using UnityEngine;
// using UniTask;

namespace BrewMonster.Scripts
{
    public class CECSunMoon : MonoSingleton<CECSunMoon>
    {
        private const float TIME_SCALE = 6f;
        private const float NIGHT_DAY_START = (3.0f / 24.0f);
        private const float NIGHT_SUN_RISE_MIN = (4.0f / 24.0f);
        private const float NIGHT_DAY_END = (7.0f / 24.0f);
        private const float DAY_NIGHT_START = (18.0f / 24.0f);
        private const float DAY_SUN_SET_MAX = (19.5f / 24.0f);
        private const float DAY_NIGHT_END = (21.0f / 24.0f);
        
        public double m_vTimeOfTheDay;		// time of the day 0.0f means 00:00, 1.0f means 24:00
        public float m_fDNFactor;			// day or night factor
        public float m_fDNFactorDest;		// day or night factor dest

        [SerializeField] GlobalShaderVariableSetting _globalShaderVariables;

        protected override void Initialize()
        {
            base.Initialize();

            // keep this alive when scene is loaded
            DontDestroyOnLoad(gameObject);
        }

        public void Update()
        {
            m_vTimeOfTheDay += Time.deltaTime / 3600.0 / 24.0 * TIME_SCALE;
            while (m_vTimeOfTheDay > 1.0)
                m_vTimeOfTheDay -= 1.0;
            RefreshDayNightFactorsFromPhase();
        }

        public float GetTimeOfTheDay() => (float)m_vTimeOfTheDay;
        public float GetDNFactor() => m_fDNFactor;
        public float GetDNFactorDest() => m_fDNFactorDest;

        /// <summary>
        /// 设置一天中的时刻（与 PC 版 CECSunMoon::SetTimeOfTheDay 对齐） // Set time-of-day phase [0,1), aligned with PC CECSunMoon::SetTimeOfTheDay
        /// </summary>
        public bool SetTimeOfTheDay(float vTime)
        {
            while (vTime < 0f)
                vTime += 1f;
            while (vTime > 1f)
                vTime -= 1f;
            m_vTimeOfTheDay = vTime;
            RefreshDayNightFactorsFromPhase();
            return true;
        }

        /// <summary>
        /// PC EC_SunMoon::UpdateWithTime 中昼夜因子段（供 minimap 与场景一致） // DN factor block from PC EC_SunMoon::UpdateWithTime
        /// </summary>
        void RefreshDayNightFactorsFromPhase()
        {
            float v = (float)m_vTimeOfTheDay;

            // update day night factor — same branches as PC EC_SunMoon.cpp UpdateWithTime (lines 894–918)
            if (v < NIGHT_DAY_START)
            {
                m_fDNFactor = 1.0f;
                m_fDNFactorDest = 1.0f;
            }
            else if (v < NIGHT_DAY_END)
            {
                m_fDNFactor = 1.0f - (v - NIGHT_DAY_START) / (NIGHT_DAY_END - NIGHT_DAY_START);
                m_fDNFactorDest = 0.0f;
            }
            else if (m_vTimeOfTheDay < DAY_NIGHT_START)
            {
                // PC 使用 m_vTimeOfTheDay 与 DAY_NIGHT_START 比较 // PC compares m_vTimeOfTheDay to DAY_NIGHT_START (see EC_SunMoon.cpp)
                m_fDNFactor = 0.0f;
                m_fDNFactorDest = 0.0f;
            }
            else if (v < DAY_NIGHT_END)
            {
                m_fDNFactor = (v - DAY_NIGHT_START) / (DAY_NIGHT_END - DAY_NIGHT_START);
                m_fDNFactorDest = 1.0f;
            }
            else
            {
                m_fDNFactor = 1.0f;
                m_fDNFactorDest = 1.0f;
            }

            _globalShaderVariables?.Apply(m_fDNFactor);
        }
    }
}