package main

import (
	"database/sql"
	"fmt"
	"github.com/jmoiron/sqlx"
	"time"
)

type sqlKey int

const (
	sqlLoadDecisions sqlKey = iota
	sqlLoadUnvotedDecisions
	sqlLoadDecisionByTag
	sqlLoadDecisionById
	sqlLoadVoteCountsForDecision
	sqlLoadVotesForDecision
	sqlLoadEnabledVoterByEmail
	sqlCountOlderThanDecision
	sqlCountOlderThanUnvotedDecision
	sqlCreateDecision
	sqlUpdateDecision
	sqlUpdateDecisionStatus
	sqlSelectClosableDecisions
	sqlGetNextPendingDecisionDue
	sqlGetReminderVoters
	sqlFindUnvotedDecisionsForVoter
	sqlGetEnabledVoterById
	sqlCreateVote
	sqlLoadVote
	sqlGetVotersForProxy
)

var sqlStatements = map[sqlKey]string{
	sqlLoadDecisions: `
SELECT decisions.id, decisions.tag, decisions.proponent, voters.name AS proposer, decisions.proposed, decisions.title,
       decisions.content, decisions.votetype, decisions.status, decisions.due, decisions.modified
FROM   decisions
JOIN   voters ON decisions.proponent=voters.id
ORDER BY proposed DESC
LIMIT 10 OFFSET 10 * $1`,
	sqlLoadUnvotedDecisions: `
SELECT decisions.id, decisions.tag, decisions.proponent, voters.name AS proposer, decisions.proposed, decisions.title,
       decisions.content, decisions.votetype, decisions.status, decisions.due, decisions.modified
FROM   decisions
JOIN   voters ON decisions.proponent=voters.id
WHERE  decisions.status = 0 AND decisions.id NOT IN (SELECT votes.decision FROM votes WHERE votes.voter = $1)
ORDER BY proposed DESC
LIMIT 10 OFFSET 10 * $2;`,
	sqlLoadDecisionByTag: `
SELECT decisions.id, decisions.tag, decisions.proponent, voters.name AS proposer, decisions.proposed, decisions.title,
       decisions.content, decisions.votetype, decisions.status, decisions.due, decisions.modified
FROM   decisions
JOIN   voters ON decisions.proponent=voters.id
WHERE  decisions.tag=$1;`,
	sqlLoadDecisionById: `
SELECT decisions.id, decisions.tag, decisions.proponent, decisions.proposed, decisions.title, decisions.content,
       decisions.votetype, decisions.status, decisions.due, decisions.modified
FROM   decisions
WHERE  decisions.id=$1;`,
	sqlLoadVoteCountsForDecision: `
SELECT vote, COUNT(vote) FROM votes WHERE decision=$1 GROUP BY vote`,
	sqlLoadVotesForDecision: `
SELECT votes.decision, votes.voter, voters.name, votes.vote, votes.voted, votes.notes
FROM   votes
JOIN   voters ON votes.voter=voters.id
WHERE  decision=$1`,
	sqlLoadEnabledVoterByEmail: `
SELECT voters.id, voters.name, voters.enabled, voters.reminder
FROM   voters
JOIN   emails ON voters.id=emails.voter
WHERE  emails.address=$1 AND voters.enabled=1`,
	sqlGetEnabledVoterById: `
SELECT id, name, enabled, reminder
FROM   voters
WHERE  enabled=1 AND id=$1`,
	sqlCountOlderThanDecision: `
SELECT COUNT(*) > 0 FROM decisions WHERE proposed < $1`,
	sqlCountOlderThanUnvotedDecision: `
SELECT COUNT(*) > 0 FROM decisions
WHERE  proposed < $1 AND status=0 AND id NOT IN (SELECT decision FROM votes WHERE votes.voter=$2)`,
	sqlCreateDecision: `
INSERT INTO decisions (proposed, proponent, title, content, votetype, status, due, modified,tag)
VALUES (
    :proposed, :proponent, :title, :content, :votetype, 0, :due, :proposed,
    'm' || strftime('%Y%m%d', :proposed) || '.' || (
	 	SELECT COUNT(*)+1 AS num
  		FROM decisions
  		WHERE proposed BETWEEN date(:proposed) AND date(:proposed, '1 day')
    )
)`,
	sqlUpdateDecision: `
UPDATE decisions
SET    proponent=:proponent, title=:title, content=:content, votetype=:votetype, due=:due, modified=:modified
WHERE  id=:id`,
	sqlUpdateDecisionStatus: `
UPDATE decisions SET status=:status, modified=:modified WHERE id=:id`,
	sqlSelectClosableDecisions: `
SELECT decisions.id, decisions.tag, decisions.proponent, decisions.proposed, decisions.title, decisions.content,
       decisions.votetype, decisions.status, decisions.due, decisions.modified
FROM   decisions
WHERE  decisions.status=0 AND :now > due`,
	sqlGetNextPendingDecisionDue: `
SELECT due FROM decisions WHERE status=0 ORDER BY due LIMIT 1`,
	sqlGetVotersForProxy: `
SELECT id, name, reminder
FROM   voters WHERE enabled=1 AND id != $1 AND id NOT IN (SELECT voter FROM votes WHERE decision=$2)`,
	sqlGetReminderVoters: `
SELECT id, name, reminder FROM voters WHERE enabled=1 AND reminder!='' AND reminder IS NOT NULL`,
	sqlFindUnvotedDecisionsForVoter: `
SELECT tag, title, votetype, due
FROM   decisions
WHERE  status = 0 AND id NOT IN (SELECT decision FROM votes WHERE voter = $1)
ORDER BY due ASC`,
	sqlCreateVote: `
INSERT OR REPLACE INTO votes (decision, voter, vote, voted, notes)
VALUES (:decision, :voter, :vote, :voted, :notes)`,
	sqlLoadVote: `
SELECT decision, voter, vote, voted, notes
FROM   votes
WHERE  decision=$1 AND voter=$2`,
}

