// Filename: internal/repository/key_crud.go
package repository

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"gemini-balancer/internal/models"

	"context"
	"math/rand"
	"strings"
	"time"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

func (r *gormKeyRepository) AddKeys(keys []models.APIKey) ([]models.APIKey, error) {
	if len(keys) == 0 {
		return []models.APIKey{}, nil
	}
	keyHashes := make([]string, len(keys))
	keyValueToHashMap := make(map[string]string)
	for i, k := range keys {
		if k.APIKey == "" {
			return nil, fmt.Errorf("cannot add key at index %d: plaintext APIKey is empty", i)
		}
		hash := sha256.Sum256([]byte(k.APIKey))
		hashStr := hex.EncodeToString(hash[:])
		keyHashes[i] = hashStr
		keyValueToHashMap[k.APIKey] = hashStr
	}
	var finalKeys []models.APIKey
	err := r.db.Transaction(func(tx *gorm.DB) error {
		var existingKeys []models.APIKey
		if err := tx.Unscoped().Where("api_key_hash IN ?", keyHashes).Find(&existingKeys).Error; err != nil {
			return err
		}
		existingKeyHashMap := make(map[string]models.APIKey)
		for _, k := range existingKeys {
			existingKeyHashMap[k.APIKeyHash] = k
		}
		var keysToCreate []models.APIKey
		var keysToRestore []uint
		for _, keyObj := range keys {
			keyVal := keyObj.APIKey
			hash := keyValueToHashMap[keyVal]
			if ek, found := existingKeyHashMap[hash]; found {
				if ek.DeletedAt.Valid {
					keysToRestore = append(keysToRestore, ek.ID)
				}
			} else {
				encryptedKey, err := r.crypto.Encrypt(keyVal)
				if err != nil {
					return fmt.Errorf("failed to encrypt key '%s...': %w", keyVal[:min(4, len(keyVal))], err)
				}
				keysToCreate = append(keysToCreate, models.APIKey{
					EncryptedKey: encryptedKey,
					APIKeyHash:   hash,
				})
			}
		}
		if len(keysToRestore) > 0 {
			if err := tx.Model(&models.APIKey{}).Unscoped().Where("id IN ?", keysToRestore).Update("deleted_at", nil).Error; err != nil {
				return err
			}
		}
		if len(keysToCreate) > 0 {
			if err := tx.Clauses(clause.OnConflict{DoNothing: true}, clause.Returning{}).Create(&keysToCreate).Error; err != nil {
				return err
			}
		}
		if err := tx.Where("api_key_hash IN ?", keyHashes).Find(&finalKeys).Error; err != nil {
			return err
		}

		return r.decryptKeys(finalKeys)
	})
	return finalKeys, err
}

func (r *gormKeyRepository) Update(key *models.APIKey) error {
	if key.APIKey != "" {
		encryptedKey, err := r.crypto.Encrypt(key.APIKey)
		if err != nil {
			return fmt.Errorf("failed to re-encrypt key on update for ID %d: %w", key.ID, err)
		}
		key.EncryptedKey = encryptedKey
		// Recalculate hash as a defensive measure.
		hash := sha256.Sum256([]byte(key.APIKey))
		key.APIKeyHash = hex.EncodeToString(hash[:])
	}
	err := r.executeTransactionWithRetry(func(tx *gorm.DB) error {

		return tx.Save(key).Error
	})
	if err != nil {
		return err
	}

	if err := r.decryptKey(key); err != nil {
		r.logger.Warnf("DB updated key ID %d, but decryption for cache failed: %v", key.ID, err)
		return nil
	}
	if err := r.updateStoreCacheForKey(key); err != nil {
		r.logger.Warnf("DB updated key ID %d, but cache update failed: %v", key.ID, err)
	}
	return nil
}

func (r *gormKeyRepository) HardDeleteByID(id uint) error {
	key, err := r.GetKeyByID(id)
	if err != nil {
		return err
	}
	err = r.executeTransactionWithRetry(func(tx *gorm.DB) error {
		return tx.Unscoped().Delete(&models.APIKey{}, id).Error
	})
	if err != nil {
		return err
	}
	if err := r.removeStoreCacheForKey(context.Background(), key); err != nil {
		r.logger.Warnf("DB deleted key ID %d, but cache removal failed: %v", id, err)
	}
	return nil
}

