using Microsoft.EntityFrameworkCore;
using System.Security.Claims;
using System.Text;
using Microsoft.AspNetCore.Http;
using Moq;
using ROLAC.API.Data;
using ROLAC.API.Data.Interceptors;
using ROLAC.API.DTOs.Expense;
using ROLAC.API.Entities;
using ROLAC.API.Services;
using ROLAC.API.Services.Storage;
using Xunit;

namespace ROLAC.API.Tests.Services;

public class ExpenseServiceTests
{
    private sealed class FakeStorage : IFileStorage
    {
        public Dictionary<string, byte[]> Files = new();
        public Task<string> SaveAsync(Stream c, string p, CancellationToken ct = default)
        { using var ms = new MemoryStream(); c.CopyTo(ms); Files[p] = ms.ToArray(); return Task.FromResult(p); }
        public Task<Stream?> OpenReadAsync(string p, CancellationToken ct = default)
        => Task.FromResult<Stream?>(Files.TryGetValue(p, out var b) ? new MemoryStream(b) : null);
        public Task DeleteAsync(string p, CancellationToken ct = default) { Files.Remove(p); return Task.CompletedTask; }
    }

    private static AppDbContext BuildDb(string userId)
    {
        var claims = new[] { new Claim(ClaimTypes.NameIdentifier, userId) };
        var ctx    = new DefaultHttpContext { User = new(new ClaimsIdentity(claims)) };
        var mock   = new Mock<IHttpContextAccessor>();
        mock.Setup(x => x.HttpContext).Returns(ctx);
        return new AppDbContext(new DbContextOptionsBuilder<AppDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .AddInterceptors(new AuditSaveChangesInterceptor(mock.Object)).Options);
    }

    private static (ExpenseService svc, AppDbContext db, FakeStorage fs) Build(string userId = "u1")
    {
        var db = BuildDb(userId);
        db.Ministries.Add(new Ministry { Id = 1, Name_en = "Worship" });
        db.ExpenseCategoryGroups.Add(new ExpenseCategoryGroup { Id = 1, Name_en = "Equipment" });
        db.ExpenseSubCategories.Add(new ExpenseSubCategory { Id = 1, GroupId = 1, Name_en = "Purchase" });
        db.SaveChanges();
        var fs = new FakeStorage();
        return (SvcAs(db, fs, userId), db, fs);
    }

    private static ExpenseService SvcAs(AppDbContext db, FakeStorage fs, string userId)
    {
        var http = new Mock<IHttpContextAccessor>();
        var ctx  = new DefaultHttpContext { User = new(new ClaimsIdentity(new[] { new Claim(ClaimTypes.NameIdentifier, userId) })) };
        http.Setup(x => x.HttpContext).Returns(ctx);
        return new ExpenseService(db, http.Object, fs);
    }

    // Builds a service whose principal carries ONLY the "sub" claim (no NameIdentifier),
    // mirroring the real JWT (NameClaimType="sub", MapInboundClaims=false).
    private static ExpenseService SvcWithSubClaim(AppDbContext db, FakeStorage fs, string userId)
    {
        var http = new Mock<IHttpContextAccessor>();
        var ctx  = new DefaultHttpContext { User = new(new ClaimsIdentity(new[] { new Claim("sub", userId) })) };
        http.Setup(x => x.HttpContext).Returns(ctx);
        return new ExpenseService(db, http.Object, fs);
    }

    private static CreateExpenseRequest Reimb() => new()
    {
        Type = "StaffReimbursement", MinistryId = 1, CategoryGroupId = 1, SubCategoryId = 1,
        Amount = 45.50m, Description = "Batteries", ExpenseDate = new DateOnly(2026, 5, 28),
    };

    private static UpdateExpenseRequest CloneToUpdate(CreateExpenseRequest r) => new()
    {
        Type = r.Type, MinistryId = r.MinistryId, CategoryGroupId = r.CategoryGroupId,
        SubCategoryId = r.SubCategoryId, Amount = r.Amount, Description = r.Description,
        VendorName = r.VendorName, MemberId = r.MemberId, CheckNumber = r.CheckNumber,
        ExpenseDate = r.ExpenseDate, Notes = r.Notes,
    };

