// Copyright © 2016 Asteris, LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package query

import (
	"errors"

	"github.com/asteris-llc/converge/resource"
	"github.com/asteris-llc/converge/resource/shell"
	"golang.org/x/net/context"
)

// Query represents an environmental query
type Query struct {
	*shell.Shell `re-export-as:"task"`
}

// Apply is a nop for queries.  Because HasChanges always returns false this
// should never be executed.
func (q *Query) Apply(context.Context) (resource.TaskStatus, error) {
	return nil, errors.New("query apply called but it should never have changes")
}

// TaskStatus implementation overrides

// Messages returns a summary of the first execution of check and/or apply.
// Subsequent runs are surpressed.
func (q *Query) Messages() (messages []string) {
	return
}

// HasChanges returns true if changes are required as determined by the the most
// recent run of check.
func (q *Query) HasChanges() bool {
	return false
}
