pstuifzand/ekster

// Package timeline contains different types of timeline backends.
//
// "sorted-set" uses Redis sorted sets as a backend
// "stream" uses Redis 5 streams as a backend
// "null" doesn't remember any items added to it
package timeline

import (
    "database/sql"
    "encoding/json"
    "log"

    "p83.nl/go/ekster/pkg/microsub"

    "github.com/gomodule/redigo/redis"
)

// Backend specifies the interface for Timeline. It supports everything that is needed
// for Ekster to implement the channel protocol for Microsub
type Backend interface {
    Items(before, after string) (microsub.Timeline, error)
    Count() (int, error)

    AddItem(item microsub.Item) (bool, error)
    MarkRead(uids []string) error

    // Not used at the moment
    // MarkUnread(uids []string) error
}

// Create creates a channel of the specified type. Return nil when the type
// is not known.
func Create(channel, timelineType string, pool *redis.Pool, db *sql.DB) Backend {
    if timelineType == "sorted-set" {
        timeline := &redisSortedSetTimeline{channel: channel, pool: pool}
        err := timeline.Init()
        if err != nil {
            return nil
        }
        return timeline
    }

    if timelineType == "stream" {
        timeline := &redisStreamTimeline{channel: channel, pool: pool}
        err := timeline.Init()
        if err != nil {
            return nil
        }
        return timeline
    }

    if timelineType == "null" {
        timeline := &nullTimeline{channel: channel}
        err := timeline.Init()
        if err != nil {
            return nil
        }
        return timeline
    }

    if timelineType == "postgres-stream" {
        timeline := &postgresStream{database: db, channel: channel}
        err := timeline.Init()
        if err != nil {
            log.Printf("Error while creating %s: %v", channel, err)
            return nil
        }
        return timeline
    }

    return nil
}

type redisItem struct {
    ID        string
    Published string
    Read      bool
    Data      []byte
}

func (ri *redisItem) Item() microsub.Item {
    var item microsub.Item
    _ = json.Unmarshal(ri.Data, &item)
    return item
}