using System.Text.Json;
using System.Text.Json.Serialization;
using Dalamud.Plugin;
using Dalamud.Plugin.Services;

namespace PlayerNotes;

/// <summary>
/// Loads, saves, and validates the PlayerNotes.json data file. The file lives in this
/// plugin's config directory (e.g. %APPDATA%\XIVLauncher\plugin_config\PlayerNotes\)
/// and is also the export/import format for moving lists between PCs.
/// </summary>
public class Storage
{
    private static readonly JsonSerializerOptions SerializerOptions = new()
    {
        WriteIndented = true,
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        // Users edit this file by hand to manage tags; allow (and ignore) comments.
        ReadCommentHandling = JsonCommentHandling.Skip,
    };

    private readonly IPluginLog log;

    public PlayerNotesData Data { get; private set; } = new();

    public string FilePath { get; }

    public Storage(IDalamudPluginInterface pluginInterface, IPluginLog log)
    {
        this.log = log;
        FilePath = Path.Combine(pluginInterface.ConfigFile.Directory!.FullName, "PlayerNotes.json");
        Load();
    }

    /// <summary>Reads the data file from disk, creating it with defaults if missing.</summary>
    public void Load()
    {
        try
        {
            if (File.Exists(FilePath))
            {
                Data = Parse(File.ReadAllText(FilePath));
                log.Debug($"Loaded player notes from {FilePath}");
            }
            else
            {
                Data = new PlayerNotesData();
                Save(); // create the file so users can find and edit it (tags etc.)
                log.Information($"Created new data file at {FilePath}");
            }
        }
        catch (Exception e)
        {
            // Never let a corrupt file kill the plugin; fall back to empty lists.
            log.Error(e, "Failed to load PlayerNotes.json, starting with empty lists.");
            Data = new PlayerNotesData();
        }
    }

    /// <summary>Writes the current data to disk.</summary>
    public void Save()
    {
        try
        {
            File.WriteAllText(FilePath, Serialize(Data));
        }
        catch (Exception e)
        {
            log.Error(e, "Failed to save PlayerNotes.json.");
        }
    }

    /// <summary>Replaces the in-memory data and persists it (used by import).</summary>
    public void Replace(PlayerNotesData newData)
    {
        Data = newData;
        Save();
    }

    /// <summary>Parses a JSON document into validated data. Throws on invalid input.</summary>
    internal static PlayerNotesData Parse(string json)
    {
        var data = JsonSerializer.Deserialize<PlayerNotesData>(json, SerializerOptions);
        if (data is null)
            throw new InvalidDataException("The file does not contain valid player notes data.");

        data.Normalize();
        return data;
    }

    internal static string Serialize(PlayerNotesData data) =>
        JsonSerializer.Serialize(data, SerializerOptions);
}