#!/usr/bin/env python3

# Adapted from: https://enix.io/en/blog/pxe-talos/

import functools
import json
import pathlib

import requests
import yaml
from jinja2 import Environment, FileSystemLoader, StrictUndefined, Template

NODES = pathlib.Path("nodes")
SCHEMATICS = pathlib.Path("schematics")
PATCHES = Environment(loader=FileSystemLoader("patches"), undefined=StrictUndefined)
TEMPLATES = Environment(loader=FileSystemLoader("templates"), undefined=StrictUndefined)


def node_encoder(node: dict):
    class Inner(json.JSONEncoder):
        def default(self, o):
            if isinstance(o, Template):
                try:
                    rendered = o.render(node)
                except Exception as e:
                    e.add_note(f"While rendering for: {node['hostname']}")
                    raise e
                # Parse the rendered yaml and convert it to a json patch
                return json.dumps(yaml.safe_load(rendered))

            return super().default(o)

    return Inner


@functools.cache
def get_schematic_id(schematic: str):
    """Lookup the schematic id associated with a given schematic"""
    r = requests.post("https://factory.talos.dev/schematics", data=schematic)
    r.raise_for_status()
    data = r.json()
    return data["id"]


def schematic_constructor(loader: yaml.SafeLoader, node: yaml.nodes.ScalarNode):
    """Load specified schematic file and get the assocatied schematic id"""
    schematic_name = loader.construct_yaml_str(node)
    try:
        schematic = SCHEMATICS.joinpath(schematic_name).with_suffix(".yaml").read_text()
        return get_schematic_id(schematic)
    except Exception:
        raise yaml.MarkedYAMLError("Failed to load schematic", node.start_mark)


def patch_constructor(loader: yaml.SafeLoader, node: yaml.nodes.ScalarNode):
    patch_name = loader.construct_scalar(node)
    try:
        template = PATCHES.get_template(f"{patch_name}.yaml")
        return template
    except Exception:
        raise yaml.MarkedYAMLError("Failed to load patch", node.start_mark)


def get_loader():
    """Add special constructors to yaml loader"""
    loader = yaml.SafeLoader
    loader.add_constructor("!schematic", schematic_constructor)
    loader.add_constructor("!patch", patch_constructor)

    return loader


@functools.cache
def get_defaults(directory: pathlib.Path, root: pathlib.Path):
    """Compute the defaults from the provided directory and parents."""
    try:
        with open(directory.joinpath("_defaults.yaml")) as fyaml:
            yml_data = yaml.load(fyaml, Loader=get_loader())
    except OSError:
        yml_data = {}

    # Stop recursion when reaching root directory
    if directory != root:
        return get_defaults(directory.parent, root) | yml_data
    else:
        return yml_data


def walk_files(root: pathlib.Path):
    """Get all files that do not start with and underscore"""
    for dirpath, _dirnames, filenames in root.walk():
        for fn in filenames:
            if not fn.startswith("_"):
                yield dirpath.joinpath(fn)


def main():
    nodes = []
    for fullname in walk_files(NODES):
        filename = str(fullname.relative_to(NODES).parent) + "/" + fullname.stem

        with open(fullname) as fyaml:
            yml_data = yaml.load(fyaml, Loader=get_loader())
        yml_data = get_defaults(fullname.parent, NODES) | yml_data
        yml_data["hostname"] = fullname.stem
        yml_data["filename"] = filename
        nodes.append(yml_data)

    final_nodes = []
    for node in nodes:
        # Quick and dirty way to resolve all the templates using a custom encoder
        final_nodes.append(json.loads(json.dumps(node, cls=node_encoder(node))))

    # Dump everything to json
    print(json.dumps(final_nodes, indent=4))


if __name__ == "__main__":
    main()