package media

import (
	"context"
	"errors"
	"fmt"
	"io"
	"strings"

	awsconfig "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"
	"github.com/aws/smithy-go"
)

// S3Config holds the settings needed to talk to any S3-compatible bucket
// (AWS S3 itself, MinIO, Cloudflare R2, ...).
type S3Config struct {
	Bucket        string
	Region        string
	Endpoint      string // leave empty for real AWS S3
	AccessKeyID   string
	SecretKey     string
	UsePathStyle  bool
	PublicBaseURL string // e.g. https://cdn.example.com or https://bucket.s3.region.amazonaws.com
}

type S3Storage struct {
	client  *s3.Client
	bucket  string
	baseURL string
}

func NewS3Storage(ctx context.Context, cfg S3Config) (*S3Storage, error) {
	awsCfg, err := awsconfig.LoadDefaultConfig(ctx,
		awsconfig.WithRegion(cfg.Region),
		awsconfig.WithCredentialsProvider(credentials.NewStaticCredentialsProvider(cfg.AccessKeyID, cfg.SecretKey, "")),
	)
	if err != nil {
		return nil, fmt.Errorf("load aws config: %w", err)
	}

	client := s3.NewFromConfig(awsCfg, func(o *s3.Options) {
		if cfg.Endpoint != "" {
			o.BaseEndpoint = &cfg.Endpoint
		}
		o.UsePathStyle = cfg.UsePathStyle
	})

	baseURL := cfg.PublicBaseURL
	if baseURL == "" {
		if cfg.Endpoint != "" {
			baseURL = strings.TrimRight(cfg.Endpoint, "/") + "/" + cfg.Bucket
		} else {
			baseURL = fmt.Sprintf("https://%s.s3.%s.amazonaws.com", cfg.Bucket, cfg.Region)
		}
	}

	return &S3Storage{client: client, bucket: cfg.Bucket, baseURL: strings.TrimRight(baseURL, "/")}, nil
}

func (s *S3Storage) Save(ctx context.Context, key string, reader io.Reader, size int64, contentType string) (string, error) {
	_, err := s.client.PutObject(ctx, &s3.PutObjectInput{
		Bucket:        &s.bucket,
		Key:           &key,
		Body:          reader,
		ContentType:   &contentType,
		ContentLength: &size,
	})
	if err != nil {
		return "", fmt.Errorf("s3 put object: %w", err)
	}
	return s.baseURL + "/" + key, nil
}

func (s *S3Storage) Delete(ctx context.Context, key string) error {
	_, err := s.client.DeleteObject(ctx, &s3.DeleteObjectInput{
		Bucket: &s.bucket,
		Key:    &key,
	})
	if err != nil {
		var apiErr smithy.APIError
		if errors.As(err, &apiErr) && apiErr.ErrorCode() == "NoSuchKey" {
			return nil
		}
		return fmt.Errorf("s3 delete object: %w", err)
	}
	return nil
}