using System.ComponentModel;
using System.Net.Http.Headers;
using System.Text.Json;

namespace MAF1.Tools;

public sealed class WeatherTools(WeatherOptions options, HttpClient http)
{
    [Description("Look up live weather for a city or location. Always call this instead of guessing.")]
    public async Task<string> GetWeather(
        [Description("City or location name, for example Amsterdam or 北京.")] string location)
    {
        if (string.IsNullOrWhiteSpace(location))
        {
            return "未提供地点，无法查询天气。";
        }

        string provider = options.Provider.Trim();
        try
        {
            if (provider.Equals("OpenWeather", StringComparison.OrdinalIgnoreCase))
            {
                if (string.IsNullOrWhiteSpace(options.OpenWeather.ApiKey))
                {
                    return "OpenWeather 已启用，但 appsettings.json 里 Weather:OpenWeather:ApiKey 为空。请填入密钥，或把 Provider 改回 Wttr。";
                }

                return await QueryOpenWeatherAsync(location);
            }

            return await QueryWttrAsync(location);
        }
        catch (Exception ex)
        {
            return $"查询天气失败（{provider} / {location}）：{ex.Message}";
        }
    }

    private async Task<string> QueryWttrAsync(string location)
    {
        string url = Expand(options.Wttr.UrlTemplate, location, apiKey: null);
        using HttpResponseMessage response = await http.GetAsync(url);
        string body = (await response.Content.ReadAsStringAsync()).Trim();
        if (!response.IsSuccessStatusCode)
        {
            return $"wttr.in 返回 {(int)response.StatusCode}：{body}";
        }

        return string.IsNullOrWhiteSpace(body)
            ? $"wttr.in 没有返回 {location} 的天气。"
            : body;
    }

    private async Task<string> QueryOpenWeatherAsync(string location)
    {
        string url = Expand(options.OpenWeather.UrlTemplate, location, options.OpenWeather.ApiKey);
        using HttpResponseMessage response = await http.GetAsync(url);
        string body = await response.Content.ReadAsStringAsync();
        if (!response.IsSuccessStatusCode)
        {
            return $"OpenWeather 返回 {(int)response.StatusCode}：{body}";
        }

        using JsonDocument doc = JsonDocument.Parse(body);
        JsonElement root = doc.RootElement;
        string name = root.TryGetProperty("name", out JsonElement nameEl) ? nameEl.GetString() ?? location : location;
        string description = root.TryGetProperty("weather", out JsonElement weather)
            && weather.ValueKind == JsonValueKind.Array
            && weather.GetArrayLength() > 0
            && weather[0].TryGetProperty("description", out JsonElement descEl)
                ? descEl.GetString() ?? ""
                : "";
        double temp = root.TryGetProperty("main", out JsonElement main) && main.TryGetProperty("temp", out JsonElement tempEl)
            ? tempEl.GetDouble()
            : double.NaN;
        int humidity = main.ValueKind == JsonValueKind.Object && main.TryGetProperty("humidity", out JsonElement humidityEl)
            ? humidityEl.GetInt32()
            : 0;

        return double.IsNaN(temp)
            ? body
            : $"{name}：{description}，气温 {temp:0.#}°C，湿度 {humidity}%";
    }

    private string Expand(string template, string location, string? apiKey)
    {
        return template
            .Replace("{location}", Uri.EscapeDataString(location), StringComparison.OrdinalIgnoreCase)
            .Replace("{lang}", Uri.EscapeDataString(options.Language), StringComparison.OrdinalIgnoreCase)
            .Replace("{apiKey}", apiKey ?? "", StringComparison.OrdinalIgnoreCase);
    }

    public static HttpClient CreateHttpClient()
    {
        HttpClient http = new() { Timeout = TimeSpan.FromSeconds(20) };
        http.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue("MAF1", "1.0"));
        http.DefaultRequestHeaders.AcceptLanguage.ParseAdd("zh-CN,zh;q=0.9,en;q=0.8");
        return http;
    }
}