package services

import (
	"context"
	"errors"
	"fmt"
	"strings"

	"github.com/creativenoz/aurganize-v62/backend/internal/config"
	"github.com/creativenoz/aurganize-v62/backend/internal/models"
	"github.com/creativenoz/aurganize-v62/backend/internal/repositories"
	"github.com/creativenoz/aurganize-v62/backend/pkg/slug"
	"github.com/google/uuid"
	"github.com/jmoiron/sqlx"
	"github.com/lib/pq"
	"github.com/rs/zerolog/log"
)

var (
	ErrTenantNotFound = errors.New("tenant not found")
	ErrSlugExists     = errors.New("tenant slug already exists")
)

type TenantService struct {
	config     *config.Config
	tenantRepo *repositories.TenantRepository
	userRepo   *repositories.UserRepository
	db         *sqlx.DB
}

func NewTenantService(
	config *config.Config,
	tenantRepo *repositories.TenantRepository,
	userRepo *repositories.UserRepository,
	db *sqlx.DB,
) *TenantService {
	log.Info().
		Str("service", "tenant").
		Str("component", "service_init").
		Bool("has_tenant_repo", tenantRepo != nil).
		Bool("has_user_repo", userRepo != nil).
		Bool("has_db", db != nil).
		Msg("tenant service initialized")
	return &TenantService{
		config:     config,
		tenantRepo: tenantRepo,
		userRepo:   userRepo,
		db:         db,
	}
}

func (ts *TenantService) Create(ctx context.Context, input *models.CreateTenantInput) (*models.Tenant, error) {
	const maxRetries = 5
	log.Info().
		Str("service", "tenant").
		Str("action", "create_tenant_started").
		Str("tenant_name", input.Name).
		Str("email", *input.Email).
		Int("max_retries", maxRetries).
		Msg("creating tenant (standalone, not with user)")
	if input.Name == "" {
		log.Warn().
			Str("service", "tenant").
			Str("action", "create_tenant_validation_failed").
			Str("validation_error", "empty_name").
			Msg("tenant creation failed - tenant name is required")
		return nil, fmt.Errorf("tenant name is required")
	}
	if *input.Email == "" {
		log.Warn().
			Str("service", "tenant").
			Str("action", "create_tenant_validation_failed").
			Str("validation_error", "empty_email").
			Msg("tenant creation failed - tenant email is required")
		return nil, fmt.Errorf("tenant email is required")
	}

	for attempt := 0; attempt < maxRetries; attempt++ {
		baseSlug := slug.Generate(input.Name)
		log.Debug().
			Str("service", "tenant").
			Str("action", "generating_unique_slug").
			Int("attempt", attempt+1).
			Int("max_retries", maxRetries).
			Str("tenant_name", input.Name).
			Str("base_slug", baseSlug).
			Msg("attempting to generate unique slug for tenant")
		uniqueSlug := slug.GenerateUnique(baseSlug, func(candidate string) bool {
			exits, err := ts.tenantRepo.SlugExists(ctx, candidate)
			if err != nil {
				log.Error().
					Str("service", "tenant").
					Str("action", "slug_exists_check_error").
					Str("candidate_slug", candidate).
					Err(err).
					Msg("database error while checking slug existence")
				return true
			}
			return exits
		})

		log.Debug().
			Str("service", "tenant").
			Str("action", "unique_slug_generated").
			Str("tenant_name", input.Name).
			Str("unique_slug", uniqueSlug).
			Int("attempt", attempt+1).
			Msg("unique slug generated for tenant")

		tenant, err := ts.tenantRepo.Create(ctx, input, uniqueSlug)

		if err == nil {
			log.Info().
				Str("service", "tenant").
				Str("action", "create_tenant_success").
				Str("tenant_id", tenant.ID.String()).
				Str("tenant_name", tenant.Name).
				Str("slug", tenant.Slug).
				Int("attempts_needed", attempt+1).
				Msg("tenant created successfully")
			return tenant, nil
		}

		if isUniqueViolationError(err, "tenant_slug_key") {
			log.Warn().
				Str("service", "tenant").
				Str("action", "slug_collision_detected").
				Str("tenant_name", input.Name).
				Str("attempted_slug", uniqueSlug).
				Int("attempt", attempt+1).
				Int("remaining_attempts", maxRetries-attempt-1).
				Msg("slug collision detected, retrying with different slug")
			continue
		}
		log.Error().
			Str("service", "tenant").
			Str("action", "create_tenant_database_error").
			Str("tenant_name", input.Name).
			Str("slug", uniqueSlug).
			Err(err).
			Msg("tenant creation failed with database error")

