package repositories

import (
	"crypto/rand"
	"errors"
	"math/big"
	"time"

	"gorm.io/gorm"

	"github.com/treytartt/casera-api/internal/models"
)

// ResidenceRepository handles database operations for residences
type ResidenceRepository struct {
	db *gorm.DB
}

// NewResidenceRepository creates a new residence repository
func NewResidenceRepository(db *gorm.DB) *ResidenceRepository {
	return &ResidenceRepository{db: db}
}

// FindByID finds a residence by ID with preloaded relations
func (r *ResidenceRepository) FindByID(id uint) (*models.Residence, error) {
	var residence models.Residence
	err := r.db.Preload("Owner").
		Preload("Users").
		Preload("PropertyType").
		Where("id = ? AND is_active = ?", id, true).
		First(&residence).Error
	if err != nil {
		return nil, err
	}
	return &residence, nil
}

// FindByIDSimple finds a residence by ID without preloading (for quick checks)
func (r *ResidenceRepository) FindByIDSimple(id uint) (*models.Residence, error) {
	var residence models.Residence
	err := r.db.Where("id = ? AND is_active = ?", id, true).First(&residence).Error
	if err != nil {
		return nil, err
	}
	return &residence, nil
}

// FindByUser finds all residences accessible to a user (owned or shared)
func (r *ResidenceRepository) FindByUser(userID uint) ([]models.Residence, error) {
	var residences []models.Residence

	// Find residences where user is owner OR user is in the shared users list
	err := r.db.Preload("Owner").
		Preload("Users").
		Preload("PropertyType").
		Where("is_active = ?", true).
		Where("owner_id = ? OR id IN (?)",
			userID,
			r.db.Table("residence_residence_users").Select("residence_id").Where("user_id = ?", userID),
		).
		Order("is_primary DESC, created_at DESC").
		Find(&residences).Error

	if err != nil {
		return nil, err
	}
	return residences, nil
}

// FindOwnedByUser finds all residences owned by a user
func (r *ResidenceRepository) FindOwnedByUser(userID uint) ([]models.Residence, error) {
	var residences []models.Residence
	err := r.db.Preload("Owner").
		Preload("Users").
		Preload("PropertyType").
		Where("owner_id = ? AND is_active = ?", userID, true).
		Order("is_primary DESC, created_at DESC").
		Find(&residences).Error

	if err != nil {
		return nil, err
	}
	return residences, nil
}

// Create creates a new residence
func (r *ResidenceRepository) Create(residence *models.Residence) error {
	return r.db.Create(residence).Error
}

// Update updates a residence
func (r *ResidenceRepository) Update(residence *models.Residence) error {
	return r.db.Save(residence).Error
}

// Delete soft-deletes a residence by setting is_active to false
func (r *ResidenceRepository) Delete(id uint) error {
	return r.db.Model(&models.Residence{}).
		Where("id = ?", id).
		Update("is_active", false).Error
}

// AddUser adds a user to a residence's shared users
func (r *ResidenceRepository) AddUser(residenceID, userID uint) error {
	// Using raw SQL for the many-to-many join table
	return r.db.Exec(
		"INSERT INTO residence_residence_users (residence_id, user_id) VALUES (?, ?) ON CONFLICT DO NOTHING",
		residenceID, userID,
	).Error
}

// RemoveUser removes a user from a residence's shared users
func (r *ResidenceRepository) RemoveUser(residenceID, userID uint) error {
	return r.db.Exec(
		"DELETE FROM residence_residence_users WHERE residence_id = ? AND user_id = ?",
		residenceID, userID,
	).Error
}

// GetResidenceUsers returns all users with access to a residence
func (r *ResidenceRepository) GetResidenceUsers(residenceID uint) ([]models.User, error) {
	residence, err := r.FindByID(residenceID)
	if err != nil {
		return nil, err
	}

	users := make([]models.User, 0, len(residence.Users)+1)
	users = append(users, residence.Owner)
	users = append(users, residence.Users...)
	return users, nil
}

// HasAccess checks if a user has access to a residence
func (r *ResidenceRepository) HasAccess(residenceID, userID uint) (bool, error) {
	var count int64

	// Check if user is owner
	err := r.db.Model(&models.Residence{}).
		Where("id = ? AND owner_id = ? AND is_active = ?", residenceID, userID, true).
		Count(&count).Error
	if err != nil {
		return false, err
	}
	if count > 0 {
		return true, nil
	}

	// Check if user is in shared users
	err = r.db.Table("residence_residence_users").
		Where("residence_id = ? AND user_id = ?", residenceID, userID).
		Count(&count).Error
	if err != nil {
		return false, err
	}

	return count > 0, nil
}

// IsOwner checks if a user is the owner of a residence
func (r *ResidenceRepository) IsOwner(residenceID, userID uint) (bool, error) {
	var count int64
	err := r.db.Model(&models.Residence{}).
		Where("id = ? AND owner_id = ? AND is_active = ?", residenceID, userID, true).
		Count(&count).Error
	if err != nil {
		return false, err
	}
	return count > 0, nil
}

