using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using AibisDream.UI;
using UnityEditor;
using UnityEditor.Build;
using UnityEditor.Build.Reporting;
using UnityEngine;

namespace AibisDream.EditorTools.Localization
{
    public readonly struct LocalizedObjSpriteValidationIssue
    {
        public LocalizedObjSpriteValidationIssue(string assetPath, string message)
        {
            AssetPath = assetPath;
            Message = message;
        }

        public string AssetPath { get; }
        public string Message { get; }

        public override string ToString()
        {
            return $"{AssetPath}: {Message}";
        }
    }

    /// <summary>
    /// Validates localized Obj sprite groups without depending on Yarn references or
    /// Unity Localization asset tables. A group becomes localized as soon as one
    /// supported non-Chinese suffix is present.
    /// </summary>
    public static class LocalizedObjSpriteValidator
    {
        internal const string DefaultObjSpriteRoot = "Assets/RawResources/Art/Obj";
        private const string MenuPath =
            "Tools/AIBIS/Localization/Validate Localized Obj Sprites";

        [MenuItem(MenuPath)]
        public static void ValidateFromMenu()
        {
            IReadOnlyList<LocalizedObjSpriteValidationIssue> issues = Validate();
            LogIssues(issues);
            if (issues.Count == 0)
            {
                Debug.Log(
                    "[LocalizedObjSpriteValidator] Validation passed. " +
                    "All detected localized Obj sprite groups are complete.");
            }
        }

        public static IReadOnlyList<LocalizedObjSpriteValidationIssue> Validate(
            string rootPath = DefaultObjSpriteRoot)
        {
            var issues = new List<LocalizedObjSpriteValidationIssue>();
            if (!Directory.Exists(rootPath))
            {
                issues.Add(new LocalizedObjSpriteValidationIssue(
                    ToAssetPath(rootPath),
                    "Obj sprite root does not exist."));
                return issues;
            }

            var localizedGroups = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            foreach (string filePath in Directory.EnumerateFiles(
                         rootPath,
                         "*.png",
                         SearchOption.AllDirectories))
            {
                string fileName = Path.GetFileNameWithoutExtension(filePath);
                if (!LocalizedObjSpriteNaming.TryParseLocalizedVariant(
                        fileName,
                        out string logicalName,
                        out _))
                {
                    continue;
                }

                if (string.IsNullOrWhiteSpace(logicalName))
                {
                    issues.Add(new LocalizedObjSpriteValidationIssue(
                        ToAssetPath(filePath),
                        "Localized variant has an empty logical name."));
                    continue;
                }

                string directory = Path.GetDirectoryName(filePath) ?? rootPath;
                localizedGroups.Add(Path.Combine(directory, logicalName));
            }

            foreach (string groupPath in localizedGroups.OrderBy(
                         path => path,
                         StringComparer.OrdinalIgnoreCase))
            {
                ValidateRequiredFile(
                    $"{groupPath}.png",
                    LocalizedObjSpriteNaming.DefaultLocaleCode,
                    issues);

                foreach (string localeCode in
                         LocalizedObjSpriteNaming.NonDefaultLocaleCodes)
                {
                    ValidateRequiredFile(
                        $"{groupPath}-{localeCode}.png",
                        localeCode,
                        issues);
                }
            }

            return issues;
        }

        internal static void LogIssues(
            IReadOnlyList<LocalizedObjSpriteValidationIssue> issues)
        {
            foreach (LocalizedObjSpriteValidationIssue issue in issues)
                Debug.LogError($"[LocalizedObjSpriteValidator] {issue}");
        }

        private static void ValidateRequiredFile(
            string filePath,
            string localeCode,
            ICollection<LocalizedObjSpriteValidationIssue> issues)
        {
            if (File.Exists(filePath))
                return;

            issues.Add(new LocalizedObjSpriteValidationIssue(
                ToAssetPath(filePath),
                $"Missing required '{localeCode}' sprite variant."));
        }

        private static string ToAssetPath(string path)
        {
            return path.Replace('\\', '/');
        }
    }

    public sealed class LocalizedObjSpriteBuildValidator : IPreprocessBuildWithReport
    {
        // Run before build preprocessors that mutate version information.
        public int callbackOrder => -1000;

        public void OnPreprocessBuild(BuildReport report)
        {
            IReadOnlyList<LocalizedObjSpriteValidationIssue> issues =
                LocalizedObjSpriteValidator.Validate();
            if (issues.Count == 0)
                return;

            LocalizedObjSpriteValidator.LogIssues(issues);
            string summary = string.Join(
                Environment.NewLine,
                issues.Take(20).Select(issue => issue.ToString()));
            if (issues.Count > 20)
            {
                summary += Environment.NewLine +
                           $"... and {issues.Count - 20} more issue(s).";
            }

            throw new BuildFailedException(
                "Localized Obj sprite validation failed:" +
                Environment.NewLine + summary);
        }
    }
}