using System.Net;
using System.Net.Http.Json;
using System.Text.Json;
using LehrerApp.Core.Models;

namespace LehrerApp.Desktop.Services;

public sealed class SchoolWeatherException(string message) : Exception(message);

/// <summary>Client für das serverseitige Schulstandort-/Wetterprofil. Liest URL und Token je
/// Aufruf, damit ein Login oder Serverwechsel in den Einstellungen sofort berücksichtigt wird.</summary>
public sealed class SchoolWeatherService(HttpClient http, SyncSettingsService syncSettings)
{
    public bool IsAvailable => !string.IsNullOrWhiteSpace(syncSettings.ServerUrl) && syncSettings.IsLoggedIn;

    public async Task<SchoolLocationProfile?> GetLocationAsync(CancellationToken cancellationToken = default)
    {
        using var response = await SendAsync(HttpMethod.Get, "/api/school/location", null, cancellationToken);
        if (response.StatusCode == HttpStatusCode.NotFound) return null;
        await EnsureSuccessAsync(response);
        return await response.Content.ReadFromJsonAsync<SchoolLocationProfile>(cancellationToken);
    }

    public async Task<SchoolLocationProfile> SaveLocationAsync(SchoolLocationRequest location,
        CancellationToken cancellationToken = default)
    {
        using var response = await SendAsync(HttpMethod.Put, "/api/school/location", location, cancellationToken);
        await EnsureSuccessAsync(response);
        return await response.Content.ReadFromJsonAsync<SchoolLocationProfile>(cancellationToken)
            ?? throw new SchoolWeatherException("Der Server hat keine Standortdaten zurückgegeben.");
    }

    public async Task<WeatherSnapshot?> GetWeatherAsync(CancellationToken cancellationToken = default)
    {
        using var response = await SendAsync(HttpMethod.Get, "/api/school/weather", null, cancellationToken);
        if (response.StatusCode == HttpStatusCode.NotFound) return null;
        await EnsureSuccessAsync(response);
        return await response.Content.ReadFromJsonAsync<WeatherSnapshot>(cancellationToken);
    }

    private async Task<HttpResponseMessage> SendAsync(HttpMethod method, string path, object? body,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(syncSettings.ServerUrl) || !syncSettings.IsLoggedIn)
            throw new SchoolWeatherException("Bitte zuerst im Reiter „Synchronisation“ am Server anmelden.");
        using var request = new HttpRequestMessage(method, new Uri(new Uri(syncSettings.ServerUrl), path));
        var token = syncSettings.GetToken();
        if (token is not null)
            request.Headers.Authorization = new("Bearer", token);
        if (body is not null) request.Content = JsonContent.Create(body);
        try { return await http.SendAsync(request, cancellationToken); }
        catch (HttpRequestException)
        {
            throw new SchoolWeatherException("Der LehrerApp-Server ist nicht erreichbar.");
        }
    }

    private static async Task EnsureSuccessAsync(HttpResponseMessage response)
    {
        if (response.IsSuccessStatusCode) return;
        if (response.StatusCode == HttpStatusCode.Unauthorized)
            throw new SchoolWeatherException("Die Server-Anmeldung ist abgelaufen. Bitte erneut anmelden.");
        try
        {
            using var document = JsonDocument.Parse(await response.Content.ReadAsStringAsync());
            if (document.RootElement.TryGetProperty("detail", out var detail) &&
                !string.IsNullOrWhiteSpace(detail.GetString()))
                throw new SchoolWeatherException(detail.GetString()!);
        }
        catch (JsonException) { }
        throw new SchoolWeatherException("Der Schulstandort konnte nicht gespeichert werden.");
    }
}