using System.Text.Json;
using System.Text.Json.Serialization;

namespace BlueLaminate.Scraper.Skins;

/// <summary>
/// Loads the CS2 skin catalogue from the ByMykel/CSGO-API static dataset
/// (skins.json) and maps it to <see cref="CatalogSkin"/> records. This replaces
/// the old HTML scraper: one JSON file carries every skin with its weapon,
/// category, rarity, wear range, and the collections/containers it comes from.
/// </summary>
public sealed class SkinCatalogClient
{
    private static readonly JsonSerializerOptions Options = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower,
        PropertyNameCaseInsensitive = true,
        NumberHandling = JsonNumberHandling.AllowReadingFromString,
    };

    private readonly HttpClient _http;
    private readonly string _url;

    public SkinCatalogClient(HttpClient http, SkinCatalogOptions options)
    {
        _http = http;
        _url = options.Url;
    }

    public async Task<IReadOnlyList<CatalogSkin>> FetchAsync(CancellationToken ct = default)
    {
        await using var stream = await _http.GetStreamAsync(_url, ct);
        var dtos = await JsonSerializer.DeserializeAsync<List<SkinDto>>(stream, Options, ct)
            ?? throw new InvalidOperationException("skins.json deserialized to null.");

        return dtos.Select(Map).ToList();
    }

    private static CatalogSkin Map(SkinDto dto)
    {
        var sources = new List<CatalogSource>();
        AddSources(sources, dto.Collections, "Collection");
        AddSources(sources, dto.Crates, "Container");

        return new CatalogSkin(
            Id: dto.Id,
            WeaponName: dto.Weapon?.Name ?? "Unknown",
            DefIndex: dto.Weapon?.WeaponId,
            PaintIndex: dto.PaintIndex,
            Category: dto.Category?.Name ?? "Unknown",
            Team: MapTeam(dto.Team?.Id),
            // Knives with no finish carry a null pattern; "Vanilla" is the community term.
            Name: dto.Pattern?.Name ?? "Vanilla",
            Rarity: dto.Rarity?.Name ?? "Unknown",
            Description: dto.Description,
            ImageUrl: dto.Image,
            StatTrakAvailable: dto.Stattrak,
            SouvenirAvailable: dto.Souvenir,
            FloatMin: dto.MinFloat,
            FloatMax: dto.MaxFloat,
            Sources: sources);
    }

    private static void AddSources(List<CatalogSource> into, List<NamedDto>? items, string type)
    {
        if (items is null)
        {
            return;
        }

        foreach (var item in items)
        {
            if (string.IsNullOrEmpty(item.Id) || string.IsNullOrEmpty(item.Name))
            {
                continue;
            }

            if (into.Any(s => s.Id == item.Id))
            {
                continue;
            }

            into.Add(new CatalogSource(item.Id, item.Name, type));
        }
    }

    private static string MapTeam(string? teamId) => teamId switch
    {
        "terrorists" => "T",
        "counter-terrorists" => "CT",
        _ => "Both",
    };

    private sealed record SkinDto(
        string Id,
        string? Name,
        string? Description,
        WeaponDto? Weapon,
        NamedDto? Category,
        NamedDto? Pattern,
        // Top-level paint index. AllowReadingFromString handles its string form.
        int? PaintIndex,
        decimal? MinFloat,
        decimal? MaxFloat,
        NamedDto? Rarity,
        bool Stattrak,
        bool Souvenir,
        string? Image,
        NamedDto? Team,
        List<NamedDto>? Collections,
        List<NamedDto>? Crates);

    private sealed record NamedDto(string? Id, string? Name);

    // Weapon carries a numeric weapon_id (the def_index) alongside id/name.
    private sealed record WeaponDto(string? Id, int? WeaponId, string? Name);
}