using System.ComponentModel.DataAnnotations;
using System.Net;
using Galaeth.ApiServer.Constants;
using Galaeth.ApiServer.Models.Common;
using Galaeth.Core.Constants;
using Galaeth.Core.Exceptions;

namespace Galaeth.ApiServer.Middleware;

/// <summary>
/// Handle exceptions caught in a request.
/// </summary>
public class ExceptionMiddleware
{
    private readonly RequestDelegate _next;
    private readonly ILogger<ExceptionMiddleware> _logger;

    /// <summary>
    /// Initializes a new instance of the <see cref="ExceptionMiddleware"/> class.
    /// </summary>
    /// <param name="next">Instance of <see cref="RequestDelegate"/>.</param>
    /// <param name="logger">Instance of <see cref="ILogger"/>.</param>
    public ExceptionMiddleware(
        RequestDelegate next,
        ILogger<ExceptionMiddleware> logger)
    {
        _next = next;
        _logger = logger;
    }

     /// <summary>
    /// Invoke middleware.
    /// </summary>
    /// <param name="httpContext">Instance of <see cref="HttpContext"/>.</param>
    public async Task InvokeAsync(HttpContext httpContext)
    {
        try
        {
            await _next(httpContext);
        }
        catch (ServiceException exception)
        {
            await HandleServiceExceptionAsync(httpContext, exception);
        }
        catch (ValidationException exception)
        {
            await HandleValidationExceptionAsync(httpContext, exception);
        }
        catch (Exception exception)
        {
            _logger.LogError(
                "Unhandled Exception: {path} using {method}: {exception}",
                httpContext.Request.Path,
                httpContext.Request.Method,
                exception);
            await HandleOtherExceptionAsync(httpContext);
        }
    }

    /// <summary>
    /// Api exception.
    /// </summary>
    /// <param name="context">Instance of <see cref="HttpContext"/>.</param>
    /// <param name="exception">Instance of <see cref="ValidationException"/>.</param>
    private static async Task HandleServiceExceptionAsync(HttpContext context, ServiceException exception)
    {
        context.Response.ContentType = "application/json";
        context.Response.StatusCode = (int)exception.HttpStatusCode;
        await context.Response.WriteAsJsonAsync(new ErrorResultModel
        {
            Error = exception.ErrorCode,
            Message = exception.ErrorMessage,
        });
    }

    /// <summary>
    /// Validation failed.
    /// </summary>
    /// <param name="context">Instance of <see cref="HttpContext"/>.</param>
    /// <param name="exception">Instance of <see cref="ValidationException"/>.</param>
    private static async Task HandleValidationExceptionAsync(HttpContext context, ValidationException exception)
    {
        context.Response.ContentType = "application/json";
        context.Response.StatusCode = StatusCodes.Status422UnprocessableEntity;
        await context.Response.WriteAsJsonAsync(new ErrorResultModel
        {
            Error = CoreErrorCodes.ValidationError,
            Message = exception.Message,
        });
    }

    /// <summary>
    /// Unexpected exception.
    /// </summary>
    /// <param name="context">Instance of <see cref="HttpContext"/>.</param>
    private static async Task HandleOtherExceptionAsync(HttpContext context)
    {
        context.Response.ContentType = "application/json";
        context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
        await context.Response.WriteAsJsonAsync(new ErrorResultModel()
        {
            Success = false,
            Error = ApiErrorCodes.UnknownError,
            Message = "Something went wrong. Try again later",
        });
    }
}