// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package postgres

import (
	"context"
	"database/sql"

	"golang.org/x/discovery/internal/derrors"
	"golang.org/x/discovery/internal/log"
)

// IsExcluded reports whether the path matches the excluded list.
func (db *DB) IsExcluded(ctx context.Context, path string) (_ bool, err error) {
	defer derrors.Wrap(&err, "DB.IsExcluded(ctx, %q)", path)

	const query = "SELECT prefix FROM excluded_prefixes WHERE starts_with($1, prefix);"
	row := db.db.QueryRow(ctx, query, path)
	var prefix string
	err = row.Scan(&prefix)
	switch err {
	case nil:
		log.Infof(ctx, "path %q matched excluded prefix %q", path, prefix)
		return true, nil
	case sql.ErrNoRows:
		return false, nil
	default:
		return false, err
	}
}

// InsertExcludedPrefix inserts prefix into the excluded_prefixes table.
//
// For real-time administration (e.g. DOS prevention), use the dbadmin tool.
// to exclude or unexclude a prefix. If the exclusion is permanent (e.g. a user
// request), also add the prefix and reason to the excluded.txt file.
func (db *DB) InsertExcludedPrefix(ctx context.Context, prefix, user, reason string) (err error) {
	defer derrors.Wrap(&err, "DB.InsertExcludedPrefix(ctx, %q, %q)", prefix, reason)

	_, err = db.db.Exec(ctx, "INSERT INTO excluded_prefixes (prefix, created_by, reason) VALUES ($1, $2, $3)",
		prefix, user, reason)
	return err
}