using foodmarket.Application.Common.Tenancy;
using foodmarket.Domain.Sales;
using foodmarket.Infrastructure.Persistence;
using foodmarket.Api.Infrastructure.Authorization;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace foodmarket.Api.Controllers.Promotions;

/// <summary>CRUD-промокодов/акций. Org-scoped. PromotionsManage permission.
/// Уникальность кода в рамках org — обеспечивается БД-индексом, но и в
/// контроллере отдаём 409 с понятным текстом если дубль.</summary>
[ApiController]
[Authorize]
[Route("api/promotions")]
public class PromotionsController : ControllerBase
{
    private readonly AppDbContext _db;
    private readonly ITenantContext _tenant;

    public PromotionsController(AppDbContext db, ITenantContext tenant)
    {
        _db = db;
        _tenant = tenant;
    }

    public sealed record PromotionDto(Guid Id, string Name, string? Description, string? Code,
        PromotionType Type, decimal Value, PromotionScope Scope, decimal MinSaleAmount,
        DateTime StartsAt, DateTime? EndsAt, bool IsActive,
        IReadOnlyList<Guid> ProductGroupIds, IReadOnlyList<Guid> ProductIds);

    public sealed record PromotionInput(string Name, string? Description, string? Code,
        PromotionType Type, decimal Value, PromotionScope Scope, decimal MinSaleAmount,
        DateTime StartsAt, DateTime? EndsAt, bool IsActive,
        List<Guid> ProductGroupIds, List<Guid> ProductIds);

    [HttpGet]
    public async Task<ActionResult<foodmarket.Application.Common.PagedResult<PromotionDto>>> List(
        [FromQuery] int page = 1, [FromQuery] int pageSize = 50,
        [FromQuery] string? search = null,
        CancellationToken ct = default)
    {
        var take = Math.Clamp(pageSize, 1, 200);
        var skip = Math.Max(0, (page - 1) * take);
        var q = _db.Promotions.AsNoTracking();
        if (!string.IsNullOrWhiteSpace(search))
        {
            var s = search.Trim().ToLowerInvariant();
            q = q.Where(p => p.Name.ToLower().Contains(s)
                            || (p.Code != null && p.Code.ToLower().Contains(s)));
        }
        var total = await q.CountAsync(ct);
        var items = await q.OrderByDescending(p => p.CreatedAt)
            .Skip(skip).Take(take)
            .Select(p => new PromotionDto(p.Id, p.Name, p.Description, p.Code, p.Type, p.Value,
                p.Scope, p.MinSaleAmount, p.StartsAt, p.EndsAt, p.IsActive,
                p.ProductGroupIds, p.ProductIds))
            .ToListAsync(ct);
        return Ok(new foodmarket.Application.Common.PagedResult<PromotionDto>
        {
            Items = items, Total = total, Page = page, PageSize = take,
        });
    }

    [HttpGet("{id:guid}")]
    public async Task<ActionResult<PromotionDto>> Get(Guid id, CancellationToken ct)
    {
        var p = await _db.Promotions.AsNoTracking().FirstOrDefaultAsync(x => x.Id == id, ct);
        if (p is null) return NotFound();
        return Ok(new PromotionDto(p.Id, p.Name, p.Description, p.Code, p.Type, p.Value,
            p.Scope, p.MinSaleAmount, p.StartsAt, p.EndsAt, p.IsActive, p.ProductGroupIds, p.ProductIds));
    }

