using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Threading;
using System.Threading.Tasks;
using FinlyticCore.Services;
using FinlyticNotify.Settings;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace FinlyticNotify.Services;

/// <summary>
/// Model representing a notification payload to be dispatched via ntfy.
/// </summary>
public record NtfyNotification(
    string Topic,
    string Title,
    string Message,
    int Priority = 3,
    List<string>? Tags = null,
    string? ClickUrl = null
);

/// <summary>
/// Client interface for sending push notifications to an ntfy instance.
/// </summary>
public interface INtfyClient
{
    /// <summary>
    /// Sends a notification to the specified ntfy topic.
    /// </summary>
    /// <param name="notification">The notification payload.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>True if successfully delivered, false otherwise.</returns>
    Task<bool> SendNotificationAsync(NtfyNotification notification, CancellationToken cancellationToken = default);
}

/// <summary>
/// High-performance HTTP client for dispatching push notifications to self-hosted ntfy server via JSON payload.
/// </summary>
public class NtfyClient : INtfyClient
{
    private readonly HttpClient _httpClient;
    private readonly ISettingsService? _settingsService;
    private readonly IConfiguration _configuration;
    private readonly IFinlyticLogger<NtfyClient>? _finlyticLogger;
    private readonly ILogger<NtfyClient> _logger;

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
    };

    /// <summary>
    /// Initializes a new instance of the <see cref="NtfyClient"/> class.
    /// </summary>
    public NtfyClient(
        HttpClient httpClient,
        IConfiguration configuration,
        ILogger<NtfyClient> logger,
        ISettingsService? settingsService = null,
        IFinlyticLogger<NtfyClient>? finlyticLogger = null)
    {
        _httpClient = httpClient;
        _configuration = configuration;
        _logger = logger;
        _settingsService = settingsService;
        _finlyticLogger = finlyticLogger;
    }

    /// <inheritdoc />
    public async Task<bool> SendNotificationAsync(NtfyNotification notification, CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(notification.Topic))
        {
            _logger.LogWarning("[NtfyClient] Aborting send: Topic is empty.");
            return false;
        }

        string baseUrl = "http://localhost:8080";
        if (_settingsService != null)
        {
            try
            {
                baseUrl = await _settingsService.GetSettingAsync(NotifySettingKeys.NtfyBaseUrl, cancellationToken);
            }
            catch
            {
                baseUrl = _configuration.GetValue<string>("Ntfy:BaseUrl") ?? NotifySettingKeys.NtfyBaseUrl.DefaultValue;
            }
        }
        else
        {
            baseUrl = _configuration.GetValue<string>("Ntfy:BaseUrl") ?? NotifySettingKeys.NtfyBaseUrl.DefaultValue;
        }

        baseUrl = baseUrl.TrimEnd('/');

        // Build native ntfy JSON payload (preserves full UTF-8 Unicode, Emojis, and Markdown without HTTP header ASCII constraints)
        var payload = new Dictionary<string, object?>
        {
            ["topic"] = notification.Topic.TrimStart('/'),
            ["title"] = notification.Title,
            ["message"] = notification.Message,
            ["priority"] = Math.Clamp(notification.Priority, 1, 5),
            ["tags"] = notification.Tags,
            ["click"] = notification.ClickUrl,
            ["markdown"] = true
        };

        string json = JsonSerializer.Serialize(payload, JsonOptions);

        string? token = null;
        string? authUser = null;
        string? authPass = null;

        if (_settingsService != null)
        {
            try
            {
                token = await _settingsService.GetSettingAsync(NotifySettingKeys.NtfyAuthToken, cancellationToken);
                authUser = await _settingsService.GetSettingAsync(NotifySettingKeys.NtfyUsername, cancellationToken);
                authPass = await _settingsService.GetSettingAsync(NotifySettingKeys.NtfyPassword, cancellationToken);
            }
            catch { }
        }

        token = string.IsNullOrWhiteSpace(token) ? _configuration.GetValue<string>("Ntfy:AuthToken") : token;
        authUser = string.IsNullOrWhiteSpace(authUser) ? _configuration.GetValue<string>("Ntfy:Username") : authUser;
        authPass = string.IsNullOrWhiteSpace(authPass) ? _configuration.GetValue<string>("Ntfy:Password") : authPass;

        try
        {
            using var request = new HttpRequestMessage(HttpMethod.Post, baseUrl);
            request.Content = new StringContent(json, Encoding.UTF8, "application/json");

            if (!string.IsNullOrWhiteSpace(token))
            {
                request.Headers.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", token.Trim());
            }
            else if (!string.IsNullOrWhiteSpace(authUser) && !string.IsNullOrWhiteSpace(authPass))
            {
                var authBytes = Encoding.UTF8.GetBytes($"{authUser}:{authPass}");
                request.Headers.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Basic", Convert.ToBase64String(authBytes));
            }

            var response = await _httpClient.SendAsync(request, cancellationToken);
            if (response.IsSuccessStatusCode)
            {
                _logger.LogInformation("[NtfyClient] Push notification successfully delivered to {TargetUrl} (Topic: {Topic})", baseUrl, notification.Topic);
                if (_finlyticLogger != null)
                {
                    await _finlyticLogger.LogInfoAsync(NotifySettingKeys.NotificationDeliveryChannel,
                        "[NtfyDelivery] Push notification successfully delivered to topic '{Topic}' (HTTP {StatusCode})",
                        notification.Topic, (int)response.StatusCode);
                }
                return true;
            }

            string errorBody = await response.Content.ReadAsStringAsync(cancellationToken);
            _logger.LogWarning("[NtfyClient] Failed to send notification to {TargetUrl} for topic {Topic}. HTTP {Status}: {Body}",
                baseUrl, notification.Topic, (int)response.StatusCode, errorBody);

            if (_finlyticLogger != null)
            {
                await _finlyticLogger.LogWarningAsync(NotifySettingKeys.NotificationDeliveryChannel,
                    "[NtfyDelivery] Failed to send push notification to topic '{Topic}' (HTTP {StatusCode})",
                    notification.Topic, (int)response.StatusCode);
            }

            return false;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "[NtfyClient] Unexpected error sending push notification to {TargetUrl} for topic {Topic}", baseUrl, notification.Topic);
            if (_finlyticLogger != null)
            {
                await _finlyticLogger.LogErrorAsync(NotifySettingKeys.NotificationDeliveryChannel, ex,
                    "[NtfyDelivery] Error sending push notification to topic '{Topic}'", notification.Topic);
            }
            return false;
        }
    }
}