package common

import (
	"database/sql"
	//"log"
	"strconv"

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

var Recalc RecalcInt

type RecalcInt interface {
    Replies() (count int, err error)
    Forums() (count int, err error)
    Subscriptions() (count int, err error)
    ActivityStream() (count int, err error)
    Users() error
    Attachments() (count int, err error)
}

type DefaultRecalc struct {
    getActivitySubscriptions *sql.Stmt
    getActivityStream        *sql.Stmt
    getAttachments           *sql.Stmt
    getTopicCount            *sql.Stmt
    resetTopicCount          *sql.Stmt
}

func NewDefaultRecalc(acc *qgen.Accumulator) (*DefaultRecalc, error) {
    return &DefaultRecalc{
        getActivitySubscriptions: acc.Select("activity_subscriptions").Columns("targetID,targetType").Prepare(),
        getActivityStream:        acc.Select("activity_stream").Columns("asid,event,elementID,elementType,extra").Prepare(),
        getAttachments:           acc.Select("attachments").Columns("attachID,originID,originTable").Prepare(),
        getTopicCount:            acc.Count("topics").Where("parentID=?").Prepare(),
        //resetTopicCount:          acc.SimpleUpdateSelect("forums", "topicCount = tc", "topics", "count(*) as tc", "parentID=?", "", ""),
        // TODO: Avoid using RawPrepare
        resetTopicCount: acc.RawPrepare("UPDATE forums, (SELECT COUNT(*) as tc FROM topics WHERE parentID=?) AS src SET forums.topicCount=src.tc WHERE forums.fid=?"),
    }, acc.FirstError()
}

func (s *DefaultRecalc) Replies() (count int, err error) {
    var ltid int
    err = Rstore.Each(func(r *Reply) error {
        if ltid == r.ParentID && r.ParentID > 0 {
            //return nil
        }
        if !Topics.Exists(r.ParentID) {
            // TODO: Delete in chunks not one at a time?
            if err := r.Delete(); err != nil {
                return err
            }
            count++
        }
        return nil
    })
    return count, err
}

func (s *DefaultRecalc) Forums() (count int, err error) {
    err = Forums.Each(func(f *Forum) error {
        _, err := s.resetTopicCount.Exec(f.ID, f.ID)
        if err != nil {
            return err
        }
        count++
        return nil
    })
    return count, err
}

func (s *DefaultRecalc) Subscriptions() (count int, err error) {
    err = eachall(s.getActivitySubscriptions, func(r *sql.Rows) error {
        var targetID int
        var targetType string
        err := r.Scan(&targetID, &targetType)
        if err != nil {
            return err
        }
        if targetType == "topic" {
            if !Topics.Exists(targetID) {
                // TODO: Delete in chunks not one at a time?
                err := Subscriptions.DeleteResource(targetID, targetType)
                if err != nil {
                    return err
                }
                count++
            }
        }
        return nil
    })
    return count, err
}

type Existable interface {
    Exists(id int) bool
}

func (s *DefaultRecalc) ActivityStream() (count int, err error) {
    err = eachall(s.getActivityStream, func(r *sql.Rows) error {
        var asid, elementID int
        var event, elementType, extra string
        err := r.Scan(&asid, &event, &elementID, &elementType, &extra)
        if err != nil {
            return err
        }
        //log.Print("asid:",asid)
        var s Existable
        switch elementType {
        case "user":
            if event == "reply" {
                extraI, _ := strconv.Atoi(extra)
                if extraI > 0 {
                    s = Prstore
                    elementID = extraI
                } else {
                    return nil
                }
            } else {
                return nil
            }
        case "topic":
            s = Topics
            // TODO: Delete reply events with an empty extra field
            if event == "reply" {
                extraI, _ := strconv.Atoi(extra)
                if extraI > 0 {
                    s = Rstore
                    elementID = extraI
                }
            }
        case "post":
            s = Rstore
            // TODO: Add a TopicExistsByReplyID for efficiency
            /*_, err = TopicByReplyID(elementID)
            if err == sql.ErrNoRows {
                // TODO: Delete in chunks not one at a time?
                err := Activity.Delete(asid)
                if err != nil {
                    return err
                }
                count++
            } else if err != nil {
                return err
            }*/
        default:
            return nil
        }
        if !s.Exists(elementID) {
            // TODO: Delete in chunks not one at a time?
            err := Activity.Delete(asid)
            if err != nil {
                return err
            }
            count++
        }
        return nil
    })
    return count, err
}

func (s *DefaultRecalc) Users() error {
    return Users.Each(func(u *User) error {
        return u.RecalcPostStats()
    })
}

func (s *DefaultRecalc) Attachments() (count int, err error) {
    err = eachall(s.getAttachments, func(r *sql.Rows) error {
        var aid, originID int
        var originType string
        err := r.Scan(&aid, &originID, &originType)
        if err != nil {
            return err
        }
        var s Existable
        switch originType {
        case "topics":
            s = Topics
        case "replies":
            s = Rstore
        default:
            return nil
        }
        if !s.Exists(originID) {
            // TODO: Delete in chunks not one at a time?
            err := Attachments.Delete(aid)
            if err != nil {
                return err
            }
            count++
        }
        return nil
    })
    return count, err
}