    [HttpPost, RequiresPermission("PromotionsManage")]
    public async Task<ActionResult<PromotionDto>> Create([FromBody] PromotionInput input, CancellationToken ct)
    {
        var orgId = _tenant.OrganizationId ?? throw new InvalidOperationException("No tenant.");
        if (string.IsNullOrWhiteSpace(input.Name)) return BadRequest(new { error = "Имя обязательно." });
        if (input.Value < 0) return BadRequest(new { error = "Скидка не может быть отрицательной." });
        if (input.Type == PromotionType.Percent && input.Value > 100)
            return BadRequest(new { error = "Процент в диапазоне [0..100]." });
        if (input.EndsAt is { } end && end <= input.StartsAt)
            return BadRequest(new { error = "Дата окончания должна быть позже даты начала." });

        var p = new Promotion
        {
            OrganizationId = orgId,
            Name = input.Name.Trim(),
            Description = string.IsNullOrWhiteSpace(input.Description) ? null : input.Description.Trim(),
            Code = string.IsNullOrWhiteSpace(input.Code) ? null : input.Code.Trim().ToUpperInvariant(),
            Type = input.Type,
            Value = input.Value,
            Scope = input.Scope,
            MinSaleAmount = input.MinSaleAmount,
            StartsAt = input.StartsAt,
            EndsAt = input.EndsAt,
            IsActive = input.IsActive,
            ProductGroupIds = input.ProductGroupIds ?? new List<Guid>(),
            ProductIds = input.ProductIds ?? new List<Guid>(),
        };
        _db.Promotions.Add(p);
        try
        {
            await _db.SaveChangesAsync(ct);
        }
        catch (DbUpdateException ex) when (ex.InnerException is Npgsql.PostgresException { SqlState: "23505" } pg
            && pg.ConstraintName?.Contains("Code") == true)
        {
            return Conflict(new { error = $"Промокод «{p.Code}» уже существует.", field = "Code" });
        }
        return CreatedAtAction(nameof(Get), new { id = p.Id }, ToDto(p));
    }

    [HttpPut("{id:guid}"), RequiresPermission("PromotionsManage")]
    public async Task<IActionResult> Update(Guid id, [FromBody] PromotionInput input, CancellationToken ct)
    {
        var p = await _db.Promotions.FirstOrDefaultAsync(x => x.Id == id, ct);
        if (p is null) return NotFound();
        if (input.EndsAt is { } end && end <= input.StartsAt)
            return BadRequest(new { error = "Дата окончания должна быть позже даты начала." });
        p.Name = input.Name.Trim();
        p.Description = string.IsNullOrWhiteSpace(input.Description) ? null : input.Description.Trim();
        p.Code = string.IsNullOrWhiteSpace(input.Code) ? null : input.Code.Trim().ToUpperInvariant();
        p.Type = input.Type;
        p.Value = input.Value;
        p.Scope = input.Scope;
        p.MinSaleAmount = input.MinSaleAmount;
        p.StartsAt = input.StartsAt;
        p.EndsAt = input.EndsAt;
        p.IsActive = input.IsActive;
        p.ProductGroupIds = input.ProductGroupIds ?? new List<Guid>();
        p.ProductIds = input.ProductIds ?? new List<Guid>();
        p.UpdatedAt = DateTime.UtcNow;
        try
        {
            await _db.SaveChangesAsync(ct);
        }
        catch (DbUpdateException ex) when (ex.InnerException is Npgsql.PostgresException { SqlState: "23505" } pg
            && pg.ConstraintName?.Contains("Code") == true)
        {
            return Conflict(new { error = $"Промокод «{p.Code}» уже существует.", field = "Code" });
        }
        return NoContent();
    }

    [HttpDelete("{id:guid}"), RequiresPermission("PromotionsManage")]
    public async Task<IActionResult> Delete(Guid id, CancellationToken ct)
    {
        var p = await _db.Promotions.FirstOrDefaultAsync(x => x.Id == id, ct);
        if (p is null) return NotFound();
        // Не валим если на акцию ссылаются чеки — promotionId в RetailSale хранится
        // как snapshot, его можно оставить orphaned (на уровне БД ON DELETE SET NULL не делаем).
        _db.Promotions.Remove(p);
        await _db.SaveChangesAsync(ct);
        return NoContent();
    }

    private static PromotionDto ToDto(Promotion p) => new(p.Id, p.Name, p.Description, p.Code, p.Type, p.Value,
        p.Scope, p.MinSaleAmount, p.StartsAt, p.EndsAt, p.IsActive, p.ProductGroupIds, p.ProductIds);
}