package common

import (
	"database/sql"

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

var Likes LikeStore

type LikeStore interface {
    BulkExists(ids []int, sentBy int, targetType string) ([]int, error)
    BulkExistsFunc(ids []int, sentBy int, targetType string, f func(int) error) error
    Delete(targetID int, targetType string) error
    Count() (count int)
}

type DefaultLikeStore struct {
    count        *sql.Stmt
    delete       *sql.Stmt
    singleExists *sql.Stmt
}

func NewDefaultLikeStore(acc *qgen.Accumulator) (*DefaultLikeStore, error) {
    return &DefaultLikeStore{
        count:        acc.Count("likes").Prepare(),
        delete:       acc.Delete("likes").Where("targetItem=? AND targetType=?").Prepare(),
        singleExists: acc.Select("likes").Columns("targetItem").Where("sentBy=? AND targetType=? AND targetItem=?").Prepare(),
    }, acc.FirstError()
}

// TODO: Write a test for this
func (s *DefaultLikeStore) BulkExists(ids []int, sentBy int, targetType string) (eids []int, e error) {
    if len(ids) == 0 {
        return nil, nil
    }
    var rows *sql.Rows
    if len(ids) == 1 {
        rows, e = s.singleExists.Query(sentBy, targetType, ids[0])
    } else {
        rows, e = qgen.NewAcc().Select("likes").Columns("targetItem").Where("sentBy=? AND targetType=?").In("targetItem", ids).Query(sentBy, targetType)
    }
    if e == sql.ErrNoRows {
        return nil, nil
    } else if e != nil {
        return nil, e
    }
    defer rows.Close()

    var id int
    for rows.Next() {
        if e := rows.Scan(&id); e != nil {
            return nil, e
        }
        eids = append(eids, id)
    }
    return eids, rows.Err()
}

// TODO: Write a test for this
func (s *DefaultLikeStore) BulkExistsFunc(ids []int, sentBy int, targetType string, f func(id int) error) (e error) {
    if len(ids) == 0 {
        return nil
    }
    var rows *sql.Rows
    if len(ids) == 1 {
        rows, e = s.singleExists.Query(sentBy, targetType, ids[0])
    } else {
        rows, e = qgen.NewAcc().Select("likes").Columns("targetItem").Where("sentBy=? AND targetType=?").In("targetItem", ids).Query(sentBy, targetType)
    }
    if e == sql.ErrNoRows {
        return nil
    } else if e != nil {
        return e
    }
    defer rows.Close()

    var id int
    for rows.Next() {
        if e := rows.Scan(&id); e != nil {
            return e
        }
        if e := f(id); e != nil {
            return e
        }
    }
    return rows.Err()
}

func (s *DefaultLikeStore) Delete(targetID int, targetType string) error {
    _, err := s.delete.Exec(targetID, targetType)
    return err
}

// TODO: Write a test for this
// Count returns the total number of likes globally
func (s *DefaultLikeStore) Count() (count int) {
    e := s.count.QueryRow().Scan(&count)
    if e != nil {
        LogError(e)
    }
    return count
}