var db *sqlx.DB

func init() {
	for _, sqlStatement := range sqlStatements {
		var stmt *sqlx.Stmt
		stmt, err := db.Preparex(sqlStatement)
		if err != nil {
			logger.Fatalf("ERROR parsing statement %s: %s", sqlStatement, err)
		}
		stmt.Close()
	}
}

type VoteType uint8
type VoteStatus int8

type Decision struct {
	Id          int64
	Proposed    time.Time
	ProponentId int64 `db:"proponent"`
	Title       string
	Content     string
	Quorum      int
	Majority    int
	Status      VoteStatus
	Due         time.Time
	Modified    time.Time
	Tag         string
	VoteType    VoteType
}

type Email struct {
	VoterId int64 `db:"voter"`
	Address string
}

type Voter struct {
	Id       int64
	Name     string
	Enabled  bool
	Reminder string // reminder email address
}

type VoteChoice int

const (
	voteAye     = 1
	voteNaye    = -1
	voteAbstain = 0
)

const (
	voteTypeMotion = 0
	voteTypeVeto   = 1
)

func (v VoteType) String() string {
	switch v {
	case voteTypeMotion:
		return "motion"
	case voteTypeVeto:
		return "veto"
	default:
		return "unknown"
	}
}

func (v VoteType) QuorumAndMajority() (int, int) {
	switch v {
	case voteTypeMotion:
		return 3, 50
	default:
		return 1, 99
	}
}

func (v VoteChoice) String() string {
	switch v {
	case voteAye:
		return "aye"
	case voteNaye:
		return "naye"
	case voteAbstain:
		return "abstain"
	default:
		return "unknown"
	}
}

var VoteValues = map[string]VoteChoice{
	"aye":     voteAye,
	"naye":    voteNaye,
	"abstain": voteAbstain,
}

var VoteChoices = map[int64]VoteChoice{
	1:  voteAye,
	0:  voteAbstain,
	-1: voteNaye,
}

const (
	voteStatusDeclined  = -1
	voteStatusPending   = 0
	voteStatusApproved  = 1
	voteStatusWithdrawn = -2
)

func (v VoteStatus) String() string {
	switch v {
	case voteStatusDeclined:
		return "declined"
	case voteStatusPending:
		return "pending"
	case voteStatusApproved:
		return "approved"
	case voteStatusWithdrawn:
		return "withdrawn"
	default:
		return "unknown"
	}
}

type Vote struct {
	DecisionId int64 `db:"decision"`
	VoterId    int64 `db:"voter"`
	Vote       VoteChoice
	Voted      time.Time
	Notes      string
}

func (v *Vote) Save() (err error) {
	insertVoteStmt, err := db.PrepareNamed(sqlStatements[sqlCreateVote])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer insertVoteStmt.Close()

