source: code/trunk/msgstore_fs.go@ 601

package soju

import (
        "bufio"
        "fmt"
        "io"
        "os"
        "path/filepath"
        "sort"
        "strings"
        "time"

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

const fsMessageStoreMaxTries = 100

func escapeFilename(unsafe string) (safe string) {
        if unsafe == "." {
                return "-"
        } else if unsafe == ".." {
                return "--"
        } else {
                return strings.NewReplacer("/", "-", "\\", "-").Replace(unsafe)
        }
}

type date struct {
        Year, Month, Day int
}

func newDate(t time.Time) date {
        year, month, day := t.Date()
        return date{year, int(month), day}
}

func (d date) Time() time.Time {
        return time.Date(d.Year, time.Month(d.Month), d.Day, 0, 0, 0, 0, time.Local)
}

type fsMsgID struct {
        Date   date
        Offset bare.Int
}

func (fsMsgID) msgIDType() msgIDType {
        return msgIDFS
}

func parseFSMsgID(s string) (netID int64, entity string, t time.Time, offset int64, err error) {
        var id fsMsgID
        netID, entity, err = parseMsgID(s, &id)
        if err != nil {
                return 0, "", time.Time{}, 0, err
        }
        return netID, entity, id.Date.Time(), int64(id.Offset), nil
}

func formatFSMsgID(netID int64, entity string, t time.Time, offset int64) string {
        id := fsMsgID{
                Date:   newDate(t),
                Offset: bare.Int(offset),
        }
        return formatMsgID(netID, entity, &id)
}

// fsMessageStore is a per-user on-disk store for IRC messages.
type fsMessageStore struct {
        root string

        files map[string]*os.File // indexed by entity
}

var _ messageStore = (*fsMessageStore)(nil)
var _ chatHistoryMessageStore = (*fsMessageStore)(nil)

func newFSMessageStore(root, username string) *fsMessageStore {
        return &fsMessageStore{
                root:  filepath.Join(root, escapeFilename(username)),
                files: make(map[string]*os.File),
        }
}

func (ms *fsMessageStore) logPath(network *network, entity string, t time.Time) string {
        year, month, day := t.Date()
        filename := fmt.Sprintf("%04d-%02d-%02d.log", year, month, day)
        return filepath.Join(ms.root, escapeFilename(network.GetName()), escapeFilename(entity), filename)
}

// nextMsgID queries the message ID for the next message to be written to f.
func nextFSMsgID(network *network, entity string, t time.Time, f *os.File) (string, error) {
        offset, err := f.Seek(0, io.SeekEnd)
        if err != nil {
                return "", fmt.Errorf("failed to query next FS message ID: %v", err)
        }
        return formatFSMsgID(network.ID, entity, t, offset), nil
}

func (ms *fsMessageStore) LastMsgID(network *network, entity string, t time.Time) (string, error) {
        p := ms.logPath(network, entity, t)
        fi, err := os.Stat(p)
        if os.IsNotExist(err) {
                return formatFSMsgID(network.ID, entity, t, -1), nil
        } else if err != nil {
                return "", fmt.Errorf("failed to query last FS message ID: %v", err)
        }
        return formatFSMsgID(network.ID, entity, t, fi.Size()-1), nil
}

func (ms *fsMessageStore) Append(network *network, entity string, msg *irc.Message) (string, error) {
        s := formatMessage(msg)
        if s == "" {
                return "", nil
        }

        var t time.Time
        if tag, ok := msg.Tags["time"]; ok {
                var err error
                t, err = time.Parse(serverTimeLayout, string(tag))
                if err != nil {
                        return "", fmt.Errorf("failed to parse message time tag: %v", err)
                }
                t = t.In(time.Local)
        } else {
                t = time.Now()
        }

        // TODO: enforce maximum open file handles (LRU cache of file handles)
        f := ms.files[entity]

        // TODO: handle non-monotonic clock behaviour
        path := ms.logPath(network, entity, t)
        if f == nil || f.Name() != path {
                if f != nil {
                        f.Close()
                }

                dir := filepath.Dir(path)
                if err := os.MkdirAll(dir, 0750); err != nil {
                        return "", fmt.Errorf("failed to create message logs directory %q: %v", dir, err)
                }

                var err error
                f, err = os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0640)
                if err != nil {
                        return "", fmt.Errorf("failed to open message log file %q: %v", path, err)
                }

                ms.files[entity] = f
        }

        msgID, err := nextFSMsgID(network, entity, t, f)
        if err != nil {
                return "", fmt.Errorf("failed to generate message ID: %v", err)
        }

