package services

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/url"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"time"

	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
	"go.etcd.io/bbolt"
)

var storageBackendsBucket = []byte("storage_backends")

const (
	StorageBackendLocal = "local"
	StorageBackendS3    = "s3"

	StorageProviderS3      = "s3"
	StorageProviderContabo = "contabo"
)

type StorageObject struct {
	Key         string
	Size        int64
	ContentType string
	ModTime     time.Time
	Body        io.ReadCloser
}

type StorageBackend interface {
	ID() string
	Type() string
	Put(ctx context.Context, key string, body io.Reader, size int64, contentType string) error
	Get(ctx context.Context, key string) (StorageObject, error)
	Delete(ctx context.Context, key string) error
	DeletePrefix(ctx context.Context, prefix string) error
	Usage(ctx context.Context) (int64, error)
	Test(ctx context.Context) error
}

type StorageBackendConfig struct {
	ID              string    `json:"id"`
	Name            string    `json:"name"`
	Type            string    `json:"type"`
	Provider        string    `json:"provider,omitempty"`
	Enabled         bool      `json:"enabled"`
	LocalPath       string    `json:"localPath,omitempty"`
	Endpoint        string    `json:"endpoint,omitempty"`
	Region          string    `json:"region,omitempty"`
	Bucket          string    `json:"bucket,omitempty"`
	AccessKey       string    `json:"accessKey,omitempty"`
	SecretKey       string    `json:"secretKey,omitempty"`
	UseSSL          bool      `json:"useSsl,omitempty"`
	PathStyle       bool      `json:"pathStyle,omitempty"`
	CreatedAt       time.Time `json:"createdAt"`
	UpdatedAt       time.Time `json:"updatedAt"`
	LastTestedAt    time.Time `json:"lastTestedAt,omitempty"`
	LastTestError   string    `json:"lastTestError,omitempty"`
	LastTestSuccess bool      `json:"lastTestSuccess,omitempty"`
}

type StorageBackendView struct {
	Config     StorageBackendConfig
	UsageBytes int64
	UsageLabel string
	InUse      bool
}

type StorageService struct {
	db            *bbolt.DB
	localFilesDir string
}

func NewStorageService(db *bbolt.DB, dataDir string) (*StorageService, error) {
	filesDir := filepath.Join(dataDir, "files")
	if err := os.MkdirAll(filesDir, 0o755); err != nil {
		return nil, err
	}
	service := &StorageService{db: db, localFilesDir: filesDir}
	err := db.Update(func(tx *bbolt.Tx) error {
		_, err := tx.CreateBucketIfNotExists(storageBackendsBucket)
		return err
	})
	if err != nil {
		return nil, err
	}
	return service, nil
}

func (s *StorageService) LocalFilesDir() string {
	return s.localFilesDir
}

func (s *StorageService) Backend(id string) (StorageBackend, error) {
	cfg, err := s.BackendConfig(id)
	if err != nil {
		return nil, err
	}
	if !cfg.Enabled {
		return nil, fmt.Errorf("storage backend is disabled")
	}
	return s.backendFromConfig(cfg)
}

func (s *StorageService) BackendConfig(id string) (StorageBackendConfig, error) {
	id = strings.TrimSpace(id)
	if id == "" || id == StorageBackendLocal {
		return s.localConfig(), nil
	}
	var cfg StorageBackendConfig
	err := s.db.View(func(tx *bbolt.Tx) error {
		data := tx.Bucket(storageBackendsBucket).Get([]byte(id))
		if data == nil {
			return os.ErrNotExist
		}
		return json.Unmarshal(data, &cfg)
	})
	if err != nil {
		return StorageBackendConfig{}, err
	}
	return cfg, nil
}

func (s *StorageService) ListBackendConfigs() ([]StorageBackendConfig, error) {
	configs := []StorageBackendConfig{s.localConfig()}
	err := s.db.View(func(tx *bbolt.Tx) error {
		return tx.Bucket(storageBackendsBucket).ForEach(func(_, value []byte) error {
			var cfg StorageBackendConfig
			if err := json.Unmarshal(value, &cfg); err != nil {
				return err
			}
			configs = append(configs, cfg)
			return nil
		})
	})
	sort.Slice(configs, func(i, j int) bool {
		if configs[i].ID == StorageBackendLocal {
			return true
		}
		if configs[j].ID == StorageBackendLocal {
			return false
		}
		return strings.ToLower(configs[i].Name) < strings.ToLower(configs[j].Name)
	})
	return configs, err
}