    [Fact]
    public async Task Create_Reimbursement_ResolvesUserId_FromSubClaim()
    {
        // Regression: the real JWT exposes the user id as "sub", not ClaimTypes.NameIdentifier.
        // SubmittedBy must be the sub value (not "system"), or the self-ownership guard breaks.
        var db = BuildDb("ignored");
        db.Ministries.Add(new Ministry { Id = 1, Name_en = "Worship" });
        db.ExpenseCategoryGroups.Add(new ExpenseCategoryGroup { Id = 1, Name_en = "Equipment" });
        db.ExpenseSubCategories.Add(new ExpenseSubCategory { Id = 1, GroupId = 1, Name_en = "Purchase" });
        await db.SaveChangesAsync();
        var svc = SvcWithSubClaim(db, new FakeStorage(), "user-guid-123");

        var id = await svc.CreateAsync(Reimb(), isFinance: false);

        var e = await db.Expenses.FindAsync(id);
        Assert.Equal("user-guid-123", e!.SubmittedBy);
    }

    [Fact]
    public async Task Create_Vendor_AsFinance_IsImmediatelyPaid()
    {
        var (svc, db, _) = Build();
        var r = Reimb(); r.Type = "VendorPayment"; r.VendorName = "ABC"; r.CheckNumber = "2051";
        var id = await svc.CreateAsync(r, isFinance: true);
        Assert.Equal("Paid", (await db.Expenses.FindAsync(id))!.Status);
    }

    [Fact]
    public async Task Create_Reimbursement_IsDraft_WithSubmitter()
    {
        var (svc, db, _) = Build("alice");
        var id = await svc.CreateAsync(Reimb(), isFinance: false);
        var e = await db.Expenses.FindAsync(id);
        Assert.Equal("Draft", e!.Status);
        Assert.Equal("alice", e.SubmittedBy);
    }

    [Fact]
    public async Task StateMachine_HappyPath_Submit_Approve_Pay()
    {
        var (svc, db, _) = Build("alice");
        var id = await svc.CreateAsync(Reimb(), isFinance: false);
        await svc.SubmitAsync(id);
        Assert.Equal("PendingApproval", (await db.Expenses.FindAsync(id))!.Status);
        await svc.ApproveAsync(id);
        Assert.Equal("Approved", (await db.Expenses.FindAsync(id))!.Status);
        await svc.PayAsync(id, "3001", new DateOnly(2026, 6, 1));
        var paid = await db.Expenses.FindAsync(id);
        Assert.Equal("Paid", paid!.Status);
        Assert.Equal("3001", paid.CheckNumber);
    }

    [Fact]
    public async Task Approve_FromDraft_Throws()
    {
        var (svc, _, _) = Build("alice");
        var id = await svc.CreateAsync(Reimb(), isFinance: false);
        await Assert.ThrowsAsync<InvalidOperationException>(() => svc.ApproveAsync(id));
    }

    [Fact]
    public async Task Reject_RecordsNotes_AndStatus()
    {
        var (svc, db, _) = Build("alice");
        var id = await svc.CreateAsync(Reimb(), isFinance: false);
        await svc.SubmitAsync(id);
        await svc.RejectAsync(id, "Missing receipt");
        var e = await db.Expenses.FindAsync(id);
        Assert.Equal("Rejected", e!.Status);
        Assert.Equal("Missing receipt", e.ReviewNotes);
    }

    [Fact]
    public async Task Update_OthersDraft_AsNonFinance_Throws()
    {
        var (aliceSvc, db, fs) = Build("alice");
        var id = await aliceSvc.CreateAsync(Reimb(), isFinance: false);
        var bobSvc = SvcAs(db, fs, "bob");
        await Assert.ThrowsAsync<InvalidOperationException>(() =>
            bobSvc.UpdateAsync(id, CloneToUpdate(Reimb()), isFinance: false));
    }

    [Fact]
    public async Task SoftDelete_HidesFromQueries()
    {
        var (svc, db, _) = Build("alice");
        var id = await svc.CreateAsync(Reimb(), isFinance: false);
        await svc.DeleteAsync(id, isFinance: true);
        Assert.Null(await db.Expenses.FirstOrDefaultAsync(e => e.Id == id));
    }

    [Fact]
    public async Task Receipt_SaveThenOpen_RoundTrips()
    {
        var (svc, _, _) = Build("alice");
        var id = await svc.CreateAsync(Reimb(), isFinance: false);
        using var input = new MemoryStream(Encoding.UTF8.GetBytes("img"));
        await svc.SaveReceiptAsync(id, input, "r.jpg", isFinance: false);
        var got = await svc.OpenReceiptAsync(id, isFinance: true);
        Assert.NotNull(got);
    }
}