        _, err = fmt.Fprintf(f, "[%02d:%02d:%02d] %s\n", t.Hour(), t.Minute(), t.Second(), s)
        if err != nil {
                return "", fmt.Errorf("failed to log message to %q: %v", f.Name(), err)
        }

        return msgID, nil
}

func (ms *fsMessageStore) Close() error {
        var closeErr error
        for _, f := range ms.files {
                if err := f.Close(); err != nil {
                        closeErr = fmt.Errorf("failed to close message store: %v", err)
                }
        }
        return closeErr
}

// formatMessage formats a message log line. It assumes a well-formed IRC
// message.
func formatMessage(msg *irc.Message) string {
        switch strings.ToUpper(msg.Command) {
        case "NICK":
                return fmt.Sprintf("*** %s is now known as %s", msg.Prefix.Name, msg.Params[0])
        case "JOIN":
                return fmt.Sprintf("*** Joins: %s (%s@%s)", msg.Prefix.Name, msg.Prefix.User, msg.Prefix.Host)
        case "PART":
                var reason string
                if len(msg.Params) > 1 {
                        reason = msg.Params[1]
                }
                return fmt.Sprintf("*** Parts: %s (%s@%s) (%s)", msg.Prefix.Name, msg.Prefix.User, msg.Prefix.Host, reason)
        case "KICK":
                nick := msg.Params[1]
                var reason string
                if len(msg.Params) > 2 {
                        reason = msg.Params[2]
                }
                return fmt.Sprintf("*** %s was kicked by %s (%s)", nick, msg.Prefix.Name, reason)
        case "QUIT":
                var reason string
                if len(msg.Params) > 0 {
                        reason = msg.Params[0]
                }
                return fmt.Sprintf("*** Quits: %s (%s@%s) (%s)", msg.Prefix.Name, msg.Prefix.User, msg.Prefix.Host, reason)
        case "TOPIC":
                var topic string
                if len(msg.Params) > 1 {
                        topic = msg.Params[1]
                }
                return fmt.Sprintf("*** %s changes topic to '%s'", msg.Prefix.Name, topic)
        case "MODE":
                return fmt.Sprintf("*** %s sets mode: %s", msg.Prefix.Name, strings.Join(msg.Params[1:], " "))
        case "NOTICE":
                return fmt.Sprintf("-%s- %s", msg.Prefix.Name, msg.Params[1])
        case "PRIVMSG":
                if cmd, params, ok := parseCTCPMessage(msg); ok && cmd == "ACTION" {
                        return fmt.Sprintf("* %s %s", msg.Prefix.Name, params)
                } else {
                        return fmt.Sprintf("<%s> %s", msg.Prefix.Name, msg.Params[1])
                }
        default:
                return ""
        }
}

func parseMessage(line, entity string, ref time.Time) (*irc.Message, time.Time, error) {
        var hour, minute, second int
        _, err := fmt.Sscanf(line, "[%02d:%02d:%02d] ", &hour, &minute, &second)
        if err != nil {
                return nil, time.Time{}, fmt.Errorf("malformed timestamp prefix: %v", err)
        }
        line = line[11:]

        var cmd, sender, text string
        if strings.HasPrefix(line, "<") {
                cmd = "PRIVMSG"
                parts := strings.SplitN(line[1:], "> ", 2)
                if len(parts) != 2 {
                        return nil, time.Time{}, nil
                }
                sender, text = parts[0], parts[1]
        } else if strings.HasPrefix(line, "-") {
                cmd = "NOTICE"
                parts := strings.SplitN(line[1:], "- ", 2)
                if len(parts) != 2 {
                        return nil, time.Time{}, nil
                }
                sender, text = parts[0], parts[1]
        } else if strings.HasPrefix(line, "* ") {
                cmd = "PRIVMSG"
                parts := strings.SplitN(line[2:], " ", 2)
                if len(parts) != 2 {
                        return nil, time.Time{}, nil
                }
                sender, text = parts[0], "\x01ACTION "+parts[1]+"\x01"
        } else {
                return nil, time.Time{}, nil
        }

