/*
*
* Gosora Alerts System
* Copyright Azareal 2017 - 2020
*
 */
package common

import (
	"database/sql"
	"errors"
	"strconv"
	"strings"
	"time"

	//"fmt"

	"git.tuxpa.in/a/gosora/common/phrases"
	qgen "git.tuxpa.in/a/gosora/query_gen"
)

type Alert struct {
    ASID         int
    ActorID      int
    TargetUserID int
    Event        string
    ElementType  string
    ElementID    int
    CreatedAt    time.Time
    Extra        string

    Actor *User
}

type AlertStmts struct {
    notifyWatchers *sql.Stmt
    getWatchers    *sql.Stmt
}

var alertStmts AlertStmts

// TODO: Move these statements into some sort of activity abstraction
// TODO: Rewrite the alerts logic
func init() {
    DbInits.Add(func(acc *qgen.Accumulator) error {
        alertStmts = AlertStmts{
            notifyWatchers: acc.SimpleInsertInnerJoin(
                qgen.DBInsert{"activity_stream_matches", "watcher,asid", ""},
                qgen.DBJoin{"activity_stream", "activity_subscriptions", "activity_subscriptions.user, activity_stream.asid", "activity_subscriptions.targetType = activity_stream.elementType AND activity_subscriptions.targetID = activity_stream.elementID AND activity_subscriptions.user != activity_stream.actor", "asid=?", "", ""},
            ),
            getWatchers: acc.SimpleInnerJoin("activity_stream", "activity_subscriptions", "activity_subscriptions.user", "activity_subscriptions.targetType = activity_stream.elementType AND activity_subscriptions.targetID = activity_stream.elementID AND activity_subscriptions.user != activity_stream.actor", "asid=?", "", ""),
        }
        return acc.FirstError()
    })
}

const AlertsGrowHint = len(`{"msgs":[],"count":,"tc":}`) + 1 + 10

// TODO: See if we can json.Marshal instead?
func escapeTextInJson(in string) string {
    in = strings.Replace(in, "\"", "\\\"", -1)
    return strings.Replace(in, "/", "\\/", -1)
}

func BuildAlert(a Alert, user User /* The current user */) (out string, err error) {
    var targetUser *User
    if a.Actor == nil {
        a.Actor, err = Users.Get(a.ActorID)
        if err != nil {
            return "", errors.New(phrases.GetErrorPhrase("alerts_no_actor"))
        }
    }

    /*if a.ElementType != "forum" {
        targetUser, err = users.Get(a.TargetUserID)
        if err != nil {
            LocalErrorJS("Unable to find the target user",w,r)
            return
        }
    }*/
    if a.Event == "friend_invite" {
        return buildAlertString(".new_friend_invite", []string{a.Actor.Name}, a.Actor.Link, a.Actor.Avatar, a.ASID), nil
    }

    // Not that many events for us to handle in a forum
    if a.ElementType == "forum" {
        if a.Event == "reply" {
            topic, err := Topics.Get(a.ElementID)
            if err != nil {
                DebugLogf("Unable to find linked topic %d", a.ElementID)
                return "", errors.New(phrases.GetErrorPhrase("alerts_no_linked_topic"))
            }
            // Store the forum ID in the targetUser column instead of making a new one? o.O
            // Add an additional column for extra information later on when we add the ability to link directly to posts. We don't need the forum data for now...
            return buildAlertString(".forum_new_topic", []string{a.Actor.Name, topic.Title}, topic.Link, a.Actor.Avatar, a.ASID), nil
        }
        return buildAlertString(".forum_unknown_action", []string{a.Actor.Name}, "", a.Actor.Avatar, a.ASID), nil
    }

