using System.Net;
using System.Security.Claims;
using System.Text;
using System.Text.Encodings.Web;
using Microsoft.AspNetCore.Authentication;
using Microsoft.Extensions.Options;
using Microsoft.Data.Sqlite;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddAuthentication("Basic")
    .AddScheme<AuthenticationSchemeOptions, BasicAuthenticationHandler>("Basic", null);
builder.Services.AddAuthorization();
builder.Services.AddSingleton<Database>();

var app = builder.Build();

app.UseDefaultFiles();
app.UseStaticFiles();
app.UseAuthentication();
app.UseAuthorization();

await app.Services.GetRequiredService<Database>().InitializeAsync();

app.MapPost("/api/visitors", async (VisitorInput input, Database database) =>
{
    var errors = Validate(input);
    if (errors.Count > 0)
    {
        return Results.ValidationProblem(errors);
    }

    await using var connection = await database.OpenConnectionAsync();
    await using var command = connection.CreateCommand();
    command.CommandText = """
        insert into visitors (name, street_address, postal_code, city, birthday, email)
        values ($name, $street, $postal, $city, $birthday, $email)
        returning id
        """;
    command.Parameters.AddWithValue("$name", input.Name.Trim());
    command.Parameters.AddWithValue("$street", input.StreetAddress.Trim());
    command.Parameters.AddWithValue("$postal", input.PostalCode.Trim());
    command.Parameters.AddWithValue("$city", input.City.Trim());
    command.Parameters.AddWithValue("$birthday", DateOnly.Parse(input.Birthday).ToString("yyyy-MM-dd"));
    command.Parameters.AddWithValue("$email", input.Email?.Trim().ToLowerInvariant() ?? "");
    var number = Convert.ToInt64(await command.ExecuteScalarAsync());

    return Results.Created("/api/visitors", new { number });
});

app.MapGet("/api/visitors", async (Database database) =>
{
    var visitors = new List<VisitorListItem>();
    await using var connection = await database.OpenConnectionAsync();
    await using var command = connection.CreateCommand();
    command.CommandText = """
        select id, name, street_address, postal_code, city, birthday, email, created_at, result, x10
        from visitors
        order by created_at desc, id desc
        """;
    await using var reader = await command.ExecuteReaderAsync();

    while (await reader.ReadAsync())
    {
        visitors.Add(new VisitorListItem(
            reader.GetInt64(0),
            reader.GetString(1),
            reader.GetString(2),
            reader.GetString(3),
            reader.GetString(4),
            DateOnly.Parse(reader.GetString(5)),
            reader.GetString(6),
            DateTime.SpecifyKind(reader.GetDateTime(7), DateTimeKind.Utc),
            reader.GetString(8),
            reader.IsDBNull(9) ? null : reader.GetInt32(9)
        ));
    }

    return Results.Ok(visitors);
}).RequireAuthorization();

app.MapPut("/api/visitors/{id:long}/result", async (long id, VisitorResultInput input, Database database) =>
{
    var result = input.Result?.Trim() ?? "";
    if (input.X10 < 0)
        return Results.ValidationProblem(new Dictionary<string, string[]> { ["x10"] = ["X-10 skal være et heltal på mindst 0."] });
    if (result.Length > 100)
        return Results.ValidationProblem(new Dictionary<string, string[]> { ["result"] = ["Resultatet må højst være 100 tegn."] });
    await using var connection = await database.OpenConnectionAsync();
    await using var command = connection.CreateCommand();
    command.CommandText = "update visitors set result = $result, x10 = $x10 where id = $id";
    command.Parameters.AddWithValue("$x10", (object?)input.X10 ?? DBNull.Value);
    command.Parameters.AddWithValue("$result", result);
    command.Parameters.AddWithValue("$id", id);
    return await command.ExecuteNonQueryAsync() == 0 ? Results.NotFound() : Results.Ok(new { result, x10 = input.X10 });
}).RequireAuthorization();

app.MapDelete("/api/visitors/{id:long}", async (long id, Database database) =>
{
    await using var connection = await database.OpenConnectionAsync();
    await using var command = connection.CreateCommand();
    command.CommandText = "delete from visitors where id = $id";
    command.Parameters.AddWithValue("$id", id);
    var deleted = await command.ExecuteNonQueryAsync();
    return deleted == 0 ? Results.NotFound() : Results.NoContent();
}).RequireAuthorization();

app.MapGet("/admin", (IWebHostEnvironment environment) =>
    Results.File(Path.Combine(environment.WebRootPath, "admin.html"), "text/html"));

app.MapFallbackToFile("index.html");

app.Run();

static Dictionary<string, string[]> Validate(VisitorInput input)
{
    var errors = new Dictionary<string, string[]>();

    if (string.IsNullOrWhiteSpace(input.Name))
    {
        errors["name"] = ["Navn mangler."];
    }

    if (string.IsNullOrWhiteSpace(input.StreetAddress))
    {
        errors["streetAddress"] = ["Vejnavn og husnummer mangler."];
    }

    if (string.IsNullOrWhiteSpace(input.PostalCode) || input.PostalCode.Trim().Length != 4 || !input.PostalCode.All(char.IsDigit))
    {
        errors["postalCode"] = ["Postnummer skal være 4 cifre."];
    }

    if (string.IsNullOrWhiteSpace(input.City))
    {
        errors["city"] = ["Postby mangler."];
    }