        year, month, day := ref.Date()
        t := time.Date(year, month, day, hour, minute, second, 0, time.Local)

        msg := &irc.Message{
                Tags: map[string]irc.TagValue{
                        "time": irc.TagValue(t.UTC().Format(serverTimeLayout)),
                },
                Prefix:  &irc.Prefix{Name: sender},
                Command: cmd,
                Params:  []string{entity, text},
        }
        return msg, t, nil
}

func (ms *fsMessageStore) parseMessagesBefore(network *network, entity string, ref time.Time, end time.Time, limit int, afterOffset int64) ([]*irc.Message, error) {
        path := ms.logPath(network, entity, ref)
        f, err := os.Open(path)
        if err != nil {
                if os.IsNotExist(err) {
                        return nil, nil
                }
                return nil, fmt.Errorf("failed to parse messages before ref: %v", err)
        }
        defer f.Close()

        historyRing := make([]*irc.Message, limit)
        cur := 0

        sc := bufio.NewScanner(f)

        if afterOffset >= 0 {
                if _, err := f.Seek(afterOffset, io.SeekStart); err != nil {
                        return nil, nil
                }
                sc.Scan() // skip till next newline
        }

        for sc.Scan() {
                msg, t, err := parseMessage(sc.Text(), entity, ref)
                if err != nil {
                        return nil, err
                } else if msg == nil || !t.After(end) {
                        continue
                } else if !t.Before(ref) {
                        break
                }

                historyRing[cur%limit] = msg
                cur++
        }
        if sc.Err() != nil {
                return nil, fmt.Errorf("failed to parse messages before ref: scanner error: %v", sc.Err())
        }

        n := limit
        if cur < limit {
                n = cur
        }
        start := (cur - n + limit) % limit

        if start+n <= limit { // ring doesnt wrap
                return historyRing[start : start+n], nil
        } else { // ring wraps
                history := make([]*irc.Message, n)
                r := copy(history, historyRing[start:])
                copy(history[r:], historyRing[:n-r])
                return history, nil
        }
}

func (ms *fsMessageStore) parseMessagesAfter(network *network, entity string, ref time.Time, end time.Time, limit int) ([]*irc.Message, error) {
        path := ms.logPath(network, entity, ref)
        f, err := os.Open(path)
        if err != nil {
                if os.IsNotExist(err) {
                        return nil, nil
                }
                return nil, fmt.Errorf("failed to parse messages after ref: %v", err)
        }
        defer f.Close()

        var history []*irc.Message
        sc := bufio.NewScanner(f)
        for sc.Scan() && len(history) < limit {
                msg, t, err := parseMessage(sc.Text(), entity, ref)
                if err != nil {
                        return nil, err
                } else if msg == nil || !t.After(ref) {
                        continue
                } else if !t.Before(end) {
                        break
                }

                history = append(history, msg)
        }
        if sc.Err() != nil {
                return nil, fmt.Errorf("failed to parse messages after ref: scanner error: %v", sc.Err())
        }

        return history, nil
}

func (ms *fsMessageStore) LoadBeforeTime(network *network, entity string, start time.Time, end time.Time, limit int) ([]*irc.Message, error) {
        history := make([]*irc.Message, limit)
        remaining := limit
        tries := 0
        for remaining > 0 && tries < fsMessageStoreMaxTries && end.Before(start) {
                buf, err := ms.parseMessagesBefore(network, entity, start, end, remaining, -1)
                if err != nil {
                        return nil, err
                }
                if len(buf) == 0 {
                        tries++
                } else {
                        tries = 0
                }
                copy(history[remaining-len(buf):], buf)
                remaining -= len(buf)
                year, month, day := start.Date()
                start = time.Date(year, month, day, 0, 0, 0, 0, start.Location()).Add(-1)
        }

