using System.Text.Json;
using Microsoft.AspNetCore.Mvc;
using SVSim.Database.Enums;
using SVSim.Database.Models;
using SVSim.Database.Models.Config;
using SVSim.Database.Repositories.Deck;
using SVSim.Database.Repositories.Viewer;
using SVSim.Database.Services;
using SVSim.Database.Services.Inventory;
using SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
using SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
using SVSim.EmulatedEntrypoint.Models.Dtos.Requests.ArenaColosseum;
using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaColosseum;

namespace SVSim.EmulatedEntrypoint.Controllers;

/// <summary>
/// Arena Colosseum (Grand Prix) lobby. Phase 1 covers the three read endpoints (<c>/top</c>,
/// <c>/get_fee_info</c>, <c>/event_info</c>) plus the entry/register-deck pair. Defaults to
/// "no event scheduled" via <see cref="ColosseumSeasonConfig.IsColosseumPeriod"/> — flipping
/// the event on is an admin operation per <c>docs/operations/grand-prix-event-setup.md</c>.
/// </summary>
[Route("arena_colosseum")]
public class ArenaColosseumController : SVSimController
{
    private readonly IGameConfigService _config;
    private readonly IArenaColosseumRunRepository _runs;
    private readonly IInventoryService _inventory;
    private readonly IDeckRepository _decks;

    public ArenaColosseumController(
        IGameConfigService config,
        IArenaColosseumRunRepository runs,
        IInventoryService inventory,
        IDeckRepository decks)
    {
        _config = config;
        _runs = runs;
        _inventory = inventory;
        _decks = decks;
    }

    [HttpPost("top")]
    public async Task<IActionResult> Top([FromBody] BaseRequest _)
    {
        if (!TryGetViewerId(out var vid)) return Unauthorized();

        var season = _config.Get<ColosseumSeasonConfig>();
        var run = await _runs.GetByViewerIdAsync(vid);

        var response = new TopResponse
        {
            ColosseumInfo = BuildColosseumInfo(season),
            ColosseumStatus = BuildOwnStatus(run),
            LeaderSkinId = run?.LeaderSkinId ?? 0,
        };

        if (run is not null)
        {
            response.EntryInfo = new ColosseumEntryRef { Id = run.EntryId };
            response.NowRoundId = run.RoundId;
            response.MaxBattleCount = run.MaxBattleCountThisRound;
            response.IsFinish = run.IsChampion;
            response.FinalRoundEliminateCount = season.FinalRoundEliminateCount;
            response.EndTime = FormatTime(season.EventEndTime);
            response.BattleResults = new ColosseumBattleResults
            {
                WinCount = run.WinCount,
                ResultList = ParseIntList(run.ResultListJson),
            };
            response.BreakthroughNumber = run.BreakthroughNumberThisRound > 0 ? run.BreakthroughNumberThisRound : null;
        }

        return Ok(response);
    }

    [HttpPost("get_fee_info")]
    public async Task<IActionResult> GetFeeInfo([FromBody] BaseRequest _)
    {
        if (!TryGetViewerId(out var vid)) return Unauthorized();

        var season = _config.Get<ColosseumSeasonConfig>();
        var run = await _runs.GetByViewerIdAsync(vid);

        var response = new GetFeeInfoResponseDto
        {
            ColosseumInfo = BuildColosseumInfo(season),
            ColosseumStatus = BuildOwnStatus(run),
        };

        if (!season.IsColosseumPeriod)
        {
            return Ok(response);
        }

        response.IsUnfinishedEntryExists = run is not null;
        response.IsAllowedFreeEntry = season.IsAllowedFreeEntry;
        response.FeeList = new ColosseumFeeList
        {
            RupyCost = season.RupyCost,
            TicketCost = season.TicketCost,
            CrystalCost = season.CrystalCost,
        };

        if (run is not null)
        {
            response.DeckFormat = (int)run.DeckFormat;
        }

        return Ok(response);
    }

    [HttpPost("event_info")]
    public async Task<IActionResult> EventInfo([FromBody] BaseRequest _)
    {
        if (!TryGetViewerId(out var vid)) return Unauthorized();

        var season = _config.Get<ColosseumSeasonConfig>();
        var rounds = _config.Get<ColosseumRoundsConfig>();
        var run = await _runs.GetByViewerIdAsync(vid);

        return Ok(new EventInfoResponse
        {
            ColosseumInfo = new ColosseumEventInfo
            {
                Format = (int)season.DeckFormat,
                StartTime = FormatTime(season.EventStartTime),
                EndTime = FormatTime(season.EventEndTime),
                AnnounceId = season.AnnounceId,
                FinalRoundEliminateCount = season.FinalRoundEliminateCount,
            },
            Round1 = BuildRoundDetail(rounds, 1),
            Round2 = BuildRoundDetail(rounds, 2),
            Round3 = BuildRoundDetail(rounds, 3),
            ColosseumStatus = BuildOwnStatus(run),
        });
    }

