using System.Security.Claims;
using System.Text.Json;
using Microsoft.AspNetCore.Components.Authorization;
using Microsoft.Extensions.Logging;
using ZB.MOM.WW.Audit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.AdminUI.Audit;

/// <summary>
///     #835 review I-1: every Test Connect / live browse whose config carries an in-scope credential reference
///     (<c>secret:</c> / <c>env:</c>) is recorded — who, which driver, which endpoint host(s), and the outcome — as an
///     <see cref="AuditEvent"/> (category <see cref="Category"/>) AND a structured Information log line, because those are
///     the two operations that resolve a stored credential and send it to an endpoint typed into an unsaved form. Never the
///     reference value or the credential.
/// </summary>
public static class CredentialUseAudit
{
    /// <summary>The audit category.</summary>
    public const string Category = "CredentialUse";

    /// <summary>The Test Connect action.</summary>
    public const string TestConnectAction = "TestConnect";

    /// <summary>The live-browse action.</summary>
    public const string BrowseAction = "Browse";

    /// <summary>
    ///     The endpoint hosts of a config, print-safe: <c>host[:port]</c> for a URI (user-info dropped), the trimmed value
    ///     otherwise (capped).
    /// </summary>
    /// <param name="driverType">The driver type.</param>
    /// <param name="configJson">The config.</param>
    /// <returns>The hosts.</returns>
    public static IReadOnlyList<string> Hosts(string? driverType, string? configJson) =>
        DriverCredentialPolicy.EndpointValues(driverType, configJson)
            .Select(v => Uri.TryCreate(v, UriKind.Absolute, out var u) && !string.IsNullOrEmpty(u.Host)
                ? (u.IsDefaultPort || u.Port < 0 ? u.Host : $"{u.Host}:{u.Port}")
                : (v.Length > 128 ? v[..128] : v))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .ToList();

    /// <summary>Builds the audit event.</summary>
    /// <param name="action"><see cref="TestConnectAction"/> or <see cref="BrowseAction"/>.</param>
    /// <param name="actor">The user.</param>
    /// <param name="driverType">The driver type.</param>
    /// <param name="driverInstanceId">The driver the caller named, or null.</param>
    /// <param name="hosts">The endpoint hosts.</param>
    /// <param name="ok">Whether the operation succeeded.</param>
    /// <param name="message">The refusal / failure message, if any.</param>
    /// <returns>The event.</returns>
    public static AuditEvent Build(
        string action, string actor, string driverType, string? driverInstanceId, IReadOnlyList<string> hosts, bool ok, string? message) =>
        new()
        {
            EventId = Guid.NewGuid(),
            OccurredAtUtc = DateTimeOffset.UtcNow,
            Actor = actor,
            Action = action,
            Category = Category,
            Target = driverInstanceId ?? "(unsaved driver)",
            Outcome = ok ? AuditOutcome.Success : AuditOutcome.Failure,
            DetailsJson = JsonSerializer.Serialize(new { driverType, endpoints = hosts, message }),
        };

    /// <summary>
    ///     Records one operation when the config carries an in-scope credential reference; a no-op otherwise. Never throws
    ///     (an audit failure is logged, not surfaced).
    /// </summary>
    /// <param name="audit">The audit writer, or null (log only).</param>
    /// <param name="auth">The circuit's authentication state, or null.</param>
    /// <param name="logger">The logger.</param>
    /// <param name="action">The action.</param>
    /// <param name="driverType">The driver type.</param>
    /// <param name="configJson">The config.</param>
    /// <param name="driverInstanceId">The driver the caller named.</param>
    /// <param name="ok">Whether it succeeded.</param>
    /// <param name="message">The refusal / failure message.</param>
    /// <returns>A task.</returns>
    public static async Task RecordAsync(
        IAuditWriter? audit, AuthenticationStateProvider? auth, ILogger logger, string action, string driverType, string configJson,
        string? driverInstanceId, bool ok, string? message)
    {
        if (!DriverCredentialPolicy.HasCredentialReferences(driverType, configJson)) return;
        try
        {
            var actor = await ActorAsync(auth).ConfigureAwait(false);
            var hosts = Hosts(driverType, configJson);
            logger.LogInformation(
                "Credential use: {Action} by {User} driverType={DriverType} driver={DriverInstanceId} endpoints={Endpoints} outcome={Outcome} {Message}",
                action, actor, driverType, driverInstanceId ?? "(unsaved)", string.Join(",", hosts), ok ? "Success" : "Failure", message);
            if (audit is not null)
                await audit.WriteAsync(Build(action, actor, driverType, driverInstanceId, hosts, ok, message)).ConfigureAwait(false);
        }
        catch (Exception ex)
        {
            logger.LogWarning(ex, "Credential-use audit for {Action} could not be written.", action);
        }
    }

    private static async Task<string> ActorAsync(AuthenticationStateProvider? auth)
    {
        if (auth is null) return "unknown";
        var state = await auth.GetAuthenticationStateAsync().ConfigureAwait(false);
        return state.User.Identity?.Name ?? state.User.FindFirst(ClaimTypes.NameIdentifier)?.Value ?? "unknown";
    }
}