"""Image-generation JSON-RPC handler (ws twin of the image_generate tool), so UI
surfaces (avatar pickers, artifact panes) can generate directly. The result is
returned as a data URL: a remote desktop can't read a gateway file path and hosted
URLs are often CORS-opaque to a renderer canvas.

Bodies are rebound onto server.py's globals at install time (see
method_ctx.bind_module), so they reference server.py globals bare.
"""

from .method_ctx import HandlerRegistry, bind_module

_registry = HandlerRegistry()
method = _registry.method


def _image_gen_available() -> bool:
    try:
        from tools.image_generation_tool import check_image_generation_requirements

        return bool(check_image_generation_requirements())
    except Exception:
        return False


def _image_to_data_url(ref: str, cap: int):
    """Fetch a URL or read a local path into a data URL; None when missing, over *cap*, or failing."""
    import base64
    import mimetypes
    import os

    try:
        if ref.startswith(("http://", "https://")):
            import urllib.request

            req = urllib.request.Request(ref, headers={"User-Agent": "hermes-agent"})
            with urllib.request.urlopen(req, timeout=60) as resp:
                if resp.length is not None and resp.length > cap:
                    return None
                data = resp.read(cap + 1)
                mime = resp.headers.get_content_type() or "image/png"
        elif os.path.isfile(ref):
            if os.path.getsize(ref) > cap:
                return None
            with open(ref, "rb") as fh:
                data = fh.read(cap + 1)
            mime = mimetypes.guess_type(ref)[0] or "image/png"
        else:
            return None
        if len(data) > cap:
            return None
        if not mime.startswith("image/"):
            mime = "image/png"
        return f"data:{mime};base64,{base64.b64encode(data).decode('ascii')}"
    except Exception:
        return None


@method("image.generate")
def _(rid, params: dict) -> dict:
    """Params: ``prompt`` (required unless ``probe``), ``aspect_ratio``
    (landscape|square|portrait), ``probe`` (availability only), ``max_bytes`` (cap
    on the data URL, default 8MB, max 16MB). Result: ``{available, success, image,
    image_data, error}`` — ``image_data`` is omitted when the download fails, so
    callers fall back to ``image`` (the backend's URL/path)."""
    available = _image_gen_available()
    if is_truthy_value(params.get("probe", False)):
        return _ok(rid, {"available": available})
    if not available:
        return _ok(
            rid,
            {
                "available": False,
                "success": False,
                "error": "No image generation backend configured (run `hermes tools` to enable one).",
            },
        )

    prompt = str(params.get("prompt") or "").strip()
    if not prompt:
        return _err(rid, 4071, "prompt required")

    aspect = str(params.get("aspect_ratio") or "square").strip().lower()
    try:
        cap = min(int(params.get("max_bytes", 8_000_000) or 8_000_000), 16_000_000)
    except (TypeError, ValueError):
        cap = 8_000_000

    try:
        from tools.image_generation_tool import _handle_image_generate

        # Full provider dispatcher — same path as the model tool (source-image
        # confinement, plugin providers, managed routing, FAL fallback); calling
        # the FAL leaf directly bypassed configured providers.
        raw = _handle_image_generate({"prompt": prompt, "aspect_ratio": aspect})
        result = json.loads(raw)
    except Exception as e:
        return _err(rid, 5071, str(e))

    if not result.get("success"):
        return _ok(
            rid,
            {
                "available": True,
                "success": False,
                "error": str(result.get("error") or "generation failed"),
            },
        )

    image_ref = str(result.get("image") or "")
    payload = {"available": True, "success": True, "image": image_ref}
    data_url = _image_to_data_url(image_ref, cap) if image_ref else None
    if data_url:
        payload["image_data"] = data_url
    return _ok(rid, payload)


def register(server) -> None:
    """Publish this module's helpers + handlers onto ``server``, rebound to its globals."""
    bind_module(globals(), server, skip=("_",))