func (s *StorageService) CreateS3Backend(input StorageBackendConfig) (StorageBackendConfig, error) {
	input.ID = randomID(10)
	input.Type = StorageBackendS3
	input.Provider = normalizeStorageProvider(input.Provider)
	if input.Provider == StorageProviderContabo {
		input.UseSSL = true
		input.PathStyle = true
	}
	input.Name = strings.TrimSpace(input.Name)
	input.Endpoint = strings.TrimSpace(input.Endpoint)
	input.Region = strings.TrimSpace(input.Region)
	input.Bucket = strings.TrimSpace(input.Bucket)
	input.AccessKey = strings.TrimSpace(input.AccessKey)
	input.SecretKey = strings.TrimSpace(input.SecretKey)
	if input.Name == "" {
		input.Name = input.Bucket
	}
	if input.Name == "" || input.Endpoint == "" || input.Bucket == "" || input.AccessKey == "" || input.SecretKey == "" {
		return StorageBackendConfig{}, fmt.Errorf("name, endpoint, bucket, access key, and secret key are required")
	}
	now := time.Now().UTC()
	input.Enabled = true
	input.CreatedAt = now
	input.UpdatedAt = now
	if err := s.SaveBackendConfig(input); err != nil {
		return StorageBackendConfig{}, err
	}
	return input, nil
}

func (s *StorageService) UpdateS3Backend(id string, input StorageBackendConfig) (StorageBackendConfig, error) {
	current, err := s.BackendConfig(id)
	if err != nil {
		return StorageBackendConfig{}, err
	}
	if current.ID == StorageBackendLocal || current.Type != StorageBackendS3 {
		return StorageBackendConfig{}, fmt.Errorf("only S3-compatible storage can be edited")
	}

	current.Provider = normalizeStorageProvider(input.Provider)
	if current.Provider == StorageProviderContabo {
		input.UseSSL = true
		input.PathStyle = true
	}
	current.Name = strings.TrimSpace(input.Name)
	current.Endpoint = strings.TrimSpace(input.Endpoint)
	current.Region = strings.TrimSpace(input.Region)
	current.Bucket = strings.TrimSpace(input.Bucket)
	current.AccessKey = strings.TrimSpace(input.AccessKey)
	if strings.TrimSpace(input.SecretKey) != "" {
		current.SecretKey = strings.TrimSpace(input.SecretKey)
	}
	current.UseSSL = input.UseSSL
	current.PathStyle = input.PathStyle
	if current.Name == "" {
		current.Name = current.Bucket
	}
	if current.Name == "" || current.Endpoint == "" || current.Bucket == "" || current.AccessKey == "" || current.SecretKey == "" {
		return StorageBackendConfig{}, fmt.Errorf("name, endpoint, bucket, access key, and secret key are required")
	}
	if err := s.SaveBackendConfig(current); err != nil {
		return StorageBackendConfig{}, err
	}
	return current, nil
}

func (s *StorageService) SaveBackendConfig(cfg StorageBackendConfig) error {
	if cfg.ID == "" || cfg.ID == StorageBackendLocal {
		return fmt.Errorf("invalid storage backend id")
	}
	cfg.UpdatedAt = time.Now().UTC()
	data, err := json.Marshal(cfg)
	if err != nil {
		return err
	}
	return s.db.Update(func(tx *bbolt.Tx) error {
		return tx.Bucket(storageBackendsBucket).Put([]byte(cfg.ID), data)
	})
}

func (s *StorageService) DisableBackend(id string, inUse bool) error {
	if id == "" || id == StorageBackendLocal {
		return fmt.Errorf("local storage cannot be disabled")
	}
	if inUse {
		return fmt.Errorf("storage backend is in use")
	}
	cfg, err := s.BackendConfig(id)
	if err != nil {
		return err
	}
	cfg.Enabled = false
	return s.SaveBackendConfig(cfg)
}

func (s *StorageService) DeleteBackend(id string, inUse bool) error {
	if id == "" || id == StorageBackendLocal {
		return fmt.Errorf("local storage cannot be deleted")
	}
	if inUse {
		return fmt.Errorf("storage backend is in use")
	}
	return s.db.Update(func(tx *bbolt.Tx) error {
		return tx.Bucket(storageBackendsBucket).Delete([]byte(id))
	})
}

