package upload

import (
	"context"
	"fmt"
	"os"
	"strings"

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

// PutObjectAPI is the subset of *s3.Client used here. Tests inject a fake.
type PutObjectAPI interface {
	PutObject(ctx context.Context, in *s3.PutObjectInput, opts ...func(*s3.Options)) (*s3.PutObjectOutput, error)
}

// Opts configures a single upload.
type Opts struct {
	Bucket   string
	Key      string
	FilePath string
}

// RenderKey substitutes {version} and {filename} placeholders.
func RenderKey(template, version, filename string) string {
	r := strings.NewReplacer("{version}", version, "{filename}", filename)
	return r.Replace(template)
}

// Upload PUTs FilePath at s3://Bucket/Key and returns the s3:// URL.
func Upload(ctx context.Context, c PutObjectAPI, o Opts) (string, error) {
	f, err := os.Open(o.FilePath)
	if err != nil {
		return "", fmt.Errorf("open %s: %w", o.FilePath, err)
	}
	defer f.Close()

	if _, err := c.PutObject(ctx, &s3.PutObjectInput{
		Bucket: aws.String(o.Bucket),
		Key:    aws.String(o.Key),
		Body:   f,
	}); err != nil {
		return "", fmt.Errorf("s3 put: %w", err)
	}
	return fmt.Sprintf("s3://%s/%s", o.Bucket, o.Key), nil
}

// WriteFileForTest is exposed for use from this package's tests.
func WriteFileForTest(path string, b []byte) error {
	return os.WriteFile(path, b, 0o600)
}

// NewClient builds an *s3.Client honouring an optional custom endpoint
// for S3-compatible storage.
func NewClient(ctx context.Context, region, endpointURL string) (*s3.Client, error) {
	cfg, err := awsconfig.LoadDefaultConfig(ctx, awsconfig.WithRegion(region))
	if err != nil {
		return nil, fmt.Errorf("aws config: %w", err)
	}
	opts := []func(*s3.Options){}
	if endpointURL != "" {
		opts = append(opts, func(o *s3.Options) {
			o.BaseEndpoint = aws.String(endpointURL)
			o.UsePathStyle = true
		})
	}
	return s3.NewFromConfig(cfg, opts...), nil
}