package common

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

	qgen "github.com/Azareal/Gosora/query_gen"
)

var Polls PollStore

type PollOption struct {
	ID    int
	Value string
}

type Pollable interface {
	GetID() int
	GetTable() string
	SetPoll(pollID int) error
}

type PollStore interface {
	Get(id int) (*Poll, error)
	Exists(id int) bool
	Create(parent Pollable, pollType int, pollOptions map[int]string) (int, error)
	CastVote(optionIndex, pollID, uid int, ip string) error
	Reload(id int) error
	//Count() int

	SetCache(cache PollCache)
	GetCache() PollCache
}

type DefaultPollStore struct {
	cache PollCache

	get                   *sql.Stmt
	exists                *sql.Stmt
	createPoll            *sql.Stmt
	createPollOption      *sql.Stmt
	addVote               *sql.Stmt
	incVoteCount          *sql.Stmt
	incVoteCountForOption *sql.Stmt
	delete                *sql.Stmt
	//count      *sql.Stmt
}

func NewDefaultPollStore(cache PollCache) (*DefaultPollStore, error) {
	acc := qgen.NewAcc()
	if cache == nil {
		cache = NewNullPollCache()
	}
	// TODO: Add an admin version of registerStmt with more flexibility?
	return &DefaultPollStore{
		cache:                 cache,
		get:                   acc.Select("polls").Columns("parentID, parentTable, type, options, votes").Where("pollID = ?").Prepare(),
		exists:                acc.Select("polls").Columns("pollID").Where("pollID = ?").Prepare(),
		createPoll:            acc.Insert("polls").Columns("parentID, parentTable, type, options").Fields("?,?,?,?").Prepare(),
		createPollOption:      acc.Insert("polls_options").Columns("pollID, option, votes").Fields("?,?,0").Prepare(),
		addVote:               acc.Insert("polls_votes").Columns("pollID,uid,option,castAt,ip").Fields("?,?,?,UTC_TIMESTAMP(),?").Prepare(),
		incVoteCount:          acc.Update("polls").Set("votes = votes + 1").Where("pollID = ?").Prepare(),
		incVoteCountForOption: acc.Update("polls_options").Set("votes = votes + 1").Where("option=? AND pollID=?").Prepare(),
		//count: acc.SimpleCount("polls", "", ""),
	}, acc.FirstError()
}

func (s *DefaultPollStore) Exists(id int) bool {
	err := s.exists.QueryRow(id).Scan(&id)
	if err != nil && err != ErrNoRows {
		LogError(err)
	}
	return err != ErrNoRows
}

func (s *DefaultPollStore) Get(id int) (*Poll, error) {
	p, err := s.cache.Get(id)
	if err == nil {
		return p, nil
	}

	p = &Poll{ID: id}
	var optionTxt []byte
	err = s.get.QueryRow(id).Scan(&p.ParentID, &p.ParentTable, &p.Type, &optionTxt, &p.VoteCount)
	if err != nil {
		return nil, err
	}

	err = json.Unmarshal(optionTxt, &p.Options)
	if err == nil {
		p.QuickOptions = s.unpackOptionsMap(p.Options)
		s.cache.Set(p)
	}
	return p, err
}

// TODO: Optimise the query to avoid preparing it on the spot? Maybe, use knowledge of the most common IN() parameter counts?
// TODO: ID of 0 should always error?
func (s *DefaultPollStore) BulkGetMap(ids []int) (list map[int]*Poll, err error) {
	idCount := len(ids)
	list = make(map[int]*Poll)
	if idCount == 0 {
		return list, nil
	}

	var stillHere []int
	sliceList := s.cache.BulkGet(ids)
	for i, sliceItem := range sliceList {
		if sliceItem != nil {
			list[sliceItem.ID] = sliceItem
		} else {
			stillHere = append(stillHere, ids[i])
		}
	}
	ids = stillHere

	// If every user is in the cache, then return immediately
	if len(ids) == 0 {
		return list, nil
	}

