package db

import (
	"context"
	"crypto/md5"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"
)

type User struct {
	ID                int64     `json:"id"`
	Username          string    `json:"username"`
	Email             string    `json:"email"`
	APIKey            string    `json:"apiKey,omitempty"`
	StorageLimitBytes int64     `json:"storageLimitBytes"`
	CreatedAt         time.Time `json:"createdAt"`
}

type Bucket struct {
	ID               int64     `json:"id"`
	Name             string    `json:"name"`
	OwnerID          int64     `json:"ownerId"`
	StorageUsedBytes int64     `json:"storageUsedBytes"`
	CreatedAt        time.Time `json:"createdAt"`
}

type Object struct {
	ID             int64             `json:"id"`
	BucketID       int64             `json:"bucketId"`
	Key            string            `json:"key"`
	SizeBytes      int64             `json:"sizeBytes"`
	ContentType    string            `json:"contentType"`
	LastModified   time.Time         `json:"lastModified"`
	VersionID      string            `json:"versionId"`
	MD5Checksum    string            `json:"md5Checksum"`
	CustomMetadata map[string]string `json:"customMetadata"`
}

type BucketService struct {
	pool *pgxpool.Pool
}

func NewBucketService(pool *pgxpool.Pool) *BucketService {
	return &BucketService{pool: pool}
}

func (s *BucketService) CreateUser(ctx context.Context, username, email, apiKey string, storageLimit int64) (*User, error) {
	var user User
	err := s.pool.QueryRow(ctx, `
		INSERT INTO users (username, email, api_key, storage_limit_bytes) 
		VALUES ($1, $2, $3, $4) 
		RETURNING id, username, email, storage_limit_bytes, created_at`,
		username, email, apiKey, storageLimit).Scan(
		&user.ID, &user.Username, &user.Email, &user.StorageLimitBytes, &user.CreatedAt)
	if err != nil {
		return nil, fmt.Errorf("failed to create user: %w", err)
	}
	return &user, nil
}

func (s *BucketService) GetUserByAPIKey(ctx context.Context, apiKey string) (*User, error) {
	var user User
	err := s.pool.QueryRow(ctx, `
		SELECT id, username, email, api_key, storage_limit_bytes, created_at 
		FROM users WHERE api_key = $1`,
		apiKey).Scan(&user.ID, &user.Username, &user.Email, &user.APIKey, &user.StorageLimitBytes, &user.CreatedAt)
	if err != nil {
		return nil, fmt.Errorf("failed to get user by API key: %w", err)
	}
	return &user, nil
}

func (s *BucketService) CreateBucket(ctx context.Context, name string, ownerID int64) (*Bucket, error) {
	var bucket Bucket
	err := s.pool.QueryRow(ctx, `
		INSERT INTO buckets (name, owner_id) 
		VALUES ($1, $2) 
		RETURNING id, name, owner_id, storage_used_bytes, created_at`,
		name, ownerID).Scan(
		&bucket.ID, &bucket.Name, &bucket.OwnerID, &bucket.StorageUsedBytes, &bucket.CreatedAt)
	if err != nil {
		return nil, fmt.Errorf("failed to create bucket: %w", err)
	}
	return &bucket, nil
}

func (s *BucketService) GetUserBuckets(ctx context.Context, ownerID int64) ([]Bucket, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT id, name, owner_id, storage_used_bytes, created_at 
		FROM buckets WHERE owner_id = $1 ORDER BY created_at DESC`,
		ownerID)
	if err != nil {
		return nil, fmt.Errorf("failed to get user buckets: %w", err)
	}
	defer rows.Close()

	var buckets []Bucket
	for rows.Next() {
		var bucket Bucket
		err := rows.Scan(&bucket.ID, &bucket.Name, &bucket.OwnerID, &bucket.StorageUsedBytes, &bucket.CreatedAt)
		if err != nil {
			return nil, fmt.Errorf("failed to scan bucket: %w", err)
		}
		buckets = append(buckets, bucket)
	}
	return buckets, nil
}

func (s *BucketService) GetBucket(ctx context.Context, bucketName string, ownerID int64) (*Bucket, error) {
	var bucket Bucket
	err := s.pool.QueryRow(ctx, `
		SELECT id, name, owner_id, storage_used_bytes, created_at 
		FROM buckets WHERE name = $1 AND owner_id = $2`,
		bucketName, ownerID).Scan(
		&bucket.ID, &bucket.Name, &bucket.OwnerID, &bucket.StorageUsedBytes, &bucket.CreatedAt)
	if err != nil {
		return nil, fmt.Errorf("failed to get bucket: %w", err)
	}
	return &bucket, nil
}

func (s *BucketService) DeleteBucket(ctx context.Context, bucketName string, ownerID int64) error {
	bucket, err := s.GetBucket(ctx, bucketName, ownerID)
	if err != nil {
		return err
	}

	objects, err := s.ListObjects(ctx, bucket.ID)
	if err != nil {
		return fmt.Errorf("failed to list objects for deletion: %w", err)
	}

	for _, obj := range objects {
		if err := os.Remove(filepath.Join("storage", bucketName, obj.Key)); err != nil {
			continue
		}
	}

	os.RemoveAll(filepath.Join("storage", bucketName))

