using Microsoft.AspNetCore.Identity;
using Microsoft.Data.Sqlite;
using Microsoft.EntityFrameworkCore;
using Hua.Todo.Application.Repositories;
using Hua.Todo.Application.Services.DataSeeder;
using Hua.Todo.Core.Entities;
using Xunit;

namespace Hua.Todo.Host.Tests.DataSeederTests;

/// <summary>
/// <see cref="DataSeeder"/> 验收测试。
/// 对应研发工单 v1.2.0 工单 10 的验收标准（Given-When-Then），
/// 详见 docs/project/研发工单-v1.2.0/10-数据库初始化默认管理员.md 第五章。
/// </summary>
public sealed class DataSeederTests : IDisposable
{
    private readonly SqliteConnection _connection;
    private readonly DbContextOptions<TodoDbContext> _options;
    private readonly IPasswordHasher<UserEntity> _passwordHasher;

    public DataSeederTests()
    {
        _connection = new SqliteConnection("Data Source=:memory:");
        _connection.Open();

        _options = new DbContextOptionsBuilder<TodoDbContext>()
            .UseSqlite(_connection)
            .Options;

        _passwordHasher = new PasswordHasher<UserEntity>();
    }

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

    /// <summary>
    /// 创建并迁移数据库上下文（每个测试独立实例，避免数据互相污染）。
    /// </summary>
    private TodoDbContext CreateContext()
    {
        var context = new TodoDbContext(_options);
        context.Database.Migrate();
        return context;
    }

    /// <summary>
    /// 创建使用默认配置的 DataSeeder。
    /// </summary>
    private static DataSeeder CreateSeeder(TodoDbContext db, IPasswordHasher<UserEntity> hasher, AdminBootstrapOptions? options = null)
        => new(db, hasher, options ?? new AdminBootstrapOptions());

    // ========== 5.1 主流程 ==========

    /// <summary>
    /// Given 全新空数据库（Migrate 完成，Users 表无任何云用户）
    /// When  调用 IDataSeeder.SeedAsync()
    /// Then  Users 表新增一条记录，Role="admin"，UserName 取配置值，MustChangePassword=true
    /// And   SecurityPolicies 表新增对应记录（AllowPersist=true, AllowSync=true）
    /// And   AuditLogs 表新增一条 EventType="SeedBootstrap" 记录
    /// </summary>
    [Fact]
    public async Task SeedAsync_EmptyDatabase_CreatesDefaultAdminWithPolicyAndAuditLog()
    {
        using var db = CreateContext();
        var options = new AdminBootstrapOptions { UserName = "admin", Password = "Admin@123", Enabled = true };
        var seeder = CreateSeeder(db, _passwordHasher, options);

        await seeder.SeedAsync();

        var admin = await db.Users.SingleOrDefaultAsync(u => u.Role == "admin");
        Assert.NotNull(admin);
        Assert.Equal("admin", admin!.UserName);
        Assert.True(admin.MustChangePassword);

        var policy = await db.SecurityPolicies.SingleOrDefaultAsync(p => p.UserId == admin.Id);
        Assert.NotNull(policy);
        Assert.True(policy!.AllowPersist);
        Assert.True(policy.AllowSync);

        var audit = await db.AuditLogs.SingleOrDefaultAsync(a => a.EventType == "SeedBootstrap");
        Assert.NotNull(audit);
        Assert.True(audit!.IsSuccess);
    }

    // ========== 5.2 幂等性 ==========

    /// <summary>
    /// Given 数据库已存在 Role="admin" 的云用户
    /// When  调用 SeedAsync()
    /// Then  Users 表不新增记录
    /// And   AuditLogs 表不新增 SeedBootstrap 记录
    /// </summary>
    [Fact]
    public async Task SeedAsync_ExistingCloudUser_DoesNotCreateDuplicate()
    {
        using var db = CreateContext();
        var existingAdmin = await SeedExistingAdminAsync(db, "admin");

        var seeder = CreateSeeder(db, _passwordHasher);
        await seeder.SeedAsync();

        var admins = await db.Users.Where(u => u.Role == "admin").ToListAsync();
        Assert.Single(admins);
        Assert.Equal(existingAdmin.Id, admins[0].Id);

        var seedAudits = await db.AuditLogs.Where(a => a.EventType == "SeedBootstrap").ToListAsync();
        Assert.Empty(seedAudits);
    }