        return history[remaining:], nil
}

func (ms *fsMessageStore) LoadAfterTime(network *network, entity string, start time.Time, end time.Time, limit int) ([]*irc.Message, error) {
        var history []*irc.Message
        remaining := limit
        tries := 0
        for remaining > 0 && tries < fsMessageStoreMaxTries && start.Before(end) {
                buf, err := ms.parseMessagesAfter(network, entity, start, end, remaining)
                if err != nil {
                        return nil, err
                }
                if len(buf) == 0 {
                        tries++
                } else {
                        tries = 0
                }
                history = append(history, buf...)
                remaining -= len(buf)
                year, month, day := start.Date()
                start = time.Date(year, month, day+1, 0, 0, 0, 0, start.Location())
        }
        return history, nil
}

func (ms *fsMessageStore) LoadLatestID(network *network, entity, id string, limit int) ([]*irc.Message, error) {
        var afterTime time.Time
        var afterOffset int64
        if id != "" {
                var idNet int64
                var idEntity string
                var err error
                idNet, idEntity, afterTime, afterOffset, err = parseFSMsgID(id)
                if err != nil {
                        return nil, err
                }
                if idNet != network.ID || idEntity != entity {
                        return nil, fmt.Errorf("cannot find message ID: message ID doesn't match network/entity")
                }
        }

        history := make([]*irc.Message, limit)
        t := time.Now()
        remaining := limit
        tries := 0
        for remaining > 0 && tries < fsMessageStoreMaxTries && !truncateDay(t).Before(afterTime) {
                var offset int64 = -1
                if afterOffset >= 0 && truncateDay(t).Equal(afterTime) {
                        offset = afterOffset
                }

                buf, err := ms.parseMessagesBefore(network, entity, t, time.Time{}, remaining, offset)
                if err != nil {
                        return nil, err
                }
                if len(buf) == 0 {
                        tries++
                } else {
                        tries = 0
                }
                copy(history[remaining-len(buf):], buf)
                remaining -= len(buf)
                year, month, day := t.Date()
                t = time.Date(year, month, day, 0, 0, 0, 0, t.Location()).Add(-1)
        }

        return history[remaining:], nil
}

func (ms *fsMessageStore) ListTargets(network *network, start, end time.Time, limit int) ([]chatHistoryTarget, error) {
        rootPath := filepath.Join(ms.root, escapeFilename(network.GetName()))
        root, err := os.Open(rootPath)
        if err != nil {
                return nil, err
        }

        // The returned targets are escaped, and there is no way to un-escape
        // TODO: switch to ReadDir (Go 1.16+)
        targetNames, err := root.Readdirnames(0)
        root.Close()
        if err != nil {
                return nil, err
        }

        var targets []chatHistoryTarget
        for _, target := range targetNames {
                // target is already escaped here
                targetPath := filepath.Join(rootPath, target)
                targetDir, err := os.Open(targetPath)
                if err != nil {
                        return nil, err
                }

                entries, err := targetDir.Readdir(0)
                targetDir.Close()
                if err != nil {
                        return nil, err
                }

                // We use mtime here, which may give imprecise or incorrect results
                var t time.Time
                for _, entry := range entries {
                        if entry.ModTime().After(t) {
                                t = entry.ModTime()
                        }
                }

                // The timestamps we get from logs have second granularity
                t = truncateSecond(t)

                // Filter out targets that don't fullfil the time bounds
                if !isTimeBetween(t, start, end) {
                        continue
                }

                targets = append(targets, chatHistoryTarget{
                        Name:          target,
                        LatestMessage: t,
                })
        }

        // Sort targets by latest message time, backwards or forwards depending on
        // the order of the time bounds
        sort.Slice(targets, func(i, j int) bool {
                t1, t2 := targets[i].LatestMessage, targets[j].LatestMessage
                if start.Before(end) {
                        return t1.Before(t2)
                } else {
                        return !t1.Before(t2)
                }
        })

        // Truncate the result if necessary
        if len(targets) > limit {
                targets = targets[:limit]
        }

        return targets, nil
}

func truncateDay(t time.Time) time.Time {
        year, month, day := t.Date()
        return time.Date(year, month, day, 0, 0, 0, 0, t.Location())
}

func truncateSecond(t time.Time) time.Time {
        year, month, day := t.Date()
        return time.Date(year, month, day, t.Hour(), t.Minute(), t.Second(), 0, t.Location())
}

func isTimeBetween(t, start, end time.Time) bool {
        if end.Before(start) {
                end, start = start, end
        }
        return start.Before(t) && t.Before(end)
}