using System.Text.Json;
using LyricFlow.Core.Dtos;
using LyricFlow.Core.Serialization;

namespace LyricFlow.Core.Services;

public class SessionStoreService
{
    public const string GlobalWorkspaceKey = "__global__";

    private readonly string _storagePath;

    // MARK: - Lifecycle
    #region Lifecycle

    public SessionStoreService(string? storagePath = null)
    {
        _storagePath = storagePath ?? Path.Combine(AppPaths.AppDataDirectory(), "session_snapshots.json");
        var directory = Path.GetDirectoryName(_storagePath);
        if (!string.IsNullOrWhiteSpace(directory))
        {
            Directory.CreateDirectory(directory);
        }
    }

    #endregion

    // MARK: - Public Operations
    #region Public Operations

    public List<SessionTabSnapshotDto> Load(string? workspaceRoot)
    {
        var payload = ReadPayload();
        return payload.Workspaces.TryGetValue(WorkspaceKey(workspaceRoot), out var snapshots) ? snapshots : [];
    }

    public void Save(string? workspaceRoot, List<SessionTabSnapshotDto> snapshots)
    {
        var payload = ReadPayload();
        var key = WorkspaceKey(workspaceRoot);
        if (snapshots.Count == 0)
        {
            payload.Workspaces.Remove(key);
        }
        else
        {
            payload.Workspaces[key] = snapshots;
        }

        WritePayload(payload);
    }

    public void Clear(string? workspaceRoot = null)
    {
        if (workspaceRoot is null)
        {
            if (File.Exists(_storagePath))
            {
                File.Delete(_storagePath);
            }

            return;
        }

        var payload = ReadPayload();
        payload.Workspaces.Remove(WorkspaceKey(workspaceRoot));
        if (payload.Workspaces.Count == 0)
        {
            if (File.Exists(_storagePath))
            {
                File.Delete(_storagePath);
            }

            return;
        }

        WritePayload(payload);
    }

    #endregion

    // MARK: - Payload Persistence
    #region Payload Persistence

    private SessionPayload ReadPayload()
    {
        if (!File.Exists(_storagePath))
        {
            return new SessionPayload();
        }

        try
        {
            var payload = JsonSerializer.Deserialize(File.ReadAllText(_storagePath), LyricFlowCoreJsonContext.Default.SessionPayload);
            return payload ?? new SessionPayload();
        }
        catch (IOException)
        {
            return new SessionPayload();
        }
        catch (JsonException)
        {
            return new SessionPayload();
        }
    }

    private void WritePayload(SessionPayload payload)
    {
        payload.Version = 1;
        File.WriteAllText(_storagePath, JsonSerializer.Serialize(payload, LyricFlowCoreJsonContext.Default.SessionPayload));
    }

    #endregion

    // MARK: - Workspace Keys
    #region Workspace Keys

    private static string WorkspaceKey(string? workspaceRoot)
    {
        if (string.IsNullOrWhiteSpace(workspaceRoot))
        {
            return GlobalWorkspaceKey;
        }

        var fullPath = Path.GetFullPath(workspaceRoot);
        return OperatingSystem.IsWindows() ? fullPath.ToLowerInvariant() : fullPath;
    }

    #endregion

    // MARK: - Payload Model
    #region Payload Model

    #endregion
}

internal sealed class SessionPayload
{
    public int Version { get; set; } = 1;
    public Dictionary<string, List<SessionTabSnapshotDto>> Workspaces { get; set; } = new(StringComparer.OrdinalIgnoreCase);
}