using line_gestao_api.Data;
using line_gestao_api.Dtos;
using line_gestao_api.Models;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace line_gestao_api.Controllers;

[ApiController]
[Route("api/parcelamentos")]
[Authorize]
public class ParcelamentosController : ControllerBase
{
    private readonly AppDbContext _db;

    public ParcelamentosController(AppDbContext db)
    {
        _db = db;
    }

    [HttpGet]
    public async Task<ActionResult<PagedResult<ParcelamentoListDto>>> GetAll(
        [FromQuery] int? anoRef,
        [FromQuery] string? linha,
        [FromQuery] string? cliente,
        [FromQuery] int? competenciaAno,
        [FromQuery] int? competenciaMes,
        [FromQuery] int page = 1,
        [FromQuery] int pageSize = 20)
    {
        page = page < 1 ? 1 : page;
        pageSize = pageSize < 1 ? 20 : pageSize;

        var query = _db.ParcelamentoLines.AsNoTracking();

        if (anoRef.HasValue)
        {
            query = query.Where(x => x.AnoRef == anoRef.Value);
        }

        if (!string.IsNullOrWhiteSpace(linha))
        {
            var l = linha.Trim();
            query = query.Where(x => x.Linha == l);
        }

        if (!string.IsNullOrWhiteSpace(cliente))
        {
            var c = cliente.Trim();
            query = query.Where(x => x.Cliente != null && EF.Functions.ILike(x.Cliente, $"%{c}%"));
        }

        if (competenciaAno.HasValue && competenciaMes.HasValue)
        {
            var competencia = new DateOnly(competenciaAno.Value, competenciaMes.Value, 1);
            query = query.Where(x => x.MonthValues.Any(m => m.Competencia == competencia));
        }

        var total = await query.CountAsync();
        var today = DateOnly.FromDateTime(DateTime.Today);

        var rows = await query
            .OrderBy(x => x.Item)
            .Skip((page - 1) * pageSize)
            .Take(pageSize)
            .Select(x => new
            {
                x.Id,
                x.AnoRef,
                x.Item,
                x.Linha,
                x.Cliente,
                x.QtParcelas,
                x.ParcelaAtual,
                x.TotalParcelas,
                x.ValorCheio,
                x.Desconto,
                x.ValorComDesconto,
                ParcelaAtualCalc = x.MonthValues.Count(m => m.Competencia <= today),
                TotalMeses = x.MonthValues.Count()
            })
            .ToListAsync();

        var items = rows.Select(x =>
        {
            var (parcelaAtual, totalParcelas) = ResolveParcelasFromCounts(
                x.ParcelaAtual,
                x.TotalParcelas,
                x.QtParcelas,
                x.ParcelaAtualCalc,
                x.TotalMeses);

            return new ParcelamentoListDto
            {
                Id = x.Id,
                AnoRef = x.AnoRef,
                Item = x.Item,
                Linha = x.Linha,
                Cliente = x.Cliente,
                QtParcelas = BuildQtParcelas(parcelaAtual, totalParcelas, x.QtParcelas),
                ParcelaAtual = parcelaAtual,
                TotalParcelas = totalParcelas,
                ValorCheio = x.ValorCheio,
                Desconto = x.Desconto,
                ValorComDesconto = x.ValorComDesconto
            };
        }).ToList();

        return Ok(new PagedResult<ParcelamentoListDto>
        {
            Page = page,
            PageSize = pageSize,
            Total = total,
            Items = items
        });
    }

    [HttpGet("{id:guid}")]
    public async Task<ActionResult<ParcelamentoDetailDto>> GetById(Guid id)
    {
        var entity = await _db.ParcelamentoLines
            .AsNoTracking()
            .Include(x => x.MonthValues)
            .FirstOrDefaultAsync(x => x.Id == id);

        if (entity == null)
        {
            return NotFound();
        }

        var monthValues = entity.MonthValues
            .OrderBy(m => m.Competencia)
            .Select(m => new ParcelamentoMonthDto
            {
                Competencia = m.Competencia,
                Valor = m.Valor
            })
            .ToList();

        var (parcelaAtual, totalParcelas) = ResolveParcelasFromCompetencias(
            entity.ParcelaAtual,
            entity.TotalParcelas,
            entity.QtParcelas,
            monthValues.Select(m => m.Competencia));

        var dto = new ParcelamentoDetailDto
        {
            Id = entity.Id,
            AnoRef = entity.AnoRef,
            Item = entity.Item,
            Linha = entity.Linha,
            Cliente = entity.Cliente,
            QtParcelas = BuildQtParcelas(parcelaAtual, totalParcelas, entity.QtParcelas),
            ParcelaAtual = parcelaAtual,
            TotalParcelas = totalParcelas,
            ValorCheio = entity.ValorCheio,
            Desconto = entity.Desconto,
            ValorComDesconto = entity.ValorComDesconto,
            MonthValues = monthValues,
            AnnualRows = BuildAnnualRows(monthValues)
        };