	_, err = s.pool.Exec(ctx, "DELETE FROM buckets WHERE name = $1 AND owner_id = $2", bucketName, ownerID)
	if err != nil {
		return fmt.Errorf("failed to delete bucket: %w", err)
	}
	return nil
}

func (s *BucketService) UploadObject(ctx context.Context, bucketID int64, key string, size int64, contentType string, content io.Reader) (*Object, error) {
	bucket, err := s.getBucketByID(ctx, bucketID)
	if err != nil {
		return nil, err
	}

	user, err := s.getUserByID(ctx, bucket.OwnerID)
	if err != nil {
		return nil, err
	}

	if bucket.StorageUsedBytes+size > user.StorageLimitBytes {
		return nil, fmt.Errorf("storage limit exceeded")
	}

	bucketDir := filepath.Join("storage", bucket.Name)
	if err := os.MkdirAll(bucketDir, 0755); err != nil {
		return nil, fmt.Errorf("failed to create bucket directory: %w", err)
	}

	filePath := filepath.Join(bucketDir, key)
	file, err := os.Create(filePath)
	if err != nil {
		return nil, fmt.Errorf("failed to create file: %w", err)
	}
	defer file.Close()

	hasher := md5.New()
	writer := io.MultiWriter(file, hasher)

	if _, err := io.Copy(writer, content); err != nil {
		os.Remove(filePath)
		return nil, fmt.Errorf("failed to write file: %w", err)
	}

	md5Sum := fmt.Sprintf("%x", hasher.Sum(nil))

	var object Object
	err = s.pool.QueryRow(ctx, `
		INSERT INTO objects (bucket_id, key, size_bytes, content_type, md5_checksum) 
		VALUES ($1, $2, $3, $4, $5) 
		ON CONFLICT (bucket_id, key) 
		DO UPDATE SET size_bytes = $3, content_type = $4, md5_checksum = $5, last_modified = NOW()
		RETURNING id, bucket_id, key, size_bytes, content_type, last_modified, md5_checksum`,
		bucketID, key, size, contentType, md5Sum).Scan(
		&object.ID, &object.BucketID, &object.Key, &object.SizeBytes, &object.ContentType, &object.LastModified, &object.MD5Checksum)
	if err != nil {
		os.Remove(filePath)
		return nil, fmt.Errorf("failed to create object record: %w", err)
	}

	return &object, nil
}

func (s *BucketService) ListObjects(ctx context.Context, bucketID int64) ([]Object, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT id, bucket_id, key, size_bytes, content_type, last_modified, 
			   COALESCE(version_id, ''), COALESCE(md5_checksum, '') 
		FROM objects WHERE bucket_id = $1 ORDER BY last_modified DESC`,
		bucketID)
	if err != nil {
		return nil, fmt.Errorf("failed to list objects: %w", err)
	}
	defer rows.Close()

	var objects []Object
	for rows.Next() {
		var object Object
		err := rows.Scan(&object.ID, &object.BucketID, &object.Key, &object.SizeBytes,
			&object.ContentType, &object.LastModified, &object.VersionID, &object.MD5Checksum)
		if err != nil {
			return nil, fmt.Errorf("failed to scan object: %w", err)
		}
		objects = append(objects, object)
	}
	return objects, nil
}

func (s *BucketService) GetObject(ctx context.Context, bucketID int64, key string) (*Object, error) {
	var object Object
	err := s.pool.QueryRow(ctx, `
		SELECT id, bucket_id, key, size_bytes, content_type, last_modified, 
			   COALESCE(version_id, ''), COALESCE(md5_checksum, '') 
		FROM objects WHERE bucket_id = $1 AND key = $2`,
		bucketID, key).Scan(
		&object.ID, &object.BucketID, &object.Key, &object.SizeBytes,
		&object.ContentType, &object.LastModified, &object.VersionID, &object.MD5Checksum)
	if err != nil {
		return nil, fmt.Errorf("failed to get object: %w", err)
	}
	return &object, nil
}

func (s *BucketService) DeleteObject(ctx context.Context, bucketID int64, key string) error {
	bucket, err := s.getBucketByID(ctx, bucketID)
	if err != nil {
		return err
	}

	filePath := filepath.Join("storage", bucket.Name, key)
	if err := os.Remove(filePath); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("failed to remove file: %w", err)
	}

	_, err = s.pool.Exec(ctx, "DELETE FROM objects WHERE bucket_id = $1 AND key = $2", bucketID, key)
	if err != nil {
		return fmt.Errorf("failed to delete object record: %w", err)
	}
	return nil
}

func (s *BucketService) GetObjectFile(ctx context.Context, bucketName, key string, ownerID int64) (*os.File, error) {
	bucket, err := s.GetBucket(ctx, bucketName, ownerID)
	if err != nil {
		return nil, err
	}

	_, err = s.GetObject(ctx, bucket.ID, key)
	if err != nil {
		return nil, err
	}

	filePath := filepath.Join("storage", bucketName, key)
	file, err := os.Open(filePath)
	if err != nil {
		return nil, fmt.Errorf("failed to open file: %w", err)
	}
	return file, nil
}

func (s *BucketService) getBucketByID(ctx context.Context, bucketID int64) (*Bucket, error) {
	var bucket Bucket
	err := s.pool.QueryRow(ctx, `
		SELECT id, name, owner_id, storage_used_bytes, created_at 
		FROM buckets WHERE id = $1`,
		bucketID).Scan(
		&bucket.ID, &bucket.Name, &bucket.OwnerID, &bucket.StorageUsedBytes, &bucket.CreatedAt)
	if err != nil {
		return nil, fmt.Errorf("failed to get bucket by ID: %w", err)
	}
	return &bucket, nil
}

func (s *BucketService) getUserByID(ctx context.Context, userID int64) (*User, error) {
	var user User
	err := s.pool.QueryRow(ctx, `
		SELECT id, username, email, storage_limit_bytes, created_at 
		FROM users WHERE id = $1`,
		userID).Scan(&user.ID, &user.Username, &user.Email, &user.StorageLimitBytes, &user.CreatedAt)
	if err != nil {
		return nil, fmt.Errorf("failed to get user by ID: %w", err)
	}
	return &user, nil
}