// CountByOwner counts residences owned by a user
func (r *ResidenceRepository) CountByOwner(userID uint) (int64, error) {
	var count int64
	err := r.db.Model(&models.Residence{}).
		Where("owner_id = ? AND is_active = ?", userID, true).
		Count(&count).Error
	return count, err
}

// === Share Code Operations ===

// CreateShareCode creates a new share code for a residence
func (r *ResidenceRepository) CreateShareCode(residenceID, createdByID uint, expiresIn time.Duration) (*models.ResidenceShareCode, error) {
	// Deactivate existing codes for this residence
	err := r.db.Model(&models.ResidenceShareCode{}).
		Where("residence_id = ? AND is_active = ?", residenceID, true).
		Update("is_active", false).Error
	if err != nil {
		return nil, err
	}

	// Generate unique 6-character code
	code, err := r.generateUniqueCode()
	if err != nil {
		return nil, err
	}

	expiresAt := time.Now().UTC().Add(expiresIn)
	shareCode := &models.ResidenceShareCode{
		ResidenceID: residenceID,
		Code:        code,
		CreatedByID: createdByID,
		IsActive:    true,
		ExpiresAt:   &expiresAt,
	}

	if err := r.db.Create(shareCode).Error; err != nil {
		return nil, err
	}

	return shareCode, nil
}

// FindShareCodeByCode finds an active share code by its code string
func (r *ResidenceRepository) FindShareCodeByCode(code string) (*models.ResidenceShareCode, error) {
	var shareCode models.ResidenceShareCode
	err := r.db.Preload("Residence").
		Where("code = ? AND is_active = ?", code, true).
		First(&shareCode).Error
	if err != nil {
		return nil, err
	}

	// Check if expired
	if shareCode.ExpiresAt != nil && time.Now().UTC().After(*shareCode.ExpiresAt) {
		return nil, errors.New("share code has expired")
	}

	return &shareCode, nil
}

// DeactivateShareCode deactivates a share code
func (r *ResidenceRepository) DeactivateShareCode(codeID uint) error {
	return r.db.Model(&models.ResidenceShareCode{}).
		Where("id = ?", codeID).
		Update("is_active", false).Error
}

// GetActiveShareCode gets the active share code for a residence (if any)
func (r *ResidenceRepository) GetActiveShareCode(residenceID uint) (*models.ResidenceShareCode, error) {
	var shareCode models.ResidenceShareCode
	err := r.db.Where("residence_id = ? AND is_active = ?", residenceID, true).
		First(&shareCode).Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, nil
		}
		return nil, err
	}

	// Check if expired
	if shareCode.ExpiresAt != nil && time.Now().UTC().After(*shareCode.ExpiresAt) {
		// Auto-deactivate expired code
		r.DeactivateShareCode(shareCode.ID)
		return nil, nil
	}

	return &shareCode, nil
}

// generateUniqueCode generates a unique 6-character alphanumeric code
func (r *ResidenceRepository) generateUniqueCode() (string, error) {
	const charset = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789" // Removed ambiguous chars: 0, O, I, 1
	const codeLength = 6
	maxAttempts := 10

	for attempt := 0; attempt < maxAttempts; attempt++ {
		code := make([]byte, codeLength)
		for i := range code {
			num, err := rand.Int(rand.Reader, big.NewInt(int64(len(charset))))
			if err != nil {
				return "", err
			}
			code[i] = charset[num.Int64()]
		}

		codeStr := string(code)

		// Check if code already exists
		var count int64
		r.db.Model(&models.ResidenceShareCode{}).
			Where("code = ? AND is_active = ?", codeStr, true).
			Count(&count)

		if count == 0 {
			return codeStr, nil
		}
	}

	return "", errors.New("failed to generate unique share code")
}

// === Residence Type Operations ===

// GetAllResidenceTypes returns all residence types
func (r *ResidenceRepository) GetAllResidenceTypes() ([]models.ResidenceType, error) {
	var types []models.ResidenceType
	err := r.db.Order("id").Find(&types).Error
	return types, err
}

// FindResidenceTypeByID finds a residence type by ID
func (r *ResidenceRepository) FindResidenceTypeByID(id uint) (*models.ResidenceType, error) {
	var residenceType models.ResidenceType
	err := r.db.First(&residenceType, id).Error
	if err != nil {
		return nil, err
	}
	return &residenceType, nil
}

// GetTasksForReport returns all tasks for a residence with related data for report generation
func (r *ResidenceRepository) GetTasksForReport(residenceID uint) ([]models.Task, error) {
	var tasks []models.Task
	err := r.db.
		Preload("Category").
		Preload("Priority").
		Preload("Status").
		Preload("Completions").
		Where("residence_id = ?", residenceID).
		Order("due_date ASC NULLS LAST, created_at DESC").
		Find(&tasks).Error
	return tasks, err
}