s.db.Pool.QueryRow(ctx, query, stripeSubID).Scan(
		&sub.ID, &sub.UserID, &stripeCustomerID, &subID, &sub.PlanID,
		&sub.Status, &trialEnd, &periodEnd, &sub.CancelAtPeriodEnd,
		&sub.CreatedAt, &sub.UpdatedAt,
	)

	if err != nil {
		if err.Error() == "no rows in result set" {
			return nil, nil
		}
		return nil, err
	}

	if stripeCustomerID != nil {
		sub.StripeCustomerID = *stripeCustomerID
	}
	if subID != nil {
		sub.StripeSubscriptionID = *subID
	}
	sub.TrialEnd = trialEnd
	sub.CurrentPeriodEnd = periodEnd

	return &sub, nil
}

// Create creates a new subscription
func (s *SubscriptionService) Create(ctx context.Context, sub *models.Subscription) error {
	query := `
		INSERT INTO subscriptions (
			user_id, stripe_customer_id, stripe_subscription_id, plan_id,
			status, trial_end, current_period_end, cancel_at_period_end
		) VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
		RETURNING id, created_at, updated_at
	`

	return s.db.Pool.QueryRow(ctx, query,
		sub.UserID, sub.StripeCustomerID, sub.StripeSubscriptionID, sub.PlanID,
		sub.Status, sub.TrialEnd, sub.CurrentPeriodEnd, sub.CancelAtPeriodEnd,
	).Scan(&sub.ID, &sub.CreatedAt, &sub.UpdatedAt)
}

// Update updates an existing subscription
func (s *SubscriptionService) Update(ctx context.Context, sub *models.Subscription) error {
	query := `
		UPDATE subscriptions SET
			stripe_customer_id = $2,
			stripe_subscription_id = $3,
			plan_id = $4,
			status = $5,
			trial_end = $6,
			current_period_end = $7,
			cancel_at_period_end = $8,
			updated_at = NOW()
		WHERE id = $1
	`

	_, err := s.db.Pool.Exec(ctx, query,
		sub.ID, sub.StripeCustomerID, sub.StripeSubscriptionID, sub.PlanID,
		sub.Status, sub.TrialEnd, sub.CurrentPeriodEnd, sub.CancelAtPeriodEnd,
	)
	return err
}

// UpdateStatus updates the subscription status
func (s *SubscriptionService) UpdateStatus(ctx context.Context, id uuid.UUID, status models.SubscriptionStatus) error {
	query := `UPDATE subscriptions SET status = $2, updated_at = NOW() WHERE id = $1`
	_, err := s.db.Pool.Exec(ctx, query, id, status)
	return err
}

// GetAvailablePlans retrieves all active billing plans
func (s *SubscriptionService) GetAvailablePlans(ctx context.Context) ([]models.BillingPlan, error) {
	query := `
		SELECT id, stripe_price_id, name, description, price_cents,
		       currency, interval, features, is_active, sort_order
		FROM billing_plans
		WHERE is_active = true
		ORDER BY sort_order ASC
	`

	rows, err := s.db.Pool.Query(ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var plans []models.BillingPlan
	for rows.Next() {
		var plan models.BillingPlan
		var stripePriceID *string
		var featuresJSON []byte

		err := rows.Scan(
			&plan.ID, &stripePriceID, &plan.Name, &plan.Description,
			&plan.PriceCents, &plan.Currency, &plan.Interval,
			&featuresJSON, &plan.IsActive, &plan.SortOrder,
		)
		if err != nil {
			return nil, err
		}

		if stripePriceID != nil {
			plan.StripePriceID = *stripePriceID
		}

		// Parse features JSON
		if len(featuresJSON) > 0 {
			json.Unmarshal(featuresJSON, &plan.Features)
		}

		plans = append(plans, plan)
	}

	return plans, nil
}

// GetPlanByID retrieves a billing plan by ID
func (s *SubscriptionService) GetPlanByID(ctx context.Context, planID string) (*models.BillingPlan, error) {
	query := `
		SELECT id, stripe_price_id, name, description, price_cents,
		       currency, interval, features, is_active, sort_order
		FROM billing_plans
		WHERE id = $1
	`

