source: code/trunk/msgstore_fs.go@ 797

package soju

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

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

const (
        fsMessageStoreMaxFiles = 20
        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)
}

type fsMessageStoreFile struct {
        *os.File
        lastUse time.Time
}

// fsMessageStore is a per-user on-disk store for IRC messages.
//
// It mimicks the ZNC log layout and format. See the ZNC source:
// https://github.com/znc/znc/blob/master/modules/log.cpp
type fsMessageStore struct {
        root string
        user *User

        // Write-only files used by Append
        files map[string]*fsMessageStoreFile // indexed by entity
}

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

func newFSMessageStore(root string, user *User) *fsMessageStore {
        return &fsMessageStore{
                root:  filepath.Join(root, escapeFilename(user.Username)),
                user:  user,
                files: make(map[string]*fsMessageStoreFile),
        }
}

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()
        }

        f := ms.files[entity]

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

                ff, 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)
                }

                if f != nil {
                        f.Close()
                }
                f = &fsMessageStoreFile{File: ff}
                ms.files[entity] = f
        }

        f.lastUse = time.Now()

        if len(ms.files) > fsMessageStoreMaxFiles {
                entities := make([]string, 0, len(ms.files))
                for name := range ms.files {
                        entities = append(entities, name)
                }
                sort.Slice(entities, func(i, j int) bool {
                        a, b := entities[i], entities[j]
                        return ms.files[a].lastUse.Before(ms.files[b].lastUse)
                })
                entities = entities[0 : len(entities)-fsMessageStoreMaxFiles]
                for _, name := range entities {
                        ms.files[name].Close()
                        delete(ms.files, name)
                }
        }

        msgID, err := nextFSMsgID(network, entity, t, f.File)
        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 (ms *fsMessageStore) parseMessage(line string, network *Network, entity string, ref time.Time, events bool) (*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 string
        var prefix *irc.Prefix
        var params []string
        if events && strings.HasPrefix(line, "*** ") {
                parts := strings.SplitN(line[4:], " ", 2)
                if len(parts) != 2 {
                        return nil, time.Time{}, nil
                }
                switch parts[0] {
                case "Joins:", "Parts:", "Quits:":
                        args := strings.SplitN(parts[1], " ", 3)
                        if len(args) < 2 {
                                return nil, time.Time{}, nil
                        }
                        nick := args[0]
                        mask := strings.TrimSuffix(strings.TrimPrefix(args[1], "("), ")")
                        maskParts := strings.SplitN(mask, "@", 2)
                        if len(maskParts) != 2 {
                                return nil, time.Time{}, nil
                        }
                        prefix = &irc.Prefix{
                                Name: nick,
                                User: maskParts[0],
                                Host: maskParts[1],
                        }
                        var reason string
                        if len(args) > 2 {
                                reason = strings.TrimSuffix(strings.TrimPrefix(args[2], "("), ")")
                        }
                        switch parts[0] {
                        case "Joins:":
                                cmd = "JOIN"
                                params = []string{entity}
                        case "Parts:":
                                cmd = "PART"
                                if reason != "" {
                                        params = []string{entity, reason}
                                } else {
                                        params = []string{entity}
                                }
                        case "Quits:":
                                cmd = "QUIT"
                                if reason != "" {
                                        params = []string{reason}
                                }
                        }
                default:
                        nick := parts[0]
                        rem := parts[1]
                        if r := strings.TrimPrefix(rem, "is now known as "); r != rem {
                                cmd = "NICK"
                                prefix = &irc.Prefix{
                                        Name: nick,
                                }
                                params = []string{r}
                        } else if r := strings.TrimPrefix(rem, "was kicked by "); r != rem {
                                args := strings.SplitN(r, " ", 2)
                                if len(args) != 2 {
                                        return nil, time.Time{}, nil
                                }
                                cmd = "KICK"
                                prefix = &irc.Prefix{
                                        Name: args[0],
                                }
                                reason := strings.TrimSuffix(strings.TrimPrefix(args[1], "("), ")")
                                params = []string{entity, nick}
                                if reason != "" {
                                        params = append(params, reason)
                                }
                        } else if r := strings.TrimPrefix(rem, "changes topic to "); r != rem {
                                cmd = "TOPIC"
                                prefix = &irc.Prefix{
                                        Name: nick,
                                }
                                topic := strings.TrimSuffix(strings.TrimPrefix(r, "'"), "'")
                                params = []string{entity, topic}
                        } else if r := strings.TrimPrefix(rem, "sets mode: "); r != rem {
                                cmd = "MODE"
                                prefix = &irc.Prefix{
                                        Name: nick,
                                }
                                params = append([]string{entity}, strings.Split(r, " ")...)
                        } else {
                                return nil, time.Time{}, nil
                        }
                }
        } else {
                var 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
                }

