using System;
using System.Collections.Generic;
using System.Text;
using UnityEngine;

namespace ET
{
    public static class MoveHelper
    {
        public const float AtkDis = 2.7f * 2.7f;

        public static ETTask<bool> MoveTo(Unit unit, Vector2 target, ETCancellationToken token = null)
        {
            UnitScene unitScene = unit.GetComponent<UnitScene>();
            Vector2 pos = unitScene.Position;
            int yAngle = pos.x <= target.x? 0 : 180;
            return MoveTo(unit, target, yAngle);
        }

        public static async ETTask<bool> MoveTo(Unit unit, Vector2 target, int yAngle, ETCancellationToken token = null)
        {
            try
            {
                UnitScene unitScene = unit.GetComponent<UnitScene>();
                unitScene.targetPos = target;
                unitScene.isMoved = true;
                bool ret = await FindPathMoveToAsync(unit, target, token);
                unitScene.YAngle = yAngle;
                unitScene.isMoved = false;
                return ret;
            }
            catch (Exception e)
            {
                Log.Error(e);
            }

            return false;
        }

        // 可以多次调用，多次调用的话会取消上一次的协程
        private static async ETTask<bool> FindPathMoveToAsync(this Unit unit, Vector3 target, ETCancellationToken cancellationToken = null)
        {
            float speed = ConstDefine.MoveSpeed;

            using ListComponent<Vector3> list = ListComponent<Vector3>.Create();
            UnitScene unitScene = unit.GetComponent<UnitScene>();
            list.List.Add(unitScene.Position);
            list.List.Add(target);

            // 广播寻路路径
            M2C_PathfindingResult m2CPathfindingResult = new M2C_PathfindingResult
            {
                Id = unit.Id,
                X = unitScene.X,
                Y = unitScene.Y,
                TX = target.x,
                TY = target.y,
                MoveSpeed = ConstDefine.MoveSpeed
            };
            BrocastComponent brocast = unit.GetComponent<BrocastComponent>();
            brocast.Brocast(m2CPathfindingResult);

            bool ret = await unit.GetComponent<MoveComponent>().MoveToAsync(list.List, speed, cancellationToken);
            if (ret) // 如果返回false，说明被其它移动取消了，这时候不需要通知客户端stop
            {
                SendStop(unit, 0);
            }

            return ret;
        }

        public static void Stop(this Unit unit)
        {
            unit.GetComponent<MoveComponent>().Stop();
            SendStop(unit, 0);
        }

        private static void SendStop(Unit unit, int error)
        {
            if (!unit.IsTeamLeader) return;
            UnitScene unitScene = unit.GetComponent<UnitScene>();
            BrocastComponent brocast = unit.GetComponent<BrocastComponent>();
            brocast.Brocast(new M2C_Stop()
            {
                Error = error,
                Id = unit.Id,
                X = unitScene.X,
                Y = unitScene.Y,
                YAngle = unitScene.YAngle
            });
        }

        public static async ETVoid TeamMoveTo(Team team, Vector2 target)
        {
            var list = team.GetUnits();
            for (var curr = list.First; curr != null; curr = curr.Next)
            {
                Unit item = curr.Value;
                long unitInstanceId = item.InstanceId;
                await TimerComponent.Instance.WaitAsync(300);
                if (!item)
                    continue;
                if (unitInstanceId != item.InstanceId) continue;
                UnitScene unitScene = item.GetComponent<UnitScene>();
                Vector2 delta = MoveHelper.CalucateDistanceXandY(unitScene.Position, target);
                int index = team.GetIndex(item.Id);
                Vector2 targetPos = new(target.x - delta.x * index, target.y - delta.y * index);
                MoveHelper.MoveTo(item, targetPos).Coroutine(); // 移动到目标点, 返回false表示协程取消
            }
        }

        public static Vector2 CalucateDistanceXandY(Vector2 posA, Vector2 posB)
        {
            const float TeamDistanceBetweenUnits = 0.8f;
            float dx = posB.x - posA.x;
            int positive = dx >= 0? 1 : -1;
            float gradient = (posB.y - posA.y) / dx;
            return new Vector2(positive * TeamDistanceBetweenUnits / Mathf.Sqrt(1 + gradient * gradient)
                , positive * gradient * TeamDistanceBetweenUnits / Mathf.Sqrt(1 + gradient * gradient));
        }
    }
}