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

public class FreeCameraController : MonoBehaviour
{
    [Header("移动")]
    public float moveSpeed = 10f;
    public float fastSpeedMultiplier = 2f;
    [Range(0f, 1f)] public float moveSmooth = 0.15f;   // 0=无平滑, 1=很丝滑

    [Header("旋转")]
    public float rotateSpeed = 120f;                   // 角速度(度/秒)，右键拖动
    [Range(0f, 1f)] public float rotateSmooth = 0.12f; // 0=无平滑
    public float minPitch = -80f, maxPitch = 80f;

    [Header("缩放/推进(滚轮)")]
    public float zoomSpeed = 8f;
    [Range(0f, 1f)] public float zoomSmooth = 0.15f;   // 滚轮惯性

    [Header("拖拽")]
    public float dragSpeed = 0.5f;   // 中键左右拖动速度

    [Header("按键")]
    public KeyCode fastKey = KeyCode.LeftShift;

    [Header("调试")]
    public bool showDebug = false;

    float yaw, pitch;
    Vector3 targetPos;
    Quaternion targetRot;

    // 滚轮惯性速度
    float zoomVel = 0f;

    // 拖拽用
    Vector3 lastMousePos;

    void Awake()
    {
        var e = transform.eulerAngles;
        yaw = e.y; pitch = e.x;
        targetPos = transform.position;
        targetRot = transform.rotation;
    }

    void Update()
    {
        ReadInput();

        // 位置插值（moveSmooth=0 -> 立即到位）
        float mt = LerpFactor(moveSmooth);
        transform.position = Vector3.Lerp(transform.position, targetPos, mt);

        // 旋转插值（rotateSmooth=0 -> 立即到位）
        float rt = LerpFactor(rotateSmooth);
        transform.rotation = Quaternion.Slerp(transform.rotation, targetRot, rt);
    }

    void ReadInput()
    {
        // —— 移动 —— //
        float speed = moveSpeed * (Input.GetKey(fastKey) ? fastSpeedMultiplier : 1f);
        Vector3 move = Vector3.zero;
        if (Input.GetKey(KeyCode.W)) move += transform.forward;
        if (Input.GetKey(KeyCode.S)) move -= transform.forward;
        if (Input.GetKey(KeyCode.D)) move += transform.right;
        if (Input.GetKey(KeyCode.A)) move -= transform.right;
        if (Input.GetKey(KeyCode.E)) move += transform.up;
        if (Input.GetKey(KeyCode.Q)) move -= transform.up;

        if (move.sqrMagnitude > 0f)
            targetPos += move.normalized * speed * Time.unscaledDeltaTime;

        // —— 旋转（右键）—— //
        if (Input.GetMouseButton(1))
        {
            yaw += Input.GetAxis("Mouse X") * rotateSpeed * Time.unscaledDeltaTime;
            pitch -= Input.GetAxis("Mouse Y") * rotateSpeed * Time.unscaledDeltaTime;
            pitch = Mathf.Clamp(pitch, minPitch, maxPitch);
            targetRot = Quaternion.Euler(pitch, yaw, 0f);
        }

        // —— 滚轮推进（带惯性）—— //
        float scroll = Input.mouseScrollDelta.y;
        if (Mathf.Abs(scroll) > 0.001f)
            zoomVel += scroll * zoomSpeed;

        zoomVel = Mathf.Lerp(zoomVel, 0f, LerpFactor(zoomSmooth));

        if (Mathf.Abs(zoomVel) > 0.0001f)
            targetPos += transform.forward * zoomVel * Time.unscaledDeltaTime;

        // —— 中键左右拖动 —— //
        if (Input.GetMouseButtonDown(2))
        {
            lastMousePos = Input.mousePosition;
        }
        if (Input.GetMouseButton(2))
        {
            Vector3 delta = Input.mousePosition - lastMousePos;
            lastMousePos = Input.mousePosition;

            // 只取 x 分量（左右拖动），用相机的 right 向量
            Vector3 right = transform.right;
            targetPos -= right * delta.x * dragSpeed * Time.unscaledDeltaTime;
        }

        if (showDebug)
            Debug.Log($"move:{move} speed:{speed} scroll:{scroll} zoomVel:{zoomVel} pos:{transform.position}");
    }

    float LerpFactor(float smooth)
    {
        if (smooth <= 0f) return 1f;
        return 1f - Mathf.Pow(1f - Mathf.Clamp01(smooth), Time.unscaledDeltaTime * 60f);
    }

    public void SnapTo(Transform target)
    {
        transform.position = target.position;
        transform.rotation = target.rotation;

        targetPos = target.position;
        targetRot = target.rotation;

        Vector3 euler = target.rotation.eulerAngles;
        yaw = euler.y;
        pitch = euler.x;
    }
}