using Microsoft.EntityFrameworkCore;
using ProposalSystem.Application.DTOs;
using ProposalSystem.Application.Interfaces;
using ProposalSystem.Domain.Entities;
using ProposalSystem.Infrastructure.Data;

namespace ProposalSystem.Infrastructure.Services;

public class SimilarProposalService : ISimilarProposalService
{
    private readonly ProposalDbContext _db;
    private readonly ICurrentUserService _currentUser;

    public SimilarProposalService(ProposalDbContext db, ICurrentUserService currentUser)
    {
        _db = db;
        _currentUser = currentUser;
    }

    public async Task<IReadOnlyList<SimilarProposalResponse>> GetSimilarProposalsAsync(
        Guid proposalId,
        CancellationToken ct = default)
    {
        var references = await _db.SimilarProposalReferences
            .Where(r => r.ProposalId == proposalId)
            .OrderByDescending(r => r.SimilarityScore)
            .Take(5)
            .ToListAsync(ct);

        if (references.Count == 0)
            return [];

        var libraryItemIds = references.Select(r => r.ReferencedLibraryItemId).ToList();

        var proposals = await _db.Proposals
            .Include(p => p.LineItems)
            .Where(p => libraryItemIds.Contains(p.ProposalNumber))
            .ToListAsync(ct);

        var proposalsByNumber = proposals.ToDictionary(p => p.ProposalNumber);

        var results = new List<SimilarProposalResponse>();
        foreach (var reference in references)
        {
            if (!proposalsByNumber.TryGetValue(reference.ReferencedLibraryItemId, out var referencedProposal))
                continue;

            results.Add(new SimilarProposalResponse(
                referencedProposal.ProposalNumber,
                referencedProposal.CustomerName,
                referencedProposal.ServiceCategory.ToString(),
                reference.SimilarityScore,
                referencedProposal.TotalBidAmount,
                referencedProposal.LineItems
                    .OrderBy(li => li.SortOrder)
                    .Select(li => new SimilarLineItemResponse(
                        li.Description,
                        li.Quantity,
                        li.Unit,
                        li.UnitPrice,
                        li.TotalPrice
                    ))
                    .ToList()
            ));
        }

        return results;
    }

    public async Task AddReferenceAsync(
        Guid proposalId,
        CreateSimilarReferenceRequest request,
        CancellationToken ct = default)
    {
        var reference = new SimilarProposalReference
        {
            Id = Guid.NewGuid(),
            ProposalId = proposalId,
            ReferencedLibraryItemId = request.ReferencedLibraryItemId,
            SimilarityScore = request.SimilarityScore,
            ReferencedAt = DateTime.UtcNow,
            ReferencedById = _currentUser.UserId,
        };

        _db.SimilarProposalReferences.Add(reference);
        await _db.SaveChangesAsync(ct);
    }
}