package otelsetup

import (
	"context"
	"fmt"
	"log/slog"
	"runtime/debug"

	"github.com/99designs/gqlgen/graphql"
	"github.com/vektah/gqlparser/v2/gqlerror"
	"go.opentelemetry.io/otel/codes"
	"go.opentelemetry.io/otel/trace"
)

// Recover is a gqlgen recover function, installed with srv.SetRecoverFunc(otelsetup.Recover).
// Unlike graphql.DefaultRecover, which prints the stack to stderr line by line, it logs the
// panic as a single structured ERROR record (via slog.Default) with the stack as an attribute,
// records it on the active span and marks the span as failed. The client gets the same generic
// "internal system error" as with the default, without the panic text.
func Recover(ctx context.Context, err any) error {
	stack := string(debug.Stack())
	panicErr, ok := err.(error)
	if !ok {
		panicErr = fmt.Errorf("%v", err)
	}

	attrs := []any{
		slog.String("panic", panicErr.Error()),
		slog.String("stack", stack),
	}
	if fc := graphql.GetFieldContext(ctx); fc != nil {
		attrs = append(attrs, slog.String("path", fc.Path().String()))
	}
	slog.Default().ErrorContext(ctx, "recovered panic in graphql resolver", attrs...)

	span := trace.SpanFromContext(ctx)
	span.RecordError(panicErr, trace.WithStackTrace(true))
	span.SetStatus(codes.Error, "panic: "+panicErr.Error())

	return gqlerror.Errorf("internal system error")
}