	_, err = insertVoteStmt.Exec(v)
	if err != nil {
		logger.Println("Error saving vote:", err)
		return
	}

	getVoteStmt, err := db.Preparex(sqlStatements[sqlLoadVote])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer getVoteStmt.Close()

	err = getVoteStmt.Get(v, v.DecisionId, v.VoterId)
	if err != nil {
		logger.Println("Error getting inserted vote:", err)
	}

	return
}

type VoteSums struct {
	Ayes     int
	Nayes    int
	Abstains int
}

func (v *VoteSums) VoteCount() int {
	return v.Ayes + v.Nayes + v.Abstains
}

func (v *VoteSums) TotalVotes() int {
	return v.Ayes + v.Nayes
}

func (v *VoteSums) Percent() int {
	totalVotes := v.TotalVotes()
	if totalVotes == 0 {
		return 0
	}
	return v.Ayes * 100 / totalVotes
}

type VoteForDisplay struct {
	Vote
	Name string
}

type DecisionForDisplay struct {
	Decision
	Proposer string `db:"proposer"`
	*VoteSums
	Votes []VoteForDisplay
}

func FindDecisionForDisplayByTag(tag string) (decision *DecisionForDisplay, err error) {
	decisionStmt, err := db.Preparex(sqlStatements[sqlLoadDecisionByTag])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer decisionStmt.Close()

	decision = &DecisionForDisplay{}
	if err = decisionStmt.Get(decision, tag); err != nil {
		if err == sql.ErrNoRows {
			decision = nil
			err = nil
		} else {
			logger.Printf("Error getting motion %s: %v\n", tag, err)
		}
	}
	decision.VoteSums, err = decision.Decision.VoteSums()
	return
}

// FindDecisionsForDisplayOnPage loads a set of decisions from the database.
//
// This function uses OFFSET for pagination which is not a good idea for larger data sets.
//
// TODO: migrate to timestamp base pagination
func FindDecisionsForDisplayOnPage(page int64, unvoted bool, voter *Voter) (decisions []*DecisionForDisplay, err error) {
	var decisionsStmt *sqlx.Stmt
	if unvoted && voter != nil {
		decisionsStmt, err = db.Preparex(sqlStatements[sqlLoadUnvotedDecisions])
	} else {
		decisionsStmt, err = db.Preparex(sqlStatements[sqlLoadDecisions])
	}
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer decisionsStmt.Close()

	var rows *sqlx.Rows
	if unvoted && voter != nil {
		rows, err = decisionsStmt.Queryx(voter.Id, page-1)
	} else {
		rows, err = decisionsStmt.Queryx(page - 1)
	}
	if err != nil {
		logger.Printf("Error loading motions for page %d: %v\n", page, err)
		return
	}
	defer rows.Close()

	for rows.Next() {
		var d DecisionForDisplay
		if err = rows.StructScan(&d); err != nil {
			logger.Printf("Error loading motions for page %d: %v\n", page, err)
			return
		}
		d.VoteSums, err = d.Decision.VoteSums()
		if err != nil {
			return
		}
		decisions = append(decisions, &d)
	}
	return
}

func (d *Decision) VoteSums() (sums *VoteSums, err error) {
	votesStmt, err := db.Preparex(sqlStatements[sqlLoadVoteCountsForDecision])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer votesStmt.Close()

	voteRows, err := votesStmt.Queryx(d.Id)
	if err != nil {
		logger.Printf("Error fetching vote sums for motion %s: %v\n", d.Tag, err)
		return
	}
	defer voteRows.Close()

	sums = &VoteSums{}
	for voteRows.Next() {
		var vote VoteChoice
		var count int
		if err = voteRows.Scan(&vote, &count); err != nil {
			logger.Printf("Error fetching vote sums for motion %s: %v\n", d.Tag, err)
			return
		}
		switch vote {
		case voteAye:
			sums.Ayes = count
		case voteNaye:
			sums.Nayes = count
		case voteAbstain:
			sums.Abstains = count
		}
	}
	return
}

func (d *DecisionForDisplay) LoadVotes() (err error) {
	votesStmt, err := db.Preparex(sqlStatements[sqlLoadVotesForDecision])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer votesStmt.Close()
	err = votesStmt.Select(&d.Votes, d.Id)
	if err != nil {
		logger.Printf("Error selecting votes for motion %s: %v\n", d.Tag, err)
	}
	return
}

