using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.InputSystem;

public class ItemPipe : MonoBehaviour
{
    [Header("Pipe")]
    [SerializeField] private Transform spawnPoint;

    [Header("Configuration")]
    [SerializeField] private ItemPipeConfig config;

    [Header("Temporary testing")]
    [SerializeField] private bool spawnOnE = true;

    private bool isSpawning;

    public float CooldownDuration => config != null ? config.SpawnCooldown : 0f;
    public float CooldownRemaining { get; private set; }
    public int CooldownSecondsRemaining => Mathf.CeilToInt(CooldownRemaining);
    public bool CanSpawnItems => config != null && !isSpawning && CooldownRemaining <= 0f;

    private void Update()
    {
        if (CooldownRemaining > 0f)
            CooldownRemaining = Mathf.Max(0f, CooldownRemaining - Time.deltaTime);

        if (!spawnOnE || Keyboard.current == null)
            return;

        if (Keyboard.current.eKey.wasPressedThisFrame)
            SpawnItems();
    }

    public void SpawnItems()
    {
        if (!CanSpawnItems)
            return;

        StartCoroutine(SpawnSequence(config));
    }

    private IEnumerator SpawnSequence(ItemPipeConfig activeConfig)
    {
        isSpawning = true;

        List<GameObject> spawnQueue = BuildSpawnQueue(activeConfig);

        for (int i = 0; i < spawnQueue.Count; i++)
        {
            Spawn(spawnQueue[i], activeConfig);

            if (i < spawnQueue.Count - 1)
                yield return new WaitForSeconds(activeConfig.SpawnInterval);
        }

        isSpawning = false;
        CooldownRemaining = activeConfig.SpawnCooldown;
    }

    private List<GameObject> BuildSpawnQueue(ItemPipeConfig activeConfig)
    {
        List<GameObject> queue = new();

        // Добавляем предметы в точном количестве.
        foreach (ItemPipeConfig.GuaranteedItem item in activeConfig.GuaranteedItems)
        {
            if (item.prefab == null)
                continue;

            for (int i = 0; i < item.amount; i++)
                queue.Add(item.prefab);
        }

        // Выбираем указанное количество случайных предметов.
        for (int i = 0; i < activeConfig.RandomItemCount; i++)
        {
            GameObject selectedPrefab = ChooseWeightedRandom(activeConfig);

            if (selectedPrefab != null)
                queue.Add(selectedPrefab);
        }

        // Перемешиваем гарантированные и случайные предметы вместе.
        Shuffle(queue);

        return queue;
    }

    private GameObject ChooseWeightedRandom(ItemPipeConfig activeConfig)
    {
        float totalWeight = 0f;

        foreach (ItemPipeConfig.RandomItem item in activeConfig.RandomItems)
        {
            if (item.prefab != null && item.weight > 0f)
                totalWeight += item.weight;
        }

        if (totalWeight <= 0f)
            return null;

        float roll = Random.value * totalWeight;
        float currentWeight = 0f;

        foreach (ItemPipeConfig.RandomItem item in activeConfig.RandomItems)
        {
            if (item.prefab == null || item.weight <= 0f)
                continue;

            currentWeight += item.weight;

            if (roll < currentWeight)
                return item.prefab;
        }

        return null;
    }

    private void Shuffle(List<GameObject> queue)
    {
        for (int i = queue.Count - 1; i > 0; i--)
        {
            int randomIndex = Random.Range(0, i + 1);

            (queue[i], queue[randomIndex]) =
                (queue[randomIndex], queue[i]);
        }
    }

    private void Spawn(GameObject prefab, ItemPipeConfig activeConfig)
    {
        if (prefab == null || spawnPoint == null)
            return;

        float offsetX = RandomRange(-activeConfig.RandomSpawnX, activeConfig.RandomSpawnX);
        float offsetZ = RandomRange(-activeConfig.RandomSpawnZ, activeConfig.RandomSpawnZ);

        Vector3 spawnPosition =
            spawnPoint.position +
            spawnPoint.right * offsetX +
            spawnPoint.forward * offsetZ;

        GameObject item = Instantiate(
            prefab,
            spawnPosition,
            Random.rotationUniform
        );

        if (item.TryGetComponent(out Rigidbody body))
        {
            Vector3 worldVelocityChange =
                spawnPoint.TransformDirection(activeConfig.LocalVelocityChange);

            body.AddForce(worldVelocityChange, ForceMode.VelocityChange);
        }
    }

    private float RandomRange(float min, float max)
    {
        return Random.Range(min, max);
    }
}