using System;
using System.Collections.Generic;
using AibisDream.Framework;

namespace AibisDream.UI
{
    /// <summary>
    /// Defines the file-name convention used by localized Obj sprites.
    /// Chinese uses the unsuffixed source asset; every other supported locale uses
    /// "{logicalName}-{localeCode}".
    /// </summary>
    internal static class LocalizedObjSpriteNaming
    {
        internal const string DefaultLocaleCode = "zh-Hans";

        private static readonly string[] NonDefaultLocaleCodeValues =
        {
            "en",
            "ja-JP",
            "ru",
            "es",
            "pt-BR"
        };

        internal static IReadOnlyList<string> NonDefaultLocaleCodes =>
            NonDefaultLocaleCodeValues;

        internal static string NormalizeLogicalName(string picName)
        {
            if (string.IsNullOrEmpty(picName)) return picName;
            return picName.EndsWith(".png", StringComparison.OrdinalIgnoreCase)
                ? picName.Substring(0, picName.Length - 4)
                : picName;
        }

        internal static string GetAssetLocaleCode(string localeCode)
        {
            return LocalizationKit.GetLocaleKind(localeCode) switch
            {
                LocaleKind.En => "en",
                LocaleKind.Ja => "ja-JP",
                LocaleKind.Ru => "ru",
                LocaleKind.Es => "es",
                LocaleKind.PtBr => "pt-BR",
                _ => DefaultLocaleCode
            };
        }

        internal static string GetPicName(string logicalName, string localeCode)
        {
            string normalizedName = NormalizeLogicalName(logicalName);
            string assetLocaleCode = GetAssetLocaleCode(localeCode);
            return string.Equals(
                assetLocaleCode,
                DefaultLocaleCode,
                StringComparison.Ordinal)
                ? normalizedName
                : $"{normalizedName}-{assetLocaleCode}";
        }

        internal static IReadOnlyList<string> GetCandidatePicNames(
            string logicalName,
            string localeCode)
        {
            string normalizedName = NormalizeLogicalName(logicalName);
            string localizedName = GetPicName(normalizedName, localeCode);
            if (string.Equals(localizedName, normalizedName, StringComparison.Ordinal))
                return new[] { normalizedName };

            return new[] { localizedName, normalizedName };
        }

        internal static bool TryParseLocalizedVariant(
            string fileNameWithoutExtension,
            out string logicalName,
            out string localeCode)
        {
            foreach (string candidateCode in NonDefaultLocaleCodeValues)
            {
                string suffix = $"-{candidateCode}";
                if (!fileNameWithoutExtension.EndsWith(
                    suffix,
                    StringComparison.OrdinalIgnoreCase))
                {
                    continue;
                }

                logicalName = fileNameWithoutExtension.Substring(
                    0,
                    fileNameWithoutExtension.Length - suffix.Length);
                localeCode = candidateCode;
                return true;
            }

            logicalName = null;
            localeCode = null;
            return false;
        }
    }
}