using Microsoft.Extensions.Options;
using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Text.Json;

namespace Evergreen.Health.Application.Health.Integrations.HomeAssistant;

public sealed class HomeAssistantClient
{
    private readonly HttpClient _httpClient;
    private readonly HomeAssistantOptions _options;

    public HomeAssistantClient(HttpClient httpClient, IOptions<HomeAssistantOptions> options)
    {
        _httpClient = httpClient;
        _options = options.Value;
        _httpClient.Timeout = TimeSpan.FromSeconds(Math.Clamp(_options.TimeoutSeconds, 3, 60));
    }

    public async Task<IReadOnlyList<HomeAssistantState>> GetStatesAsync(CancellationToken cancellationToken = default)
    {
        using var request = CreateRequest(HttpMethod.Get, "api/states");
        using var response = await _httpClient.SendAsync(request, cancellationToken);
        await EnsureSuccessAsync(response, cancellationToken);
        return await response.Content.ReadFromJsonAsync<List<HomeAssistantState>>(cancellationToken: cancellationToken) ?? [];
    }

    public async Task CallServiceAsync(
        string domain,
        string service,
        IReadOnlyDictionary<string, object?> data,
        CancellationToken cancellationToken = default)
    {
        using var request = CreateRequest(HttpMethod.Post, $"api/services/{domain}/{service}");
        request.Content = JsonContent.Create(data);
        using var response = await _httpClient.SendAsync(request, cancellationToken);
        await EnsureSuccessAsync(response, cancellationToken);
    }

    private HttpRequestMessage CreateRequest(HttpMethod method, string path)
    {
        if (!_options.Enabled)
            throw new InvalidOperationException("Home Assistant 接入未启用");
        if (string.IsNullOrWhiteSpace(_options.BaseUrl))
            throw new InvalidOperationException("Home Assistant 地址未配置");
        if (string.IsNullOrWhiteSpace(_options.AccessToken))
            throw new InvalidOperationException("Home Assistant 访问令牌未配置");

        var baseUrl = _options.BaseUrl.TrimEnd('/') + "/";
        var request = new HttpRequestMessage(method, new Uri(new Uri(baseUrl), path));
        request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", _options.AccessToken);
        request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        return request;
    }

    private static async Task EnsureSuccessAsync(HttpResponseMessage response, CancellationToken cancellationToken)
    {
        if (response.IsSuccessStatusCode) return;
        var body = await response.Content.ReadAsStringAsync(cancellationToken);
        var message = body.Length > 300 ? body[..300] : body;
        throw new HttpRequestException($"Home Assistant 返回 {(int)response.StatusCode}: {message}");
    }
}