using System.Collections.Generic;
using UnityEngine;

namespace Code.Track
{
    public class TrackBuilder : MonoBehaviour
    {
        [SerializeField] private GameObject roadTilePrefab;
        [SerializeField] private float roadWidth = 8f;

        [SerializeField] private GameObject leftBarrierPrefab;
        [SerializeField] private GameObject rightBarrierPrefab;
        [SerializeField] private float barrierSpacing = 2f;

        [SerializeField] private GameObject mountainPrefab;

        [SerializeField] private float mountainSpacing = 10f;
        [SerializeField] private float mountainOffsetFromRoad = 10f;
        [SerializeField] [Range(1f, 100f)] private float mountainMinDistance = 30f;
        [SerializeField] [Range(1f, 3f)] private float mountainScaleMin = 1f;
        [SerializeField] [Range(1f, 3f)] private float mountainScaleMax = 2f;

        private readonly List<GameObject> _spawned = new();

        public void Build(TrackData data)
        {
            Clear();
            if (data?.Waypoints == null || data.Waypoints.Count < 2) return;

            BuildRoadAndBarriers(data);
            BuildMountains(data);
        }

        private void BuildRoadAndBarriers(TrackData data)
        {
            var points = data.Waypoints;
            for (var i = 0; i < points.Count - 1; i++)
            {
                var a = points[i];
                var b = points[i + 1];
                var delta = b - a;

                if (delta.sqrMagnitude < 0.01f) continue;

                var forward = delta.normalized;
                var right = Vector3.Cross(Vector3.up, forward);
                var length = delta.magnitude;

                var roadPos = (a + b) / 2f;
                var roadRot = Quaternion.LookRotation(forward, Vector3.up);
                var road = Instantiate(roadTilePrefab, roadPos, roadRot, transform);
                road.transform.localScale = new Vector3(roadWidth, 1f, length);
                _spawned.Add(road);

                var fenceSegments = Mathf.Max(1, Mathf.CeilToInt(length / barrierSpacing));
                for (var j = 0; j <= fenceSegments; j++)
                {
                    var t = j / (float)fenceSegments;
                    var pos = Vector3.Lerp(a, b, t);
                    var leftPos = pos - right * (roadWidth * 0.5f + 0.5f);
                    var rightPos = pos + right * (roadWidth * 0.5f + 0.5f);

                    Instantiate(leftBarrierPrefab, leftPos, roadRot, transform);
                    Instantiate(rightBarrierPrefab, rightPos, roadRot, transform);
                }
            }
        }

        private void BuildMountains(TrackData data)
        {
            if (mountainPrefab == null || data.Waypoints.Count < 2) return;

            var spacing = Mathf.Max(1f, mountainMinDistance);

            for (var i = 0; i < data.Waypoints.Count - 1; i++)
            {
                var a = data.Waypoints[i];
                var b = data.Waypoints[i + 1];
                var delta = b - a;

                if (delta.sqrMagnitude < 0.01f) continue;

                var forward = delta.normalized;
                var right = Vector3.Cross(Vector3.up, forward);
                var segmentLength = delta.magnitude;

                var mountainCountOnSegment = Mathf.Max(1, Mathf.RoundToInt(segmentLength / spacing));

                for (var j = 0; j < mountainCountOnSegment; j++)
                {
                    var t = (j + 0.5f) / mountainCountOnSegment;
                    if (t > 1f) t = 1f;

                    var posOnSegment = Vector3.Lerp(a, b, t);

                    var useLeft = j % 2 == 0;
                    var outwardDir = useLeft ? -right : right;

                    var mountainPos = posOnSegment + outwardDir * (roadWidth * 0.5f + mountainOffsetFromRoad);
                    mountainPos.y = 0f;

                    var mountainRot = Quaternion.LookRotation(forward, Vector3.up);

                    var mountain = Instantiate(mountainPrefab, mountainPos, mountainRot, transform);
                    var scale = Random.Range(mountainScaleMin, mountainScaleMax);
                    mountain.transform.localScale = Vector3.one * scale;
                    _spawned.Add(mountain);
                }
            }
        }

        private void Clear()
        {
            foreach (var obj in _spawned) Destroy(obj);
            _spawned.Clear();
        }
    }
}