                prefix = &irc.Prefix{Name: sender}
                if entity == sender {
                        // This is a direct message from a user to us. We don't store own
                        // our nickname in the logs, so grab it from the network settings.
                        // Not very accurate since this may not match our nick at the time
                        // the message was received, but we can't do a lot better.
                        entity = GetNick(ms.user, network)
                }
                params = []string{entity, text}
        }

        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(formatServerTime(t)),
                },
                Prefix:  prefix,
                Command: cmd,
                Params:  params,
        }
        return msg, t, nil
}

func (ms *fsMessageStore) parseMessagesBefore(network *Network, entity string, ref time.Time, end time.Time, events bool, 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 := ms.parseMessage(sc.Text(), network, entity, ref, events)
                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, events bool, 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 := ms.parseMessage(sc.Text(), network, entity, ref, events)
                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(ctx context.Context, network *Network, entity string, start time.Time, end time.Time, limit int, events bool) ([]*irc.Message, error) {
        start = start.In(time.Local)
        end = end.In(time.Local)
        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, events, 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)

                if err := ctx.Err(); err != nil {
                        return nil, err
                }
        }

        return history[remaining:], nil
}

func (ms *fsMessageStore) LoadAfterTime(ctx context.Context, network *Network, entity string, start time.Time, end time.Time, limit int, events bool) ([]*irc.Message, error) {
        start = start.In(time.Local)
        end = end.In(time.Local)
        var history []*irc.Message
        remaining := limit
        tries := 0
        for remaining > 0 && tries < fsMessageStoreMaxTries && start.Before(end) {
                buf, err := ms.parseMessagesAfter(network, entity, start, end, events, 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())

                if err := ctx.Err(); err != nil {
                        return nil, err
                }
        }
        return history, nil
}

func (ms *fsMessageStore) LoadLatestID(ctx context.Context, 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{}, false, 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)

                if err := ctx.Err(); err != nil {
                        return nil, err
                }
        }

        return history[remaining:], nil
}

func (ms *fsMessageStore) ListTargets(ctx context.Context, network *Network, start, end time.Time, limit int, events bool) ([]chatHistoryTarget, error) {
        start = start.In(time.Local)
        end = end.In(time.Local)
        rootPath := filepath.Join(ms.root, escapeFilename(network.GetName()))
        root, err := os.Open(rootPath)
        if os.IsNotExist(err) {
                return nil, nil
        } else 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,
                })

                if err := ctx.Err(); err != nil {
                        return nil, err
                }
        }

        // 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 (ms *fsMessageStore) RenameNetwork(oldNet, newNet *Network) error {
        oldDir := filepath.Join(ms.root, escapeFilename(oldNet.GetName()))
        newDir := filepath.Join(ms.root, escapeFilename(newNet.GetName()))
        // Avoid loosing data by overwriting an existing directory
        if _, err := os.Stat(newDir); err == nil {
                return fmt.Errorf("destination %q already exists", newDir)
        }
        return os.Rename(oldDir, newDir)
}

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)
}