import gradio as gr


def _validate_target(target_b64):
    if not target_b64 or target_b64.strip() in ("", "null"):
        raise gr.Error("Please upload a target image.")


def _validate_selection(selected_indices):
    if not selected_indices:
        raise gr.Error("Please select at least one face to swap.")


def _validate_sources(selected_indices, sources):
    for idx in selected_indices:
        if not sources.get(str(idx)):
            raise gr.Error(f"Please upload a source image for face {idx + 1}.")


def _validate_bboxes(selected_indices, bboxes):
    for idx in selected_indices:
        bbox = bboxes.get(str(idx))
        if not bbox or len(bbox) != 4:
            raise gr.Error(
                f"Missing bounding box for face {idx + 1}. Please re-upload the target image."
            )