using System.Text.Json;
using SSPCTester.Logic.Models;

namespace SSPCTester.Logic.Storage;

/// <summary>
/// 项目读写：每项目一个独立文件夹，含 project.json / curves/ / report.pdf。
/// </summary>
public sealed class ProjectStore
{
    private static readonly JsonSerializerOptions _jsonOpts = new()
    {
        WriteIndented = true,
        Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping
    };

    /// <summary>项目根目录（来自设置页）。</summary>
    public string ProjectsRoot { get; set; } = "";

    public IEnumerable<string> EnumerateProjectFolders()
    {
        if (string.IsNullOrWhiteSpace(ProjectsRoot) || !Directory.Exists(ProjectsRoot))
            yield break;
        foreach (var dir in Directory.EnumerateDirectories(ProjectsRoot))
        {
            if (File.Exists(Path.Combine(dir, "project.json")))
                yield return dir;
        }
    }

    public async Task<Project?> LoadAsync(string folder)
    {
        var file = Path.Combine(folder, "project.json");
        if (!File.Exists(file)) return null;
        await using var fs = File.OpenRead(file);
        var project = await JsonSerializer.DeserializeAsync<Project>(fs, _jsonOpts);
        if (project != null)
        {
            project.FolderPath = folder;
            project.TestFunction ??= new TestFunctionNotes();
            if (HasLegacyZeroBasedChannels(project))
            {
                project.BasicResults.Clear();
                project.CurveResults.Clear();
                project.PowerResults.Clear();
            }
        }
        return project;
    }

    private static bool HasLegacyZeroBasedChannels(Project project) =>
        project.BasicResults.Any(x => x.Channel == 0) ||
        project.CurveResults.Any(x => x.Channel == 0) ||
        project.PowerResults.Any(x => x.Channel == 0);

    public async Task SaveAsync(Project project)
    {
        if (string.IsNullOrWhiteSpace(project.FolderPath))
        {
            if (string.IsNullOrWhiteSpace(ProjectsRoot))
                throw new InvalidOperationException("尚未配置 ProjectsRoot。");
            string safeName = MakeSafeName(project.Name);
            project.FolderPath = Path.Combine(ProjectsRoot, safeName);
        }
        Directory.CreateDirectory(project.FolderPath);
        Directory.CreateDirectory(Path.Combine(project.FolderPath, "curves"));
        var file = Path.Combine(project.FolderPath, "project.json");
        await using var fs = File.Create(file);
        await JsonSerializer.SerializeAsync(fs, project, _jsonOpts);
    }

    public async Task<List<Project>> LoadAllAsync()
    {
        var list = new List<Project>();
        foreach (var folder in EnumerateProjectFolders())
        {
            try
            {
                var p = await LoadAsync(folder);
                if (p != null) list.Add(p);
            }
            catch { /* 跳过损坏的项目 */ }
        }
        return list.OrderByDescending(p => p.LastTestedAt == default ? p.CreatedAt : p.LastTestedAt).ToList();
    }

    private static string MakeSafeName(string name)
    {
        var invalid = Path.GetInvalidFileNameChars();
        return string.Concat(name.Select(c => invalid.Contains(c) ? '_' : c));
    }
}