package main

import (
	"context"
	"database/sql"
	"encoding/hex"
	"fmt"
	"github.com/pkg/errors"
	"math/rand"
	"time"

	_ "github.com/lib/pq"
)

func init() {
	rand.Seed(time.Now().UnixNano())
}

type dbLayer struct {
	db *sql.DB
}

func connectToDataBase(host string, port uint32, user string, password string, dbName string) (*dbLayer, error) {
	db, err := sql.Open("postgres",
		fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=%s sslmode=disable",
			host, port, user, password, dbName,
		),
	)

	if err != nil {
		return nil, errors.Wrap(err, "Failed to connect to database")
	}

	return &dbLayer{
		db: db,
	}, nil
}

func (db *dbLayer) execInTransaction(ctx context.Context, query string, args ...interface{}) error {
	tx, err := db.db.BeginTx(ctx, &sql.TxOptions{})
	if err != nil {
		return errors.Wrap(err, "Failed to begin transaction")
	}

	getLogger(ctx).Debugf("[Run sql query]: %s, [%v]", query, args)

	_, err = tx.ExecContext(ctx, query, args...)
	if err != nil {
		_ = tx.Rollback()

		return errors.Wrapf(err, "Failed to run db query [%s] [%v]", query, args)
	}

	err = tx.Commit()
	if err != nil {
		return errors.Wrap(err, "Failed to commit transaction")
	}

	return nil
}

type Player struct {
	id             string
	name           string
	lastOnline     time.Time
	onlineDuration time.Duration
	deaths         int
	level          int
}

func fetchPlayer(r *sql.Rows, p *Player) error {
	var (
		err            error
		lastOnline     string
		onlineDuration int
	)

	err = r.Scan(&p.id, &p.name, &lastOnline, &onlineDuration, &p.deaths, &p.level)
	if err != nil {
		return errors.Wrap(err, "Failed to fetch data base")
	}

	p.lastOnline, err = time.Parse(time.RFC3339, lastOnline)
	if err != nil {
		return errors.Wrapf(err, "Failed to parse date [%s]", lastOnline)
	}

	p.onlineDuration = time.Second * time.Duration(onlineDuration)

	return nil
}

func (db *dbLayer) getPlayers(ctx context.Context) ([]Player, error) {
	var players []Player

	query := "SELECT id, name, last_login, online_duration, deaths, level FROM players"

	rows, err := db.db.QueryContext(ctx, query)
	if err != nil {
		return nil, errors.Wrapf(err, "Failed to run db query [%s]", query)
	}

	defer rows.Close()

	for rows.Next() {
		p := Player{}

		err = fetchPlayer(rows, &p)
		if err != nil {
			return nil, err
		}

		players = append(players, p)
	}

	return players, nil
}

func (db *dbLayer) getPlayerByID(ctx context.Context, id string) (*Player, error) {
	query := "SELECT id, name, last_login, online_duration, deaths, level FROM players WHERE id = $1"

	rows, err := db.db.QueryContext(ctx, query, id)
	if err != nil {
		return nil, errors.Wrapf(err, "Failed to run db query [%s]", query)
	}

	defer rows.Close()

	if rows.Next() {
		var p Player

		err = fetchPlayer(rows, &p)
		if err != nil {
			return nil, err
		}

		return &p, nil
	}

	return nil, nil
}

func (db *dbLayer) getPlayerByName(ctx context.Context, name string) (*Player, error) {
	query := "SELECT id, name, last_login, online_duration, deaths, level FROM players WHERE name = $1 LIMIT 1"

	rows, err := db.db.QueryContext(ctx, query, name)
	if err != nil {
		return nil, errors.Wrapf(err, "Failed to run db query [%s]", query)
	}

	defer rows.Close()

	if rows.Next() {
		var p Player

		err = fetchPlayer(rows, &p)
		if err != nil {
			return nil, err
		}

		return &p, nil
	}

	return nil, nil
}

func (db *dbLayer) createPlayer(ctx context.Context, name string, lastOnline time.Time) (*Player, error) {
	id := uuid()

	err := db.execInTransaction(ctx, "INSERT INTO players (id, name, last_login) VALUES ($1, $2, $3)", id, name, lastOnline.Format(time.RFC3339))

	if err != nil {
		return nil, err
	}

	return &Player{
		id:         id,
		name:       name,
		lastOnline: lastOnline,
	}, nil
}

func (db *dbLayer) increasePlayerOnlineDuration(ctx context.Context, playerID string, d time.Duration) error {
	onlineDurationSecond := int(d / time.Second)
	if onlineDurationSecond == 0 {
		return nil
	}

	return db.execInTransaction(ctx, "UPDATE players SET online_duration = online_duration + $2 WHERE id = $1", playerID, onlineDurationSecond)
}

func (db *dbLayer) updatePlayerLastOnline(ctx context.Context, playerID string, lastOnline time.Time) error {
	return db.execInTransaction(ctx, "UPDATE players SET last_login = $2 WHERE id = $1", playerID, lastOnline.Format(time.RFC3339))
}

func (db *dbLayer) increasePlayerDeath(ctx context.Context, playerID string, deaths int) error {
	return db.execInTransaction(ctx, "UPDATE players SET deaths = deaths + $2 WHERE id = $1", playerID, deaths)
}

func (db *dbLayer) increasePlayerEntryKills(ctx context.Context, playerID string, entity string, count int) error {
	return db.execInTransaction(ctx,
		"INSERT INTO killings (player_id, entity, count) VALUES ($1, $2, $3) ON CONFLICT (player_id, entity) DO UPDATE SET count = killings.count + excluded.count",
		playerID, entity, count,
	)
}

func (db *dbLayer) updatePlayerLevel(ctx context.Context, playerID string, level int) error {
	return db.execInTransaction(ctx, "UPDATE players SET level = $2 WHERE id = $1", playerID, level)
}

func uuid() string {
	token := make([]byte, 18)
	rand.Read(token)
	result := make([]byte, 36)
	hex.Encode(result, token)

	result[8] = 45
	result[13] = 45
	result[18] = 45
	result[23] = 45

	return string(result)
}