using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace DigitalData.Core.Exceptions.Middleware;

/// <summary>
/// Middleware for handling exceptions globally in the application.
/// Captures exceptions thrown during the request pipeline execution,
/// logs them, and returns an appropriate HTTP response with a JSON error message.
/// </summary>
public class GlobalExceptionHandlerMiddleware
{
    private readonly RequestDelegate _next;

    private readonly ILogger<GlobalExceptionHandlerMiddleware>? _logger;

    private readonly GlobalExceptionHandlerOptions? _options;

    /// <summary>
    /// Initializes a new instance of the <see cref="GlobalExceptionHandlerMiddleware"/> class.
    /// </summary>
    /// <param name="next">The next middleware in the request pipeline.</param>
    /// <param name="logger">The logger instance for logging exceptions.</param>
    public GlobalExceptionHandlerMiddleware(RequestDelegate next, ILogger<GlobalExceptionHandlerMiddleware>? logger = null, IOptions<GlobalExceptionHandlerOptions>? options = null)
    {
        _next = next;
        _logger = logger;
        _options = options?.Value;
    }

    /// <summary>
    /// Invokes the middleware to handle the HTTP request.
    /// </summary>
    /// <param name="context">The HTTP context of the current request.</param>
    /// <returns>A task that represents the asynchronous operation.</returns>
    public async Task InvokeAsync(HttpContext context)
    {
        try
        {
            await _next(context); // Continue down the pipeline
        }
        catch (Exception ex)
        {
            if(ex.GetType() == typeof(Exception) && _options?.DefaultHandler is not null)
                await _options.DefaultHandler.HandleExceptionAsync(context, ex, _logger);

            if (_options?.Handlers.TryGetValue(ex.GetType(), out var handler) ?? false)
                await handler.HandleExceptionAsync(context, ex, _logger);
        }
    }
}