        return Ok(dto);
    }

    [HttpPost]
    [Authorize(Roles = "admin,gestor")]
    public async Task<ActionResult<ParcelamentoDetailDto>> Create([FromBody] ParcelamentoUpsertDto req)
    {
        var now = DateTime.UtcNow;
        var entity = new ParcelamentoLine
        {
            Id = Guid.NewGuid(),
            AnoRef = req.AnoRef,
            Item = req.Item,
            Linha = TrimOrNull(req.Linha),
            Cliente = TrimOrNull(req.Cliente),
            QtParcelas = TrimOrNull(req.QtParcelas),
            ParcelaAtual = req.ParcelaAtual,
            TotalParcelas = req.TotalParcelas,
            ValorCheio = req.ValorCheio,
            Desconto = req.Desconto,
            ValorComDesconto = ResolveValorComDesconto(req.ValorComDesconto, req.ValorCheio, req.Desconto),
            CreatedAt = now,
            UpdatedAt = now
        };

        if (req.AnoRef.HasValue && req.Item.HasValue)
        {
            var exists = await _db.ParcelamentoLines.AnyAsync(x => x.AnoRef == req.AnoRef && x.Item == req.Item);
            if (exists) return Conflict("Já existe um parcelamento com o mesmo AnoRef e Item.");
        }

        entity.MonthValues = BuildMonthValues(req.MonthValues, entity.Id, now);
        ApplyComputedParcelas(entity);

        _db.ParcelamentoLines.Add(entity);
        await _db.SaveChangesAsync();

        return CreatedAtAction(nameof(GetById), new { id = entity.Id }, ToDetailDto(entity));
    }

    [HttpPut("{id:guid}")]
    [Authorize(Roles = "admin,gestor")]
    public async Task<IActionResult> Update(Guid id, [FromBody] ParcelamentoUpsertDto req)
    {
        var entity = await _db.ParcelamentoLines
            .Include(x => x.MonthValues)
            .FirstOrDefaultAsync(x => x.Id == id);

        if (entity == null) return NotFound();

        if (req.AnoRef.HasValue && req.Item.HasValue)
        {
            var exists = await _db.ParcelamentoLines.AnyAsync(x =>
                x.Id != id && x.AnoRef == req.AnoRef && x.Item == req.Item);
            if (exists) return Conflict("Já existe um parcelamento com o mesmo AnoRef e Item.");
        }

        entity.AnoRef = req.AnoRef;
        entity.Item = req.Item;
        entity.Linha = TrimOrNull(req.Linha);
        entity.Cliente = TrimOrNull(req.Cliente);
        entity.QtParcelas = TrimOrNull(req.QtParcelas);
        entity.ParcelaAtual = req.ParcelaAtual;
        entity.TotalParcelas = req.TotalParcelas;
        entity.ValorCheio = req.ValorCheio;
        entity.Desconto = req.Desconto;
        entity.ValorComDesconto = ResolveValorComDesconto(req.ValorComDesconto, req.ValorCheio, req.Desconto);
        entity.UpdatedAt = DateTime.UtcNow;

        _db.ParcelamentoMonthValues.RemoveRange(entity.MonthValues);
        entity.MonthValues = BuildMonthValues(req.MonthValues, entity.Id, entity.UpdatedAt);
        ApplyComputedParcelas(entity);

        await _db.SaveChangesAsync();
        return NoContent();
    }

    [HttpDelete("{id:guid}")]
    [Authorize(Roles = "admin")]
    public async Task<IActionResult> Delete(Guid id)
    {
        var entity = await _db.ParcelamentoLines.FirstOrDefaultAsync(x => x.Id == id);
        if (entity == null) return NotFound();

        _db.ParcelamentoLines.Remove(entity);
        await _db.SaveChangesAsync();
        return NoContent();
    }

    private static List<ParcelamentoAnnualRowDto> BuildAnnualRows(List<ParcelamentoMonthDto> monthValues)
    {
        if (monthValues.Count == 0) return new List<ParcelamentoAnnualRowDto>();

        var groups = monthValues
            .GroupBy(m => m.Competencia.Year)
            .OrderBy(g => g.Key);

        var rows = new List<ParcelamentoAnnualRowDto>();
        foreach (var group in groups)
        {
            var monthMap = group
                .GroupBy(m => m.Competencia.Month)
                .ToDictionary(g => g.Key, g => g.Sum(x => x.Valor ?? 0m));

            var months = Enumerable.Range(1, 12)
                .Select(month => new ParcelamentoAnnualMonthDto
                {
                    Month = month,
                    Valor = monthMap.TryGetValue(month, out var value) ? value : null
                })
                .ToList();

            var total = months.Sum(m => m.Valor ?? 0m);

            rows.Add(new ParcelamentoAnnualRowDto
            {
                Year = group.Key,
                Total = total,
                Months = months
            });
        }

        return rows;
    }

    private static List<ParcelamentoMonthValue> BuildMonthValues(
        List<ParcelamentoMonthInputDto> inputs,
        Guid parcelamentoId,
        DateTime now)
    {
        var map = new Dictionary<DateOnly, decimal?>();
        foreach (var input in inputs ?? new List<ParcelamentoMonthInputDto>())
        {
            if (input.Competencia == default) continue;
            map[input.Competencia] = input.Valor;
        }

