"""
Shared configuration / utility helpers for framework components:
- NamespaceWithGet: lightweight namespace behaving like a dict
- OmegaConf conversion helpers
- Config merging decorator for model __init__
- Checkpoint config/statistics loading
"""

import os
from pathlib import Path
from types import SimpleNamespace
import json

from typing import Union, List
import torchvision
import os
from pathlib import Path
from typing import Dict, List, Optional, Tuple

from types import SimpleNamespace
import torch, json
import torch.nn as nn
import numpy as np
from PIL import Image
import re
from omegaconf import OmegaConf
from types import SimpleNamespace
import inspect
import functools
from typing import Any


from starVLA.training.trainer_utils import initialize_overwatch

# Initialize Overwatch =>> Wraps `logging.Logger`
overwatch = initialize_overwatch(__name__)


from types import SimpleNamespace


class NamespaceWithGet(SimpleNamespace):
    def get(self, key, default=None):
        """
        Return attribute value if present, else default (dict-like API).

        Args:
            key: Attribute name.
            default: Fallback if attribute missing.

        Returns:
            Any: Stored value or default.
        """
        return getattr(self, key, default)

    def items(self):
        """
        Iterate (key, value) pairs like dict.items().

        Returns:
            Generator[Tuple[str, Any], None, None]
        """
        return ((key, getattr(self, key)) for key in self.__dict__)

    def __iter__(self):
        """
        Return iterator over attribute keys (enables dict unpacking **obj).

        Returns:
            Iterator[str]
        """
        return iter(self.__dict__)

    def to_dict(self):
        """
        Recursively convert nested NamespaceWithGet objects into plain dicts.

        Returns:
            dict: Fully materialized dictionary structure.
        """
        return {key: value.to_dict() if isinstance(value, NamespaceWithGet) else value for key, value in self.items()}


def dict_to_namespace(d):
    """
    Create an OmegaConf config from a plain dictionary.

    Args:
        d: Input dictionary.

    Returns:
        OmegaConf: DictConfig instance.
    """
    return OmegaConf.create(d)


def _to_omegaconf(x: Any):
    """
    Convert diverse input types into an OmegaConf object.

    Accepted types:
        - None -> empty DictConfig
        - str path -> load YAML/JSON via OmegaConf.load
        - dict -> DictConfig
        - DictConfig / ListConfig -> returned unchanged
        - NamespaceWithGet / SimpleNamespace -> converted via vars()/to_dict()

    Args:
        x: Input candidate.

    Returns:
        OmegaConf: Normalized configuration node.
    """
    if x is None:
        return OmegaConf.create({})
    if isinstance(x, OmegaConf.__class__):  # fallback, typically not hit
        return x
    try:
        # OmegaConf node detection
        from omegaconf import DictConfig, ListConfig

        if isinstance(x, (DictConfig, ListConfig)):
            return x
    except Exception:
        pass

    if isinstance(x, str):
        # treat as path
        return OmegaConf.load(x)
    if isinstance(x, dict):
        return OmegaConf.create(x)
    if isinstance(x, NamespaceWithGet) or isinstance(x, SimpleNamespace):
        # convert to plain dict
        try:
            d = x.to_dict() if hasattr(x, "to_dict") else vars(x)
        except Exception:
            d = vars(x)
        return OmegaConf.create(d)
    # fallback: try to create
    return OmegaConf.create(x)


def merge_pram_config(init):
    """
    Decorator for __init__ to unify config handling.

    Behavior:
        1. Extract 'config' kwarg / arg (path | dict | OmegaConf | namespace)
        2. Convert to OmegaConf
        3. Merge with explicitly passed init parameters (explicit overrides file)
        4. Attach merged config to self.config
        5. Call original __init__ with merged config

    Args:
        init: Original __init__ function.

    Returns:
        Wrapped initializer.
    """

    @functools.wraps(init)
    def wrapper(self, *args, **kwargs):
        # Map positional args to parameter names (excluding self)
        sig = inspect.signature(init)
        param_names = [name for i, (name, p) in enumerate(sig.parameters.items()) if i > 0]

        init_kwargs = {}
        for name, val in zip(param_names, args):
            init_kwargs[name] = val
        # override with explicit kwargs
        init_kwargs.update(kwargs)

        # get provided config (if any)
        provided_config = init_kwargs.get("config", None)

        loaded_cfg = _to_omegaconf(provided_config)

        # build params cfg from explicit init args (other than config)
        params = {k: v for k, v in init_kwargs.items() if k != "config"}
        params_cfg = OmegaConf.create(params) if params else OmegaConf.create({})

        # merge: loaded_cfg <- params_cfg (params override file)
        merged = OmegaConf.merge(loaded_cfg, params_cfg)

        # set on instance
        try:
            # prefer attaching OmegaConf directly
            self.config = merged
        except Exception:
            # fallback to dict
            self.config = OmegaConf.to_container(merged, resolve=True)

        # prepare kwargs for original init: ensure config is the merged OmegaConf
        call_kwargs = dict(init_kwargs)
        call_kwargs["config"] = merged

        # call original __init__ using keyword args only (safer)
        return init(self, **call_kwargs)

    return wrapper


_SUPPORTED_CKPT_SUFFIXES = {".pt", ".safetensors"}


def _resolve_run_dir(checkpoint_pt):
    """Resolve run directory from a checkpoint path.