func (s *StorageService) TestBackend(id string) (StorageBackendConfig, error) {
	cfg, err := s.BackendConfig(id)
	if err != nil {
		return StorageBackendConfig{}, err
	}
	backend, err := s.backendFromConfig(cfg)
	if err != nil {
		return StorageBackendConfig{}, err
	}
	err = backend.Test(context.Background())
	cfg.LastTestedAt = time.Now().UTC()
	cfg.LastTestError = ""
	cfg.LastTestSuccess = err == nil
	if err != nil {
		cfg.LastTestError = err.Error()
	}
	if cfg.ID != StorageBackendLocal {
		_ = s.SaveBackendConfig(cfg)
	}
	return cfg, err
}

func (s *StorageService) backendFromConfig(cfg StorageBackendConfig) (StorageBackend, error) {
	switch cfg.Type {
	case StorageBackendLocal:
		return localStorageBackend{id: cfg.ID, root: cfg.LocalPath}, nil
	case StorageBackendS3:
		return newS3StorageBackend(cfg)
	default:
		return nil, fmt.Errorf("unsupported storage backend type %q", cfg.Type)
	}
}

func (s *StorageService) localConfig() StorageBackendConfig {
	now := time.Now().UTC()
	return StorageBackendConfig{
		ID:        StorageBackendLocal,
		Name:      "Local files",
		Type:      StorageBackendLocal,
		Provider:  StorageBackendLocal,
		Enabled:   true,
		LocalPath: s.localFilesDir,
		CreatedAt: now,
		UpdatedAt: now,
	}
}

type localStorageBackend struct {
	id   string
	root string
}

func (b localStorageBackend) ID() string   { return b.id }
func (b localStorageBackend) Type() string { return StorageBackendLocal }

func (b localStorageBackend) Put(_ context.Context, key string, body io.Reader, _ int64, _ string) error {
	path, err := b.path(key)
	if err != nil {
		return err
	}
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return err
	}
	target, err := os.OpenFile(path, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0o644)
	if err != nil {
		return err
	}
	defer target.Close()
	_, err = io.Copy(target, body)
	return err
}

func (b localStorageBackend) Get(_ context.Context, key string) (StorageObject, error) {
	path, err := b.path(key)
	if err != nil {
		return StorageObject{}, err
	}
	source, err := os.Open(path)
	if err != nil {
		return StorageObject{}, err
	}
	stat, err := source.Stat()
	if err != nil {
		source.Close()
		return StorageObject{}, err
	}
	return StorageObject{Key: key, Size: stat.Size(), ModTime: stat.ModTime(), Body: source}, nil
}

func (b localStorageBackend) Delete(_ context.Context, key string) error {
	path, err := b.path(key)
	if err != nil {
		return err
	}
	if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
		return err
	}
	return nil
}

func (b localStorageBackend) DeletePrefix(_ context.Context, prefix string) error {
	path, err := b.path(prefix)
	if err != nil {
		return err
	}
	if err := os.RemoveAll(path); err != nil && !os.IsNotExist(err) {
		return err
	}
	return nil
}

func (b localStorageBackend) Usage(_ context.Context) (int64, error) {
	var total int64
	err := filepath.WalkDir(b.root, func(path string, entry os.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if entry.IsDir() {
			return nil
		}
		info, err := entry.Info()
		if err != nil {
			return err
		}
		total += info.Size()
		return nil
	})
	if os.IsNotExist(err) {
		return 0, nil
	}
	return total, err
}

func (b localStorageBackend) Test(ctx context.Context) error {
	key := ".warpbox-storage-test-" + randomID(6)
	if err := b.Put(ctx, key, strings.NewReader("ok"), 2, "text/plain"); err != nil {
		return err
	}
	return b.Delete(ctx, key)
}

func (b localStorageBackend) path(key string) (string, error) {
	key = filepath.Clean(strings.TrimPrefix(key, "/"))
	if key == "." || strings.HasPrefix(key, "..") || filepath.IsAbs(key) {
		return "", fmt.Errorf("invalid storage key")
	}
	path := filepath.Join(b.root, key)
	root, err := filepath.Abs(b.root)
	if err != nil {
		return "", err
	}
	abs, err := filepath.Abs(path)
	if err != nil {
		return "", err
	}
	if abs != root && !strings.HasPrefix(abs, root+string(os.PathSeparator)) {
		return "", fmt.Errorf("invalid storage key")
	}
	return abs, nil
}

