package storage

import (
	"context"
	"fmt"
	"io"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/config"
	"github.com/aws/aws-sdk-go-v2/credentials"
	"github.com/aws/aws-sdk-go-v2/service/s3"
)

// R2Store 走 Cloudflare R2 的 S3 兼容 API。endpoint 是账户级端点
// （https://<accountid>.r2.cloudflarestorage.com），R2 两种寻址都支持，
// 这里用 path-style 最稳。
//
// 端点 URL 里的路径段（如果有）不交给 SDK —— path-style 下它会被折进
// 对象 key，导致「数据库 key」和「实际对象 key」对不上（直链 404）。
// 这里只取 scheme://host 当端点；路径段由 EndpointKeyPrefix 暴露给
// 上传 handler 拼进 key，三处（存储 / 数据库 / 直链）从此一致。
type R2Store struct {
	client *s3.Client
	bucket string
}

func NewR2(endpoint, bucket, accessKey, secretKey string) (*R2Store, error) {
	if endpoint == "" || bucket == "" {
		return nil, fmt.Errorf("r2: endpoint/bucket required")
	}
	// R2 不认 region，SDK 又必须有——官方文档给的值就是 "auto"。
	cfg, err := config.LoadDefaultConfig(context.TODO(),
		config.WithRegion("auto"),
		config.WithCredentialsProvider(credentials.NewStaticCredentialsProvider(accessKey, secretKey, "")),
		config.WithBaseEndpoint(StripEndpointPath(endpoint)),
	)
	if err != nil {
		return nil, fmt.Errorf("r2: load aws config: %w", err)
	}
	client := s3.NewFromConfig(cfg, func(o *s3.Options) {
		o.UsePathStyle = true
	})
	return &R2Store{client: client, bucket: bucket}, nil
}

func (s *R2Store) Put(ctx context.Context, key string, r io.Reader, size int64, contentType string) error {
	_, err := s.client.PutObject(ctx, &s3.PutObjectInput{
		Bucket:        aws.String(s.bucket),
		Key:           aws.String(key),
		Body:          r,
		ContentLength: aws.Int64(size),
		ContentType:   aws.String(contentType),
	})
	return err
}

func (s *R2Store) Open(ctx context.Context, key string) (io.ReadCloser, int64, error) {
	out, err := s.client.GetObject(ctx, &s3.GetObjectInput{
		Bucket: aws.String(s.bucket),
		Key:    aws.String(key),
	})
	if err != nil {
		return nil, 0, err
	}
	return out.Body, *out.ContentLength, nil
}

func (s *R2Store) Delete(ctx context.Context, key string) error {
	_, err := s.client.DeleteObject(ctx, &s3.DeleteObjectInput{
		Bucket: aws.String(s.bucket),
		Key:    aws.String(key),
	})
	return err
}