using System;
using System.Globalization;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.AI;
using Newtonsoft.Json.Linq;

namespace OnDeviceAgent.AgentCore
{
public sealed class GetWeatherTool : IAgentTool
{
    const string GeocodeUrl = "https://geocoding-api.open-meteo.com/v1/search";
    const string ForecastUrl = "https://api.open-meteo.com/v1/forecast";
    // ipinfo.io resolves the caller IP to a city-granularity location.
    const string IpLocationUrl = "https://ipinfo.io/json";

    static readonly HttpClient s_Http = CreateClient();

    static HttpClient CreateClient()
    {
        var c = new HttpClient { Timeout = TimeSpan.FromSeconds(15) };
        c.DefaultRequestHeaders.Add("User-Agent", "OnDeviceAgent/1.0 (on-device voice agent)");
        return c;
    }

    public string Name => "GetWeather";
    public string Description =>
        "Get the current weather. Use when the user asks about the weather (e.g. 'what's the weather', '날씨 어때', " +
        "'서울 날씨 알려줘'). Pass a city as 'location', or 'current' for auto-location; never ask the user which place. " +
        "Always call this; never make up the weather.";

    public AITool ToAIFunction(AgentToolContext context)
    {
        Task<string> Run(
            [System.ComponentModel.Description("city/place name in English, or \"current\" for the auto-detected location")] string location = "current")
            => InvokeAsync(context, location);
        return AIFunctionFactory.Create(
            (Func<string, Task<string>>)Run, name: Name, description: Description);
    }

    async Task<string> InvokeAsync(AgentToolContext ctx, string location)
    {
        var argsJson = "{\"location\":\"" + (location ?? string.Empty).Replace("\"", "'") + "\"}";
        if (!ctx.Tracker.TryBegin(Name, "Tool GetWeather called.", argsJson, out var blocked))
            return blocked;

        if (!await ctx.Approval.IsApprovedOrRequest(this, ctx).ConfigureAwait(false))
            return ctx.Tracker.Finish(Name, argsJson, BuildApprovalRequiredMessage());

        try
        {
            var ct = ctx.CancellationToken;
            GeoPlace place;
            if (IsCurrentLocation(location))
            {
                place = await ResolveCurrentLocationAsync(ct).ConfigureAwait(false);
                if (place == null)
                    return ctx.Tracker.Finish(Name, argsJson, "Couldn't determine the current location. Please tell me a place name.");
            }
            else
            {
                place = await GeocodeAsync(location.Trim(), ct).ConfigureAwait(false);
                if (place == null)
                    return ctx.Tracker.Finish(Name, argsJson, "No location found for \"" + location.Trim() + "\".");
            }

            var summary = await FetchWeatherAsync(place, ct).ConfigureAwait(false);
            return ctx.Tracker.Finish(Name, argsJson, summary);
        }
        catch (OperationCanceledException) when (ctx.CancellationToken.IsCancellationRequested)
        {
            throw; // honour genuine run cancellation (not an HttpClient request timeout)
        }
        catch (Exception ex)
        {
            return ctx.Tracker.Finish(Name, argsJson, "GetWeather failed: " + ex.Message);
        }
    }

    sealed class GeoPlace
    {
        public double Latitude;
        public double Longitude;
        public string Label;
    }

    static bool IsCurrentLocation(string loc)
    {
        if (string.IsNullOrWhiteSpace(loc)) return true;
        var s = loc.Trim().ToLowerInvariant();
        return s == "current" || s == "current location" || s == "here" || s == "now" || s == "auto"
            || s == "my location" || s == "현재" || s == "여기" || s == "지금"
            || s.Contains("현재 위치") || s.Contains("내 위치");
    }

    static async Task<GeoPlace> GeocodeAsync(string name, CancellationToken ct)
    {
        var url = GeocodeUrl + "?name=" + Uri.EscapeDataString(name) + "&count=1&language=en&format=json";
        var json = await GetStringAsync(url, ct).ConfigureAwait(false);
        var root = JObject.Parse(json);
        var results = root["results"] as JArray;
        if (results == null || results.Count == 0)
            return null;

        var r = results[0];
        var label = (string)r["name"];
        var admin1 = (string)r["admin1"];
        var country = (string)r["country"];
        if (!string.IsNullOrEmpty(admin1) && !string.Equals(admin1, label, StringComparison.OrdinalIgnoreCase))
            label += ", " + admin1;
        if (!string.IsNullOrEmpty(country) &&
            label.IndexOf(country, StringComparison.OrdinalIgnoreCase) < 0)
            label += ", " + country;

        return new GeoPlace
        {
            Latitude = (double)r["latitude"],
            Longitude = (double)r["longitude"],
            Label = label,
        };
    }

    static async Task<GeoPlace> ResolveCurrentLocationAsync(CancellationToken ct)
    {
        var json = await GetStringAsync(IpLocationUrl, ct).ConfigureAwait(false);
        var root = JObject.Parse(json);

