package uploader

import (
	"bytes"
	"fmt"
	"image/png"
	"math/rand"
	"strings"
	"time"

	"github.com/aliyun/aliyun-oss-go-sdk/oss"
	"github.com/topfans/laserCompositor/config"
)

// OSSUploader OSS 上传器
type OSSUploader struct {
	cfg config.OSSConfig
}

// NewOSSUploader 创建 OSS 上传器
func NewOSSUploader(cfg config.OSSConfig) *OSSUploader {
	return &OSSUploader{cfg: cfg}
}

// UploadResult 上传结果
type UploadResult struct {
	OSSKey    string `json:"oss_key"`
	SignedURL string `json:"signed_url"`
}

// UploadPNG 上传 PNG 到 OSS，返回 oss_key 和 signed_url
func (u *OSSUploader) UploadPNG(data []byte, dir, filename string) (*UploadResult, error) {
	bucket, err := u.getBucket()
	if err != nil {
		return nil, err
	}

	if dir == "" {
		dir = "laser-card/"
	}
	if filename == "" {
		filename = fmt.Sprintf("%d_%d.png", time.Now().UnixMilli(), rand.Intn(10000))
	}
	ossKey := strings.TrimRight(dir, "/") + "/" + filename

	err = bucket.PutObject(ossKey, bytes.NewReader(data))
	if err != nil {
		return nil, fmt.Errorf("OSS upload failed: %w", err)
	}

	// 生成签名 URL（1 小时有效）
	signedURL, err := bucket.SignURL(ossKey, oss.HTTPGet, 3600)
	if err != nil {
		return nil, fmt.Errorf("sign URL failed: %w", err)
	}

	return &UploadResult{
		OSSKey:    ossKey,
		SignedURL: signedURL,
	}, nil
}

// UploadPNG 变体：上传并返回带签名的 URL
func (u *OSSUploader) getBucket() (*oss.Bucket, error) {
	ak := strings.TrimSpace(u.cfg.AccessKeyID)
	sk := strings.TrimSpace(u.cfg.AccessKeySecret)
	if ak == "" || sk == "" {
		return nil, fmt.Errorf("OSS credentials not configured")
	}

	endpoint := fmt.Sprintf("https://oss-%s.aliyuncs.com", u.cfg.Region)
	client, err := oss.New(endpoint, ak, sk)
	if err != nil {
		return nil, fmt.Errorf("create OSS client: %w", err)
	}

	bucket, err := client.Bucket(u.cfg.BucketName)
	if err != nil {
		return nil, fmt.Errorf("get bucket: %w", err)
	}

	return bucket, nil
}

// EncodePNG 将 compositor.ComposeResult 编码为 PNG bytes
func EncodePNG(width, height int, data []byte) ([]byte, error) {
	// 如果 data 已经是完整的 PNG 数据，直接返回
	if len(data) > 4 && data[0] == 0x89 && data[1] == 0x50 && data[2] == 0x4e && data[3] == 0x47 {
		return data, nil
	}

	var buf bytes.Buffer
	// 这里 data 预期是 raw RGBA pixels
	// 但实际上 compositor 返回的是 NRGBA image
	// 暂时返回空，由调用方在 handler 层处理
	if err := png.Encode(&buf, nil); err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}