feta/toot/toot.go

package toot

import (
	"encoding/json"
	"errors"
	"fmt"
	"strings"

	"git.eeqj.de/sneak/feta/jsonapis"
	"github.com/rs/zerolog/log"

	//import "github.com/davecgh/go-spew/spew"

	//import "encoding/hex"
	mh "github.com/multiformats/go-multihash"

	mhopts "github.com/multiformats/go-multihash/opts"
)

// Hash is a type for storing a string-based base58 multihash of a
// toot's identity

// Toot is an object we use internally for storing a discovered toot
type Toot struct {
	Original []byte
	Parsed   *jsonapis.APISerializedToot
	Hash     string
	FromHost string
}

// NewTootCollectionFromMastodonAPIResponse takes a byte array from a masto
// api response and provides you with a nice array of pointers to parsed
// toots
func NewTootCollectionFromMastodonAPIResponse(in []byte, hostname string) ([]*Toot, error) {
	var rt []json.RawMessage
	err := json.Unmarshal(in, &rt)
	if err != nil {
		return nil, errors.New("unable to parse api response")
	}

	var tc []*Toot

	// iterate over rawtoots from api
	for _, item := range rt {
		parsed := new(jsonapis.APISerializedToot)
		err := json.Unmarshal(item, parsed)
		if err != nil {
			log.Error().Msg("unable to parse toot, skipping")
			continue
		}
		t := new(Toot)
		t.Parsed = parsed
		o, err := item.MarshalJSON()
		if err != nil {
			panic(err)
		}
		t.Original = o
		t.FromHost = hostname
		t.calcHash()
		tc = append(tc, t)
	}
	return tc, nil
}

func (t *Toot) String() string {
	return fmt.Sprintf("%#v", t)
}

func (t *Toot) multiHash(in []byte) string {
	opts := new(mhopts.Options)
	opts.Algorithm = "sha2-256"
	opts.Encoding = "base58"
	var found bool
	opts.AlgorithmCode, found = mh.Names[opts.Algorithm]
	if !found {
		panic("oops")
	}
	opts.Length = mh.DefaultLengths[opts.AlgorithmCode]
	r := strings.NewReader(string(in))
	h, err := opts.Multihash(r)
	if err != nil {
		panic(err)
	}
	return h.B58String()
}

// DiskStoragePath is a helper function on a Toot that allows it to provide
// a storage path on disk.  This should probably be moved into the FSStorage
// backend instead. FIXME
// It's here because it's a pure function that just formats its own toot attributes
// into a string.
func (t *Toot) DiskStoragePath() string {
	// FIXME make this error if fields are missing
	// '/YYYYMMDD/example.com/username/YYYY-MM-DD.HHMMSS.username@fromHost.multihash.json'
	return fmt.Sprintf("%s/%s/%s/%s.%s@%s.%s.json",
		t.Parsed.CreatedAt.Format("20060102"),
		strings.ToLower(t.FromHost),
		t.Parsed.Account.Acct,
		t.Parsed.CreatedAt.Format("2006-01-02.150405"),
		t.Parsed.Account.Acct,
		strings.ToLower(t.FromHost),
		t.Hash,
	)
}

func (t *Toot) identityHashInput() string {
	return fmt.Sprintf(
		"%s.%s.%s.%s.%s",
		t.Parsed.Account.URL,
		t.Parsed.CreatedAt,
		t.Parsed.ID,
		t.Parsed.Content,
		strings.ToLower(t.FromHost),
	)
}

func (t *Toot) GetHash() string {
	if t.Hash == "" {
		t.calcHash()
	}
	return t.Hash
}

func (t *Toot) calcHash() {
	hi := t.identityHashInput()
	t.Hash = string(t.multiHash([]byte(hi)))
}