    // ========== 5.3 配置自定义账号 ==========

    /// <summary>
    /// Given AdminBootstrapOptions.UserName="root" 且 Password="MyStrong#123"
    /// When  调用 SeedAsync()
    /// Then  创建的管理员 UserName="root"
    /// And   使用该密码可通过 IPasswordHasher.VerifyHashedPassword 校验
    /// </summary>
    [Fact]
    public async Task SeedAsync_CustomOptions_UsesConfiguredCredentials()
    {
        using var db = CreateContext();
        var options = new AdminBootstrapOptions
        {
            Enabled = true,
            UserName = "root",
            Password = "MyStrong#123"
        };
        var seeder = CreateSeeder(db, _passwordHasher, options);

        await seeder.SeedAsync();

        var admin = await db.Users.SingleOrDefaultAsync(u => u.UserName == "root");
        Assert.NotNull(admin);
        Assert.Equal("admin", admin!.Role);

        var verify = _passwordHasher.VerifyHashedPassword(admin, admin.PasswordHash, "MyStrong#123");
        Assert.Equal(PasswordVerificationResult.Success, verify);
    }

    // ========== 5.4 配置禁用 ==========

    /// <summary>
    /// Given AdminBootstrapOptions.Enabled=false
    /// When  调用 SeedAsync()
    /// Then  不执行任何种子逻辑，直接返回
    /// </summary>
    [Fact]
    public async Task SeedAsync_DisabledOption_DoesNothing()
    {
        using var db = CreateContext();
        var options = new AdminBootstrapOptions { Enabled = false };
        var seeder = CreateSeeder(db, _passwordHasher, options);

        await seeder.SeedAsync();

        var userCount = await db.Users.CountAsync();
        Assert.Equal(0, userCount);

        var auditCount = await db.AuditLogs.CountAsync();
        Assert.Equal(0, auditCount);
    }

    // ========== 5.5 密码哈希安全 ==========

    /// <summary>
    /// Given 执行 SeedAsync() 成功
    /// When  查询 Users 表
    /// Then  PasswordHash 不等于明文密码
    /// And   PasswordHash 可通过 IPasswordHasher.VerifyHashedPassword(明文) 校验为 Success
    /// </summary>
    [Fact]
    public async Task SeedAsync_PasswordHashed_NotStoredInPlaintext()
    {
        using var db = CreateContext();
        const string plainPassword = "Admin@123";
        var options = new AdminBootstrapOptions { Enabled = true, UserName = "admin", Password = plainPassword };
        var seeder = CreateSeeder(db, _passwordHasher, options);

        await seeder.SeedAsync();

        var admin = await db.Users.SingleAsync(u => u.Role == "admin");

        Assert.NotEqual(plainPassword, admin.PasswordHash);
        Assert.NotEmpty(admin.PasswordHash);

        var verify = _passwordHasher.VerifyHashedPassword(admin, admin.PasswordHash, plainPassword);
        Assert.Equal(PasswordVerificationResult.Success, verify);
    }

    // ========== 5.6 既有 local 用户不影响初始化 ==========

    /// <summary>
    /// Given Users 表仅存在 Role="local" 的本地用户（嵌入式遗留数据）
    /// When  调用 SeedAsync()
    /// Then  仍然创建默认管理员（因为幂等条件是 Role != "local" 的云用户）
    /// </summary>
    [Fact]
    public async Task SeedAsync_OnlyLocalUserExists_StillCreatesAdmin()
    {
        using var db = CreateContext();
        await SeedLocalUserAsync(db, "local");

        var seeder = CreateSeeder(db, _passwordHasher);
        await seeder.SeedAsync();

        var localUser = await db.Users.SingleAsync(u => u.Role == "local");
        var admin = await db.Users.SingleOrDefaultAsync(u => u.Role == "admin");

        Assert.NotNull(admin);
        Assert.NotEqual(localUser.Id, admin!.Id);
        Assert.Equal(2, await db.Users.CountAsync());
    }

    // ========== 辅助方法 ==========

    /// <summary>
    /// 写入一个已存在的云管理员（模拟"系统已初始化"场景）。
    /// </summary>
    private async Task<UserEntity> SeedExistingAdminAsync(TodoDbContext db, string userName)
    {
        var user = new UserEntity
        {
            Id = Guid.NewGuid(),
            UserName = userName,
            Role = "admin",
            CreatedAtUtc = DateTime.UtcNow,
            UpdatedAtUtc = DateTime.UtcNow
        };
        user.PasswordHash = _passwordHasher.HashPassword(user, "Existing#123");
        db.Users.Add(user);
        await db.SaveChangesAsync();
        return user;
    }

    /// <summary>
    /// 写入一个本地用户（Role="local"，嵌入式模式遗留数据）。
    /// </summary>
    private async Task SeedLocalUserAsync(TodoDbContext db, string userName)
    {
        var user = new UserEntity
        {
            Id = Guid.NewGuid(),
            UserName = userName,
            Role = "local",
            CreatedAtUtc = DateTime.UtcNow,
            UpdatedAtUtc = DateTime.UtcNow
        };
        user.PasswordHash = _passwordHasher.HashPassword(user, "local-dummy");
        db.Users.Add(user);
        await db.SaveChangesAsync();
    }
}