    var url, area, phraseName string
    own := false
    // TODO: Avoid loading a bit of data twice
    switch a.ElementType {
    case "convo":
        convo, err := Convos.Get(a.ElementID)
        if err != nil {
            DebugLogf("Unable to find linked convo %d", a.ElementID)
            return "", errors.New(phrases.GetErrorPhrase("alerts_no_linked_convo"))
        }
        url = convo.Link
    case "topic":
        topic, err := Topics.Get(a.ElementID)
        if err != nil {
            DebugLogf("Unable to find linked topic %d", a.ElementID)
            return "", errors.New(phrases.GetErrorPhrase("alerts_no_linked_topic"))
        }
        url = topic.Link
        area = topic.Title
        own = a.TargetUserID == user.ID
    case "user":
        targetUser, err = Users.Get(a.ElementID)
        if err != nil {
            DebugLogf("Unable to find target user %d", a.ElementID)
            return "", errors.New(phrases.GetErrorPhrase("alerts_no_target_user"))
        }
        area = targetUser.Name
        url = targetUser.Link
        own = a.TargetUserID == user.ID
    case "post":
        topic, err := TopicByReplyID(a.ElementID)
        if err != nil {
            DebugLogf("Unable to find linked topic by reply ID %d", a.ElementID)
            return "", errors.New(phrases.GetErrorPhrase("alerts_no_linked_topic_by_reply"))
        }
        url = topic.Link
        area = topic.Title
        own = a.TargetUserID == user.ID
    default:
        return "", errors.New(phrases.GetErrorPhrase("alerts_invalid_elementtype"))
    }

    badEv := false
    switch a.Event {
    case "create", "like", "mention", "reply":
        // skip
    default:
        badEv = true
    }

    if own && !badEv {
        phraseName = "." + a.ElementType + "_own_" + a.Event
    } else if !badEv {
        phraseName = "." + a.ElementType + "_" + a.Event
    } else if own {
        phraseName = "." + a.ElementType + "_own"
    } else {
        phraseName = "." + a.ElementType
    }

    return buildAlertString(phraseName, []string{a.Actor.Name, area}, url, a.Actor.Avatar, a.ASID), nil
}

func buildAlertString(msg string, sub []string, path, avatar string, asid int) string {
    var sb strings.Builder
    buildAlertSb(&sb, msg, sub, path, avatar, asid)
    return sb.String()
}

const AlertsGrowHint2 = len(`{"msg":"","sub":[],"path":"","img":"","id":}`) + 5 + 3 + 1 + 1 + 1

// TODO: Use a string builder?
func buildAlertSb(sb *strings.Builder, msg string, sub []string, path, avatar string, asid int) {
    sb.WriteString(`{"msg":"`)
    sb.WriteString(escapeTextInJson(msg))
    sb.WriteString(`","sub":[`)
    for i, it := range sub {
        if i != 0 {
            sb.WriteString(",\"")
        } else {
            sb.WriteString("\"")
        }
        sb.WriteString(escapeTextInJson(it))
        sb.WriteString("\"")
    }
    sb.WriteString(`],"path":"`)
    sb.WriteString(escapeTextInJson(path))
    sb.WriteString(`","img":"`)
    sb.WriteString(escapeTextInJson(avatar))
    sb.WriteString(`","id":`)
    sb.WriteString(strconv.Itoa(asid))
    sb.WriteRune('}')
}

func BuildAlertSb(sb *strings.Builder, a *Alert, u *User /* The current user */) (err error) {
    var targetUser *User
    if a.Actor == nil {
        a.Actor, err = Users.Get(a.ActorID)
        if err != nil {
            return errors.New(phrases.GetErrorPhrase("alerts_no_actor"))
        }
    }

    /*if a.ElementType != "forum" {
        targetUser, err = users.Get(a.TargetUserID)
        if err != nil {
            LocalErrorJS("Unable to find the target user",w,r)
            return
        }
    }*/
    if a.Event == "friend_invite" {
        buildAlertSb(sb, ".new_friend_invite", []string{a.Actor.Name}, a.Actor.Link, a.Actor.Avatar, a.ASID)
        return nil
    }

    // Not that many events for us to handle in a forum
    if a.ElementType == "forum" {
        if a.Event == "reply" {
            topic, err := Topics.Get(a.ElementID)
            if err != nil {
                DebugLogf("Unable to find linked topic %d", a.ElementID)
                return errors.New(phrases.GetErrorPhrase("alerts_no_linked_topic"))
            }
            // Store the forum ID in the targetUser column instead of making a new one? o.O
            // Add an additional column for extra information later on when we add the ability to link directly to posts. We don't need the forum data for now...
            buildAlertSb(sb, ".forum_new_topic", []string{a.Actor.Name, topic.Title}, topic.Link, a.Actor.Avatar, a.ASID)
            return nil
        }
        buildAlertSb(sb, ".forum_unknown_action", []string{a.Actor.Name}, "", a.Actor.Avatar, a.ASID)
        return nil
    }

