using System.Net.Http;
using System.Net.Http.Headers;
using System.Text.Json;
using WindowsGotify.Models;

namespace WindowsGotify.Services;

public sealed class GotifyApiService
{
    private readonly GotifyConfig _config;
    private readonly Logger _logger;
    private readonly HttpClient _httpClient;

    public GotifyApiService(AppConfig config, Logger logger)
    {
        _config = config.Gotify;
        _logger = logger;
        _httpClient = new HttpClient
        {
            BaseAddress = new Uri(_config.Url.TrimEnd('/') + "/"),
            Timeout = TimeSpan.FromSeconds(15)
        };

        _httpClient.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", _config.ClientToken);
    }

    /// <summary>
    /// 拉取 lastId 之后的增量消息(去重补齐用)。
    /// </summary>
    public async Task<List<GotifyMessage>> GetMessagesSinceAsync(long sinceId, int limit, CancellationToken ct)
    {
        var path = $"message?limit={Math.Clamp(limit, 1, 100)}&since={Math.Max(0, sinceId)}";
        using var response = await _httpClient.GetAsync(path, ct);
        response.EnsureSuccessStatusCode();

        await using var stream = await response.Content.ReadAsStreamAsync(ct);
        var page = await JsonSerializer.DeserializeAsync<GotifyMessagePage>(stream, cancellationToken: ct);
        return page?.Messages ?? new List<GotifyMessage>();
    }

    /// <summary>
    /// 拉取最近 N 条消息(历史查看用)。since=0 让服务器从最新往旧返回。
    /// </summary>
    public async Task<List<GotifyMessage>> GetRecentMessagesAsync(int limit, CancellationToken ct)
    {
        var path = $"message?limit={Math.Clamp(limit, 1, 100)}&since=0";
        using var response = await _httpClient.GetAsync(path, ct);
        response.EnsureSuccessStatusCode();

        await using var stream = await response.Content.ReadAsStreamAsync(ct);
        var page = await JsonSerializer.DeserializeAsync<GotifyMessagePage>(stream, cancellationToken: ct);
        var list = page?.Messages ?? new List<GotifyMessage>();

        // Gotify 的 since=0 行为:返回数据库里所有消息中的 limit 条;按 id 降序再取一次保证正确
        return list.OrderByDescending(m => m.Id).Take(Math.Clamp(limit, 1, 100)).ToList();
    }
}