using Microsoft.AspNetCore.Diagnostics;
using Microsoft.AspNetCore.Mvc;

namespace SatelliteProvider.Api;

public sealed class GlobalExceptionHandler : IExceptionHandler
{
    private readonly ILogger<GlobalExceptionHandler> _logger;

    public GlobalExceptionHandler(ILogger<GlobalExceptionHandler> logger)
    {
        _logger = logger;
    }

    public async ValueTask<bool> TryHandleAsync(
        HttpContext httpContext,
        Exception exception,
        CancellationToken cancellationToken)
    {
        // Framework-level request-binding/parsing failures carry their own HTTP status
        // (typically 400/415). Honor that status so we don't promote a client error to 5xx.
        if (exception is BadHttpRequestException badRequest)
        {
            await WriteClientErrorAsync(httpContext, badRequest, cancellationToken);
            return true;
        }

        var correlationId = httpContext.TraceIdentifier;

        _logger.LogError(
            exception,
            "Unhandled exception while processing {Method} {Path} (correlationId={CorrelationId})",
            httpContext.Request.Method,
            httpContext.Request.Path,
            correlationId);

        httpContext.Response.StatusCode = StatusCodes.Status500InternalServerError;

        var problem = new ProblemDetails
        {
            Status = StatusCodes.Status500InternalServerError,
            Title = "Internal Server Error",
            Detail = "An unexpected error occurred. Use the correlationId to look up the server log entry.",
            Type = "https://datatracker.ietf.org/doc/html/rfc9110#name-500-internal-server-error",
        };
        problem.Extensions["correlationId"] = correlationId;

        await httpContext.Response.WriteAsJsonAsync(
            problem,
            options: null,
            contentType: "application/problem+json",
            cancellationToken: cancellationToken);
        return true;
    }

    private static async Task WriteClientErrorAsync(
        HttpContext httpContext,
        BadHttpRequestException badRequest,
        CancellationToken cancellationToken)
    {
        httpContext.Response.StatusCode = badRequest.StatusCode;

        var problem = new ProblemDetails
        {
            Status = badRequest.StatusCode,
            Title = "Bad Request",
            Detail = badRequest.Message,
        };

        await httpContext.Response.WriteAsJsonAsync(
            problem,
            options: null,
            contentType: "application/problem+json",
            cancellationToken: cancellationToken);
    }
}