		return nil, fmt.Errorf("failed to create tenant : %w", err)
	}

	log.Error().
		Str("service", "tenant").
		Str("action", "create_tenant_max_retries_exceeded").
		Str("tenant_name", input.Name).
		Int("max_retries", maxRetries).
		Msg("failed to create tenant - exhausted all slug generation attempts")
	return nil, fmt.Errorf("failed to create unique slug after %d attempts", maxRetries)
}

func (ts *TenantService) CreateWithUser(ctx context.Context, input *models.CreateTenantWithUserInput) (*models.Tenant, *models.User, error) {

	log.Info().
		Str("service", "tenant").
		Str("action", "create_tenant_with_user_started").
		Str("tenant_name", input.TenantName).
		Str("email", *input.Email).
		Bool("has_first_name", input.FirstName != nil).
		Bool("has_last_name", input.LastName != nil).
		Msg("starting tenant and user creation transaction (registration)")

	tx, err := ts.db.BeginTxx(ctx, nil)
	if err != nil {
		log.Error().
			Str("service", "tenant").
			Str("action", "transaction_begin_failed").
			Err(err).
			Msg("CRITICAL: failed to begin database transaction - registration broken")
		return nil, nil, fmt.Errorf("failed to begin transaction : %w", err)
	}

	defer func() {
		if err != nil {
			log.Info().
				Str("service", "tenant").
				Str("action", "transaction_rollback").
				Str("tenant_name", input.TenantName).
				Msg("rolling back transaction due to error")
			tx.Rollback()
		}
	}()

	if input.TenantName == "" {
		log.Warn().
			Str("service", "tenant").
			Str("action", "registration_validation_failed").
			Str("validation_error", "empty_tenant_name").
			Msg("registration failed - tenant name is required")
		return nil, nil, fmt.Errorf("tenant name is required")
	}
	if *input.Email == "" {
		log.Warn().
			Str("service", "tenant").
			Str("action", "registration_validation_failed").
			Str("validation_error", "empty_email").
			Msg("registration failed - email is required")
		return nil, nil, fmt.Errorf("tenant email is required")
	}
	if *input.Password == "" {
		log.Warn().
			Str("service", "tenant").
			Str("action", "registration_validation_failed").
			Str("validation_error", "empty_password").
			Msg("registration failed - password is required")
		return nil, nil, fmt.Errorf("password is required")
	}
	log.Debug().
		Str("service", "tenant").
		Str("action", "generating_registration_slug").
		Str("tenant_name", input.TenantName).
		Msg("generating unique slug for registration")

	baseSlug := slug.Generate(input.TenantName)
	uniqueSlug := slug.GenerateUnique(baseSlug, func(candidate string) bool {
		exists, err := ts.tenantRepo.SlugExists(ctx, candidate)
		if err != nil {
			log.Error().
				Str("service", "tenant").
				Str("action", "registration_slug_check_error").
				Str("candidate_slug", candidate).
				Err(err).
				Msg("error checking slug existence during registration")
			return true
		}
		return exists
	})

	log.Debug().
		Str("service", "tenant").
		Str("action", "registration_slug_generated").
		Str("tenant_name", input.TenantName).
		Str("unique_slug", uniqueSlug).
		Msg("unique slug generated for registration")

	tenantInput := &models.CreateTenantInput{
		Name:     input.TenantName,
		Email:    input.Email,
		Timezone: "UTC",
		Currency: "INR",
		Locale:   "en-US",
	}

	log.Debug().
		Str("service", "tenant").
		Str("action", "creating_tenant_in_transaction").
		Str("tenant_name", input.TenantName).
		Str("slug", uniqueSlug).
		Msg("creating tenant record in transaction")

	tenant, err := ts.tenantRepo.CreateTx(ctx, tx, tenantInput, uniqueSlug)
	if err != nil {
		log.Error().
			Str("service", "tenant").
			Str("action", "tenant_creation_in_transaction_failed").
			Str("tenant_name", input.TenantName).
			Str("slug", uniqueSlug).
			Err(err).
			Msg("failed to create tenant in transaction - registration will fail")
		return nil, nil, fmt.Errorf("failed to create tenant: %w", err)
	}

