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 LineItemService : ILineItemService
{
    private readonly ProposalDbContext _db;
    private readonly IAuditService _audit;

    public LineItemService(ProposalDbContext db, IAuditService audit)
    {
        _db = db;
        _audit = audit;
    }

    public async Task<IReadOnlyList<LineItemResponse>> GetByProposalIdAsync(Guid proposalId, CancellationToken ct = default)
    {
        return await _db.LineItems
            .Where(li => li.ProposalId == proposalId)
            .OrderBy(li => li.SortOrder)
            .Select(li => MapToResponse(li))
            .ToListAsync(ct);
    }

    public async Task<LineItemResponse> CreateAsync(Guid proposalId, CreateLineItemRequest request, CancellationToken ct = default)
    {
        var proposal = await _db.Proposals.FindAsync(new object[] { proposalId }, ct)
            ?? throw new KeyNotFoundException($"Proposal {proposalId} not found");

        if (proposal.Status == ProposalStatus.Approved || proposal.Status == ProposalStatus.Sent)
            throw new InvalidOperationException("Cannot modify line items on approved/sent proposals");

        var now = DateTime.UtcNow;
        var lineItem = new LineItem
        {
            Id = Guid.NewGuid(),
            ProposalId = proposalId,
            Description = request.Description,
            Quantity = request.Quantity,
            Unit = request.Unit,
            UnitPrice = request.UnitPrice,
            TotalPrice = request.TotalPrice,
            PricingMode = request.PricingMode,
            SortOrder = request.SortOrder,
            Source = request.Source,
            CreatedAt = now,
            UpdatedAt = now,
        };

        _db.LineItems.Add(lineItem);
        await _db.SaveChangesAsync(ct);

        await _audit.LogAsync(AuditAction.EditLineItem, proposalId, $"Added: {request.Description}", ct);

        return MapToResponse(lineItem);
    }

    public async Task<IReadOnlyList<LineItemResponse>> BulkUpdateAsync(Guid proposalId, BulkUpdateLineItemsRequest request, CancellationToken ct = default)
    {
        var proposal = await _db.Proposals.FindAsync(new object[] { proposalId }, ct)
            ?? throw new KeyNotFoundException($"Proposal {proposalId} not found");

        if (proposal.Status == ProposalStatus.Approved || proposal.Status == ProposalStatus.Sent)
            throw new InvalidOperationException("Cannot modify line items on approved/sent proposals");

        var existing = await _db.LineItems
            .Where(li => li.ProposalId == proposalId)
            .ToListAsync(ct);

        _db.LineItems.RemoveRange(existing);

        var now = DateTime.UtcNow;
        var newItems = request.LineItems.Select(entry => new LineItem
        {
            Id = entry.Id ?? Guid.NewGuid(),
            ProposalId = proposalId,
            Description = entry.Description,
            Quantity = entry.Quantity,
            Unit = entry.Unit,
            UnitPrice = entry.UnitPrice,
            TotalPrice = entry.TotalPrice,
            PricingMode = entry.PricingMode,
            SortOrder = entry.SortOrder,
            Source = entry.Source,
            CreatedAt = now,
            UpdatedAt = now,
        }).ToList();

        _db.LineItems.AddRange(newItems);

        proposal.TotalBidAmount = newItems.Sum(li => li.TotalPrice);
        proposal.UpdatedAt = now;

        await _db.SaveChangesAsync(ct);

        await _audit.LogAsync(AuditAction.EditLineItem, proposalId, $"Bulk update: {newItems.Count} items", ct);

        return newItems.OrderBy(li => li.SortOrder).Select(MapToResponse).ToList();
    }

    public async Task DeleteAsync(Guid proposalId, Guid lineItemId, CancellationToken ct = default)
    {
        var lineItem = await _db.LineItems
            .FirstOrDefaultAsync(li => li.Id == lineItemId && li.ProposalId == proposalId, ct)
            ?? throw new KeyNotFoundException($"Line item {lineItemId} not found");

        var proposal = await _db.Proposals.FindAsync(new object[] { proposalId }, ct)!;
        if (proposal!.Status == ProposalStatus.Approved || proposal.Status == ProposalStatus.Sent)
            throw new InvalidOperationException("Cannot modify line items on approved/sent proposals");

        _db.LineItems.Remove(lineItem);
        await _db.SaveChangesAsync(ct);

        await _audit.LogAsync(AuditAction.EditLineItem, proposalId, $"Removed: {lineItem.Description}", ct);
    }

    private static LineItemResponse MapToResponse(LineItem li) => new(
        li.Id,
        li.ProposalId,
        li.Description,
        li.Quantity,
        li.Unit,
        li.UnitPrice,
        li.TotalPrice,
        li.PricingMode,
        li.SortOrder,
        li.Source,
        li.CreatedAt,
        li.UpdatedAt
    );
}