    if (string.IsNullOrWhiteSpace(input.Birthday) || !DateOnly.TryParse(input.Birthday, out _))
    {
        errors["birthday"] = ["Fødselsdag mangler eller er ugyldig."];
    }

    if (!string.IsNullOrWhiteSpace(input.Email) && (!input.Email.Contains('@') || !input.Email.Contains('.')))
    {
        errors["email"] = ["Email er ugyldig."];
    }

    return errors;
}

public sealed record VisitorInput(string Name, string StreetAddress, string PostalCode, string City, string Birthday, string? Email);

public sealed record VisitorResultInput(string? Result, int? X10);
public sealed record VisitorListItem(long Id, string Name, string StreetAddress, string PostalCode, string City, DateOnly Birthday, string Email, DateTime CreatedAt, string Result, int? X10);

public sealed class Database
{
    private readonly string _connectionString;

    public Database(IConfiguration configuration, IWebHostEnvironment environment)
    {
        var path = configuration["Database:Path"] ?? "data/visitors.db";
        var fullPath = Path.GetFullPath(path, environment.ContentRootPath);
        Directory.CreateDirectory(Path.GetDirectoryName(fullPath)!);
        _connectionString = new SqliteConnectionStringBuilder { DataSource = fullPath }.ToString();
    }

    public async Task<SqliteConnection> OpenConnectionAsync()
    {
        var connection = new SqliteConnection(_connectionString);
        try
        {
            await connection.OpenAsync();
            return connection;
        }
        catch
        {
            await connection.DisposeAsync();
            throw;
        }
    }

    public async Task InitializeAsync()
    {
        await using var connection = await OpenConnectionAsync();
        await using var command = connection.CreateCommand();
        command.CommandText = """
            create table if not exists visitors (
              id integer primary key autoincrement,
              name text not null,
              street_address text not null,
              postal_code text not null,
              city text not null,
              birthday text not null,
              email text not null,
              created_at text not null default (strftime('%Y-%m-%dT%H:%M:%fZ', 'now'))
            );

            create index if not exists visitors_created_at_idx on visitors (created_at desc);
            """;

        await command.ExecuteNonQueryAsync();
        await using var schemaCommand = connection.CreateCommand();
        schemaCommand.CommandText = "select count(*) from pragma_table_info('visitors') where name = 'result'";
        if (Convert.ToInt64(await schemaCommand.ExecuteScalarAsync()) == 0)
        {
            schemaCommand.CommandText = "alter table visitors add column result text not null default ''";
            await schemaCommand.ExecuteNonQueryAsync();
        }
        schemaCommand.CommandText = "select count(*) from pragma_table_info('visitors') where name = 'x10'";
        if (Convert.ToInt64(await schemaCommand.ExecuteScalarAsync()) == 0)
        {
            schemaCommand.CommandText = "alter table visitors add column x10 integer";
            await schemaCommand.ExecuteNonQueryAsync();
        }
    }
}

public sealed class BasicAuthenticationHandler(
    IOptionsMonitor<AuthenticationSchemeOptions> options,
    ILoggerFactory logger,
    UrlEncoder encoder,
    IConfiguration configuration)
    : AuthenticationHandler<AuthenticationSchemeOptions>(options, logger, encoder)
{
    protected override Task<AuthenticateResult> HandleAuthenticateAsync()
    {
        var expectedUser = configuration["Admin:Username"] ?? "admin";
        var expectedPassword = configuration["Admin:Password"];

        if (string.IsNullOrWhiteSpace(expectedPassword))
        {
            return Task.FromResult(AuthenticateResult.Fail("Admin:Password mangler."));
        }

        if (!Request.Headers.TryGetValue("Authorization", out var authorizationHeaders))
        {
            return Task.FromResult(AuthenticateResult.NoResult());
        }

        var authorization = authorizationHeaders.ToString();
        if (!authorization.StartsWith("Basic ", StringComparison.OrdinalIgnoreCase))
        {
            return Task.FromResult(AuthenticateResult.NoResult());
        }

        try
        {
            var encoded = authorization["Basic ".Length..].Trim();
            var decoded = Encoding.UTF8.GetString(Convert.FromBase64String(encoded));
            var separator = decoded.IndexOf(':');
            if (separator < 0)
            {
                return Task.FromResult(AuthenticateResult.Fail("Ugyldige credentials."));
            }

            var username = decoded[..separator];
            var password = decoded[(separator + 1)..];

            if (username != expectedUser || password != expectedPassword)
            {
                return Task.FromResult(AuthenticateResult.Fail("Forkert login."));
            }

            var identity = new ClaimsIdentity([new Claim(ClaimTypes.Name, username)], Scheme.Name);
            var principal = new ClaimsPrincipal(identity);
            return Task.FromResult(AuthenticateResult.Success(new AuthenticationTicket(principal, Scheme.Name)));
        }
        catch
        {
            return Task.FromResult(AuthenticateResult.Fail("Ugyldige credentials."));
        }
    }

    protected override Task HandleChallengeAsync(AuthenticationProperties properties)
    {
        Response.Headers.WWWAuthenticate = "Basic realm=\"Skydesportens Dag\"";
        Response.StatusCode = StatusCodes.Status401Unauthorized;
        return Task.CompletedTask;
    }
}