using System.Collections;
using System.Collections.Generic;
using Unity.Collections;
using UnityEngine;
using UnityEngine.Assertions;
using UnityEngine.Experimental.AI;
using Unity.Jobs;

public class NavMeshTestAsync : MonoBehaviour
{
    [SerializeField] Transform start, end;

    const int extents = 10;
    const int maxPath = 64;

    private NavMeshQuery query;
    private NativeArray<PathQueryStatus> status;
    private NativeArray<PolygonId> path;
    private NativeArray<NavMeshLocation> pathStraigth;
    private NativeArray<StraightPathFlags> pathStreaigthFlag;
    private NativeArray<float> vertexSize;

    private JobHandle handle;

    [SerializeField]
    private int currentState = 0;

    public int CurrentState { get => currentState; set => currentState = value; }

    private void OnEnable()
    {
        status = new NativeArray<PathQueryStatus>(1, Allocator.Persistent);
        query = new NavMeshQuery(NavMeshWorld.GetDefaultWorld(), Allocator.Persistent, maxPath);

        pathStraigth = new NativeArray<NavMeshLocation>(maxPath, Allocator.Persistent);
        pathStreaigthFlag = new NativeArray<StraightPathFlags>(maxPath, Allocator.Persistent);
        vertexSize = new NativeArray<float>(maxPath, Allocator.Persistent);
    }

    private void OnDisable()
    {
        handle.Complete();
        pathStraigth.Dispose();
        pathStreaigthFlag.Dispose();
        vertexSize.Dispose();

        status.Dispose();
        query.Dispose();
    }

    void Update()
    {
        switch (CurrentState)
        {
            case 0:
                BeginPathFind();
                break;
            case 1:
                UpdatPathFind();
                break;
            case 2:
                ShowResult();
                break;
        }
    }
    void BeginPathFind()
    {
        handle = new BeginFindPathJob(query, status, start.position, end.position).Schedule();
        handle = new CheckStateJob(status).Schedule(handle);
        JobHandle.ScheduleBatchedJobs();
        CurrentState = 1;
    }

    void UpdatPathFind()
    {
        handle.Complete();
        if( status[0] != PathQueryStatus.Success)
        {
            handle = new UpdateFindPathJob(query, status).Schedule(handle);
            handle = new CheckStateJob(status).Schedule(handle);
            JobHandle.ScheduleBatchedJobs();
        }
        else
        {
            path = new NativeArray<PolygonId>(maxPath, Allocator.TempJob);
            handle = new GetResultJob(query, status, start.position, end.position, path, pathStraigth, pathStreaigthFlag, vertexSize).Schedule(handle);
            handle = new CheckStateJob(status).Schedule(handle);
            JobHandle.ScheduleBatchedJobs();
            CurrentState = 2;
        }
    }

    void ShowResult()
    {
        handle.Complete();

        for (int i = 0; i < maxPath - 1 && pathStreaigthFlag[i] != StraightPathFlags.End; i++)
            Debug.DrawLine(pathStraigth[i].position, pathStraigth[i + 1].position, Color.red);
    }
    [Unity.Burst.BurstCompile]
    private struct BeginFindPathJob : IJob
    {
        NavMeshQuery query;
        NativeArray<PathQueryStatus> status;
        Vector3 startPos, endPos;

        public BeginFindPathJob(NavMeshQuery query, NativeArray<PathQueryStatus> status, Vector3 startPos, Vector3 endPos)
        {
            this.query = query;
            this.status = status;
            this.startPos = startPos;
            this.endPos = endPos;
        }

        public void Execute()
        {
            NavMeshLocation startLocation = query.MapLocation(startPos, Vector3.up * extents, 0);
            NavMeshLocation endLocation = query.MapLocation(endPos, Vector3.up * extents, 0);

            status[0] = query.BeginFindPath(startLocation, endLocation);
        }
    }

    [Unity.Burst.BurstCompile]
    private struct UpdateFindPathJob : IJob
    {
        NavMeshQuery query;
        NativeArray<PathQueryStatus> status;

        public UpdateFindPathJob(NavMeshQuery query, NativeArray<PathQueryStatus> status)
        {
            this.query = query;
            this.status = status;
        }

        public void Execute()
        {
            status[0] = query.UpdateFindPath(32, out int iterationsPerformed);
        }
    }

    private struct CheckStateJob : IJob
    {
        public NativeArray<PathQueryStatus> status;

        public CheckStateJob(NativeArray<PathQueryStatus> status)
        {
            this.status = status;
        }

        public void Execute()
        {
            Debug.Log(status[0]);
        }
    }

    [Unity.Burst.BurstCompile]
    private struct GetResultJob : IJob
    {
        NavMeshQuery query;
        NativeArray<PathQueryStatus> status;

        Vector3 start, end;
        [DeallocateOnJobCompletion]
        NativeArray<PolygonId> path;

        NativeArray<NavMeshLocation> pathStraigth;
        NativeArray<StraightPathFlags> pathStreaigthFlag;
        NativeArray<float> vertexSize;

        public GetResultJob(NavMeshQuery query, NativeArray<PathQueryStatus> status, Vector3 start, Vector3 end, NativeArray<PolygonId> path, NativeArray<NavMeshLocation> pathStraigth, NativeArray<StraightPathFlags> pathStreaigthFlag, NativeArray<float> vertexSize)
        {
            this.query = query;
            this.status = status;
            this.start = start;
            this.end = end;
            this.path = path;
            this.pathStraigth = pathStraigth;
            this.pathStreaigthFlag = pathStreaigthFlag;
            this.vertexSize = vertexSize;
        }

        public void Execute()
        {
            query.EndFindPath(out int pathsize);
            var pathSize = query.GetPathResult(path);

            int streaigthPathCount = 0;

            status[0] = PathUtils.FindStraightPath(query, start, end, path, pathSize, ref pathStraigth, ref pathStreaigthFlag, ref vertexSize, ref streaigthPathCount, maxPath);

        }
    }
}