func (d *Decision) OlderExists(unvoted bool, voter *Voter) (result bool, err error) {
	var olderStmt *sqlx.Stmt
	if unvoted && voter != nil {
		olderStmt, err = db.Preparex(sqlStatements[sqlCountOlderThanUnvotedDecision])
	} else {
		olderStmt, err = db.Preparex(sqlStatements[sqlCountOlderThanDecision])
	}
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer olderStmt.Close()

	if unvoted && voter != nil {
		if err = olderStmt.Get(&result, d.Proposed, voter.Id); err != nil {
			logger.Printf("Error finding older motions than %s: %v\n", d.Tag, err)
		}
	} else {
		if err = olderStmt.Get(&result, d.Proposed); err != nil {
			logger.Printf("Error finding older motions than %s: %v\n", d.Tag, err)
		}
	}

	return
}

func (d *Decision) Create() (err error) {
	insertDecisionStmt, err := db.PrepareNamed(sqlStatements[sqlCreateDecision])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer insertDecisionStmt.Close()

	result, err := insertDecisionStmt.Exec(d)
	if err != nil {
		logger.Println("Error creating motion:", err)
		return
	}

	lastInsertId, err := result.LastInsertId()
	if err != nil {
		logger.Println("Error getting id of inserted motion:", err)
		return
	}
	rescheduleChannel <- JobIdCloseDecisions

	getDecisionStmt, err := db.Preparex(sqlStatements[sqlLoadDecisionById])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer getDecisionStmt.Close()

	err = getDecisionStmt.Get(d, lastInsertId)
	if err != nil {
		logger.Println("Error getting inserted motion:", err)
	}

	return
}

func (d *Decision) LoadWithId() (err error) {
	getDecisionStmt, err := db.Preparex(sqlStatements[sqlLoadDecisionById])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer getDecisionStmt.Close()

	err = getDecisionStmt.Get(d, d.Id)
	if err != nil {
		logger.Println("Error loading updated motion:", err)
	}

	return
}

func (d *Decision) Update() (err error) {
	updateDecisionStmt, err := db.PrepareNamed(sqlStatements[sqlUpdateDecision])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer updateDecisionStmt.Close()

	result, err := updateDecisionStmt.Exec(d)
	if err != nil {
		logger.Println("Error updating motion:", err)
		return
	}
	affectedRows, err := result.RowsAffected()
	if err != nil {
		logger.Print("Problem determining the affected rows")
		return
	} else if affectedRows != 1 {
		logger.Printf("WARNING wrong number of affected rows: %d (1 expected)\n", affectedRows)
	}
	rescheduleChannel <- JobIdCloseDecisions

	err = d.LoadWithId()
	return
}

func (d *Decision) UpdateStatus() (err error) {
	updateStatusStmt, err := db.PrepareNamed(sqlStatements[sqlUpdateDecisionStatus])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer updateStatusStmt.Close()

	result, err := updateStatusStmt.Exec(d)
	if err != nil {
		logger.Println("Error setting motion status:", err)
		return
	}
	affectedRows, err := result.RowsAffected()
	if err != nil {
		logger.Print("Problem determining the affected rows")
		return
	} else if affectedRows != 1 {
		logger.Printf("WARNING wrong number of affected rows: %d (1 expected)\n", affectedRows)
	}
	rescheduleChannel <- JobIdCloseDecisions

	err = d.LoadWithId()
	return
}

func (d *Decision) String() string {
	return fmt.Sprintf("%s %s (Id %d)", d.Tag, d.Title, d.Id)
}

func FindVoterByAddress(emailAddress string) (voter *Voter, err error) {
	findVoterStmt, err := db.Preparex(sqlStatements[sqlLoadEnabledVoterByEmail])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer findVoterStmt.Close()

	voter = &Voter{}
	if err = findVoterStmt.Get(voter, emailAddress); err != nil {
		if err != sql.ErrNoRows {
			logger.Printf("Error getting voter for address %s: %v\n", emailAddress, err)
		} else {
			err = nil
			voter = nil
		}
	}
	return
}

func (d *Decision) Close() (err error) {
	quorum, majority := d.VoteType.QuorumAndMajority()

	voteSums, err := d.VoteSums()

	if err != nil {
		logger.Println("Error getting vote sums")
		return
	}
	votes := voteSums.VoteCount()

