#!/usr/bin/env python3
"""Open a URL, dev server, or file in the Hermes desktop GUI's preview pane.

Gated on ``HERMES_DESKTOP`` (like ``read_terminal`` / ``close_terminal``) so it
never appears outside the GUI. Emits ``preview.open`` through the shared
``desktop_ui`` bridge; the renderer opens the pane beside the chat for the
window that asked and never steals focus for a background session.
"""

import json
import re

from tools import desktop_ui
from tools.registry import registry, tool_error
from utils import env_var_enabled


def _normalize_target(raw: str) -> str:
    """Coax a bare host/domain into a fetchable URL; leave paths + schemes alone.

    ``www.cnn.com`` → ``https://www.cnn.com``; ``localhost:3000`` →
    ``http://localhost:3000``. File paths and explicit schemes pass through for
    the renderer's preview normalizer to classify.
    """
    v = raw.strip().strip("`").strip()
    if not v or "://" in v or v.startswith(("/", "./", "../", "~", "file:")):
        return v
    if re.match(r"^(localhost|127\.0\.0\.1|0\.0\.0\.0|\[::1\])(:\d+)?(/|$)", v, re.I):
        return "http://" + v
    if re.match(r"^[\w.-]+\.[a-z]{2,}(:\d+)?(/.*)?$", v, re.I):
        return "https://" + v
    return v


def open_preview_tool(url: str, label: str = "") -> str:
    """Ask the desktop GUI to show ``url`` in the preview pane beside the chat."""
    target = _normalize_target(url or "")
    if not target:
        return tool_error(
            "url is required — a web URL (https://…), a localhost dev server, or a "
            "file path to show in the preview pane."
        )

    label = (label or "").strip()
    try:
        ok = desktop_ui.emit("preview.open", {"url": target, "label": label})
    except Exception as exc:
        return tool_error(f"Failed to open the preview pane: {exc}")
    if not ok:
        return tool_error("The preview pane is only available in the Hermes desktop app.")

    return json.dumps({"success": True, "url": target, "label": label}, ensure_ascii=False)


def check_open_preview_requirements() -> bool:
    """Desktop GUI only — HERMES_DESKTOP is set on the gateway the app spawns."""
    return env_var_enabled("HERMES_DESKTOP")


OPEN_PREVIEW_SCHEMA = {
    "name": "open_preview",
    "description": (
        "Open something in the preview pane beside the chat in the Hermes desktop "
        "app. Use this when the user asks to see a page, dev server, or file in the "
        "preview pane — e.g. \"open cnn.com in the preview pane\" or \"preview "
        "localhost:3000\". Accepts a web URL (a bare domain like www.cnn.com is fine), "
        "a localhost dev-server URL, or a file path (HTML renders live; other files "
        "show their contents). The pane opens for the current window only."
    ),
    "parameters": {
        "type": "object",
        "properties": {
            "url": {
                "type": "string",
                "description": (
                    "What to preview: a web URL (https://… or a bare domain), a "
                    "localhost URL (localhost:3000), or a file path."
                ),
            },
            "label": {
                "type": "string",
                "description": "Optional tab label; defaults to the target's name.",
            },
        },
        "required": ["url"],
    },
}


registry.register(
    name="open_preview",
    toolset="terminal",
    schema=OPEN_PREVIEW_SCHEMA,
    handler=lambda args, **kw: open_preview_tool(url=args.get("url", ""), label=args.get("label", "")),
    check_fn=check_open_preview_requirements,
    emoji="🖼️",
)