    var url, area string
    own := false
    // TODO: Avoid loading a bit of data twice
    switch a.ElementType {
    case "convo":
        convo, err := Convos.Get(a.ElementID)
        if err != nil {
            DebugLogf("Unable to find linked convo %d", a.ElementID)
            return errors.New(phrases.GetErrorPhrase("alerts_no_linked_convo"))
        }
        url = convo.Link
    case "topic":
        topic, err := Topics.Get(a.ElementID)
        if err != nil {
            DebugLogf("Unable to find linked topic %d", a.ElementID)
            return errors.New(phrases.GetErrorPhrase("alerts_no_linked_topic"))
        }
        url = topic.Link
        area = topic.Title
        own = a.TargetUserID == u.ID
    case "user":
        targetUser, err = Users.Get(a.ElementID)
        if err != nil {
            DebugLogf("Unable to find target user %d", a.ElementID)
            return errors.New(phrases.GetErrorPhrase("alerts_no_target_user"))
        }
        area = targetUser.Name
        url = targetUser.Link
        own = a.TargetUserID == u.ID
    case "post":
        t, err := TopicByReplyID(a.ElementID)
        if err != nil {
            DebugLogf("Unable to find linked topic by reply ID %d", a.ElementID)
            return errors.New(phrases.GetErrorPhrase("alerts_no_linked_topic_by_reply"))
        }
        url = t.Link
        area = t.Title
        own = a.TargetUserID == u.ID
    default:
        return errors.New(phrases.GetErrorPhrase("alerts_invalid_elementtype"))
    }

    sb.WriteString(`{"msg":".`)
    sb.WriteString(a.ElementType)
    if own {
        sb.WriteString("_own_")
    } else {
        sb.WriteRune('_')
    }
    switch a.Event {
    case "create", "like", "mention", "reply":
        sb.WriteString(a.Event)
    }

    sb.WriteString(`","sub":["`)
    sb.WriteString(escapeTextInJson(a.Actor.Name))
    sb.WriteString("\",\"")
    sb.WriteString(escapeTextInJson(area))
    sb.WriteString(`"],"path":"`)
    sb.WriteString(escapeTextInJson(url))
    sb.WriteString(`","img":"`)
    sb.WriteString(escapeTextInJson(a.Actor.Avatar))
    sb.WriteString(`","id":`)
    sb.WriteString(strconv.Itoa(a.ASID))
    sb.WriteRune('}')

    return nil
}

//const AlertsGrowHint3 = len(`{"msg":"._","sub":["",""],"path":"","img":"","id":}`) + 3 + 2 + 2 + 2 + 2 + 1

// TODO: Create a notifier structure?
func AddActivityAndNotifyAll(a Alert) error {
    id, err := Activity.Add(a)
    if err != nil {
        return err
    }
    return NotifyWatchers(id)
}

// TODO: Create a notifier structure?
func AddActivityAndNotifyTarget(a Alert) error {
    id, err := Activity.Add(a)
    if err != nil {
        return err
    }

    err = ActivityMatches.Add(a.TargetUserID, id)
    if err != nil {
        return err
    }
    a.ASID = id

    // Live alerts, if the target is online and WebSockets is enabled
    if EnableWebsockets {
        go func() {
            defer EatPanics()
            _ = WsHub.pushAlert(a.TargetUserID, a)
            //fmt.Println("err:",err)
        }()
    }
    return nil
}

// TODO: Create a notifier structure?
func NotifyWatchers(asid int) error {
    _, err := alertStmts.notifyWatchers.Exec(asid)
    if err != nil {
        return err
    }

    // Alert the subscribers about this without blocking us from doing something else
    if EnableWebsockets {
        go func() {
            defer EatPanics()
            notifyWatchers(asid)
        }()
    }
    return nil
}

func notifyWatchers(asid int) {
    rows, e := alertStmts.getWatchers.Query(asid)
    if e != nil && e != ErrNoRows {
        LogError(e)
        return
    }
    defer rows.Close()

    var uid int
    var uids []int
    for rows.Next() {
        if e := rows.Scan(&uid); e != nil {
            LogError(e)
            return
        }
        uids = append(uids, uid)
    }
    if e = rows.Err(); e != nil {
        LogError(e)
        return
    }

    alert, e := Activity.Get(asid)
    if e != nil && e != ErrNoRows {
        LogError(e)
        return
    }
    _ = WsHub.pushAlerts(uids, alert)
}

func DismissAlert(uid, aid int) {
    _ = WsHub.PushMessage(uid, `{"event":"dismiss-alert","id":`+strconv.Itoa(aid)+`}`)
}