package objectstorage

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"time"

	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
	"go.uber.org/zap"

	"github.com/geo-platform/tenant-api/internal/shared/config"
	"github.com/geo-platform/tenant-api/internal/shared/middleware"
)

type minioClient struct {
	client *minio.Client
	bucket string
	region string
	logger *zap.Logger
	cfg    config.ObjectStorageConfig
}

func NewMinIOClient(cfg config.ObjectStorageConfig, logger *zap.Logger) Client {
	endpoint := strings.TrimSpace(cfg.Endpoint)
	accessKey := strings.TrimSpace(cfg.AccessKey)
	secretKey := strings.TrimSpace(cfg.SecretKey)
	bucket := strings.TrimSpace(cfg.Bucket)
	if endpoint == "" || accessKey == "" || secretKey == "" || bucket == "" {
		return disabledClient{reason: "missing object_storage minio endpoint/access_key/secret_key/bucket"}
	}

	region := normalizeMinIORegion(cfg)
	bucketLookup := minio.BucketLookupAuto
	if cfg.ForcePathStyle || isPathStyleProvider(cfg.Provider) {
		bucketLookup = minio.BucketLookupPath
	}

	client, err := minio.New(endpoint, &minio.Options{
		Creds:        credentials.NewStaticV4(accessKey, secretKey, ""),
		Secure:       cfg.UseSSL,
		Region:       region,
		BucketLookup: bucketLookup,
	})
	if err != nil {
		return disabledClient{reason: fmt.Sprintf("init minio client failed: %v", err)}
	}

	return &minioClient{
		client: client,
		bucket: bucket,
		region: region,
		logger: logger,
		cfg:    cfg,
	}
}

func normalizeMinIORegion(cfg config.ObjectStorageConfig) string {
	region := strings.TrimSpace(cfg.Region)
	if region != "" {
		return region
	}
	if isR2Provider(cfg.Provider) {
		return "auto"
	}
	return ""
}

func isR2Provider(provider string) bool {
	switch strings.ToLower(strings.TrimSpace(provider)) {
	case "r2", "cloudflare_r2", "cloudflare-r2":
		return true
	default:
		return false
	}
}

func isPathStyleProvider(provider string) bool {
	switch strings.ToLower(strings.TrimSpace(provider)) {
	case "r2", "cloudflare_r2", "cloudflare-r2":
		return true
	default:
		return false
	}
}

func (c *minioClient) Validate() error {
	if c == nil || c.client == nil {
		return fmt.Errorf("%w: minio client is not initialized", ErrNotConfigured)
	}
	if strings.TrimSpace(c.bucket) == "" {
		return fmt.Errorf("%w: minio bucket is empty", ErrNotConfigured)
	}
	return nil
}

func (c *minioClient) PutBytes(
	ctx context.Context,
	objectKey string,
	content []byte,
	contentType string,
) error {
	return c.PutReader(ctx, objectKey, bytes.NewReader(content), int64(len(content)), contentType)
}

func (c *minioClient) PutReader(
	ctx context.Context,
	objectKey string,
	reader io.Reader,
	size int64,
	contentType string,
) error {
	if err := c.Validate(); err != nil {
		return err
	}
	if strings.TrimSpace(objectKey) == "" {
		return fmt.Errorf("object key is required")
	}
	if reader == nil {
		return fmt.Errorf("object reader is required")
	}

	exists, err := c.client.BucketExists(ctx, c.bucket)
	if err != nil {
		c.logError(ctx, "minio bucket exists check failed",
			zap.String("bucket", c.bucket),
			zap.String("object_key", objectKey),
			zap.Error(err),
		)
		return fmt.Errorf("check minio bucket: %w", err)
	}
	if !exists {
		if err := c.client.MakeBucket(ctx, c.bucket, minio.MakeBucketOptions{Region: c.region}); err != nil {
			c.logError(ctx, "minio create bucket failed",
				zap.String("bucket", c.bucket),
				zap.String("object_key", objectKey),
				zap.Error(err),
			)
			return fmt.Errorf("create minio bucket: %w", err)
		}
	}

	_, err = c.client.PutObject(ctx, c.bucket, objectKey, reader, size, minio.PutObjectOptions{
		ContentType: contentType,
	})
	if err != nil {
		c.logError(ctx, "minio put object failed",
			zap.String("bucket", c.bucket),
			zap.String("object_key", objectKey),
			zap.Int64("content_size", size),
			zap.Error(err),
		)
		return fmt.Errorf("put minio object: %w", err)
	}
	return nil
}

func (c *minioClient) GetBytes(ctx context.Context, objectKey string) ([]byte, error) {
	reader, err := c.GetReader(ctx, objectKey)
	if err != nil {
		return nil, err
	}
	defer reader.Close()

	data, err := io.ReadAll(reader)
	if err != nil {
		c.logError(ctx, "minio read object failed",
			zap.String("bucket", c.bucket),
			zap.String("object_key", objectKey),
			zap.Error(err),
		)
		if isMinIOObjectNotFound(err) {
			return nil, fmt.Errorf("%w: %s", ErrObjectNotFound, objectKey)
		}
		return nil, fmt.Errorf("read minio object: %w", err)
	}
	return data, nil
}

