using FsCheck;
using FsCheck.Xunit;
using MiAssessment.Admin.Business.Data;
using MiAssessment.Admin.Business.Models.Distribution;
using MiAssessment.Admin.Business.Services;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Moq;
using Xunit;

namespace MiAssessment.Tests.Services;

/// <summary>
/// DistributionService 属性测试
/// </summary>
public class DistributionServicePropertyTests
{
    private readonly Mock<ILogger<DistributionService>> _mockLogger = new();

    #region Property 13: Invite Code Generation Uniqueness

    /// <summary>
    /// **Feature: admin-business-modules, Property 13: Invite Code Generation Uniqueness**
    /// For any batch of generated invite codes, all codes SHALL be unique 5-character uppercase letter strings.
    /// **Validates: Requirements 14.3, 14.4**
    /// </summary>
    [Property(MaxTest = 100)]
    public bool GenerateInviteCodes_AllCodesShouldBeUnique(PositiveInt seed)
    {
        var count = (seed.Get % 50) + 1; // 1 to 50 codes

        using var dbContext = CreateDbContext();
        var service = new DistributionService(dbContext, _mockLogger.Object);

        var result = service.GenerateInviteCodesAsync(count).GetAwaiter().GetResult();

        // All codes should be unique
        var uniqueCodes = result.Codes.Distinct().Count();
        return uniqueCodes == result.Codes.Count && result.Codes.Count == count;
    }

    /// <summary>
    /// **Feature: admin-business-modules, Property 13: Invite Code Generation Uniqueness**
    /// For any batch of generated invite codes, all codes SHALL be 5-character uppercase letter strings.
    /// **Validates: Requirements 14.3, 14.4**
    /// </summary>
    [Property(MaxTest = 100)]
    public bool GenerateInviteCodes_AllCodesShouldBe5CharUppercaseLetters(PositiveInt seed)
    {
        var count = (seed.Get % 30) + 1; // 1 to 30 codes

        using var dbContext = CreateDbContext();
        var service = new DistributionService(dbContext, _mockLogger.Object);

        var result = service.GenerateInviteCodesAsync(count).GetAwaiter().GetResult();

        // All codes should be 5 characters and uppercase letters only
        return result.Codes.All(code =>
            code.Length == 5 &&
            code.All(c => c >= 'A' && c <= 'Z'));
    }

    /// <summary>
    /// **Feature: admin-business-modules, Property 13: Invite Code Generation Uniqueness**
    /// For any batch of generated invite codes, all codes in the same batch SHALL share the same BatchNo.
    /// **Validates: Requirements 14.3, 14.4**
    /// </summary>
    [Property(MaxTest = 100)]
    public bool GenerateInviteCodes_AllCodesShouldShareSameBatchNo(PositiveInt seed)
    {
        var count = (seed.Get % 20) + 1; // 1 to 20 codes

        using var dbContext = CreateDbContext();
        var service = new DistributionService(dbContext, _mockLogger.Object);

        var result = service.GenerateInviteCodesAsync(count).GetAwaiter().GetResult();

        // Verify BatchNo is not empty
        if (string.IsNullOrEmpty(result.BatchNo))
            return false;

        // Verify all codes in database have the same BatchNo
        var codesInDb = dbContext.InviteCodes
            .Where(c => result.Codes.Contains(c.Code))
            .ToList();

        return codesInDb.Count == count &&
               codesInDb.All(c => c.BatchNo == result.BatchNo);
    }

    /// <summary>
    /// **Feature: admin-business-modules, Property 13: Invite Code Generation Uniqueness**
    /// Multiple batches of generated invite codes should not have duplicate codes across batches.
    /// **Validates: Requirements 14.3, 14.4**
    /// </summary>
    [Property(MaxTest = 50)]
    public bool GenerateInviteCodes_MultipleBatchesShouldNotHaveDuplicates(PositiveInt seed)
    {
        var batch1Count = (seed.Get % 10) + 5; // 5 to 14 codes
        var batch2Count = (seed.Get % 10) + 5; // 5 to 14 codes

        using var dbContext = CreateDbContext();
        var service = new DistributionService(dbContext, _mockLogger.Object);

        // Generate first batch
        var result1 = service.GenerateInviteCodesAsync(batch1Count).GetAwaiter().GetResult();

        // Generate second batch
        var result2 = service.GenerateInviteCodesAsync(batch2Count).GetAwaiter().GetResult();

        // Verify no duplicates between batches
        var allCodes = result1.Codes.Concat(result2.Codes).ToList();
        var uniqueCodes = allCodes.Distinct().Count();

        return uniqueCodes == allCodes.Count &&
               result1.BatchNo != result2.BatchNo;
    }

    /// <summary>
    /// **Feature: admin-business-modules, Property 13: Invite Code Generation Uniqueness**
    /// Generated invite codes should be persisted to the database with correct initial status.
    /// **Validates: Requirements 14.3, 14.4**
    /// </summary>
    [Property(MaxTest = 50)]
    public bool GenerateInviteCodes_ShouldPersistWithCorrectStatus(PositiveInt seed)
    {
        var count = (seed.Get % 15) + 1; // 1 to 15 codes

        using var dbContext = CreateDbContext();
        var service = new DistributionService(dbContext, _mockLogger.Object);

        var result = service.GenerateInviteCodesAsync(count).GetAwaiter().GetResult();

        // Verify all codes are persisted with status = 1 (未分配)
        var codesInDb = dbContext.InviteCodes
            .Where(c => result.Codes.Contains(c.Code))
            .ToList();

        return codesInDb.Count == count &&
               codesInDb.All(c => c.Status == 1 && !c.IsDeleted);
    }

    #endregion

    #region Additional Uniqueness Tests

    /// <summary>
    /// **Feature: admin-business-modules, Property 13: Invite Code Generation Uniqueness**
    /// When generating codes with existing codes in database, new codes should not duplicate existing ones.
    /// **Validates: Requirements 14.3, 14.4**
    /// </summary>
    [Property(MaxTest = 50)]
    public bool GenerateInviteCodes_ShouldNotDuplicateExistingCodesInDb(PositiveInt seed)
    {
        var existingCount = (seed.Get % 5) + 1; // 1 to 5 existing codes
        var newCount = (seed.Get % 10) + 1; // 1 to 10 new codes

        using var dbContext = CreateDbContext();
        var service = new DistributionService(dbContext, _mockLogger.Object);

        // First, generate some existing codes
        var existingResult = service.GenerateInviteCodesAsync(existingCount).GetAwaiter().GetResult();

        // Then generate new codes
        var newResult = service.GenerateInviteCodesAsync(newCount).GetAwaiter().GetResult();

        // Verify no overlap between batches
        var overlap = existingResult.Codes.Intersect(newResult.Codes).Count();

        return overlap == 0 &&
               existingResult.Codes.Count == existingCount &&
               newResult.Codes.Count == newCount;
    }

    #endregion

    #region Helper Methods

    private AdminBusinessDbContext CreateDbContext()
    {
        var options = new DbContextOptionsBuilder<AdminBusinessDbContext>()
            .UseInMemoryDatabase(databaseName: Guid.NewGuid().ToString())
            .Options;

        return new AdminBusinessDbContext(options);
    }

    private static string GenerateRandomCode(Random random)
    {
        const string charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        var chars = new char[5];
        for (int i = 0; i < 5; i++)
        {
            chars[i] = charset[random.Next(charset.Length)];
        }
        return new string(chars);
    }

    #endregion
}