    [HttpPost("entry")]
    public async Task<IActionResult> Entry([FromBody] ArenaColosseumEntryRequest req)
    {
        if (!TryGetViewerId(out var vid)) return Unauthorized();

        var season = _config.Get<ColosseumSeasonConfig>();
        if (!season.IsColosseumPeriod)
        {
            return BadRequest(new { error = "colosseum_period_closed" });
        }

        var serverRoundId = ResolveServerRoundId(season);
        if (req.NowRoundId != serverRoundId)
        {
            return BadRequest(new { error = "now_round_id_mismatch", server_round_id = serverRoundId });
        }

        if (await _runs.GetByViewerIdAsync(vid) is not null)
        {
            return BadRequest(new { error = "arena_colosseum_already_in_progress" });
        }

        await using var tx = await _inventory.BeginAsync(vid);

        RewardEntryDto? feeEntry = req.ConsumeItemType switch
        {
            1 => await DebitCrystalAsync(tx, season.CrystalCost),
            3 => await DebitTicketAsync(tx, season.TicketCost),
            4 => await DebitRupyAsync(tx, season.RupyCost),
            5 when season.IsAllowedFreeEntry => null,
            _ => throw new InvalidOperationException($"invalid consume_item_type {req.ConsumeItemType}"),
        };

        var rounds = _config.Get<ColosseumRoundsConfig>();
        var roundConfig = rounds.Rounds.FirstOrDefault(r => r.RoundId == serverRoundId);
        var group = roundConfig?.Groups.FirstOrDefault();

        var run = new ViewerArenaColosseumRun
        {
            ViewerId = vid,
            EntryId = 0,
            SeasonId = season.SeasonId,
            RoundId = serverRoundId,
            DeckFormat = season.DeckFormat,
            LeaderSkinId = 0,
            ConsumeItemType = req.ConsumeItemType,
            MaxBattleCountThisRound = group?.MaxBattleCount ?? 0,
            BreakthroughNumberThisRound = group?.BreakthroughNumber ?? 0,
            RestEntryNum = 0,
        };
        await _runs.UpsertAsync(run);
        run.EntryId = run.Id;
        await _runs.UpsertAsync(run);
        await tx.CommitAsync();

        return Ok(new EntryResponse
        {
            RewardList = feeEntry is null ? new() : new() { feeEntry },
            EntryInfo = new ColosseumEntryRef
            {
                Id = run.EntryId,
                DeckFormat = (int)season.DeckFormat,
            },
        });
    }

    [HttpPost("register_deck")]
    public async Task<IActionResult> RegisterDeck([FromBody] ArenaColosseumRegisterDeckRequest req)
    {
        if (!TryGetViewerId(out var vid)) return Unauthorized();

        var run = await _runs.GetByViewerIdAsync(vid);
        if (run is null)
        {
            return BadRequest(new { error = "no_active_run" });
        }

        List<int> deckNos;
        try
        {
            deckNos = JsonSerializer.Deserialize<List<int>>(req.DeckNoList) ?? new();
        }
        catch (JsonException)
        {
            return BadRequest(new { error = "deck_no_list_malformed" });
        }

        if (deckNos.Count == 0)
        {
            return BadRequest(new { error = "deck_no_list_empty" });
        }

        // GetDeck filters by (viewerId, format, deckNo) — a slot that exists under a different
        // format returns null here, which is the format-mismatch case from the spec.
        foreach (var no in deckNos)
        {
            var deck = await _decks.GetDeck(vid, run.DeckFormat, no);
            if (deck is null)
            {
                return BadRequest(new { error = "deck_not_found", deck_no = no });
            }
        }

        run.RegisteredDeckNoListJson = JsonSerializer.Serialize(deckNos);
        run.IsPublished = req.IsPublished;
        await _runs.UpsertAsync(run);

        return Ok(new { });
    }

    private static int ResolveServerRoundId(ColosseumSeasonConfig season) => 1;

    private async Task<RewardEntryDto> DebitCrystalAsync(IInventoryTransaction tx, int cost)
    {
        var result = await tx.TrySpendAsync(SpendCurrency.Crystal, cost);
        if (!result.Success)
            throw new InvalidOperationException("insufficient_crystal");
        return new RewardEntryDto
        {
            RewardType = (int)UserGoodsType.Crystal,
            RewardId = 0,
            RewardNum = (int)result.PostStateTotal,
        };
    }

