# !/usr/bin/env python3
import argparse
import json
import os
import re
import shlex
import subprocess
import sys
from pathlib import Path
from typing import Any, Optional, Tuple, get_origin

from clan_cli.dirs import machine_settings_file, specific_flake_dir
from clan_cli.errors import ClanError
from clan_cli.git import commit_file
from clan_cli.nix import nix_eval
from clan_cli.types import FlakeName

script_dir = Path(__file__).parent


# nixos option type description to python type
def map_type(type: str) -> Any:
    if type == "boolean":
        return bool
    elif type in [
        "integer",
        "signed integer",
        "16 bit unsigned integer; between 0 and 65535 (both inclusive)",
    ]:
        return int
    elif type == "string":
        return str
    # lib.type.passwdEntry
    elif type == "string, not containing newlines or colons":
        return str
    elif type.startswith("null or "):
        subtype = type.removeprefix("null or ")
        return Optional[map_type(subtype)]
    elif type.startswith("attribute set of"):
        subtype = type.removeprefix("attribute set of ")
        return dict[str, map_type(subtype)]  # type: ignore
    elif type.startswith("list of"):
        subtype = type.removeprefix("list of ")
        return list[map_type(subtype)]  # type: ignore
    else:
        raise ClanError(f"Unknown type {type}")


# merge two dicts recursively
def merge(a: dict, b: dict, path: list[str] = []) -> dict:
    for key in b:
        if key in a:
            if isinstance(a[key], dict) and isinstance(b[key], dict):
                merge(a[key], b[key], path + [str(key)])
            elif isinstance(a[key], list) and isinstance(b[key], list):
                a[key].extend(b[key])
            elif a[key] != b[key]:
                a[key] = b[key]
        else:
            a[key] = b[key]
    return a


# A container inheriting from list, but overriding __contains__ to return True
# for all values.
# This is used to allow any value for the "choices" field of argparse
class AllContainer(list):
    def __contains__(self, item: Any) -> bool:
        return True


# value is always a list, as the arg parser cannot know the type upfront
# and therefore always allows multiple arguments.
def cast(value: Any, type: Any, opt_description: str) -> Any:
    try:
        # handle bools
        if isinstance(type, bool):
            if value[0] in ["true", "True", "yes", "y", "1"]:
                return True
            elif value[0] in ["false", "False", "no", "n", "0"]:
                return False
            else:
                raise ClanError(f"Invalid value {value} for boolean")
        # handle lists
        elif get_origin(type) == list:
            subtype = type.__args__[0]
            return [cast([x], subtype, opt_description) for x in value]
        # handle dicts
        elif get_origin(type) == dict:
            if not isinstance(value, dict):
                raise ClanError(
                    f"Cannot set {opt_description} directly. Specify a suboption like {opt_description}.<name>"
                )
            subtype = type.__args__[1]
            return {k: cast(v, subtype, opt_description) for k, v in value.items()}
        elif str(type) == "typing.Optional[str]":
            if value[0] in ["null", "None"]:
                return None
            return value[0]
        else:
            if len(value) > 1:
                raise ClanError(f"Too many values for {opt_description}")
            return type(value[0])
    except ValueError:
        raise ClanError(
            f"Invalid type for option {opt_description} (expected {type.__name__})"
        )


def options_for_machine(
    flake_name: FlakeName, machine_name: str, show_trace: bool = False
) -> dict:
    clan_dir = specific_flake_dir(flake_name)
    flags = []
    if show_trace:
        flags.append("--show-trace")
    flags.append(
        f"{clan_dir}#nixosConfigurations.{machine_name}.config.clanCore.optionsNix"
    )
    cmd = nix_eval(flags=flags)
    proc = subprocess.run(
        cmd,
        stdout=subprocess.PIPE,
        text=True,
    )
    if proc.returncode != 0:
        raise ClanError(
            f"Failed to read options for machine {machine_name}:\n{shlex.join(cmd)}\nexit with {proc.returncode}"
        )
    return json.loads(proc.stdout)


def read_machine_option_value(
    flake_name: FlakeName, machine_name: str, option: str, show_trace: bool = False
) -> str:
    clan_dir = specific_flake_dir(flake_name)
    # use nix eval to read from .#nixosConfigurations.default.config.{option}
    # this will give us the evaluated config with the options attribute
    cmd = nix_eval(
        flags=[
            "--show-trace",
            f"{clan_dir}#nixosConfigurations.{machine_name}.config.{option}",
        ],
    )
    proc = subprocess.run(cmd, stdout=subprocess.PIPE, text=True)
    if proc.returncode != 0:
        raise ClanError(
            f"Failed to read option {option}:\n{shlex.join(cmd)}\nexit with {proc.returncode}"
        )
    value = json.loads(proc.stdout)
    # print the value so that the output can be copied and fed as an input.
    # for example a list should be displayed as space separated values surrounded by quotes.
    if isinstance(value, list):
        out = " ".join([json.dumps(x) for x in value])
    elif isinstance(value, dict):
        out = json.dumps(value, indent=2)
    else:
        out = json.dumps(value, indent=2)
    return out