type s3StorageBackend struct {
	cfg    StorageBackendConfig
	client *minio.Client
}

func newS3StorageBackend(cfg StorageBackendConfig) (*s3StorageBackend, error) {
	endpoint := normalizeS3Endpoint(cfg.Endpoint)
	client, err := minio.New(endpoint, &minio.Options{
		Creds:        credentials.NewStaticV4(cfg.AccessKey, cfg.SecretKey, ""),
		Secure:       cfg.UseSSL,
		Region:       cfg.Region,
		BucketLookup: s3BucketLookup(cfg.PathStyle),
	})
	if err != nil {
		return nil, err
	}
	return &s3StorageBackend{cfg: cfg, client: client}, nil
}

func (b *s3StorageBackend) ID() string   { return b.cfg.ID }
func (b *s3StorageBackend) Type() string { return StorageBackendS3 }

func (b *s3StorageBackend) Put(ctx context.Context, key string, body io.Reader, size int64, contentType string) error {
	opts := minio.PutObjectOptions{ContentType: contentType}
	_, err := b.client.PutObject(ctx, b.cfg.Bucket, cleanObjectKey(key), body, size, opts)
	return err
}

func (b *s3StorageBackend) Get(ctx context.Context, key string) (StorageObject, error) {
	object, err := b.client.GetObject(ctx, b.cfg.Bucket, cleanObjectKey(key), minio.GetObjectOptions{})
	if err != nil {
		return StorageObject{}, err
	}
	info, err := object.Stat()
	if err != nil {
		object.Close()
		return StorageObject{}, err
	}
	return StorageObject{Key: key, Size: info.Size, ContentType: info.ContentType, ModTime: info.LastModified, Body: object}, nil
}

func (b *s3StorageBackend) Delete(ctx context.Context, key string) error {
	return b.client.RemoveObject(ctx, b.cfg.Bucket, cleanObjectKey(key), minio.RemoveObjectOptions{})
}

func (b *s3StorageBackend) DeletePrefix(ctx context.Context, prefix string) error {
	prefix = strings.TrimSuffix(cleanObjectKey(prefix), "/") + "/"
	objects := b.client.ListObjects(ctx, b.cfg.Bucket, minio.ListObjectsOptions{Prefix: prefix, Recursive: true})
	for object := range objects {
		if object.Err != nil {
			return object.Err
		}
		if err := b.Delete(ctx, object.Key); err != nil {
			return err
		}
	}
	return nil
}

func (b *s3StorageBackend) Usage(ctx context.Context) (int64, error) {
	var total int64
	for object := range b.client.ListObjects(ctx, b.cfg.Bucket, minio.ListObjectsOptions{Recursive: true}) {
		if object.Err != nil {
			return 0, object.Err
		}
		total += object.Size
	}
	return total, nil
}

func (b *s3StorageBackend) Test(ctx context.Context) error {
	exists, err := b.client.BucketExists(ctx, b.cfg.Bucket)
	if err != nil {
		return err
	}
	if !exists {
		return fmt.Errorf("bucket %q does not exist", b.cfg.Bucket)
	}
	key := ".warpbox-storage-test-" + randomID(6)
	if err := b.Put(ctx, key, bytes.NewReader([]byte("ok")), 2, "text/plain"); err != nil {
		return err
	}
	return b.Delete(ctx, key)
}

func s3BucketLookup(pathStyle bool) minio.BucketLookupType {
	if pathStyle {
		return minio.BucketLookupPath
	}
	return minio.BucketLookupAuto
}

func normalizeS3Endpoint(endpoint string) string {
	endpoint = strings.TrimSpace(endpoint)
	if parsed, err := url.Parse(endpoint); err == nil && parsed.Host != "" {
		return parsed.Host
	}
	return strings.TrimPrefix(strings.TrimPrefix(endpoint, "https://"), "http://")
}

func normalizeStorageProvider(provider string) string {
	switch strings.TrimSpace(provider) {
	case StorageProviderContabo:
		return StorageProviderContabo
	default:
		return StorageProviderS3
	}
}

func cleanObjectKey(key string) string {
	return strings.TrimPrefix(filepath.ToSlash(filepath.Clean(strings.TrimPrefix(key, "/"))), "./")
}