import json

from fasthtml.xtend import Script

from myfasthtml.core.commands import Command
from myfasthtml.core.instances import MultipleInstance


class Mouse(MultipleInstance):
  """
  Represents a mechanism to manage mouse event combinations and their associated commands.

  This class is used to add, manage, and render mouse event sequences with corresponding
  commands, providing a flexible way to handle mouse interactions programmatically.

  Combinations can be defined with:
  - A Command object: mouse.add("click", command)
  - HTMX parameters: mouse.add("click", hx_post="/url", hx_vals={...})
  - Both (named params override command): mouse.add("click", command, hx_target="#other")

  For dynamic hx_vals, use "js:functionName()" to call a client-side function.
  """
  def __init__(self, parent, _id=None, combinations=None):
    super().__init__(parent, _id=_id)
    self.combinations = combinations or {}

  def add(self, sequence: str, command: Command = None, *,
          hx_post: str = None, hx_get: str = None, hx_put: str = None,
          hx_delete: str = None, hx_patch: str = None,
          hx_target: str = None, hx_swap: str = None, hx_vals=None):
    """
    Add a mouse combination with optional command and HTMX parameters.

    Args:
        sequence: Mouse event sequence (e.g., "click", "ctrl+click", "click right_click")
        command: Optional Command object for server-side action
        hx_post: HTMX post URL (overrides command)
        hx_get: HTMX get URL (overrides command)
        hx_put: HTMX put URL (overrides command)
        hx_delete: HTMX delete URL (overrides command)
        hx_patch: HTMX patch URL (overrides command)
        hx_target: HTMX target selector (overrides command)
        hx_swap: HTMX swap strategy (overrides command)
        hx_vals: HTMX values dict or "js:functionName()" for dynamic values

    Returns:
        self for method chaining
    """
    self.combinations[sequence] = {
      "command": command,
      "hx_post": hx_post,
      "hx_get": hx_get,
      "hx_put": hx_put,
      "hx_delete": hx_delete,
      "hx_patch": hx_patch,
      "hx_target": hx_target,
      "hx_swap": hx_swap,
      "hx_vals": hx_vals,
    }
    return self

  def _build_htmx_params(self, combination_data: dict) -> dict:
    """
    Build HTMX parameters by merging command params with named overrides.

    Named parameters take precedence over command parameters.
    hx_vals is handled separately via hx-vals-extra to preserve command's hx-vals.
    """
    command = combination_data.get("command")

    # Start with command params if available
    if command is not None:
      params = command.get_htmx_params().copy()
    else:
      params = {}

    # Override with named parameters (only if explicitly set)
    # Note: hx_vals is handled separately below
    param_mapping = {
      "hx_post": "hx-post",
      "hx_get": "hx-get",
      "hx_put": "hx-put",
      "hx_delete": "hx-delete",
      "hx_patch": "hx-patch",
      "hx_target": "hx-target",
      "hx_swap": "hx-swap",
    }

    for py_name, htmx_name in param_mapping.items():
      value = combination_data.get(py_name)
      if value is not None:
        params[htmx_name] = value

    # Handle hx_vals separately - store in hx-vals-extra to not overwrite command's hx-vals
    hx_vals = combination_data.get("hx_vals")
    if hx_vals is not None:
      if isinstance(hx_vals, str) and hx_vals.startswith("js:"):
        # Dynamic values: extract function name
        func_name = hx_vals[3:].rstrip("()")
        params["hx-vals-extra"] = {"js": func_name}
      elif isinstance(hx_vals, dict):
        # Static dict values
        params["hx-vals-extra"] = {"dict": hx_vals}
      else:
        # Other string values - try to parse as JSON
        try:
          parsed = json.loads(hx_vals)
          if not isinstance(parsed, dict):
            raise ValueError(f"hx_vals must be a dict, got {type(parsed).__name__}")
          params["hx-vals-extra"] = {"dict": parsed}
        except json.JSONDecodeError as e:
          raise ValueError(f"hx_vals must be a dict or 'js:functionName()', got invalid JSON: {e}")

    return params

  def render(self):
    str_combinations = {
      sequence: self._build_htmx_params(data)
      for sequence, data in self.combinations.items()
    }
    return Script(f"add_mouse_support('{self._parent.get_id()}', '{json.dumps(str_combinations)}')")
  
  def __ft__(self):
    return self.render()