# -*- coding: utf-8 -*-

from typing import Any

import os, abc, shlex, sys

from .util import run_cmd
from .log import *
from .ExecContext import ExecContext, Result

class SSHClient(ExecContext):

    def __init__(self, hostname: str) -> None:
        super().__init__(interactive=False, verbose_default=False)
        self.___ssh = None
        self.__hostname = hostname
        self.__password: str|None = None

    @property
    def hostname(self):
        return self.__hostname

    def set_password(self, password: str) -> None:
        self.__password = password

    @property
    def password(self) -> str:
        return self.__password

    def set_username(self, username: str) -> None:
        self.__username = username

    @property
    def username(self) -> str:
        return self.__username

    @abc.abstractmethod
    async def _run_cmd(self, cmd: list[str]) -> Result:
        pass

    async def run_cmd(self, *args, **kwargs) -> Result:
        kwargs.setdefault('wd', None)
        kwargs.setdefault('throw', True)
        kwargs.setdefault('verbose', False)
        kwargs.setdefault('cmd_input', None)
        kwargs.setdefault('env', None)
        kwargs.setdefault('title', None)
        kwargs.setdefault('output_encoding', None)
        return await self._run(*args, **kwargs)

    async def _run(
            self,
            args: list[str],
            wd: str|None,
            throw: bool,
            verbose: bool,
            cmd_input: str|None,
            env: dict[str, str]|None,
            title: str,
            output_encoding: str|None,  # None => unchanged; "bytes" => return raw bytes
        ) -> Result:

        if wd is not None:
            args = ['cd', wd, '&&', *args]

        if verbose:
            log(WARNING, f'Verbose SSH commands are not yet implemented')

        interactive = (
               cmd_input == "mode:interactive"
            or (cmd_input == "mode:auto" and sys.stdin.isatty())
        )

        if interactive:
            raise NotImplementedError('Interactive SSH is not yet implemented')

        if env is not None:
            raise NotImplementedError('Passing an environment to SSH commands is not yet implemented')

        stdout_b, stderr_b, status = await self._run_cmd(args, cmd_input=cmd_input)

        if throw and status:
            raise Exception(f'SSH command returned error {status}')

        if output_encoding == 'bytes':
            return stdout_b, stderr_b, status

        if output_encoding is None:
            output_encoding = sys.stdout.encoding or "utf-8"
        stdout_s = stdout_b.decode(output_encoding, errors="replace") if stdout_b is not None else None
        stderr_s = stderr_b.decode(output_encoding, errors="replace") if stderr_b is not None else None

        return stdout_s, stderr_s, status

    async def _sudo(self, cmd: list[str], mod_env: dict[str, str], opts: list[str], *args, **kwargs) -> Result:
        if self.username != 'root':
            cmd = ['sudo', *opts, *cmd]
        if mod_env:
            log(WARNING, f'Modifying environment over SSH is not implemented, ignored')
        return await self._run(cmd, *args, **kwargs)

class SSHClientInternal(SSHClient): # export

    def __init__(self, hostname: str) -> None:
        super().__init__(hostname=hostname)
        self.__timeout: float|None = None # Untested
        self.___ssh: Any|None = None

    def __ssh_connect(self):
        import paramiko # type: ignore # error: Library stubs not installed for "paramiko"
        ret = paramiko.SSHClient()
        ret.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        path_to_key=os.path.join(os.environ['HOME'], '.ssh', 'id_rsa')
        ret.connect(self.hostname, key_filename=path_to_key, allow_agent=True)
        s = ret.get_transport().open_session()
        # set up the agent request handler to handle agent requests from the server
        paramiko.agent.AgentRequestHandler(s)
        return ret

    @property
    def __ssh(self):
        if self.___ssh is None:
            self.___ssh = self.__ssh_connect()
        return self.___ssh

    @property
    def __scp(self):
        return SCPClient(self.__ssh.get_transport())

    async def _run_cmd(self, cmd: list[str], cmd_input: str|None) -> Result:
        stdin, stdout, stderr = self.__ssh.exec_command(shlex.join(cmd), timeout=self.__timeout)
        if cmd_input is not None:
            stdin.write(cmd_input)
        exit_status = stdout.channel.recv_exit_status()
        return Result(stdout.read(), stderr.read(), exit_status)

class SSHClientCmd(SSHClient): # export

    def __init__(self, hostname: str) -> None:
        self.__askpass: str|None = None
        self.__askpass_orig: dict[str, str|None] = dict()
        super().__init__(hostname=hostname)

    def __del__(self):
        for key, val in self.__askpass_orig.items():
            if val is None:
                del os.environ[key]
            else:
                os.environ[key] = val
        if self.__askpass is not None:
            os.remove(self.__askpass)

    def __init_askpass(self):
        if self.__askpass is None and self.password is not None:
            import sys, tempfile
            prefix = os.path.basename(sys.argv[0]) + '-'
            f = tempfile.NamedTemporaryFile(mode='w+t', prefix=prefix, delete=False)
            os.chmod(f.name, 0o0700)
            self.__askpass = f.name
            f.write(f'#!/bin/bash\n\necho -n "{self.password}\n"')
            f.close()
            for key, val in {'SSH_ASKPASS': self.__askpass, 'SSH_ASKPASS_REQUIRE': 'force'}.items():
                self.__askpass_orig[key] = os.getenv(key)
                os.environ[key] = val

    async def _run_cmd(self, cmd: list[str], cmd_input: str|None) -> Result:
        self.__init_askpass()
        return await run_cmd(['ssh', self.hostname, shlex.join(cmd)],
                             output_encoding='bytes', cmd_input=cmd_input)

def ssh_client(*args, **kwargs) -> SSHClient: # export
    try:
        return SSHClientInternal(*args, **kwargs)
    except:
        pass
    return SSHClientCmd(*args, **kwargs)