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

#if UNITY_ANDROID
using UnityEngine.Android;
#endif

namespace Aisu.SIM1.Face.Samples.FaceDetectionDemo
{
    /// <summary>
    /// MVP 摄像头预览，使用 WebCamTexture。
    /// </summary>
    public sealed class FaceDetectionDemoCamera : MonoBehaviour
    {
        [SerializeField] private RawImage m_preview;                 // 预览图。
        [SerializeField] private AspectRatioFitter m_aspectFitter;   // 宽高比适配。

        private WebCamTexture m_texture;                             // 当前摄像头纹理。
        private FaceDetectionDemoLogger m_logger;                   // 日志。
        private WebCamDevice[] m_devices;                            // 当前摄像头设备列表。

        public bool IsOpen => m_texture != null && m_texture.isPlaying;

        /// <summary>
        /// 绑定 UI 和日志。
        /// </summary>
        public void Bind(RawImage preview, AspectRatioFitter aspectFitter, FaceDetectionDemoLogger logger)
        {
            m_preview = preview;
            m_aspectFitter = aspectFitter;
            m_logger = logger;
        }

        /// <summary>
        /// 枚举摄像头名称。
        /// </summary>
        public string[] GetDeviceNames()
        {
            m_devices = WebCamTexture.devices;
            var names = new List<string>();
            for (var i = 0; i < m_devices.Length; i++)
            {
                names.Add(i + ": " + m_devices[i].name);
                m_logger?.Info("摄像头[" + i + "] " + m_devices[i].name + "，前置=" + m_devices[i].isFrontFacing + "，自动对焦=" + m_devices[i].isAutoFocusPointSupported);
            }

            return names.ToArray();
        }

        /// <summary>
        /// 请求权限后枚举摄像头。
        /// </summary>
        public void GetDeviceNamesWhenAuthorized(Action<string[]> callback)
        {
            StartCoroutine(GetDeviceNamesWhenAuthorizedRoutine(callback));
        }

        /// <summary>
        /// 打开摄像头。
        /// </summary>
        public void Open(int deviceIndex)
        {
            Close();
            if (m_devices == null || m_devices.Length == 0)
            {
                m_logger?.Error("没有可用摄像头");
                return;
            }

            if (deviceIndex < 0 || deviceIndex >= m_devices.Length)
            {
                m_logger?.Error("摄像头索引无效: " + deviceIndex);
                return;
            }

            StartCoroutine(OpenWhenAuthorized(deviceIndex));
        }

        private IEnumerator OpenWhenAuthorized(int deviceIndex)
        {
            yield return EnsureCameraAuthorization();
            if (!HasCameraAuthorization())
            {
                m_logger?.Error("摄像头权限未授权");
                yield break;
            }

            var deviceName = m_devices[deviceIndex].name;
            m_texture = new WebCamTexture(deviceName, 1280, 720, 30);
            m_texture.Play();
            if (m_preview != null)
            {
                m_preview.texture = m_texture;
            }

            m_logger?.Info("摄像头已打开: " + deviceName);
        }

        private IEnumerator GetDeviceNamesWhenAuthorizedRoutine(Action<string[]> callback)
        {
            Close();
            yield return EnsureCameraAuthorization();
            if (!HasCameraAuthorization())
            {
                m_logger?.Error("摄像头权限未授权，无法枚举摄像头");
                callback?.Invoke(new string[0]);
                yield break;
            }

            string[] names = null;
            for (var i = 0; i < 5; i++)
            {
                names = GetDeviceNames();
                if (names.Length > 0)
                {
                    break;
                }

                yield return new WaitForSeconds(0.3f);
            }

            callback?.Invoke(names ?? new string[0]);
        }

        private IEnumerator EnsureCameraAuthorization()
        {
#if UNITY_ANDROID && !UNITY_EDITOR
            if (!Permission.HasUserAuthorizedPermission(Permission.Camera))
            {
                m_logger?.Info("正在请求摄像头权限");
                Permission.RequestUserPermission(Permission.Camera);
                var timeout = 10f;
                while (!Permission.HasUserAuthorizedPermission(Permission.Camera) && timeout > 0f)
                {
                    timeout -= Time.deltaTime;
                    yield return null;
                }
            }
#else
            yield return null;
#endif
        }

        private static bool HasCameraAuthorization()
        {
#if UNITY_ANDROID && !UNITY_EDITOR
            return Permission.HasUserAuthorizedPermission(Permission.Camera);
#else
            return true;
#endif
        }

        /// <summary>
        /// 关闭摄像头。
        /// </summary>
        public void Close()
        {
            if (m_texture != null)
            {
                if (m_texture.isPlaying)
                {
                    m_texture.Stop();
                }

                Destroy(m_texture);
                m_texture = null;
            }

            if (m_preview != null)
            {
                m_preview.texture = null;
            }
        }

        private void Update()
        {
            if (m_texture == null || m_aspectFitter == null || m_texture.width <= 16 || m_texture.height <= 16)
            {
                return;
            }

            m_aspectFitter.aspectRatio = (float)m_texture.width / m_texture.height;
            if (m_preview != null)
            {
                m_preview.rectTransform.localEulerAngles = new Vector3(0f, 0f, -m_texture.videoRotationAngle);
                m_preview.uvRect = m_texture.videoVerticallyMirrored ? new Rect(0f, 1f, 1f, -1f) : new Rect(0f, 0f, 1f, 1f);
            }
        }

        private void OnDestroy()
        {
            Close();
        }
    }
}