using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using ProposalSystem.Domain.Entities;
using ProposalSystem.Infrastructure.Services;
using ProposalSystem.Tests.Helpers;
using Xunit;

namespace ProposalSystem.Tests.Services;

/// <summary>
/// Tests for ProposalNumberGenerator.
/// Verifies format (SHI-YYYY-NNNN), uniqueness, and sequence logic.
/// Uses SQLite in-memory provider because the generator calls ExecuteSqlRawAsync
/// for pg_advisory_xact_lock, which requires a relational provider (InMemory throws).
/// SQLite silently accepts the Postgres-specific SQL, allowing the sequence logic to
/// be exercised end-to-end.
///
/// Related findings: QA-C1 (test coverage gaps).
/// </summary>
public class ProposalNumberGeneratorTests : IDisposable
{
    private readonly Infrastructure.Data.ProposalDbContext _db;
    private readonly ProposalNumberGenerator _sut;
    private readonly Guid _userId;

    public ProposalNumberGeneratorTests()
    {
        _db = SqliteDbContextFactory.Create();

        // Create a user required by FK constraints on Proposal.SubmittedById
        _userId = Guid.NewGuid();
        _db.Users.Add(new User
        {
            Id = _userId,
            CognitoSub = $"sub-{_userId}",
            Email = "test@seahavenind.com",
            DisplayName = "Test User",
            Role = UserRole.Dispatcher,
            CreatedAt = DateTime.UtcNow,
            UpdatedAt = DateTime.UtcNow,
        });
        _db.SaveChanges();

        _sut = new ProposalNumberGenerator(_db);
    }

    public void Dispose()
    {
        _db.Dispose();
    }

    [Fact(DisplayName = "QA-C1: GenerateAsync returns SHI-YYYY-0001 format when no prior proposals")]
    public async Task GenerateAsync_NoPriorProposals_ReturnsFirstSequenceNumber()
    {
        // Act
        var result = await _sut.GenerateAsync();

        // Assert
        var year = DateTime.UtcNow.Year;
        result.Should().Be($"SHI-{year}-0001");
    }

    [Fact(DisplayName = "QA-C1: GenerateAsync format matches SHI-YYYY-NNNN pattern")]
    public async Task GenerateAsync_MatchesExpectedFormat()
    {
        // Act
        var result = await _sut.GenerateAsync();

        // Assert
        result.Should().MatchRegex(@"^SHI-\d{4}-\d{4}$");
    }

    [Fact(DisplayName = "QA-C1: GenerateAsync increments sequence from last proposal")]
    public async Task GenerateAsync_WithExistingProposals_IncrementsSequence()
    {
        // Arrange — seed a proposal with number ending in 0042
        var year = DateTime.UtcNow.Year;
        _db.Proposals.Add(CreateProposal($"SHI-{year}-0042"));
        await _db.SaveChangesAsync();

        // Act
        var result = await _sut.GenerateAsync();

        // Assert
        result.Should().Be($"SHI-{year}-0043");
    }

    [Fact(DisplayName = "QA-C1: GenerateAsync skips revision proposals (containing -R)")]
    public async Task GenerateAsync_IgnoresRevisionProposals()
    {
        // Arrange — seed a regular and a revision proposal
        var year = DateTime.UtcNow.Year;
        _db.Proposals.Add(CreateProposal($"SHI-{year}-0010"));
        _db.Proposals.Add(CreateProposal($"SHI-{year}-0010-R2")); // revision should be ignored
        await _db.SaveChangesAsync();

        // Act
        var result = await _sut.GenerateAsync();

        // Assert — next after 0010, not after the revision
        result.Should().Be($"SHI-{year}-0011");
    }

    [Fact(DisplayName = "QA-C1: GenerateAsync ignores proposals from different years")]
    public async Task GenerateAsync_IgnoresDifferentYearProposals()
    {
        // Arrange — seed proposals from a previous year
        var lastYear = DateTime.UtcNow.Year - 1;
        _db.Proposals.Add(CreateProposal($"SHI-{lastYear}-0099"));
        await _db.SaveChangesAsync();

