// Copyright 2023 Harness, Inc.
//
// 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 scheduler

import (
	"context"

	"github.com/harness/gitness/app/store"
	"github.com/harness/gitness/lock"
	"github.com/harness/gitness/types"
)

// Filter provides filter criteria to limit stages requested
// from the scheduler.
type Filter struct {
	Kind    string
	Type    string
	OS      string
	Arch    string
	Kernel  string
	Variant string
	Labels  map[string]string
}

// Scheduler schedules Build stages for execution.
type Scheduler interface {
	// Schedule schedules the stage for execution.
	Schedule(ctx context.Context, stage *types.Stage) error

	// Request requests the next stage scheduled for execution.
	Request(ctx context.Context, filter Filter) (*types.Stage, error)

	// Cancel cancels scheduled or running jobs associated
	// with the parent build ID.
	Cancel(context.Context, int64) error

	// Cancelled blocks and listens for a cancellation event and
	// returns true if the build has been cancelled.
	Cancelled(context.Context, int64) (bool, error)
}

type scheduler struct {
	*queue
	*canceler
}

// newScheduler provides an instance of a scheduler with cancel abilities.
func newScheduler(stageStore store.StageStore, lock lock.MutexManager) (Scheduler, error) {
	q, err := newQueue(stageStore, lock)
	if err != nil {
		return nil, err
	}
	return scheduler{
		q,
		newCanceler(),
	}, nil
}