source: code/trunk/msgstore.go@ 503

package soju

import (
        "bytes"
        "encoding/base64"
        "fmt"
        "time"

        "git.sr.ht/~sircmpwn/go-bare"
        "gopkg.in/irc.v3"
)

// messageStore is a per-user store for IRC messages.
type messageStore interface {
        Close() error
        // LastMsgID queries the last message ID for the given network, entity and
        // date. The message ID returned may not refer to a valid message, but can be
        // used in history queries.
        LastMsgID(network *network, entity string, t time.Time) (string, error)
        LoadLatestID(network *network, entity, id string, limit int) ([]*irc.Message, error)
        Append(network *network, entity string, msg *irc.Message) (id string, err error)
}

// chatHistoryMessageStore is a message store that supports chat history
// operations.
type chatHistoryMessageStore interface {
        messageStore

        LoadBeforeTime(network *network, entity string, t time.Time, limit int) ([]*irc.Message, error)
        LoadAfterTime(network *network, entity string, t time.Time, limit int) ([]*irc.Message, error)
}

type msgIDType uint

const (
        msgIDNone msgIDType = iota
        msgIDMemory
        msgIDFS
)

const msgIDVersion uint = 0

type msgIDHeader struct {
        Version uint
        Network bare.Int
        Target  string
        Type    msgIDType
}

type msgIDBody interface {
        msgIDType() msgIDType
}

func formatMsgID(netID int64, target string, body msgIDBody) string {
        var buf bytes.Buffer
        w := bare.NewWriter(&buf)

        header := msgIDHeader{
                Version: msgIDVersion,
                Network: bare.Int(netID),
                Target:  target,
                Type:    body.msgIDType(),
        }
        if err := bare.MarshalWriter(w, &header); err != nil {
                panic(err)
        }
        if err := bare.MarshalWriter(w, body); err != nil {
                panic(err)
        }
        return base64.RawURLEncoding.EncodeToString(buf.Bytes())
}

func parseMsgID(s string, body msgIDBody) (netID int64, target string, err error) {
        b, err := base64.RawURLEncoding.DecodeString(s)
        if err != nil {
                return 0, "", fmt.Errorf("invalid internal message ID: %v", err)
        }

        r := bare.NewReader(bytes.NewReader(b))

        var header msgIDHeader
        if err := bare.UnmarshalBareReader(r, &header); err != nil {
                return 0, "", fmt.Errorf("invalid internal message ID: %v", err)
        }

        if header.Version != msgIDVersion {
                return 0, "", fmt.Errorf("invalid internal message ID: got version %v, want %v", header.Version, msgIDVersion)
        }

        if body != nil {
                typ := body.msgIDType()
                if header.Type != typ {
                        return 0, "", fmt.Errorf("invalid internal message ID: got type %v, want %v", header.Type, typ)
                }

                if err := bare.UnmarshalBareReader(r, body); err != nil {
                        return 0, "", fmt.Errorf("invalid internal message ID: %v", err)
                }
        }

        return int64(header.Network), header.Target, nil
}