package zombie

import (
	"fmt"
	"github.com/wahyd4/zombie/models"
)

// Application presents the actual the runner
type Application struct {
	gridSize        int
	creatures       []*models.Creature
	commands        []MoveCommand
	currentZombie   *models.Zombie
	nextZombie      *TransformedZombie
	finishedZombies []*models.Zombie
	score           int
}

// TransformedZombie defines the zombies transformed from creatures,
// and these type of zombies are linked one by one
type TransformedZombie struct {
	Zombie *models.Zombie
	Next   *TransformedZombie
}

// Run starts zombie with movements
func (app *Application) Run() {
	for _, command := range app.commands {
		command.Execute(app.currentZombie)

		collided, creature := app.checkCollisionWithCreature()
		if collided {
			app.transformCreatureToZombie(creature)
			app.IncreaseScore()
		}
	}

	app.recordedFinishedZombies()

	if app.hasTransformedZombie() {
		app.updateCurrentZombie()
		app.updateNextZombie()
		app.Run()
	}
}

// Stats prints out statistic information
func (app *Application) Stats() {
	fmt.Printf("zombies score: %d \n", app.score)
	var locations string
	for _, zombie := range app.finishedZombies {
		locations += fmt.Sprintf("%s ", zombie.PrintLocation())
	}

	fmt.Printf("zombies positions: %s \n", locations)
}

func (app *Application) checkCollisionWithCreature() (bool, *models.Creature) {
	for _, creature := range app.creatures {
		if app.currentZombie.Coordinate == creature.Coordinate {
			return true, creature
		}
	}
	return false, nil
}

func (app *Application) transformCreatureToZombie(creature *models.Creature) {
	app.appendTransformedZombie(&models.Zombie{
		GridSize:   app.gridSize,
		Coordinate: creature.Coordinate,
	})
	app.removeCreature(creature)
}

func (app *Application) removeCreature(creature *models.Creature) {
	creatures := app.creatures
	var creatureIndex int
	for index, tempCreature := range creatures {
		if creature == tempCreature {
			creatureIndex = index
		}
	}
	// assign the last index item to the deleted index, then shrink the slice
	creatures[creatureIndex] = creatures[len(creatures)-1]
	creatures[len(creatures)-1] = nil
	app.creatures = creatures[:len(creatures)-1]

}

func (app *Application) appendTransformedZombie(zombie *models.Zombie) {
	next := app.nextZombie

	for next != nil {
		next = next.Next
	}

	app.nextZombie = &TransformedZombie{
		Zombie: zombie,
		Next:   nil,
	}
}

func (app *Application) IncreaseScore() {
	app.score++
}

func (app *Application) recordedFinishedZombies() {
	app.finishedZombies = append(app.finishedZombies, app.currentZombie)
}

func (app *Application) updateNextZombie() {
	app.nextZombie = app.nextZombie.Next
}

func (app *Application) updateCurrentZombie() {
	app.currentZombie = app.nextZombie.Zombie
}

func (app *Application) hasTransformedZombie() bool {
	return app.nextZombie != nil
}