func (c *minioClient) GetReader(ctx context.Context, objectKey string) (io.ReadCloser, error) {
	if err := c.Validate(); err != nil {
		return nil, err
	}
	reader, err := c.client.GetObject(ctx, c.bucket, objectKey, minio.GetObjectOptions{})
	if err != nil {
		c.logError(ctx, "minio get object failed",
			zap.String("bucket", c.bucket),
			zap.String("object_key", objectKey),
			zap.Error(err),
		)
		if isMinIOObjectNotFound(err) {
			return nil, fmt.Errorf("%w: %s", ErrObjectNotFound, objectKey)
		}
		return nil, fmt.Errorf("get minio object: %w", err)
	}
	return reader, nil
}

func isMinIOObjectNotFound(err error) bool {
	responseErr := minio.ToErrorResponse(err)
	return responseErr.StatusCode == 404 ||
		responseErr.Code == "NoSuchKey" ||
		responseErr.Code == "NoSuchObject"
}

func (c *minioClient) Exists(ctx context.Context, objectKey string) (bool, error) {
	if err := c.Validate(); err != nil {
		return false, err
	}
	if strings.TrimSpace(objectKey) == "" {
		return false, nil
	}

	_, err := c.client.StatObject(ctx, c.bucket, objectKey, minio.StatObjectOptions{})
	if err == nil {
		return true, nil
	}

	responseErr := minio.ToErrorResponse(err)
	if responseErr.StatusCode == 404 || responseErr.Code == "NoSuchKey" || responseErr.Code == "NoSuchObject" {
		return false, nil
	}

	c.logError(ctx, "minio stat object failed",
		zap.String("bucket", c.bucket),
		zap.String("object_key", objectKey),
		zap.Error(err),
	)
	return false, fmt.Errorf("stat minio object: %w", err)
}

func (c *minioClient) Delete(ctx context.Context, objectKey string) error {
	if err := c.Validate(); err != nil {
		return err
	}
	if strings.TrimSpace(objectKey) == "" {
		return nil
	}

	err := c.client.RemoveObject(ctx, c.bucket, objectKey, minio.RemoveObjectOptions{})
	if err != nil {
		c.logError(ctx, "minio delete object failed",
			zap.String("bucket", c.bucket),
			zap.String("object_key", objectKey),
			zap.Error(err),
		)
		return fmt.Errorf("delete minio object: %w", err)
	}
	return nil
}

func (c *minioClient) PublicURL(objectKey string) (string, error) {
	if err := c.Validate(); err != nil {
		return "", err
	}
	if !c.isPublicReadable() {
		return c.DownloadURL(objectKey)
	}
	return buildPublicURL(c.cfg, objectKey, false)
}

func (c *minioClient) PublicReadableURL(objectKey string) (string, error) {
	if err := c.Validate(); err != nil {
		return "", err
	}
	if !c.isPublicReadable() {
		return "", ErrObjectNotPublic
	}
	return buildPublicURL(c.cfg, objectKey, false)
}

func (c *minioClient) isPublicReadable() bool {
	return isPublicReadACL(c.cfg.ObjectACL) || isPublicReadACL(c.cfg.BucketACL)
}

func (c *minioClient) DownloadURL(objectKey string) (string, error) {
	if err := c.Validate(); err != nil {
		return "", err
	}
	objectKey = normalizeObjectKeyPath(objectKey)
	if objectKey == "" {
		return "", fmt.Errorf("object key is required")
	}
	ttl := c.cfg.SignedURLTTL
	if ttl <= 0 {
		ttl = 30 * time.Minute
	}
	params := url.Values{}
	params.Set("response-content-disposition", downloadContentDisposition(objectKey))
	u, err := c.client.PresignedGetObject(context.Background(), c.bucket, objectKey, ttl, params)
	if err != nil {
		return "", fmt.Errorf("presign minio download url: %w", err)
	}
	return u.String(), nil
}

func (c *minioClient) PresignedPutURL(
	ctx context.Context,
	objectKey string,
	contentType string,
	contentMD5Base64 string,
	ttl time.Duration,
) (*PresignedPutResult, error) {
	if err := c.Validate(); err != nil {
		return nil, err
	}
	objectKey = normalizeObjectKeyPath(objectKey)
	if objectKey == "" {
		return nil, fmt.Errorf("object key is required")
	}
	if ttl <= 0 {
		ttl = c.cfg.SignedURLTTL
	}
	if ttl <= 0 {
		ttl = 30 * time.Minute
	}

