using System.Text.Json;
using OpenTheBox.Core.Boxes;
using OpenTheBox.Core.Interactions;
using OpenTheBox.Core.Items;

namespace OpenTheBox.Data;

/// <summary>
/// Central registry for all game content definitions (items, boxes, interaction rules).
/// Content is loaded from data files and registered here for lookup by the simulation engines.
/// </summary>
public class ContentRegistry
{
    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNameCaseInsensitive = true,
        Converters = { new System.Text.Json.Serialization.JsonStringEnumConverter() }
    };

    private readonly Dictionary<string, ItemDefinition> _items = [];
    private readonly Dictionary<string, BoxDefinition> _boxes = [];
    private readonly List<InteractionRule> _interactionRules = [];

    public void RegisterItem(ItemDefinition item) => _items[item.Id] = item;
    public void RegisterBox(BoxDefinition box) => _boxes[box.Id] = box;
    public void RegisterInteractionRule(InteractionRule rule) => _interactionRules.Add(rule);

    public ItemDefinition? GetItem(string id) => _items.GetValueOrDefault(id);
    public BoxDefinition? GetBox(string id) => _boxes.GetValueOrDefault(id);

    /// <summary>
    /// Returns true if the given definition id corresponds to a registered box.
    /// </summary>
    public bool IsBox(string id) => _boxes.ContainsKey(id);

    public IReadOnlyDictionary<string, ItemDefinition> Items => _items;
    public IReadOnlyDictionary<string, BoxDefinition> Boxes => _boxes;
    public IReadOnlyList<InteractionRule> InteractionRules => _interactionRules;

    /// <summary>
    /// Loads content definitions from JSON files and returns a populated registry.
    /// Files that do not exist are silently skipped.
    /// </summary>
    public static ContentRegistry LoadFromFiles(string itemsPath, string boxesPath, string interactionsPath)
    {
        var registry = new ContentRegistry();

        if (File.Exists(itemsPath))
        {
            var json = File.ReadAllText(itemsPath);
            var items = JsonSerializer.Deserialize<List<ItemDefinition>>(json, JsonOptions);
            if (items is not null)
            {
                foreach (var item in items)
                    registry.RegisterItem(item);
            }
        }

        if (File.Exists(boxesPath))
        {
            var json = File.ReadAllText(boxesPath);
            var boxes = JsonSerializer.Deserialize<List<BoxDefinition>>(json, JsonOptions);
            if (boxes is not null)
            {
                foreach (var box in boxes)
                    registry.RegisterBox(box);
            }
        }

        if (File.Exists(interactionsPath))
        {
            var json = File.ReadAllText(interactionsPath);
            var rules = JsonSerializer.Deserialize<List<InteractionRule>>(json, JsonOptions);
            if (rules is not null)
            {
                foreach (var rule in rules)
                    registry.RegisterInteractionRule(rule);
            }
        }

        return registry;
    }
}