        return map
            .OrderBy(x => x.Key)
            .Select(x => new ParcelamentoMonthValue
            {
                Id = Guid.NewGuid(),
                ParcelamentoLineId = parcelamentoId,
                Competencia = x.Key,
                Valor = x.Value,
                CreatedAt = now
            })
            .ToList();
    }

    private static void ApplyComputedParcelas(ParcelamentoLine entity)
    {
        var competencias = entity.MonthValues.Select(m => m.Competencia).ToList();
        var (parcelaAtual, totalParcelas) = ResolveParcelasFromCompetencias(
            entity.ParcelaAtual,
            entity.TotalParcelas,
            entity.QtParcelas,
            competencias);

        entity.ParcelaAtual = parcelaAtual;
        entity.TotalParcelas = totalParcelas;
        entity.QtParcelas = BuildQtParcelas(parcelaAtual, totalParcelas, entity.QtParcelas);
    }

    private static ParcelamentoDetailDto ToDetailDto(ParcelamentoLine entity)
    {
        var monthValues = entity.MonthValues
            .OrderBy(m => m.Competencia)
            .Select(m => new ParcelamentoMonthDto
            {
                Competencia = m.Competencia,
                Valor = m.Valor
            })
            .ToList();

        var (parcelaAtual, totalParcelas) = ResolveParcelasFromCompetencias(
            entity.ParcelaAtual,
            entity.TotalParcelas,
            entity.QtParcelas,
            monthValues.Select(m => m.Competencia));

        return new ParcelamentoDetailDto
        {
            Id = entity.Id,
            AnoRef = entity.AnoRef,
            Item = entity.Item,
            Linha = entity.Linha,
            Cliente = entity.Cliente,
            QtParcelas = BuildQtParcelas(parcelaAtual, totalParcelas, entity.QtParcelas),
            ParcelaAtual = parcelaAtual,
            TotalParcelas = totalParcelas,
            ValorCheio = entity.ValorCheio,
            Desconto = entity.Desconto,
            ValorComDesconto = entity.ValorComDesconto,
            MonthValues = monthValues,
            AnnualRows = BuildAnnualRows(monthValues)
        };
    }

    private static (int? ParcelaAtual, int? TotalParcelas) ResolveParcelasFromCounts(
        int? storedAtual,
        int? storedTotal,
        string? qtParcelas,
        int mesesAteHoje,
        int totalMeses)
    {
        var total = storedTotal ?? ParseQtParcelas(qtParcelas).Total ?? (totalMeses > 0 ? totalMeses : (int?)null);
        int? atual = totalMeses > 0 ? mesesAteHoje : storedAtual ?? ParseQtParcelas(qtParcelas).Atual;
        if (atual.HasValue && atual.Value < 0) atual = 0;
        if (total.HasValue && atual.HasValue)
        {
            atual = Math.Min(atual.Value, total.Value);
        }
        return (atual, total);
    }

    private static (int? ParcelaAtual, int? TotalParcelas) ResolveParcelasFromCompetencias(
        int? storedAtual,
        int? storedTotal,
        string? qtParcelas,
        IEnumerable<DateOnly> competencias)
    {
        var list = competencias?.ToList() ?? new List<DateOnly>();
        var totalMeses = list.Count;
        var hoje = DateOnly.FromDateTime(DateTime.Today);
        var mesesAteHoje = list.Count(c => c <= hoje);
        return ResolveParcelasFromCounts(storedAtual, storedTotal, qtParcelas, mesesAteHoje, totalMeses);
    }

    private static (int? Atual, int? Total) ParseQtParcelas(string? raw)
    {
        if (string.IsNullOrWhiteSpace(raw)) return (null, null);
        var parts = raw.Split('/', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
        int? atual = null;
        int? total = null;
        if (parts.Length >= 1 && int.TryParse(OnlyDigits(parts[0]), out var a)) atual = a;
        if (parts.Length >= 2 && int.TryParse(OnlyDigits(parts[1]), out var t)) total = t;
        return (atual, total);
    }

    private static string? BuildQtParcelas(int? atual, int? total, string? fallback)
    {
        if (atual.HasValue && total.HasValue) return $"{atual}/{total}";
        return string.IsNullOrWhiteSpace(fallback) ? null : fallback.Trim();
    }

    private static decimal? ResolveValorComDesconto(decimal? valorCom, decimal? valorCheio, decimal? desconto)
    {
        if (valorCom.HasValue) return valorCom;
        if (!valorCheio.HasValue) return null;
        return Math.Max(0, valorCheio.Value - (desconto ?? 0m));
    }

    private static string? TrimOrNull(string? s)
    {
        if (string.IsNullOrWhiteSpace(s)) return null;
        return s.Trim();
    }

    private static string OnlyDigits(string? s)
    {
        if (string.IsNullOrWhiteSpace(s)) return "";
        return new string(s.Where(char.IsDigit).ToArray());
    }
}