	headers := http.Header{}
	if contentType = strings.TrimSpace(contentType); contentType != "" {
		headers.Set("Content-Type", contentType)
	}
	if contentMD5Base64 = strings.TrimSpace(contentMD5Base64); contentMD5Base64 != "" {
		headers.Set("Content-MD5", contentMD5Base64)
	}
	var u *url.URL
	var err error
	if len(headers) > 0 {
		u, err = c.client.PresignHeader(ctx, http.MethodPut, c.bucket, objectKey, ttl, nil, headers)
	} else {
		u, err = c.client.PresignedPutObject(ctx, c.bucket, objectKey, ttl)
	}
	if err != nil {
		return nil, fmt.Errorf("presign minio put url: %w", err)
	}
	return &PresignedPutResult{
		URL:       u.String(),
		Headers:   headers,
		ExpiresAt: time.Now().UTC().Add(ttl),
	}, nil
}

func (c *minioClient) List(ctx context.Context, in ListInput) (*ListResult, error) {
	if err := c.Validate(); err != nil {
		return nil, err
	}

	limit := in.Limit
	if limit <= 0 || limit > 1000 {
		limit = 100
	}
	delimiter := strings.TrimSpace(in.Delimiter)
	if delimiter == "" && !in.Recursive {
		delimiter = "/"
	}

	core := minio.Core{Client: c.client}
	result, err := core.ListObjectsV2(
		c.bucket,
		normalizeObjectKeyPath(in.Prefix),
		normalizeObjectKeyPath(in.StartAfter),
		strings.TrimSpace(in.ContinuationToken),
		delimiter,
		limit,
	)
	if err != nil {
		c.logError(ctx, "minio list objects failed",
			zap.String("bucket", c.bucket),
			zap.String("prefix", in.Prefix),
			zap.Error(err),
		)
		return nil, fmt.Errorf("list minio objects: %w", err)
	}

	out := &ListResult{
		Objects:               make([]ObjectInfo, 0, len(result.Contents)),
		CommonPrefixes:        make([]string, 0, len(result.CommonPrefixes)),
		ContinuationToken:     result.ContinuationToken,
		NextContinuationToken: result.NextContinuationToken,
		IsTruncated:           result.IsTruncated,
		Prefix:                result.Prefix,
		Delimiter:             result.Delimiter,
	}
	for _, item := range result.Contents {
		out.Objects = append(out.Objects, ObjectInfo{
			Key:          item.Key,
			Size:         item.Size,
			ETag:         strings.Trim(item.ETag, `"`),
			LastModified: item.LastModified,
			ContentType:  item.ContentType,
			StorageClass: item.StorageClass,
		})
	}
	for _, prefix := range result.CommonPrefixes {
		if prefix.Prefix != "" {
			out.CommonPrefixes = append(out.CommonPrefixes, prefix.Prefix)
		}
	}
	return out, nil
}

func (c *minioClient) Stat(ctx context.Context, objectKey string) (*ObjectInfo, error) {
	if err := c.Validate(); err != nil {
		return nil, err
	}
	objectKey = normalizeObjectKeyPath(objectKey)
	if objectKey == "" {
		return nil, fmt.Errorf("object key is required")
	}
	item, err := c.client.StatObject(ctx, c.bucket, objectKey, minio.StatObjectOptions{})
	if err != nil {
		c.logError(ctx, "minio stat object failed",
			zap.String("bucket", c.bucket),
			zap.String("object_key", objectKey),
			zap.Error(err),
		)
		if isMinIOObjectNotFound(err) {
			return nil, fmt.Errorf("%w: %s", ErrObjectNotFound, objectKey)
		}
		return nil, fmt.Errorf("stat minio object: %w", err)
	}
	return &ObjectInfo{
		Key:          item.Key,
		Size:         item.Size,
		ETag:         strings.Trim(item.ETag, `"`),
		LastModified: item.LastModified,
		ContentType:  item.ContentType,
		StorageClass: item.StorageClass,
	}, nil
}

func (c *minioClient) Copy(ctx context.Context, sourceKey, destinationKey string) error {
	if err := c.Validate(); err != nil {
		return err
	}
	sourceKey = normalizeObjectKeyPath(sourceKey)
	destinationKey = normalizeObjectKeyPath(destinationKey)
	if sourceKey == "" || destinationKey == "" {
		return fmt.Errorf("source and destination object keys are required")
	}
	if sourceKey == destinationKey {
		return nil
	}
	_, err := c.client.CopyObject(ctx,
		minio.CopyDestOptions{Bucket: c.bucket, Object: destinationKey},
		minio.CopySrcOptions{Bucket: c.bucket, Object: sourceKey},
	)
	if err != nil {
		c.logError(ctx, "minio copy object failed",
			zap.String("bucket", c.bucket),
			zap.String("source_key", sourceKey),
			zap.String("destination_key", destinationKey),
			zap.Error(err),
		)
		if isMinIOObjectNotFound(err) {
			return fmt.Errorf("%w: %s", ErrObjectNotFound, sourceKey)
		}
		return fmt.Errorf("copy minio object: %w", err)
	}
	return nil
}

func (c *minioClient) logError(ctx context.Context, msg string, fields ...zap.Field) {
	if c == nil || c.logger == nil {
		return
	}
	if requestID := middleware.RequestIDFromContext(ctx); requestID != "" {
		fields = append(fields, zap.String("request_id", requestID))
	}
	c.logger.Error(msg, fields...)
}