	log.Debug().
		Str("service", "tenant").
		Str("action", "creating_user_in_transaction").
		Str("tenant_id", tenant.ID.String()).
		Str("tenant_name", tenant.Name).
		Str("email", *input.Email).
		Msg("tenant created, now creating user in same transaction")

	userInput := &models.CreateUserInput{
		TenantID:  tenant.ID,
		Email:     *input.Email,
		Password:  *input.Password,
		FirstName: input.FirstName,
		LastName:  input.LastName,
		Role:      "admin",
		Status:    "active",
	}

	user, err := ts.userRepo.CreateTx(ctx, tx, userInput)
	if err != nil {
		log.Error().
			Str("service", "tenant").
			Str("action", "user_creation_in_transaction_failed").
			Str("tenant_id", tenant.ID.String()).
			Str("email", *input.Email).
			Err(err).
			Msg("failed to create user in transaction - entire registration will rollback")
		return nil, nil, fmt.Errorf("failed to create user: %w", err)
	}

	log.Debug().
		Str("service", "tenant").
		Str("action", "committing_registration_transaction").
		Str("tenant_id", tenant.ID.String()).
		Str("user_id", user.ID.String()).
		Msg("committing registration transaction")

	if err = tx.Commit(); err != nil {
		log.Error().
			Str("service", "tenant").
			Str("action", "transaction_commit_failed").
			Str("tenant_id", tenant.ID.String()).
			Str("user_id", user.ID.String()).
			Err(err).
			Msg("CRITICAL: failed to commit registration transaction - data may be lost")
		return nil, nil, fmt.Errorf("failed to commit transaction: %w", err)
	}
	log.Info().
		Str("service", "tenant").
		Str("action", "create_tenant_with_user_success").
		Str("tenant_id", tenant.ID.String()).
		Str("tenant_name", tenant.Name).
		Str("slug", tenant.Slug).
		Str("user_id", user.ID.String()).
		Str("email", user.Email).
		Str("role", user.Role).
		Str("timezone", tenant.Timezone).
		Str("currency", tenant.Currency).
		Str("locale", tenant.Locale).
		Msg("registration completed successfully - new tenant and user created")
	return tenant, user, nil
}

func (ts *TenantService) GetByID(ctx context.Context, id uuid.UUID) (*models.Tenant, error) {
	log.Debug().
		Str("service", "tenant").
		Str("action", "get_tenant_by_id").
		Str("tenant_id", id.String()).
		Msg("retrieving tenant by id")

	tenant, err := ts.tenantRepo.FindByID(ctx, id)
	if err != nil {
		log.Error().
			Str("service", "tenant").
			Str("action", "get_tenant_error").
			Str("tenant_id", id.String()).
			Err(err).
			Msg("database error while retrieving tenant")
		return nil, fmt.Errorf("database error : %w", err)
	}

	if tenant == nil {
		log.Warn().
			Str("service", "tenant").
			Str("action", "tenant_not_found").
			Str("tenant_id", id.String()).
			Msg("tenant not found by id")
		return nil, ErrTenantNotFound
	}
	log.Debug().
		Str("service", "tenant").
		Str("action", "get_tenant_success").
		Str("tenant_id", tenant.ID.String()).
		Str("tenant_name", tenant.Name).
		Msg("tenant retrieved successfully")
	return tenant, nil
}

func (ts *TenantService) SlugExists(ctx context.Context, name string) (bool, error) {
	log.Debug().
		Str("service", "tenant").
		Str("action", "check_slug_exists").
		Str("name", name).
		Msg("checking if tenant name/slug is available")
	slug := slug.Generate(name)
	exists, err := ts.tenantRepo.SlugExists(ctx, slug)
	if err != nil {
		log.Error().
			Str("service", "tenant").
			Str("action", "slug_exists_check_error").
			Str("name", name).
			Str("slug", slug).
			Err(err).
			Msg("error checking slug existence")
	}
	if exists {
		log.Info().
			Str("service", "tenant").
			Str("action", "slug_unavailable").
			Str("name", name).
			Str("slug", slug).
			Msg("tenant name/slug is already taken")
	} else {
		log.Debug().
			Str("service", "tenant").
			Str("action", "slug_available").
			Str("name", name).
			Str("slug", slug).
			Msg("tenant name/slug is available")
	}
	return exists, nil
}

func isUniqueViolationError(err error, constraintName string) bool {
	if pqErr, ok := err.(*pq.Error); ok {
		return pqErr.Code == "23505" &&
			(constraintName == "" || strings.Contains(pqErr.Constraint, constraintName))
	}
	return false
}