ipfs-search/ipfs-search

package providerfilters

import (
    "errors"
    "fmt"

    "github.com/ipfs/go-cid"

    t "github.com/ipfs-search/ipfs-search/types"
)

var (
    errUnsupportedProtocol = errors.New("unsupported protocol")
    errDecodingCID         = errors.New("unable to decode CID")
    errUnsupportedCodec    = errors.New("unsupported codec")
)

// CidFilter filters out invalid CID's or those which are not Raw or DagProtobuf.
type CidFilter struct{}

// NewCidFilter returns a pointer to a new CidFilter.
func NewCidFilter() *CidFilter {
    return &CidFilter{}
}

// Filter takes a Provider and returns true when it is to be included, false
// when not and an error when unexpected condition occur.
func (f *CidFilter) Filter(p t.Provider) (bool, error) {
    if p.Resource.Protocol != t.IPFSProtocol {
        return false, fmt.Errorf("%w: %s for %v", errUnsupportedProtocol, p.Resource.Protocol, p)
    }

    c, err := cid.Decode(p.ID)

    if err != nil {
        return false, fmt.Errorf("%w: %s decoding CID %v", errDecodingCID, err, p)
    }

    switch cidType := c.Type(); cidType {
    case cid.Raw, cid.DagProtobuf:
        // (Potential) files and directories
        return true, nil
    default:
        // Can't handle other types (for now)
        return false, fmt.Errorf("%w: %s for %v", errUnsupportedCodec, cid.CodecToStr[cidType], p)
    }
}