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

namespace AibisDream
{
    /// <summary>
    /// 文字速度设置的运行时快照与规范化规则。
    /// 各文字视图在开始新行时读取 CurrentMultiplier，确保设置不会改变正在播放的行。
    /// </summary>
    public static class TextSpeedSettings
    {
        public const float SlowMultiplier = 0.5f;
        public const float DefaultMultiplier = 1f;
        public const float FastMultiplier = 3f;

        public const string SlowValue = "0.5";
        public const string DefaultValue = "1.0";
        public const string FastValue = "3.0";

        private static readonly HashSet<string> WarnedInvalidValues = new(StringComparer.Ordinal);

        public static float CurrentMultiplier { get; private set; } = DefaultMultiplier;
        public static string CurrentCanonicalValue { get; private set; } = DefaultValue;

        public static void Reset()
        {
            CurrentMultiplier = DefaultMultiplier;
            CurrentCanonicalValue = DefaultValue;
            WarnedInvalidValues.Clear();
        }

        public static bool ApplyStoredValue(string value)
        {
            var isValid = TryNormalize(value, out var multiplier, out var canonicalValue);
            CurrentMultiplier = multiplier;
            CurrentCanonicalValue = canonicalValue;

            if (!isValid)
            {
                WarnInvalidValueOnce(value);
            }

            return isValid;
        }

        public static bool TryNormalize(string value, out float multiplier, out string canonicalValue)
        {
            multiplier = DefaultMultiplier;
            canonicalValue = DefaultValue;

            if (string.IsNullOrWhiteSpace(value) ||
                !float.TryParse(value, NumberStyles.Float, CultureInfo.InvariantCulture, out var parsed) ||
                float.IsNaN(parsed) ||
                float.IsInfinity(parsed))
            {
                return false;
            }

            if (Mathf.Approximately(parsed, SlowMultiplier))
            {
                multiplier = SlowMultiplier;
                canonicalValue = SlowValue;
                return true;
            }

            if (Mathf.Approximately(parsed, DefaultMultiplier))
            {
                multiplier = DefaultMultiplier;
                canonicalValue = DefaultValue;
                return true;
            }

            if (Mathf.Approximately(parsed, FastMultiplier))
            {
                multiplier = FastMultiplier;
                canonicalValue = FastValue;
                return true;
            }

            return false;
        }

        private static void WarnInvalidValueOnce(string value)
        {
            var warningKey = value ?? "<null>";
            if (!WarnedInvalidValues.Add(warningKey))
            {
                return;
            }

            Debug.LogWarning(
                $"[TextSpeedSettings] 不支持的文字速度 '{warningKey}'，本次运行使用默认值 {DefaultValue}。");
        }
    }
}