	var plan models.BillingPlan
	var stripePriceID *string
	var featuresJSON []byte

	err := s.db.Pool.QueryRow(ctx, query, planID).Scan(
		&plan.ID, &stripePriceID, &plan.Name, &plan.Description,
		&plan.PriceCents, &plan.Currency, &plan.Interval,
		&featuresJSON, &plan.IsActive, &plan.SortOrder,
	)

	if err != nil {
		if err.Error() == "no rows in result set" {
			return nil, nil
		}
		return nil, err
	}

	if stripePriceID != nil {
		plan.StripePriceID = *stripePriceID
	}

	if len(featuresJSON) > 0 {
		json.Unmarshal(featuresJSON, &plan.Features)
	}

	return &plan, nil
}

// UpdatePlanStripePriceID updates the Stripe price ID for a plan
func (s *SubscriptionService) UpdatePlanStripePriceID(ctx context.Context, planID, stripePriceID, stripeProductID string) error {
	query := `
		UPDATE billing_plans
		SET stripe_price_id = $2, stripe_product_id = $3, updated_at = NOW()
		WHERE id = $1
	`
	_, err := s.db.Pool.Exec(ctx, query, planID, stripePriceID, stripeProductID)
	return err
}

// =============================================
// Webhook Event Tracking (Idempotency)
// =============================================

// IsEventProcessed checks if a webhook event has already been processed
func (s *SubscriptionService) IsEventProcessed(ctx context.Context, eventID string) (bool, error) {
	query := `SELECT processed FROM stripe_webhook_events WHERE stripe_event_id = $1`

	var processed bool
	err := s.db.Pool.QueryRow(ctx, query, eventID).Scan(&processed)
	if err != nil {
		if err.Error() == "no rows in result set" {
			return false, nil
		}
		return false, err
	}

	return processed, nil
}

// MarkEventProcessing marks an event as being processed
func (s *SubscriptionService) MarkEventProcessing(ctx context.Context, eventID, eventType string) error {
	query := `
		INSERT INTO stripe_webhook_events (stripe_event_id, event_type, processed)
		VALUES ($1, $2, false)
		ON CONFLICT (stripe_event_id) DO NOTHING
	`
	_, err := s.db.Pool.Exec(ctx, query, eventID, eventType)
	return err
}

// MarkEventProcessed marks an event as successfully processed
func (s *SubscriptionService) MarkEventProcessed(ctx context.Context, eventID string) error {
	query := `
		UPDATE stripe_webhook_events
		SET processed = true, processed_at = NOW()
		WHERE stripe_event_id = $1
	`
	_, err := s.db.Pool.Exec(ctx, query, eventID)
	return err
}

// MarkEventFailed marks an event as failed with an error message
func (s *SubscriptionService) MarkEventFailed(ctx context.Context, eventID, errorMsg string) error {
	query := `
		UPDATE stripe_webhook_events
		SET processed = false, error_message = $2, processed_at = NOW()
		WHERE stripe_event_id = $1
	`
	_, err := s.db.Pool.Exec(ctx, query, eventID, errorMsg)
	return err
}

// =============================================
// Audit Logging
// =============================================

// LogAuditEvent logs a billing audit event
func (s *SubscriptionService) LogAuditEvent(ctx context.Context, userID *uuid.UUID, action, entityType, entityID string, oldValue, newValue, metadata interface{}, ipAddress, userAgent string) error {
	oldJSON, _ := json.Marshal(oldValue)
	newJSON, _ := json.Marshal(newValue)
	metaJSON, _ := json.Marshal(metadata)

	query := `
		INSERT INTO billing_audit_log (
			user_id, action, entity_type, entity_id,
			old_value, new_value, metadata, ip_address, user_agent
		) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
	`

	_, err := s.db.Pool.Exec(ctx, query,
		userID, action, entityType, entityID,
		oldJSON, newJSON, metaJSON, ipAddress, userAgent,
	)
	return err
}