using System.Linq;
using System.Net;
using System.Text.Encodings.Web;
using System.Text.Json.Serialization;
using DTLib.Extensions;

namespace ParadoxSaveParser.WebAPI;

public partial class Program
{
    private static readonly JsonSerializerOptions _responseJsonSerializerOptions = new()
    {
        WriteIndented = false,
        Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping,
        MaxDepth = 1024
    };
    
    public static async Task<HttpStatusCode> ReturnResponseString(HttpListenerContext ctx,
        string value, HttpStatusCode statusCode = HttpStatusCode.OK)
    {
        ctx.Response.StatusCode = (int)statusCode;
        ctx.Response.ContentType = "text/plain";
        await ctx.Response.OutputStream.WriteAsync(
            value.ToBytes(),
            _mainCancel.Token);
        return statusCode;
    }

    public static async Task<HttpStatusCode> ReturnResponseJson(HttpListenerContext ctx,
        object value, HttpStatusCode statusCode = HttpStatusCode.OK)
    {
        ctx.Response.StatusCode = (int)statusCode;
        ctx.Response.ContentType = "application/json";
        await JsonSerializer.SerializeAsync(
            ctx.Response.OutputStream,
            value,
            value.GetType(),
            _responseJsonSerializerOptions,
            _mainCancel.Token);
        return statusCode;
    }

    public static async Task<HttpStatusCode> ReturnResponseError(HttpListenerContext ctx, ErrorMessage error)
    {
        ctx.Response.StatusCode = (int)error.StatusCode;
        ctx.Response.ContentType = "application/json";
        await JsonSerializer.SerializeAsync(
            ctx.Response.OutputStream,
            error,
            typeof(ErrorMessage),
            _responseJsonSerializerOptions,
            _mainCancel.Token);
        return error.StatusCode;
    }

    public record ErrorMessage
    {
        public ErrorMessage(HttpStatusCode statusCode, string message)
        {
            StatusCode = statusCode;
            Message = message;
        }

        [JsonIgnore] public HttpStatusCode StatusCode { get; }

        [JsonPropertyName("errorMessage")] public string Message { get; }
    }

    public class ValueOrError<T>
    {
        public readonly ErrorMessage? Error;
        public readonly T? Value;

        private ValueOrError(T? value, ErrorMessage? error)
        {
            Value = value;
            Error = error;
        }

        public bool HasError => Error is not null;

        public static implicit operator ValueOrError<T>(T v) => new(v, null);

        public static implicit operator ValueOrError<T>(ErrorMessage e) => new(default, e);
    }
    
    
    internal static ValueOrError<string> GetRequestQueryValue(HttpListenerContext ctx, string paramName)
    {
        string[]? values = ctx.Request.QueryString.GetValues(paramName);
        string? value = values?.FirstOrDefault();
        if (string.IsNullOrEmpty(value))
            return new ErrorMessage(HttpStatusCode.BadRequest,
                $"No request parameter '{paramName}' provided");
        return value;
    }
}