s3-share/internal/client/client.go

package client

import (
	"context"
	"errors"
	"math/rand"
	"path/filepath"
	"time"

	"git.kapelle.org/niklas/s3share/internal/db"
	"git.kapelle.org/niklas/s3share/internal/s3"
	"git.kapelle.org/niklas/s3share/internal/types"
)

var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")

type Client struct {
	db db.DB
	s3 s3.S3
}

func NewClient(db db.DB, s3 s3.S3) *Client {
	rand.Seed(time.Now().UnixNano())
	return &Client{
		db: db,
		s3: s3,
	}
}

// createRandomString creates a random string of length 6 to be used as a slug
func createRandomString() string {
	s := make([]rune, 6)
	for i := range s {
		s[i] = letters[rand.Intn(len(letters))]
	}
	return string(s)
}

// createValidSlug creates a valid slug that is not yet in use
func (c *Client) createValidSlug(ctx context.Context) (string, error) {
	for i := 0; i < 10; i++ {
		slug := createRandomString()

		res, err := c.db.GetShare(ctx, slug)
		if err != nil {
			return "", err
		}

		if res == nil {
			return slug, nil
		}
	}

	return "", errors.New("could not create valid slug after 10 tries")
}

// GetShare returns the share with the given slug, nil if not found
func (c *Client) GetShare(ctx context.Context, slug string) (*types.Share, error) {
	return c.db.GetShare(ctx, slug)
}

// CreateShare creates a new share with the given key and returns the share with the slug
func (c *Client) CreateShare(ctx context.Context, key string) (*types.Share, error) {
	slug, err := c.createValidSlug(ctx)
	if err != nil {
		return nil, err
	}

	share := &types.Share{
		Slug: slug,
		Key:  key,
	}

	exists, err := c.s3.KeyExists(ctx, key)
	if err != nil {
		return nil, err
	}

	if !exists {
		return nil, types.ErrKeyNotFound
	}

	err = c.db.CreateShare(ctx, share)
	if err != nil {
		return nil, err
	}

	return share, nil
}

// GetObjectFromShare returns the s3 object to the given share
func (c *Client) GetObjectFromShare(ctx context.Context, share *types.Share) (s3.ObjectReader, error) {
	return c.s3.GetObject(ctx, share.Key)
}

// DeleteShare deletes the share with the given slug
func (c *Client) DeleteShare(ctx context.Context, slug string) error {
	return c.db.DeleteShare(ctx, slug)
}

// GetObjectMetadata returns the metadata of the object with the given key
func (c *Client) GetObjectMetadata(ctx context.Context, key string) (*types.Metadata, error) {
	metadata, err := c.s3.GetObjectMetadata(ctx, key)
	if err != nil {
		return nil, err
	}

	if metadata == nil {
		return nil, nil
	}

	if metadata.Filename == "" {
		metadata.Filename = filepath.Base(key)
	}

	return metadata, nil
}

// GetAllShares returns all shares
func (c *Client) GetAllShares(ctx context.Context) ([]*types.Share, error) {
	return c.db.GetAllShares(ctx)
}