// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
// SPDX-License-Identifier: Apache-2.0

package storage // import "miniflux.app/v2/internal/storage"

import (
	"crypto/rand"
	"database/sql"
	"errors"
	"fmt"
	"time"

	"miniflux.app/v2/internal/model"
)

// UserSessions returns the list of sessions for the given user.
func (s *Storage) UserSessions(userID int64) ([]model.UserSession, error) {
	query := `
		SELECT
			id,
			user_id,
			token,
			created_at,
			user_agent,
			ip
		FROM
			user_sessions
		WHERE
			user_id=$1 ORDER BY id DESC
	`
	rows, err := s.db.Query(query, userID)
	if err != nil {
		return nil, fmt.Errorf(`store: unable to fetch user sessions: %v`, err)
	}
	defer rows.Close()

	var sessions []model.UserSession
	for rows.Next() {
		var session model.UserSession
		err := rows.Scan(
			&session.ID,
			&session.UserID,
			&session.Token,
			&session.CreatedAt,
			&session.UserAgent,
			&session.IP,
		)
		if err != nil {
			return nil, fmt.Errorf(`store: unable to fetch user session row: %v`, err)
		}

		sessions = append(sessions, session)
	}

	return sessions, nil
}

// CreateUserSessionFromUsername creates a new user session.
func (s *Storage) CreateUserSessionFromUsername(username, userAgent, ip string) (sessionID string, userID int64, err error) {
	token := rand.Text()

	tx, err := s.db.Begin()
	if err != nil {
		return "", 0, fmt.Errorf(`store: unable to start transaction: %v`, err)
	}

	err = tx.QueryRow(`SELECT id FROM users WHERE username = LOWER($1)`, username).Scan(&userID)
	if err != nil {
		tx.Rollback()
		return "", 0, fmt.Errorf(`store: unable to fetch user ID: %v`, err)
	}

	_, err = tx.Exec(
		`INSERT INTO user_sessions (token, user_id, user_agent, ip) VALUES ($1, $2, $3, $4)`,
		token,
		userID,
		userAgent,
		ip,
	)
	if err != nil {
		tx.Rollback()
		return "", 0, fmt.Errorf(`store: unable to create user session: %v`, err)
	}

	if err := tx.Commit(); err != nil {
		return "", 0, fmt.Errorf(`store: unable to commit transaction: %v`, err)
	}

	return token, userID, nil
}

// UserSessionByToken finds a session by the token.
func (s *Storage) UserSessionByToken(token string) (*model.UserSession, error) {
	var session model.UserSession

	query := `
		SELECT
			id,
			user_id,
			token,
			created_at,
			user_agent,
			ip 
		FROM
			user_sessions
		WHERE
			token = $1
	`
	err := s.db.QueryRow(query, token).Scan(
		&session.ID,
		&session.UserID,
		&session.Token,
		&session.CreatedAt,
		&session.UserAgent,
		&session.IP,
	)

	switch {
	case err == sql.ErrNoRows:
		return nil, nil
	case err != nil:
		return nil, fmt.Errorf(`store: unable to fetch user session: %v`, err)
	default:
		return &session, nil
	}
}

// RemoveUserSessionByToken remove a session by using the token.
func (s *Storage) RemoveUserSessionByToken(userID int64, token string) error {
	query := `DELETE FROM user_sessions WHERE user_id=$1 AND token=$2`
	result, err := s.db.Exec(query, userID, token)
	if err != nil {
		return fmt.Errorf(`store: unable to remove this user session: %v`, err)
	}

	count, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf(`store: unable to remove this user session: %v`, err)
	}

	if count != 1 {
		return errors.New(`store: nothing has been removed`)
	}

	return nil
}

// RemoveUserSessionByID remove a session by using the ID.
func (s *Storage) RemoveUserSessionByID(userID, sessionID int64) error {
	query := `DELETE FROM user_sessions WHERE user_id=$1 AND id=$2`
	result, err := s.db.Exec(query, userID, sessionID)
	if err != nil {
		return fmt.Errorf(`store: unable to remove this user session: %v`, err)
	}

	count, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf(`store: unable to remove this user session: %v`, err)
	}

	if count != 1 {
		return errors.New(`store: nothing has been removed`)
	}

	return nil
}

// CleanOldUserSessions removes user sessions older than specified interval (24h minimum).
func (s *Storage) CleanOldUserSessions(interval time.Duration) int64 {
	query := `
		DELETE FROM
			user_sessions
		WHERE
			created_at < now() - $1::interval
	`

	days := max(int(interval/(24*time.Hour)), 1)

	result, err := s.db.Exec(query, fmt.Sprintf("%d days", days))
	if err != nil {
		return 0
	}

	n, _ := result.RowsAffected()
	return n
}
