package storage

import (
	"context"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/credentials"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/s3"
	"github.com/aws/aws-sdk-go/service/s3/s3manager"

	"github.com/break/junhong_cmp_fiber/pkg/config"
)

type S3Provider struct {
	client   *s3.S3
	uploader *s3manager.Uploader
	bucket   string
	tempDir  string
}

func NewS3Provider(cfg *config.StorageConfig) (*S3Provider, error) {
	if cfg.S3.Endpoint == "" || cfg.S3.Bucket == "" {
		return nil, fmt.Errorf("S3 配置不完整：endpoint 和 bucket 必填")
	}

	if cfg.S3.AccessKeyID == "" || cfg.S3.SecretAccessKey == "" {
		return nil, fmt.Errorf("S3 凭证未配置：access_key_id 和 secret_access_key 必填")
	}

	sess, err := session.NewSession(&aws.Config{
		Endpoint:         aws.String(cfg.S3.Endpoint),
		Region:           aws.String(cfg.S3.Region),
		Credentials:      credentials.NewStaticCredentials(cfg.S3.AccessKeyID, cfg.S3.SecretAccessKey, ""),
		DisableSSL:       aws.Bool(!cfg.S3.UseSSL),
		S3ForcePathStyle: aws.Bool(cfg.S3.PathStyle),
	})
	if err != nil {
		return nil, fmt.Errorf("创建 S3 session 失败: %w", err)
	}

	tempDir := cfg.TempDir
	if tempDir == "" {
		tempDir = "/tmp/junhong-storage"
	}

	return &S3Provider{
		client:   s3.New(sess),
		uploader: s3manager.NewUploader(sess),
		bucket:   cfg.S3.Bucket,
		tempDir:  tempDir,
	}, nil
}

func (p *S3Provider) Upload(ctx context.Context, key string, reader io.Reader, contentType string) error {
	input := &s3manager.UploadInput{
		Bucket:      aws.String(p.bucket),
		Key:         aws.String(key),
		Body:        reader,
		ContentType: aws.String(contentType),
	}

	_, err := p.uploader.UploadWithContext(ctx, input)
	if err != nil {
		return fmt.Errorf("上传文件失败: %w", err)
	}
	return nil
}

func (p *S3Provider) Download(ctx context.Context, key string, writer io.Writer) error {
	input := &s3.GetObjectInput{
		Bucket: aws.String(p.bucket),
		Key:    aws.String(key),
	}

	result, err := p.client.GetObjectWithContext(ctx, input)
	if err != nil {
		if strings.Contains(err.Error(), "NoSuchKey") {
			return fmt.Errorf("文件不存在: %s", key)
		}
		return fmt.Errorf("下载文件失败: %w", err)
	}
	defer result.Body.Close()

	_, err = io.Copy(writer, result.Body)
	if err != nil {
		return fmt.Errorf("写入文件内容失败: %w", err)
	}
	return nil
}

func (p *S3Provider) DownloadToTemp(ctx context.Context, key string) (string, func(), error) {
	ext := filepath.Ext(key)
	if ext == "" {
		ext = ".tmp"
	}

	tempFile, err := os.CreateTemp(p.tempDir, "download-*"+ext)
	if err != nil {
		return "", nil, fmt.Errorf("创建临时文件失败: %w", err)
	}
	tempPath := tempFile.Name()

	cleanup := func() {
		_ = os.Remove(tempPath)
	}

	if err := p.Download(ctx, key, tempFile); err != nil {
		tempFile.Close()
		cleanup()
		return "", nil, err
	}

	if err := tempFile.Close(); err != nil {
		cleanup()
		return "", nil, fmt.Errorf("关闭临时文件失败: %w", err)
	}

	return tempPath, cleanup, nil
}

func (p *S3Provider) Delete(ctx context.Context, key string) error {
	input := &s3.DeleteObjectInput{
		Bucket: aws.String(p.bucket),
		Key:    aws.String(key),
	}

	_, err := p.client.DeleteObjectWithContext(ctx, input)
	if err != nil {
		return fmt.Errorf("删除文件失败: %w", err)
	}
	return nil
}

func (p *S3Provider) Exists(ctx context.Context, key string) (bool, error) {
	input := &s3.HeadObjectInput{
		Bucket: aws.String(p.bucket),
		Key:    aws.String(key),
	}

	_, err := p.client.HeadObjectWithContext(ctx, input)
	if err != nil {
		if strings.Contains(err.Error(), "NotFound") || strings.Contains(err.Error(), "404") {
			return false, nil
		}
		return false, fmt.Errorf("检查文件存在性失败: %w", err)
	}
	return true, nil
}

func (p *S3Provider) GetUploadURL(ctx context.Context, key string, contentType string, expires time.Duration) (string, error) {
	input := &s3.PutObjectInput{
		Bucket:      aws.String(p.bucket),
		Key:         aws.String(key),
		ContentType: aws.String(contentType),
	}

	req, _ := p.client.PutObjectRequest(input)
	url, err := req.Presign(expires)
	if err != nil {
		return "", fmt.Errorf("生成上传预签名 URL 失败: %w", err)
	}
	return url, nil
}

func (p *S3Provider) GetDownloadURL(ctx context.Context, key string, expires time.Duration) (string, error) {
	input := &s3.GetObjectInput{
		Bucket: aws.String(p.bucket),
		Key:    aws.String(key),
	}

	req, _ := p.client.GetObjectRequest(input)
	url, err := req.Presign(expires)
	if err != nil {
		return "", fmt.Errorf("生成下载预签名 URL 失败: %w", err)
	}
	return url, nil
}