using Microsoft.AspNetCore.Mvc;
using SVSim.Database.Repositories.Card;
using SVSim.EmulatedEntrypoint.Models.Dtos;
using SVSim.EmulatedEntrypoint.Models.Dtos.Requests.Card;
using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.Card;
using System.Text.Json;

namespace SVSim.EmulatedEntrypoint.Controllers;

/// <summary>
/// /card/* — viewer card-inventory mutations. v1 implements /card/destruct only; reserved
/// for /card/create, /card/protect, /card/create-foil-card.
/// </summary>
[Route("card")]
public class CardController : SVSimController
{
    private readonly ICardInventoryRepository _inventory;
    private readonly ILogger<CardController> _log;

    public CardController(ICardInventoryRepository inventory, ILogger<CardController> log)
    {
        _inventory = inventory;
        _log = log;
    }

    [HttpPost("destruct")]
    public async Task<ActionResult<CardDestructResponse>> Destruct(CardDestructRequest request)
    {
        if (!TryGetViewerId(out long viewerId)) return Unauthorized();

        if (!TryParseDestructDict(request.CardIdNumberArray, out var destructCounts, out var snapshots, out var parseError))
            return BadRequest(new { error = parseError });

        if (destructCounts.Count == 0)
            return BadRequest(new { error = "malformed_request" });

        var outcome = await _inventory.DestructCards(viewerId, destructCounts);
        if (!outcome.IsSuccess)
            return BadRequest(new { error = ErrorKey(outcome.Error!.Value) });

        // Client snapshot mismatch is warn-log only; never blocks the request.
        foreach (var (cardId, snapshot) in snapshots)
        {
            // We don't carry pre-state counts back, but post + destructed = pre.
            int destructedNum = destructCounts[cardId];
            int reconstructedPre = outcome.Result!.NewOwnedCounts[cardId] + destructedNum;
            if (reconstructedPre != snapshot)
            {
                _log.LogWarning(
                    "Destruct possession-snapshot mismatch: card={CardId} client_snapshot={Snapshot} server_pre={ServerPre}",
                    cardId, snapshot, reconstructedPre);
            }
        }

        // Wire spec is int; clamp the ulong total so a hypothetical 2B+ balance can't underflow
        // to a negative wire value. Realistic balances are well under int.MaxValue.
        int redEtherWire = outcome.Result!.NewRedEtherTotal > int.MaxValue
            ? int.MaxValue
            : (int)outcome.Result!.NewRedEtherTotal;
        var rewardList = new List<RewardListEntry>
        {
            new() { RewardType = 1, RewardId = 0, RewardNum = redEtherWire },
        };
        foreach (var (cardId, postCount) in outcome.Result!.NewOwnedCounts)
        {
            rewardList.Add(new RewardListEntry { RewardType = 5, RewardId = cardId, RewardNum = postCount });
        }

        return new CardDestructResponse { RewardList = rewardList };
    }

    private static string ErrorKey(DestructError error) => error switch
    {
        DestructError.UnknownCard       => "unknown_card",
        DestructError.NotDestructible   => "not_destructible",
        DestructError.CardProtected     => "card_protected",
        DestructError.InsufficientCards => "insufficient_cards",
        _ => "malformed_request",
    };

    /// <summary>
    /// Decodes the inner JSON of <c>card_id_number_array</c>. Values are
    /// <c>"&lt;num_to_destruct&gt;,&lt;client_possession_snapshot&gt;"</c> — both strings.
    /// Returns false (and sets <paramref name="errorKey"/>) on any structural problem.
    /// </summary>
    private static bool TryParseDestructDict(
        string raw,
        out Dictionary<long, int> destructCounts,
        out Dictionary<long, int> clientSnapshots,
        out string errorKey)
    {
        destructCounts = new();
        clientSnapshots = new();
        errorKey = "malformed_request";

        if (string.IsNullOrWhiteSpace(raw))
            return false;

        JsonDocument? doc;
        try { doc = JsonDocument.Parse(raw); }
        catch (JsonException) { return false; }

        using (doc)
        {
            if (doc.RootElement.ValueKind != JsonValueKind.Object)
                return false;

            foreach (var prop in doc.RootElement.EnumerateObject())
            {
                if (!long.TryParse(prop.Name, out long cardId))
                    return false;
                if (prop.Value.ValueKind != JsonValueKind.String)
                    return false;

                var pair = prop.Value.GetString()!.Split(',');
                if (pair.Length != 2)
                    return false;
                if (!int.TryParse(pair[0], out int num) || num <= 0)
                    return false;
                if (!int.TryParse(pair[1], out int snapshot) || snapshot < 0)
                    return false;

                destructCounts[cardId] = num;
                clientSnapshots[cardId] = snapshot;
            }
        }

        return true;
    }
}