	if votes < quorum {
		d.Status = voteStatusDeclined
	} else {
		votes = voteSums.TotalVotes()
		if (voteSums.Ayes / votes) > (majority / 100) {
			d.Status = voteStatusApproved
		} else {
			d.Status = voteStatusDeclined
		}
	}

	closeDecisionStmt, err := db.PrepareNamed(sqlStatements[sqlUpdateDecisionStatus])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer closeDecisionStmt.Close()

	result, err := closeDecisionStmt.Exec(d)
	if err != nil {
		logger.Println("Error closing vote:", err)
		return
	}
	affectedRows, err := result.RowsAffected()
	if err != nil {
		logger.Println("Error getting affected rows:", err)
	}
	if affectedRows != 1 {
		logger.Printf("WARNING wrong number of affected rows: %d (1 expected)\n", affectedRows)
	}

	NotifyMailChannel <- NewNotificationClosedDecision(d, voteSums)

	return
}

func CloseDecisions() (err error) {
	getClosableDecisionsStmt, err := db.PrepareNamed(sqlStatements[sqlSelectClosableDecisions])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer getClosableDecisionsStmt.Close()

	decisions := make([]*Decision, 0)
	rows, err := getClosableDecisionsStmt.Queryx(struct{ Now time.Time }{time.Now().UTC()})
	if err != nil {
		logger.Println("Error fetching closable decisions", err)
		return
	}
	defer rows.Close()
	for rows.Next() {
		decision := &Decision{}
		if err = rows.StructScan(decision); err != nil {
			logger.Println("Error scanning row", err)
			return
		}
		decisions = append(decisions, decision)
	}
	rows.Close()

	for _, decision := range decisions {
		logger.Println("DEBUG found closable decision", decision)
		if err = decision.Close(); err != nil {
			logger.Printf("Error closing decision %s: %s\n", decision, err)
			return
		}
	}

	return
}

func GetNextPendingDecisionDue() (due *time.Time, err error) {
	getNextPendingDecisionDueStmt, err := db.Preparex(sqlStatements[sqlGetNextPendingDecisionDue])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer getNextPendingDecisionDueStmt.Close()

	row := getNextPendingDecisionDueStmt.QueryRow()

	var dueTimestamp time.Time
	if err = row.Scan(&dueTimestamp); err != nil {
		if err == sql.ErrNoRows {
			logger.Println("DEBUG No pending decisions")
			return nil, nil
		}
		logger.Println("Error parsing result", err)
		return
	}
	due = &dueTimestamp

	return
}

func GetReminderVoters() (voters *[]Voter, err error) {
	getReminderVotersStmt, err := db.Preparex(sqlStatements[sqlGetReminderVoters])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer getReminderVotersStmt.Close()

	voterSlice := make([]Voter, 0)

	if err = getReminderVotersStmt.Select(&voterSlice); err != nil {
		logger.Println("Error getting voters:", err)
		return
	}
	voters = &voterSlice

	return
}

func FindUnvotedDecisionsForVoter(voter *Voter) (decisions *[]Decision, err error) {
	findUnvotedDecisionsForVoterStmt, err := db.Preparex(sqlStatements[sqlFindUnvotedDecisionsForVoter])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer findUnvotedDecisionsForVoterStmt.Close()

	decisionsSlice := make([]Decision, 0)

	if err = findUnvotedDecisionsForVoterStmt.Select(&decisionsSlice, voter.Id); err != nil {
		logger.Println("Error getting unvoted decisions:", err)
		return
	}
	decisions = &decisionsSlice

	return
}

func GetVoterById(id int64) (voter *Voter, err error) {
	getVoterByIdStmt, err := db.Preparex(sqlStatements[sqlGetEnabledVoterById])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer getVoterByIdStmt.Close()

	voter = &Voter{}
	if err = getVoterByIdStmt.Get(voter, id); err != nil {
		logger.Println("Error getting voter:", err)
		return
	}

	return
}

func GetVotersForProxy(proxy *Voter, decision *Decision) (voters *[]Voter, err error) {
	getVotersForProxyStmt, err := db.Preparex(sqlStatements[sqlGetVotersForProxy])
	if err != nil {
		logger.Println("Error preparing statement:", err)
		return
	}
	defer getVotersForProxyStmt.Close()

	votersSlice := make([]Voter, 0)

	if err = getVotersForProxyStmt.Select(&votersSlice, proxy.Id, decision.Id); err != nil {
		logger.Println("Error getting voters for proxy:", err)
		return
	}
	voters = &votersSlice

	return
}