// Copyright (C) 2018 spdfg
//
// This file is part of Elektron.
//
// Elektron is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Elektron is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Elektron.  If not, see <http://www.gnu.org/licenses/>.
//

package def

import (
	"encoding/json"
	"github.com/spdfg/elektron/utilities/validation"
	"os"

	mesos "github.com/mesos/mesos-go/api/v0/mesosproto"
	"github.com/pkg/errors"
	"github.com/spdfg/elektron/constants"
	"github.com/spdfg/elektron/utilities/offerUtils"
)

type Task struct {
	Name         string             `json:"name"`
	CPU          float64            `json:"cpu"`
	RAM          float64            `json:"ram"`
	Watts        float64            `json:"watts"`
	Image        string             `json:"image"`
	CMD          string             `json:"cmd"`
	Instances    *int               `json:"inst"`
	Host         string             `json:"host"`
	TaskID       string             `json:"taskID"`
	ClassToWatts map[string]float64 `json:"class_to_watts"`
}

func TasksFromJSON(uri string) ([]Task, error) {

	var tasks []Task

	file, err := os.Open(uri)
	if err != nil {
		return nil, errors.Wrap(err, "Error opening file")
	}

	err = json.NewDecoder(file).Decode(&tasks)
	if err != nil {
		return nil, errors.Wrap(err, "Error unmarshalling")
	}

	// Validating task definitions.
	for _, task := range tasks {
		err := validation.Validate("invalid task definition",
			ValidatorForTask(task,
				withNameValidator(),
				withImageValidator(),
				withResourceValidator()))
		if err != nil {
			return tasks, err
		}
	}

	initTaskResourceRequirements(tasks)
	return tasks, nil
}

// Update the host on which the task needs to be scheduled.
func (tsk *Task) UpdateHost(newHost string) bool {
	// Validation
	isCorrectHost := false
	for existingHost, _ := range constants.Hosts {
		if newHost == existingHost {
			isCorrectHost = true
		}
	}
	if !isCorrectHost {
		return false
	} else {
		tsk.Host = newHost
		return true
	}
}

// Set the taskID of the task.
func (tsk *Task) SetTaskID(taskID string) bool {
	// Validation
	if taskID == "" {
		return false
	} else {
		tsk.TaskID = taskID
		return true
	}
}

/*
 Determine the watts value to consider for each task.

 This value could either be task.Watts or task.ClassToWatts[<power class>]
 If task.ClassToWatts is not present, then return task.Watts (this would be for workloads which don't have classMapWatts).
*/
func WattsToConsider(task Task, classMapWatts bool, offer *mesos.Offer) (float64, error) {
	if classMapWatts {
		// Checking if ClassToWatts was present in the workload.
		if task.ClassToWatts != nil {
			return task.ClassToWatts[offerUtils.PowerClass(offer)], nil
		} else {
			// Checking whether task.Watts is 0.0. If yes, then throwing an error.
			if task.Watts == 0.0 {
				return task.Watts, errors.New("Configuration error in task. Watts attribute is 0 for " + task.Name)
			}
			return task.Watts, nil
		}
	} else {
		// Checking whether task.Watts is 0.0. If yes, then throwing an error.
		if task.Watts == 0.0 {
			return task.Watts, errors.New("Configuration error in task. Watts attribute is 0 for " + task.Name)
		}
		return task.Watts, nil
	}
}

// Compare two tasks.
func Compare(task1 *Task, task2 *Task) bool {
	// If comparing the same pointers (checking the addresses).
	if task1 == task2 {
		return true
	}
	if task1.TaskID != task2.TaskID {
		return false
	} else {
		return true
	}
}