import argparse
import json
import os
import sys
from pathlib import Path
from typing import List, Optional, Tuple, Type

from knot_resolver.client.command import Command, CommandArgs, CompWords, register_command
from knot_resolver.utils import which
from knot_resolver.utils.requests import request

PROCS_TYPE = List


@register_command
class DebugCommand(Command):
    def __init__(self, namespace: argparse.Namespace) -> None:
        self.proc_type: Optional[str] = namespace.proc_type
        self.sudo: bool = namespace.sudo
        self.gdb: str = namespace.gdb
        self.gdb_args: List[str] = namespace.extra
        super().__init__(namespace)

    @staticmethod
    def register_args_subparser(
        subparser: "argparse._SubParsersAction[argparse.ArgumentParser]",
    ) -> Tuple[argparse.ArgumentParser, "Type[Command]"]:
        debug = subparser.add_parser(
            "debug",
            help="Run GDB on the manager's subprocesses",
        )
        debug.add_argument(
            "proc_type",
            help="Optional, the type of process to debug. May be 'kresd' (default), 'gc', or 'all'.",
            type=str,
            nargs="?",
            default="kresd",
        )
        debug.add_argument(
            "--sudo",
            dest="sudo",
            help="Run GDB with sudo",
            action="store_true",
        )
        debug.add_argument(
            "--gdb",
            help="Custom GDB executable (may be a command on PATH, or an absolute path)",
            type=str,
            default=None,
        )
        return debug, DebugCommand

    @staticmethod
    def completion(args: List[str], parser: argparse.ArgumentParser) -> CompWords:
        return {}

    def run(self, args: CommandArgs) -> None:  # noqa: PLR0912, PLR0915
        if self.gdb is None:
            try:
                gdb_cmd = str(which.which("gdb"))
            except RuntimeError:
                print("Could not find 'gdb' in $PATH. Is GDB installed?", file=sys.stderr)
                sys.exit(1)
        elif "/" not in self.gdb:
            try:
                gdb_cmd = str(which.which(self.gdb))
            except RuntimeError:
                print(f"Could not find '{self.gdb}' in $PATH.", file=sys.stderr)
                sys.exit(1)
        else:
            gdb_cmd_path = Path(self.gdb).absolute()
            if not gdb_cmd_path.exists():
                print(f"Could not find '{self.gdb}'.", file=sys.stderr)
                sys.exit(1)
            gdb_cmd = str(gdb_cmd_path)

        response = request(args.socket, "GET", f"processes/{self.proc_type}")
        if response.status != 200:
            print(response, file=sys.stderr)
            sys.exit(1)

        procs = json.loads(response.body)
        if not isinstance(procs, PROCS_TYPE):
            print(
                f"Unexpected response type '{type(procs).__name__}' from manager. Expected '{PROCS_TYPE.__name__}'",
                file=sys.stderr,
            )
            sys.exit(1)
        if len(procs) == 0:
            print(
                f"There are no processes of type '{self.proc_type}' available to debug",
                file=sys.stderr,
            )

        exec_args = []

        # Put `sudo --` at the beginning of the command.
        if self.sudo:
            try:
                sudo_cmd = str(which.which("sudo"))
            except RuntimeError:
                print("Could not find 'sudo' in $PATH. Is sudo installed?", file=sys.stderr)
                sys.exit(1)
            exec_args.extend([sudo_cmd, "--"])

        # Attach GDB to processes - the processes are attached using the `add-inferior` and `attach` GDB
        # commands. This way, we can debug multiple processes.
        exec_args.extend([gdb_cmd])
        exec_args.extend(["-init-eval-command", "set detach-on-fork off"])
        exec_args.extend(["-init-eval-command", "set schedule-multiple on"])
        exec_args.extend(["-init-eval-command", f'attach {procs[0]["pid"]}'])
        inferior = 2
        for proc in procs[1:]:
            exec_args.extend(["-init-eval-command", "add-inferior"])
            exec_args.extend(["-init-eval-command", f"inferior {inferior}"])
            exec_args.extend(["-init-eval-command", f'attach {proc["pid"]}'])
            inferior += 1

        num_inferiors = inferior - 1
        if num_inferiors > 1:
            # Now we switch back to the first process and add additional provided GDB arguments.
            exec_args.extend(["-init-eval-command", "inferior 1"])
            exec_args.extend(
                [
                    "-init-eval-command",
                    "echo \\n\\nYou are now debugging multiple Knot Resolver processes. To switch between "
                    "them, use the 'inferior <n>' command, where <n> is an integer from 1 to "
                    f"{num_inferiors}.\\n\\n",
                ]
            )
        exec_args.extend(self.gdb_args)

        print(f"exec_args = {exec_args}")
        os.execl(*exec_args)