func (r *gormKeyRepository) HardDeleteByValues(keyValues []string) (int64, error) {
	if len(keyValues) == 0 {
		return 0, nil
	}
	hashes := make([]string, len(keyValues))
	for i, v := range keyValues {
		hash := sha256.Sum256([]byte(v))
		hashes[i] = hex.EncodeToString(hash[:])
	}
	var keysToDelete []models.APIKey
	if err := r.db.Where("api_key_hash IN ?", hashes).Find(&keysToDelete).Error; err != nil {
		return 0, err
	}
	if len(keysToDelete) == 0 {
		return 0, nil
	}
	if err := r.decryptKeys(keysToDelete); err != nil {
		r.logger.Warnf("Decryption failed for keys before hard delete, cache removal may be impacted: %v", err)
	}
	var deletedCount int64
	err := r.executeTransactionWithRetry(func(tx *gorm.DB) error {
		ids := pluckIDs(keysToDelete)
		result := tx.Unscoped().Where("id IN ?", ids).Delete(&models.APIKey{})
		if result.Error != nil {
			return result.Error
		}
		deletedCount = result.RowsAffected
		return nil
	})
	if err != nil {
		return 0, err
	}
	for i := range keysToDelete {
		if err := r.removeStoreCacheForKey(context.Background(), &keysToDelete[i]); err != nil {
			r.logger.Warnf("DB deleted key ID %d, but cache removal failed: %v", keysToDelete[i].ID, err)
		}
	}
	return deletedCount, nil
}

func (r *gormKeyRepository) GetKeyByID(id uint) (*models.APIKey, error) {
	var key models.APIKey
	if err := r.db.First(&key, id).Error; err != nil {
		return nil, err
	}
	if err := r.decryptKey(&key); err != nil {
		return nil, err
	}
	return &key, nil
}

func (r *gormKeyRepository) GetKeysByIDs(ids []uint) ([]models.APIKey, error) {
	if len(ids) == 0 {
		return []models.APIKey{}, nil
	}
	var keys []models.APIKey
	err := r.db.Where("id IN ?", ids).Find(&keys).Error
	if err != nil {
		return nil, err
	}
	return keys, r.decryptKeys(keys)
}

func (r *gormKeyRepository) GetKeyByValue(keyValue string) (*models.APIKey, error) {
	hash := sha256.Sum256([]byte(keyValue))
	hashStr := hex.EncodeToString(hash[:])
	var key models.APIKey
	if err := r.db.Where("api_key_hash = ?", hashStr).First(&key).Error; err != nil {
		return nil, err
	}
	key.APIKey = keyValue
	return &key, nil
}

func (r *gormKeyRepository) GetKeysByValues(keyValues []string) ([]models.APIKey, error) {
	if len(keyValues) == 0 {
		return []models.APIKey{}, nil
	}
	hashes := make([]string, len(keyValues))
	for i, v := range keyValues {
		hash := sha256.Sum256([]byte(v))
		hashes[i] = hex.EncodeToString(hash[:])
	}
	var keys []models.APIKey
	err := r.db.Where("api_key_hash IN ?", hashes).Find(&keys).Error
	if err != nil {
		return nil, err
	}
	return keys, r.decryptKeys(keys)
}

func (r *gormKeyRepository) GetKeysByGroup(groupID uint) ([]models.APIKey, error) {
	var keys []models.APIKey
	err := r.db.Joins("JOIN group_api_key_mappings on group_api_key_mappings.api_key_id = api_keys.id").
		Where("group_api_key_mappings.key_group_id = ?", groupID).
		Find(&keys).Error
	if err != nil {
		return nil, err
	}
	return keys, r.decryptKeys(keys)
}

func (r *gormKeyRepository) CountByGroup(groupID uint) (int64, error) {
	var count int64
	err := r.db.Model(&models.APIKey{}).
		Joins("JOIN group_api_key_mappings on group_api_key_mappings.api_key_id = api_keys.id").
		Where("group_api_key_mappings.key_group_id = ?", groupID).
		Count(&count).Error
	return count, err
}

// --- Helpers ---

func (r *gormKeyRepository) executeTransactionWithRetry(operation func(tx *gorm.DB) error) error {
	const maxRetries = 3
	const baseDelay = 50 * time.Millisecond
	const maxJitter = 150 * time.Millisecond
	var err error

	for i := 0; i < maxRetries; i++ {
		err = r.db.Transaction(operation)
		if err == nil {
			return nil
		}
		if strings.Contains(err.Error(), "database is locked") {
			jitter := time.Duration(rand.Intn(int(maxJitter)))
			totalDelay := baseDelay + jitter
			r.logger.Debugf("Database is locked, retrying in %v... (attempt %d/%d)", totalDelay, i+1, maxRetries)
			time.Sleep(totalDelay)
			continue
		}
		break
	}
	return err
}

func pluckIDs(keys []models.APIKey) []uint {
	ids := make([]uint, 0, len(keys))
	for _, key := range keys {
		ids = append(ids, key.ID)
	}
	return ids
}