def get_or_set_option(args: argparse.Namespace) -> None:
    if args.value == []:
        print(
            read_machine_option_value(
                args.flake, args.machine, args.option, args.show_trace
            )
        )
    else:
        # load options
        if args.options_file is None:
            options = options_for_machine(
                args.flake, machine_name=args.machine, show_trace=args.show_trace
            )
        else:
            with open(args.options_file) as f:
                options = json.load(f)
        # compute settings json file location
        if args.settings_file is None:
            settings_file = machine_settings_file(args.flake, args.machine)
        else:
            settings_file = args.settings_file
        # set the option with the given value
        set_option(
            flake_name=args.flake,
            option=args.option,
            value=args.value,
            options=options,
            settings_file=settings_file,
            option_description=args.option,
            show_trace=args.show_trace,
        )
        if not args.quiet:
            new_value = read_machine_option_value(args.flake, args.machine, args.option)
            print(f"New Value for {args.option}:")
            print(new_value)


def find_option(
    option: str, value: Any, options: dict, option_description: Optional[str] = None
) -> Tuple[str, Any]:
    """
    The option path specified by the user doesn't have to match exactly to an
    entry in the options.json file. Examples

    Example 1:
        $ clan config services.openssh.settings.SomeSetting 42
    This is a freeform option that does not appear in the options.json
    The actual option is `services.openssh.settings`
    And the value must be wrapped: {"SomeSettings": 42}

    Example 2:
        $ clan config users.users.my-user.name my-name
    The actual option is `users.users.<name>.name`
    """

    # option description is used for error messages
    if option_description is None:
        option_description = option

    option_path = option.split(".")

    # fuzzy search the option paths, so when
    #   specified option path: "foo.bar.baz.bum"
    #   available option path: "foo.<name>.baz.<name>"
    # we can still find the option
    first = option_path[0]
    regex = rf"({first}|<name>)"
    for elem in option_path[1:]:
        regex += rf"\.({elem}|<name>)"
    for opt in options.keys():
        if re.match(regex, opt):
            return opt, value

    # if the regex search did not find the option, start stripping the last
    # element of the option path and find matching parent option
    # (see examples above for why this is needed)
    if len(option_path) == 1:
        raise ClanError(f"Option {option_description} not found")
    option_path_parent = option_path[:-1]
    attr_prefix = option_path[-1]
    return find_option(
        option=".".join(option_path_parent),
        value={attr_prefix: value},
        options=options,
        option_description=option_description,
    )


def set_option(
    flake_name: FlakeName,
    option: str,
    value: Any,
    options: dict,
    settings_file: Path,
    option_description: str = "",
    show_trace: bool = False,
) -> None:
    option_path_orig = option.split(".")

    # returns for example:
    #   option: "users.users.<name>.name"
    #   value: "my-name"
    option, value = find_option(
        option=option,
        value=value,
        options=options,
        option_description=option_description,
    )
    option_path = option.split(".")

    option_path_store = option_path_orig[: len(option_path)]

    target_type = map_type(options[option]["type"])
    casted = cast(value, target_type, option)

    # construct a nested dict from the option path and set the value
    result: dict[str, Any] = {}
    current = result
    for part in option_path_store[:-1]:
        current[part] = {}
        current = current[part]
    current[option_path_store[-1]] = value

    current[option_path_store[-1]] = casted

    # check if there is an existing config file
    if os.path.exists(settings_file):
        with open(settings_file) as f:
            current_config = json.load(f)
    else:
        current_config = {}
    # merge and save the new config file
    new_config = merge(current_config, result)
    settings_file.parent.mkdir(parents=True, exist_ok=True)
    with open(settings_file, "w") as f:
        json.dump(new_config, f, indent=2)
        print(file=f)  # add newline at the end of the file to make git happy

    if settings_file.resolve().is_relative_to(specific_flake_dir(flake_name)):
        commit_file(settings_file, commit_message=f"Set option {option_description}")


# takes a (sub)parser and configures it
def register_parser(
    parser: Optional[argparse.ArgumentParser],
) -> None:
    if parser is None:
        parser = argparse.ArgumentParser(
            description="Set or show NixOS options",
        )

    # inject callback function to process the input later
    parser.set_defaults(func=get_or_set_option)
    parser.add_argument(
        "--machine",
        "-m",
        help="Machine to configure",
        type=str,
        default="default",
    )

    parser.add_argument(
        "--show-trace",
        help="Show nix trace on evaluation error",
        action="store_true",
    )

    parser.add_argument(
        "--options-file",
        help="JSON file with options",
        type=Path,
    )

    parser.add_argument(
        "--settings-file",
        help="JSON file with settings",
        type=Path,
    )
    parser.add_argument(
        "--quiet",
        help="Do not print the value",
        action="store_true",
    )

    parser.add_argument(
        "option",
        help="Option to read or set (e.g. foo.bar)",
        type=str,
    )

    parser.add_argument(
        "value",
        # force this arg to be set
        nargs="*",
        help="option value to set (if omitted, the current value is printed)",
    )
    parser.add_argument(
        "flake",
        type=str,
        help="name of the flake to set machine options for",
    )


def main(argv: Optional[list[str]] = None) -> None:
    if argv is None:
        argv = sys.argv
    parser = argparse.ArgumentParser()
    register_parser(parser)
    parser.parse_args(argv[1:])


if __name__ == "__main__":
    main()