package db

import (
	"database/sql"
	"crypto/rand"
	"encoding/base64"
	"errors"
	"time"
)


func (p *Phlox) CreateSession(user User) (Session, error) {
	bytes := make([]byte, 32)
	_, err := rand.Read(bytes)
	if err != nil {
		return Session{}, err
	}

	sessionid := base64.StdEncoding.EncodeToString(bytes)
	userid := user.Id
	now := time.Now().UTC()
	nowStr := now.Format(time.RFC3339)

	_, err = p.db.Exec(
		"insert into sessions (sessionid, userid, created, modified) values (?, ?, ?, ?);", 
		sessionid, 
		userid,
		nowStr, nowStr,
	)
	if err != nil {
		return Session{}, err
	}

	return Session{
		Id: sessionid,
		UserId: userid,
		Created: now,
		Modified: now,
	}, nil
}


func (p *Phlox) DeleteSession(session Session) error {
	_, err := p.db.Exec("delete from sessions where sessionid = ?;", session.Id)
	return err
}


func extractSession(s Scanner) (Session, error) {
	var (
		session Session
		createdStr string
		modifiedStr string
	)

	// scan
	err := s.Scan(&session.Id, &session.UserId, &createdStr, &modifiedStr)
	if err != nil {
		return Session{}, err
	}

	// parse times
	session.Created, err = time.Parse(time.RFC3339, createdStr)
	if err != nil {
		return Session{}, err
	}
	session.Modified, err = time.Parse(time.RFC3339, modifiedStr)
	if err != nil {
		return Session{}, err
	}

	return session, nil
}


func (p *Phlox) TouchSession(session Session) error {
	now := time.Now().UTC()
	nowStr := now.Format(time.RFC3339)
	_, err := p.db.Exec("update sessions set modified=? where sessionid=?;", nowStr, session.Id)
	return err
}


func (p *Phlox) CheckSession(session Session) (bool, error) {
	row := p.db.QueryRow("select * from sessions where sessionid = ?", session.Id)
	session, err := extractSession(row)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			// no row returned, so invalid session
			return false, nil
		} else {
			// some other error
			return false, err
		}
	}

	return true, nil
}


func (p *Phlox) TouchSession(session Session) error {
	now := time.Now().UTC().Format(time.RFC3339)
	_, err := p.db.Exec(
		"update sessions set modified = ? where sessionid = ?;",
		now, session.Id,
	)
	return err
}


func (p *Phlox) CleanSessions(maxIdle time.Duration) error {
	expire := time.Now().UTC().Add(-maxIdle).Format(time.RFC3339)
	_, err := p.db.Exec("delete from sessions where modified < ?;", expire)
	return err
}


func (p *Phlox) AllSessions() ([]Session, error) {
	sessions := make([]Session, 0)
	rows, err := p.db.Query("select * from sessions;")
	if err != nil {
		return sessions, err
	}
	defer rows.Close()

	for rows.Next() {
		session, err := extractSession(rows)
		if err != nil {
			return sessions, err
		}
		sessions = append(sessions, session)
	}

	return sessions, nil
}