        // ipinfo.io packs lat/lon into a single "loc" field, e.g. "37.4842,127.0322".
        var loc = (string)root["loc"];
        if (string.IsNullOrEmpty(loc))
            return null;
        var parts = loc.Split(',');
        if (parts.Length != 2) return null;
        var inv = CultureInfo.InvariantCulture;
        if (!double.TryParse(parts[0], NumberStyles.Float, inv, out var lat) ||
            !double.TryParse(parts[1], NumberStyles.Float, inv, out var lon))
            return null;

        var city = (string)root["city"];
        var region = (string)root["region"];
        var country = (string)root["country"];
        var label = city;
        if (!string.IsNullOrEmpty(region) && !string.Equals(region, label, StringComparison.OrdinalIgnoreCase))
            label = string.IsNullOrEmpty(label) ? region : label + ", " + region;
        if (!string.IsNullOrEmpty(country) &&
            (string.IsNullOrEmpty(label) || label.IndexOf(country, StringComparison.OrdinalIgnoreCase) < 0))
            label = string.IsNullOrEmpty(label) ? country : label + ", " + country;
        if (string.IsNullOrEmpty(label))
            label = "your area";

        return new GeoPlace { Latitude = lat, Longitude = lon, Label = label };
    }

    static async Task<string> FetchWeatherAsync(GeoPlace place, CancellationToken ct)
    {
        var inv = CultureInfo.InvariantCulture;
        var url = ForecastUrl +
            "?latitude=" + place.Latitude.ToString(inv) +
            "&longitude=" + place.Longitude.ToString(inv) +
            "&current=temperature_2m,relative_humidity_2m,wind_speed_10m,weather_code";
        var json = await GetStringAsync(url, ct).ConfigureAwait(false);
        var current = JObject.Parse(json)["current"];
        if (current == null)
            return "Weather data unavailable for " + place.Label + ".";

        var temp = (double?)current["temperature_2m"];
        var humidity = (double?)current["relative_humidity_2m"];
        var wind = (double?)current["wind_speed_10m"];
        var code = (int?)current["weather_code"] ?? -1;

        var sb = new System.Text.StringBuilder();
        sb.Append("Weather in ").Append(place.Label).Append(": ").Append(DescribeWeatherCode(code));
        if (temp.HasValue) sb.Append(", ").Append(temp.Value.ToString("0.#", inv)).Append("°C");
        if (humidity.HasValue) sb.Append(", humidity ").Append(humidity.Value.ToString("0", inv)).Append('%');
        if (wind.HasValue) sb.Append(", wind ").Append(wind.Value.ToString("0.#", inv)).Append(" km/h");
        sb.Append('.');
        return sb.ToString();
    }

    static async Task<string> GetStringAsync(string url, CancellationToken ct)
    {
        using (var resp = await s_Http.GetAsync(url, ct).ConfigureAwait(false))
            {
                resp.EnsureSuccessStatusCode();
                return await resp.Content.ReadAsStringAsync().ConfigureAwait(false);
            }
        }

        static string DescribeWeatherCode(int code)
        {
            switch (code)
            {
                case 0: return "clear sky";
                case 1: return "mainly clear";
                case 2: return "partly cloudy";
                case 3: return "overcast";
                case 45: case 48: return "fog";
                case 51: case 53: case 55: return "drizzle";
                case 56: case 57: return "freezing drizzle";
                case 61: case 63: case 65: return "rain";
                case 66: case 67: return "freezing rain";
                case 71: case 73: case 75: return "snow";
                case 77: return "snow grains";
                case 80: case 81: case 82: return "rain showers";
                case 85: case 86: return "snow showers";
                case 95: return "thunderstorm";
                case 96: case 99: return "thunderstorm with hail";
                default: return "unknown conditions";
            }
        }

        string BuildApprovalRequiredMessage()
        {
            return "Approval required for tool " + Name + ". Choose an approval option in the modal to run this command.";
        }
    }
}