package store

import (
	"database/sql"
	"fmt"
	"net"

	"git.t-juice.club/torjus/apiary/models"
	_ "github.com/jackc/pgx/v4/stdlib"
)

var _ LoginAttemptStore = &PostgresStore{}

const DBSchema = `
CREATE TABLE IF NOT EXISTS login_attempts(
	id serial PRIMARY KEY,
	date timestamptz,
	remote_ip inet,
	username text,
	password text,
	client_version text,
	connection_uuid uuid,
	country varchar(2)
);
`

type PostgresStore struct {
	db *sql.DB
}

func NewPostgresStore(dsn string) (*PostgresStore, error) {
	db, err := sql.Open("pgx", dsn)
	if err != nil {
		return nil, err
	}
	rs := &PostgresStore{
		db: db,
	}
	return rs, nil
}

func (s *PostgresStore) InitDB() error {
	_, err := s.db.Exec(DBSchema)
	return err
}

func (s *PostgresStore) AddAttempt(l *models.LoginAttempt) error {
	stmt := `INSERT INTO 
login_attempts(date, remote_ip, username, password, client_version, connection_uuid, country)
VALUES ($1, $2, $3, $4, $5, $6, $7)
RETURNING id;`
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback() // nolint: errcheck

	var id int
	if err := tx.QueryRow(stmt, l.Date, l.RemoteIP.String(), l.Username, l.Password, l.SSHClientVersion, l.ConnectionUUID, l.Country).Scan(&id); err != nil {
		return err
	}
	l.ID = id
	return tx.Commit()
}

func (s *PostgresStore) All() (<-chan models.LoginAttempt, error) {
	stmt := `SELECT date, remote_ip, username, password, client_version, connection_uuid, country FROM login_attempts`

	rows, err := s.db.Query(stmt)
	if err != nil {
		return nil, err
	}

	ch := make(chan models.LoginAttempt)
	go func() {
		defer rows.Close()
		for rows.Next() {
			var a models.LoginAttempt
			var ip string
			if err := rows.Scan(&a.Date, &ip, &a.Username, &a.Password, &a.SSHClientVersion, &a.SSHClientVersion, &a.Country); err != nil {
				panic(err)
			}
			a.RemoteIP = net.ParseIP(ip)
			ch <- a
		}
		close(ch)
	}()

	return ch, nil
}

func (s *PostgresStore) Stats(statType LoginStats, limit int) ([]StatsResult, error) {
	var stmt string

	if statType == LoginStatsTotals {
		return s.statsTotal(limit)
	}

	switch statType {
	case LoginStatsCountry:
		stmt = `select country, count(country) from login_attempts group by country order by count desc`
	case LoginStatsIP:
		stmt = `select remote_ip, count(remote_ip) from login_attempts group by remote_ip order by count desc`
	case LoginStatsPasswords:
		stmt = `select password, count(password) from login_attempts group by password order by count desc`
	case LoginStatsUsername:
		stmt = `select username, count(username) from login_attempts group by username order by count desc`
	default:
		return nil, fmt.Errorf("invalid stat type")
	}

	if limit > 0 {
		stmt = fmt.Sprintf("%s limit %d", stmt, limit)
	}
	rows, err := s.db.Query(stmt)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var results []StatsResult
	for rows.Next() {
		var r StatsResult

		if err := rows.Scan(&r.Name, &r.Count); err != nil {
			return nil, err
		}
		results = append(results, r)
	}

	return results, nil
}

func (s *PostgresStore) IsHealthy() error {
	if err := s.db.Ping(); err != nil {
		return ErrStoreUnhealthy
	}
	return nil
}

func (s *PostgresStore) statsTotal(limit int) ([]StatsResult, error) {
	uniquePasswordStmt := `select count(*) from (select distinct password from login_attempts) as temp`
	uniqueUsernameStmt := `select count(*) from (select distinct username from login_attempts) as temp`
	uniqueIPStmt := `select count(*) from (select distinct remote_ip from login_attempts) as temp`
	uniqueCountryStmt := `select count(*) from (select distinct country from login_attempts) as temp`
	attemptsCountStmt := `select count(1) from login_attempts`

	var uniquePasswordsCount int
	if err := s.db.QueryRow(uniquePasswordStmt).Scan(&uniquePasswordsCount); err != nil {
		return nil, err
	}
	var uniqueUsernameCount int
	if err := s.db.QueryRow(uniqueUsernameStmt).Scan(&uniqueUsernameCount); err != nil {
		return nil, err
	}
	var uniqueIPCount int
	if err := s.db.QueryRow(uniqueIPStmt).Scan(&uniqueIPCount); err != nil {
		return nil, err
	}
	var uniqueCountryCount int
	if err := s.db.QueryRow(uniqueCountryStmt).Scan(&uniqueCountryCount); err != nil {
		return nil, err
	}
	var attemptsCount int
	if err := s.db.QueryRow(attemptsCountStmt).Scan(&attemptsCount); err != nil {
		return nil, err
	}
	return []StatsResult{
		{Name: "UniquePasswords", Count: uniquePasswordsCount},
		{Name: "UniqueUsernames", Count: uniqueUsernameCount},
		{Name: "UniqueIPs", Count: uniqueIPCount},
		{Name: "UniqueCountries", Count: uniqueCountryCount},
		{Name: "TotalLoginAttempts", Count: attemptsCount},
	}, nil
}

func (s *PostgresStore) Query(query AttemptQuery) ([]models.LoginAttempt, error) {
	var stmt string
	queryString := query.Query

	const limit = 10000

	switch query.QueryType {
	case AttemptQueryTypeIP:
		stmt = `SELECT id, date, remote_ip, username, password, client_version, connection_uuid, country
					FROM login_attempts WHERE remote_ip = $1 order by date desc limit $2`
	case AttemptQueryTypePassword:
		stmt = `SELECT id, date, remote_ip, username, password, client_version, connection_uuid, country
					FROM login_attempts WHERE password = $1 order by date desc limit $2`
	case AttemptQueryTypeUsername:
		stmt = `SELECT id, date, remote_ip, username, password, client_version, connection_uuid, country
					FROM login_attempts WHERE username = $1 order by date desc limit $2`
	default:
		return nil, fmt.Errorf("invalid query type")
	}

	rows, err := s.db.Query(stmt, queryString, limit)
	if err != nil {
		return nil, fmt.Errorf("unable to query database: %w", err)
	}
	defer rows.Close()

	var results []models.LoginAttempt
	for rows.Next() {
		var la models.LoginAttempt
		var ipString string
		if err := rows.Scan(&la.ID, &la.Date, &ipString, &la.Username, &la.Password, &la.SSHClientVersion, &la.ConnectionUUID, &la.Country); err != nil {
			return nil, fmt.Errorf("unable to unmarshal data from database: %w", err)
		}
		la.RemoteIP = net.ParseIP(ipString)
		results = append(results, la)
	}

	return results, nil
}