        // Act
        var result = await _sut.GenerateAsync();

        // Assert — starts at 0001 for the current year
        var year = DateTime.UtcNow.Year;
        result.Should().Be($"SHI-{year}-0001");
    }

    [Fact(DisplayName = "QA-C1: GenerateAsync produces unique numbers across multiple calls")]
    public async Task GenerateAsync_MultipleCalls_ProducesUniqueNumbers()
    {
        // Act — generate several numbers, persisting each to DB between calls
        var numbers = new List<string>();
        for (int i = 0; i < 5; i++)
        {
            var number = await _sut.GenerateAsync();
            numbers.Add(number);
            // Persist so the next call sees it
            _db.Proposals.Add(CreateProposal(number));
            await _db.SaveChangesAsync();
        }

        // Assert
        numbers.Should().OnlyHaveUniqueItems();
        var year = DateTime.UtcNow.Year;
        numbers.Should().BeEquivalentTo(new[]
        {
            $"SHI-{year}-0001",
            $"SHI-{year}-0002",
            $"SHI-{year}-0003",
            $"SHI-{year}-0004",
            $"SHI-{year}-0005",
        });
    }

    [Fact(DisplayName = "QA-C1: GenerateAsync zero-pads sequence to 4 digits")]
    public async Task GenerateAsync_ZeroPadsToFourDigits()
    {
        // Arrange
        var year = DateTime.UtcNow.Year;
        _db.Proposals.Add(CreateProposal($"SHI-{year}-0003"));
        await _db.SaveChangesAsync();

        // Act
        var result = await _sut.GenerateAsync();

        // Assert
        result.Should().EndWith("-0004");
        // Verify the sequence part is exactly 4 characters
        var sequencePart = result.Split('-').Last();
        sequencePart.Should().HaveLength(4);
    }

    [Fact(DisplayName = "QA-C1: GenerateAsync handles sequence above 9999 (5+ digits)")]
    public async Task GenerateAsync_HighSequenceNumber_StillFormatsCorrectly()
    {
        // Arrange — seed a proposal at 9999
        var year = DateTime.UtcNow.Year;
        _db.Proposals.Add(CreateProposal($"SHI-{year}-9999"));
        await _db.SaveChangesAsync();

        // Act
        var result = await _sut.GenerateAsync();

        // Assert — D4 format will produce 5 digits at 10000
        result.Should().Be($"SHI-{year}-10000");
    }

    [Fact(DisplayName = "QA-C1: GenerateAsync picks highest existing sequence, not last inserted")]
    public async Task GenerateAsync_OutOfOrderInsertion_PicksHighest()
    {
        // Arrange — insert out of order
        var year = DateTime.UtcNow.Year;
        _db.Proposals.Add(CreateProposal($"SHI-{year}-0050"));
        _db.Proposals.Add(CreateProposal($"SHI-{year}-0020"));
        _db.Proposals.Add(CreateProposal($"SHI-{year}-0075"));
        await _db.SaveChangesAsync();

        // Act
        var result = await _sut.GenerateAsync();

        // Assert — should pick 75 + 1 = 76 since OrderByDescending picks the highest
        result.Should().Be($"SHI-{year}-0076");
    }

    private Proposal CreateProposal(string proposalNumber)
    {
        return new Proposal
        {
            Id = Guid.NewGuid(),
            ProposalNumber = proposalNumber,
            WorkOrderNumber = "WO-TEST",
            CustomerName = "Test Customer",
            CustomerAddress = "123 Test St",
            ScopeOfWork = "Test scope",
            ServiceCategory = ServiceCategory.General,
            Priority = Priority.Standard,
            Status = ProposalStatus.InReview,
            Notes = "",
            SubmittedById = _userId,
            SubmittedAt = DateTime.UtcNow,
            CurrentRevision = 1,
            CreatedAt = DateTime.UtcNow,
            UpdatedAt = DateTime.UtcNow,
        };
    }
}