using System.ComponentModel.DataAnnotations;

namespace DodoSSH.Api.Setup;

/// <summary>Identity provider settings.</summary>
/// <remarks>
/// Provider-agnostic by design. Claim names differ between providers — Keycloak nests roles at
/// <c>realm_access.roles</c>, Entra uses <c>roles</c> and <c>groups</c>, Auth0 namespaces them,
/// Authentik uses <c>groups</c> — so the mapping is configuration rather than code.
/// </remarks>
public sealed class OidcOptions
{
    /// <summary>Configuration section name.</summary>
    public const string SectionName = "Oidc";

    /// <summary>Issuer URL. Discovery and JWKS are fetched from here.</summary>
    [Required]
    [Url]
    public string Authority { get; set; } = string.Empty;

    /// <summary>Expected audience of access tokens.</summary>
    [Required]
    public string Audience { get; set; } = string.Empty;

    /// <summary>Public client identifier the desktop app uses.</summary>
    [Required]
    public string ClientId { get; set; } = string.Empty;

    /// <summary>Scopes the client should request.</summary>
    public IList<string> Scopes { get; } = ["openid", "profile", "email", "offline_access"];

    /// <summary>
    /// Registered loopback redirect pattern. RFC 8252: a native client uses a loopback redirect on
    /// an ephemeral port with the system browser, never a custom scheme and never an embedded
    /// browser, so the user can see the real address bar.
    /// </summary>
    /// <remarks>
    /// No wildcard in the port. RFC 8252 requires a native client to use an ephemeral loopback port, and
    /// providers implement that by ignoring the port when the host is a loopback literal — Keycloak
    /// included. Writing <c>http://127.0.0.1:*/callback</c> looks more explicit and is worse: Keycloak
    /// parses the <c>*</c> as a literal port and rejects every real redirect with "Invalid parameter:
    /// redirect_uri". Pinning the path is the part that matters, since it stops another local process
    /// having a code delivered somewhere else.
    /// </remarks>
    public string LoopbackRedirectPattern { get; set; } = "http://127.0.0.1/callback";

    /// <summary>Whether HTTPS metadata is required. Only ever false for local development.</summary>
    public bool RequireHttpsMetadata { get; set; } = true;

    /// <summary>
    /// Whether a new identity-provider subject may be linked to an existing account by matching
    /// email.
    /// </summary>
    /// <remarks>
    /// Defaults to false, and must stay that way. If an attacker can obtain a token from any
    /// configured provider carrying a victim's email address, email linking hands them the
    /// victim's account.
    /// </remarks>
    public bool AllowEmailLinking { get; set; }

    /// <summary>Claim type holding the user's email.</summary>
    public string EmailClaim { get; set; } = "email";

    /// <summary>Claim type holding the user's display name.</summary>
    public string NameClaim { get; set; } = "name";
}

/// <summary>Relay settings. See ADR 0004.</summary>
public sealed class RelayOptions
{
    /// <summary>Configuration section name.</summary>
    public const string SectionName = "Relay";

    /// <summary>Whether this deployment offers a relay at all.</summary>
    public bool Enabled { get; set; }

    /// <summary>Public WebSocket URL clients should dial. Required when enabled.</summary>
    public string? WebSocketUrl { get; set; }

    /// <summary>
    /// Whether RFC1918 and other private ranges may be dialled.
    /// </summary>
    /// <remarks>
    /// Defaults to true, unlike a typical SSRF allow-list, because reaching private
    /// infrastructure is the entire purpose of a self-hosted SSH tool. The control that matters is
    /// the ACL: only hosts in a vault the caller holds Connect on can be dialled at all. Loopback,
    /// link-local and cloud metadata ranges are denied unconditionally and are not configurable.
    /// </remarks>
    public bool AllowPrivateNetworks { get; set; } = true;

    /// <summary>Maximum concurrent sessions per user.</summary>
    [Range(1, 1000)]
    public int MaxConcurrentSessionsPerUser { get; set; } = 10;

    /// <summary>Maximum concurrent sessions per node.</summary>
    [Range(1, 100_000)]
    public int MaxConcurrentSessionsTotal { get; set; } = 200;

    /// <summary>Maximum session lifetime.</summary>
    public TimeSpan MaxSessionDuration { get; set; } = TimeSpan.FromHours(12);

    /// <summary>Idle timeout.</summary>
    public TimeSpan IdleTimeout { get; set; } = TimeSpan.FromMinutes(10);

    /// <summary>Timeout for the outbound TCP connect.</summary>
    public TimeSpan ConnectTimeout { get; set; } = TimeSpan.FromSeconds(5);

    /// <summary>Ticket lifetime. Deliberately tiny: single-use and single-host.</summary>
    public TimeSpan TicketLifetime { get; set; } = TimeSpan.FromSeconds(30);

    /// <summary>How long to keep draining live sessions during shutdown.</summary>
    public TimeSpan DrainTimeout { get; set; } = TimeSpan.FromSeconds(30);
}

/// <summary>Sync protocol limits.</summary>
public sealed class SyncOptions
{
    /// <summary>Configuration section name.</summary>
    public const string SectionName = "Sync";

    /// <summary>Maximum operations in one push. Enforced before the transaction opens.</summary>
    [Range(1, 10_000)]
    public int MaxOperationsPerPush { get; set; } = 500;

    /// <summary>Maximum total ciphertext in one push.</summary>
    [Range(1024, 1024L * 1024 * 1024)]
    public long MaxPayloadBytes { get; set; } = 8L * 1024 * 1024;

    /// <summary>Maximum ciphertext for a single item.</summary>
    [Range(1024, 1024L * 1024 * 1024)]
    public long MaxItemPayloadBytes { get; set; } = 256L * 1024;

    /// <summary>Default page size for a pull.</summary>
    [Range(1, 10_000)]
    public int DefaultPullLimit { get; set; } = 200;

    /// <summary>Maximum page size for a pull.</summary>
    [Range(1, 10_000)]
    public int MaxPullLimit { get; set; } = 1000;

    /// <summary>How long tombstones are retained before collection.</summary>
    [Range(1, 3650)]
    public int TombstoneRetentionDays { get; set; } = 90;

    /// <summary>
    /// Key used to sign sync cursors, base64.
    /// </summary>
    /// <remarks>
    /// Cursors are integrity-tagged so a tampered one is rejected rather than silently
    /// mis-serving. Generated per deployment; losing it only invalidates in-flight cursors, since
    /// clients simply resync from the beginning.
    /// </remarks>
    public string? CursorSigningKey { get; set; }
}

/// <summary>Server identity and client compatibility.</summary>
public sealed class ServerOptions
{
    /// <summary>Configuration section name.</summary>
    public const string SectionName = "Server";

    /// <summary>Public base URL clients should use for API calls.</summary>
    [Required]
    [Url]
    public string PublicBaseUrl { get; set; } = string.Empty;

    /// <summary>
    /// Oldest client version this server will serve.
    /// </summary>
    /// <remarks>
    /// Self-hosted means version skew is normal, not exceptional. A client below this must be
    /// shown a clear remediation screen rather than failing obscurely mid-sync.
    /// </remarks>
    public string? MinClientVersion { get; set; }
}