    For files in checkpoints/ (e.g. run_dir/checkpoints/model.pt), go up 2 levels.
    """
    return checkpoint_pt.parents[1]


def read_model_config(pretrained_checkpoint):
    """
    Load global model configuration and dataset normalization statistics
    associated with a saved checkpoint (.pt or .safetensors).

    Expected directory layout:
        <run_dir>/checkpoints/<name>.pt|.safetensors
        <run_dir>/config.json
        <run_dir>/dataset_statistics.json

    Args:
        pretrained_checkpoint: Path to a .pt or .safetensors checkpoint file.

    Returns:
        tuple:
            global_cfg (dict): Loaded config.json contents.
            norm_stats (dict): Dataset statistics for (de)normalization.

    Raises:
        FileNotFoundError: If checkpoint or required JSON files are missing.
        AssertionError: If file suffix or structure invalid.
    """
    if os.path.isfile(pretrained_checkpoint):
        checkpoint_pt = Path(pretrained_checkpoint)
        overwatch.info(f"Loading from local checkpoint path `{checkpoint_pt}`")

        assert checkpoint_pt.suffix in _SUPPORTED_CKPT_SUFFIXES, (
            f"Unsupported checkpoint suffix `{checkpoint_pt.suffix}`, expected one of {_SUPPORTED_CKPT_SUFFIXES}"
        )
        run_dir = _resolve_run_dir(checkpoint_pt)

        # Get paths for `config.json`, `dataset_statistics.json` and pretrained checkpoint
        config_json, dataset_statistics_json = run_dir / "config.json", run_dir / "dataset_statistics.json"
        assert config_json.exists(), f"Missing `config.json` for `{run_dir = }`"
        assert dataset_statistics_json.exists(), f"Missing `dataset_statistics.json` for `{run_dir = }`"

        with open(config_json, "r") as f:
            global_cfg = json.load(f)

        with open(dataset_statistics_json, "r") as f:
            norm_stats = json.load(f)
    else:
        overwatch.error(f"❌ Pretrained checkpoint `{pretrained_checkpoint}` does not exist.")
        raise FileNotFoundError(f"Pretrained checkpoint `{pretrained_checkpoint}` does not exist.")
    return global_cfg, norm_stats


def read_mode_config(pretrained_checkpoint):
    """
    Load YAML model configuration and dataset normalization statistics
    associated with a saved checkpoint (.pt or .safetensors).

    Args:
        pretrained_checkpoint: Path to a .pt or .safetensors checkpoint file.

    Returns:
        tuple:
            vla_cfg (dict)
            norm_stats (dict)
    """
    if os.path.isfile(pretrained_checkpoint):
        checkpoint_pt = Path(pretrained_checkpoint)
        overwatch.info(f"Loading from local checkpoint path `{checkpoint_pt}`")

        assert checkpoint_pt.suffix in _SUPPORTED_CKPT_SUFFIXES, (
            f"Unsupported checkpoint suffix `{checkpoint_pt.suffix}`, expected one of {_SUPPORTED_CKPT_SUFFIXES}"
        )
        run_dir = _resolve_run_dir(checkpoint_pt)

        config_yaml, dataset_statistics_json = run_dir / "config.yaml", run_dir / "dataset_statistics.json"
        assert config_yaml.exists(), f"Missing `config.yaml` for `{run_dir = }`"
        assert dataset_statistics_json.exists(), f"Missing `dataset_statistics.json` for `{run_dir = }`"

        try:
            ocfg = OmegaConf.load(str(config_yaml))
            global_cfg = OmegaConf.to_container(ocfg, resolve=True)
        except Exception as e:
            overwatch.error(f"❌ Failed to load YAML config `{config_yaml}`: {e}")
            raise

        with open(dataset_statistics_json, "r") as f:
            norm_stats = json.load(f)
    else:
        overwatch.error(f"❌ Pretrained checkpoint `{pretrained_checkpoint}` does not exist.")
        raise FileNotFoundError(f"Pretrained checkpoint `{pretrained_checkpoint}` does not exist.")
    return global_cfg, norm_stats