    private async Task<RewardEntryDto> DebitRupyAsync(IInventoryTransaction tx, int cost)
    {
        var result = await tx.TrySpendAsync(SpendCurrency.Rupee, cost);
        if (!result.Success)
            throw new InvalidOperationException("insufficient_rupy");
        return new RewardEntryDto
        {
            RewardType = (int)UserGoodsType.Rupy,
            RewardId = 0,
            RewardNum = (int)result.PostStateTotal,
        };
    }

    private async Task<RewardEntryDto> DebitTicketAsync(IInventoryTransaction tx, int cost)
    {
        // Colosseum's ticket id is server-internal — using ArenaTwoPick's TicketItemId convention
        // (item id 1) until a per-season override is captured.
        const int ticketItemId = 1;
        var result = await tx.TryDebitAsync(UserGoodsType.Item, ticketItemId, cost);
        if (!result.Success)
            throw new InvalidOperationException("insufficient_ticket");
        return new RewardEntryDto
        {
            RewardType = (int)UserGoodsType.Item,
            RewardId = ticketItemId,
            RewardNum = (int)result.PostStateTotal,
        };
    }

    // --- helpers ---

    private static ColosseumLobbyInfo BuildColosseumInfo(ColosseumSeasonConfig season)
    {
        if (!season.IsColosseumPeriod)
        {
            return new ColosseumLobbyInfo { IsColosseumPeriod = false };
        }

        return new ColosseumLobbyInfo
        {
            IsColosseumPeriod = true,
            DeckFormat = (int)season.DeckFormat,
            IsNormalTwoPick = season.IsNormalTwoPick ? "1" : "0",
            ColosseumName = season.ColosseumName,
            IsRoundPeriod = true,
            IsSpecialMode = season.IsSpecialMode,
            CardPoolName = string.IsNullOrEmpty(season.CardPoolName) ? null : season.CardPoolName,
            NowRound = 1,
            StartTime = FormatTime(season.EventStartTime),
            EndTime = FormatTime(season.EventEndTime),
            IsAllCardEnabled = season.IsAllCardEnabled ? 1 : 0,
            SalesPeriodInfo = new SVSim.EmulatedEntrypoint.Models.Dtos.ColosseumSalesPeriodInfo
            {
                SalesPeriodTime = FormatTime(season.SalesPeriodEnd),
            },
            StrategyPickNum = season.StrategyPickNum > 0 ? season.StrategyPickNum : null,
        };
    }

    /// <summary>Builds the <c>colosseum_status</c> block. When the viewer has no run, every
    /// property is null and global WhenWritingNull renders <c>{}</c> — the client
    /// (<c>SetColosseumOwnStatus</c>) short-circuits on <c>status.Count == 0</c>.</summary>
    private static ColosseumOwnStatus BuildOwnStatus(ViewerArenaColosseumRun? run)
    {
        if (run is null) return new ColosseumOwnStatus();

        return new ColosseumOwnStatus
        {
            RestEntryNum = run.RestEntryNum,
            NowRoundId = run.RoundId,
            IsChampion = run.IsChampion ? true : null,
        };
    }

    private static ColosseumRoundDetail BuildRoundDetail(ColosseumRoundsConfig rounds, int roundId)
    {
        var match = rounds.Rounds.FirstOrDefault(r => r.RoundId == roundId);
        if (match is null) return new ColosseumRoundDetail();

        return new ColosseumRoundDetail
        {
            StartTime = FormatTime(match.StartTime),
            EndTime = FormatTime(match.EndTime),
            IsNowRound = IsNowRound(match),
            RoundDetail = match.Groups.Select(g => new ColosseumGroupRow
            {
                Group = g.Group,
                MaxBattleCount = g.MaxBattleCount,
                BreakthroughNumber = g.BreakthroughNumber,
                EntryNumber = g.EntryNumber,
            }).ToList(),
        };
    }

    private static bool IsNowRound(ColosseumRoundsConfig.RoundEntry round)
    {
        var now = DateTime.UtcNow;
        return now >= round.StartTime && now <= round.EndTime;
    }

    private static string FormatTime(DateTime t) =>
        t == default ? "" : t.ToString("yyyy-MM-dd HH:mm:ss");

    private static List<int> ParseIntList(string json) =>
        string.IsNullOrEmpty(json)
            ? new()
            : System.Text.Json.JsonSerializer.Deserialize<List<int>>(json) ?? new();
}