	// TODO: Add a function for the qlist stuff
	var q string
	idList := make([]interface{}, len(ids))
	for i, id := range ids {
		idList[i] = strconv.Itoa(id)
		q += "?,"
	}
	q = q[0 : len(q)-1]

	rows, err := qgen.NewAcc().Select("polls").Columns("pollID,parentID,parentTable,type,options,votes").Where("pollID IN(" + q + ")").Query(idList...)
	if err != nil {
		return list, err
	}

	for rows.Next() {
		p := &Poll{ID: 0}
		var optionTxt []byte
		err := rows.Scan(&p.ID, &p.ParentID, &p.ParentTable, &p.Type, &optionTxt, &p.VoteCount)
		if err != nil {
			return list, err
		}

		err = json.Unmarshal(optionTxt, &p.Options)
		if err != nil {
			return list, err
		}
		p.QuickOptions = s.unpackOptionsMap(p.Options)
		s.cache.Set(p)

		list[p.ID] = p
	}

	// Did we miss any polls?
	if idCount > len(list) {
		var sidList string
		for _, id := range ids {
			_, ok := list[id]
			if !ok {
				sidList += strconv.Itoa(id) + ","
			}
		}

		// We probably don't need this, but it might be useful in case of bugs in BulkCascadeGetMap
		if sidList == "" {
			// TODO: Bulk log this
			if Dev.DebugMode {
				log.Print("This data is sampled later in the BulkCascadeGetMap function, so it might miss the cached IDs")
				log.Print("idCount", idCount)
				log.Print("ids", ids)
				log.Print("list", list)
			}
			return list, errors.New("We weren't able to find a poll, but we don't know which one")
		}
		sidList = sidList[0 : len(sidList)-1]

		err = errors.New("Unable to find the polls with the following IDs: " + sidList)
	}

	return list, err
}

func (s *DefaultPollStore) Reload(id int) error {
	p := &Poll{ID: id}
	var optionTxt []byte
	err := s.get.QueryRow(id).Scan(&p.ParentID, &p.ParentTable, &p.Type, &optionTxt, &p.VoteCount)
	if err != nil {
		s.cache.Remove(id)
		return err
	}

	err = json.Unmarshal(optionTxt, &p.Options)
	if err != nil {
		s.cache.Remove(id)
		return err
	}

	p.QuickOptions = s.unpackOptionsMap(p.Options)
	_ = s.cache.Set(p)
	return nil
}

func (s *DefaultPollStore) unpackOptionsMap(rawOptions map[int]string) []PollOption {
	options := make([]PollOption, len(rawOptions))
	for id, option := range rawOptions {
		options[id] = PollOption{id, option}
	}
	return options
}

// TODO: Use a transaction for this?
func (s *DefaultPollStore) CastVote(optionIndex, pollID, uid int, ip string) error {
	if Config.DisablePollIP {
		ip = ""
	}
	_, err := s.addVote.Exec(pollID, uid, optionIndex, ip)
	if err != nil {
		return err
	}
	_, err = s.incVoteCount.Exec(pollID)
	if err != nil {
		return err
	}
	_, err = s.incVoteCountForOption.Exec(optionIndex, pollID)
	return err
}

// TODO: Use a transaction for this
func (s *DefaultPollStore) Create(parent Pollable, pollType int, pollOptions map[int]string) (id int, err error) {
	pollOptionsTxt, err := json.Marshal(pollOptions)
	if err != nil {
		return 0, err
	}

	res, err := s.createPoll.Exec(parent.GetID(), parent.GetTable(), pollType, pollOptionsTxt)
	if err != nil {
		return 0, err
	}
	lastID, err := res.LastInsertId()
	if err != nil {
		return 0, err
	}

	for i := 0; i < len(pollOptions); i++ {
		_, err := s.createPollOption.Exec(lastID, i)
		if err != nil {
			return 0, err
		}
	}

	id = int(lastID)
	return id, parent.SetPoll(id) // TODO: Delete the poll (and options) if SetPoll fails
}

func (s *DefaultPollStore) SetCache(cache PollCache) {
	s.cache = cache
}

// TODO: We're temporarily doing this so that you can do ucache != nil in getTopicUser. Refactor it.
func (s *DefaultPollStore) GetCache() PollCache {
	_, ok := s.cache.(*NullPollCache)
	if ok {
		return nil
	}
	return s.cache
}