history.go

package bot

import (
	"sort"
	"time"

	"github.com/jonas747/dstate"
	"github.com/jonas747/yagpdb/common"
)

// GetMessages Gets messages from state if possible, if not then it retrieves from the discord api
// Puts the messages in the state aswell
func GetMessages(channelID int64, limit int, deleted bool) ([]*dstate.MessageState, error) {
	if limit < 1 {
		return []*dstate.MessageState{}, nil
	}

	// check state
	msgBuf := make([]*dstate.MessageState, limit)

	cs := State.Channel(true, channelID)
	if cs == nil {
		return []*dstate.MessageState{}, nil
	}
	cs.Owner.RLock()

	n := len(msgBuf) - 1
	for i := len(cs.Messages) - 1; i >= 0; i-- {
		if cs.Messages[i] == nil {
			continue
		}

		if !deleted {
			if cs.Messages[i].Deleted {
				continue
			}
		}
		m := cs.Messages[i].Copy()
		msgBuf[n] = m

		n--
		if n < 0 {
			break
		}
	}

	cs.Owner.RUnlock()

	// Check if the state was full
	if n < 0 {
		return msgBuf, nil
	}

	// Not enough messages in state, retrieve them from the api
	// Initialize the before id to the oldest message we have
	var before int64
	if n+1 < len(msgBuf) {
		if msgBuf[n+1] != nil {
			before = msgBuf[n+1].ID
		}
	}

	// Start fetching from the api
	for n >= 0 {
		toFetch := n + 1
		if toFetch > 100 {
			toFetch = 100
		}
		msgs, err := common.BotSession.ChannelMessages(channelID, toFetch, before, 0, 0)
		if err != nil {
			return nil, err
		}

		logger.WithField("num_msgs", len(msgs)).Info("API history req finished")

		if len(msgs) < 1 { // Nothing more
			break
		}

		// Copy over to buffer
		for k, m := range msgs {
			ms := dstate.MessageStateFromMessage(m)
			msgBuf[n-k] = ms
		}

		// Oldest message is last
		before = msgs[len(msgs)-1].ID
		n -= len(msgs)

		if len(msgs) < toFetch {
			break
		}
	}

	// remove nil entries if it wasn't big enough
	if n+1 > 0 {
		msgBuf = msgBuf[n+1:]
	}

	maxChannelMessages, maxMessageAge := State.MaxChannelMessages, State.MaxMessageAge
	if State.CustomLimitProvider != nil {
		maxChannelMessages, maxMessageAge = State.CustomLimitProvider.MessageLimits(cs)
	}

	// merge the current state with this new one and sort
	cs.Owner.Lock()
	defer cs.Owner.Unlock()

	for _, m := range msgBuf {
		if cs.Message(false, m.ID) != nil {
			continue
		}

		cs.Messages = append(cs.Messages, m.Copy())
		// cs.MessageAddUpdate(false, m.Message, -1, 0, false, false)
	}

	sort.Sort(DiscordMessages(cs.Messages))

	cs.UpdateMessages(false, maxChannelMessages, time.Now().Add(-maxMessageAge))

	// Return at most limit results
	if limit < len(msgBuf) {
		return msgBuf[len(msgBuf)-limit:], nil
	} else {
		return msgBuf, nil
	}
}

type DiscordMessages []*dstate.MessageState

// Len is the number of elements in the collection.
func (d DiscordMessages) Len() int { return len(d) }

// Less reports whether the element with
// index i should sort before the element with index j.
func (d DiscordMessages) Less(i, j int) bool {
	return d[i].ParsedCreated.Before(d[j].ParsedCreated)
}

// Swap swaps the elements with indexes i and j.
func (d DiscordMessages) Swap(i, j int) {
	temp := d[i]
	d[i] = d[j]
	d[j] = temp
}