package au.id.zancanaro.javacheck.statem;

import au.id.zancanaro.javacheck.Generator;
import au.id.zancanaro.javacheck.annotations.DataSource;
import au.id.zancanaro.javacheck.annotations.Property;
import au.id.zancanaro.javacheck.junit.Properties;
import org.junit.runner.RunWith;

import java.util.*;

import static au.id.zancanaro.javacheck.Generator.pure;
import static au.id.zancanaro.javacheck.Generators.integer;
import static au.id.zancanaro.javacheck.Generators.oneOf;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

@RunWith(Properties.class)
public class QueueTest {
    private static final Queue<Integer> queue = new LinkedList<>();

    @DataSource
    public static Generator<CommandList<List<Integer>>> commandGenerator =
            new CommandListGenerator<>(state -> oneOf(
                    pure(new QueuePushCommand()),
                    pure(new QueuePopCommand())
            ));

    @Property
    public void test(CommandList<List<Integer>> commands) {
        queue.clear();
        CommandResult<List<Integer>> result = commands.run(null);
        assertFalse(result.isFailed());
    }

    private static class QueuePushCommand extends Command<List<Integer>, Integer, Void> {
        @Override
        public Generator<Integer> argsGenerator(List<Integer> integers) {
            return integer();
        }

        @Override
        public Void runCommand(Integer integer) {
            queue.offer(integer);
            return null;
        }

        @Override
        public List<Integer> nextState(List<Integer> integers, Integer integer, CommandValue<Void> result) {
            List<Integer> nextState = new ArrayList<>(integers == null ? new ArrayList<>() : integers);
            nextState.add(integer);
            return nextState;
        }

        @Override
        public String toString() {
            return "push";
        }
    }

    private static class QueuePopCommand extends Command<List<Integer>, Void, Integer> {
        @Override
        public boolean preCondition(List<Integer> integers, Void aVoid) {
            return integers != null && !integers.isEmpty();
        }

        @Override
        public Integer runCommand(Void aVoid) {
            return queue.poll();
        }

        @Override
        public boolean postCondition(List<Integer> oldState, List<Integer> newState, Void aVoid, Integer integer) {
            return Objects.equals(integer, oldState.get(0));
        }

        @Override
        public List<Integer> nextState(List<Integer> integers, Void aVoid, CommandValue<Integer> result) {
            List<Integer> nextState = new ArrayList<>(integers == null ? new ArrayList<>() : integers);
            nextState.remove(0);
            return nextState;
        }

        @Override
        public String toString() {
            return "pop";
        }
    }
}