package db

import (
	"context"
	"database/sql"
	"errors"
)

// SessionUser is the identity attached to a request by the session cookie.
type SessionUser struct {
	ID            int64
	Username      string
	IsAdmin       bool
	AvatarVersion int64
	// SessionCreatedAt is when this session signed in, in ISOLayout.
	SessionCreatedAt string
}

func (d *DB) CreateSession(ctx context.Context, id string, userID int64, expiresAt, createdAt string) error {
	_, err := d.ExecContext(ctx,
		`INSERT INTO sessions (id, user_id, expires_at, created_at) VALUES (?, ?, ?, ?)`,
		id, userID, expiresAt, createdAt)
	return err
}

func (d *DB) DeleteSession(ctx context.Context, id string) error {
	_, err := d.ExecContext(ctx, `DELETE FROM sessions WHERE id = ?`, id)
	return err
}

// DeleteOtherSessions signs a user out everywhere except the session keepID.
func (d *DB) DeleteOtherSessions(ctx context.Context, userID int64, keepID string) error {
	_, err := d.ExecContext(ctx, `DELETE FROM sessions WHERE user_id = ? AND id != ?`, userID, keepID)
	return err
}

func (d *DB) DeleteExpiredSessions(ctx context.Context) error {
	// expires_at is stored in the ISO form NowISO writes. datetime('now') uses
	// a space instead of the T, which compares wrong for the same day.
	_, err := d.ExecContext(ctx, `DELETE FROM sessions WHERE expires_at < ?`, NowISO())
	return err
}

// SessionUser resolves a session cookie. Expired sessions and pending users
// resolve to nil.
func (d *DB) SessionUser(ctx context.Context, sessionID, now string) (*SessionUser, error) {
	return d.sessionUser(ctx, sessionID, now, false)
}

// SessionUserAllowPending also resolves the session of an account that is
// still awaiting approval. Only the passkey registration ceremony uses it:
// in queue mode the account exists but must not be usable yet.
func (d *DB) SessionUserAllowPending(ctx context.Context, sessionID, now string) (*SessionUser, error) {
	return d.sessionUser(ctx, sessionID, now, true)
}

func (d *DB) sessionUser(ctx context.Context, sessionID, now string, allowPending bool) (*SessionUser, error) {
	query := `SELECT users.id, users.username, users.avatar_version, sessions.created_at
		 FROM sessions
		 JOIN users ON users.id = sessions.user_id
		 WHERE sessions.id = ? AND sessions.expires_at > ?`
	if !allowPending {
		query += ` AND users.is_pending = 0`
	}
	var u SessionUser
	err := d.QueryRowContext(ctx, query, sessionID, now).Scan(&u.ID, &u.Username, &u.AvatarVersion, &u.SessionCreatedAt)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	u.IsAdmin = u.Username == AdminUsername
	return &u, nil
}