#!/usr/bin/env python
# License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>

import os
import sys
import termios
from collections import defaultdict
from collections.abc import Generator, Iterable, Mapping, Sequence
from contextlib import contextmanager, suppress
from itertools import count
from time import monotonic
from typing import TYPE_CHECKING, DefaultDict, Optional, TypedDict

import kitty.fast_data_types as fast_data_types

from .constants import handled_signals, is_freebsd, is_macos, kitten_exe, kitty_base_dir, shell_path, terminfo_dir
from .types import run_once
from .utils import cmdline_for_hold, log_error, resolved_shell, which

if TYPE_CHECKING:
    from .window import CwdRequest


if is_macos:
    from kitty.fast_data_types import abspath_of_process as _abspath_of_process
    from kitty.fast_data_types import cmdline_of_process as cmdline_
    from kitty.fast_data_types import cwd_of_process as _cwd
    from kitty.fast_data_types import environ_of_process as _environ_of_process
    from kitty.fast_data_types import process_group_map as _process_group_map

    def cwd_of_process(pid: int) -> str:
        # The underlying code on macos returns a path with symlinks resolved
        # anyway but we use realpath for extra safety.
        return os.path.realpath(_cwd(pid), strict=True)

    def abspath_of_exe(pid: int) -> str:
        return os.path.realpath(_abspath_of_process(pid), strict=True)

    def process_group_map() -> DefaultDict[int, list[int]]:
        ans: DefaultDict[int, list[int]] = defaultdict(list)
        for pid, pgid in _process_group_map():
            ans[pgid].append(pid)
        return ans

    def cmdline_of_pid(pid: int) -> list[str]:
        return cmdline_(pid)
else:

    def cmdline_of_pid(pid: int) -> list[str]:
        with open(f'/proc/{pid}/cmdline', 'rb') as f:
            return list(filter(None, f.read().decode('utf-8').split('\0')))

    if is_freebsd:
        def cwd_of_process(pid: int) -> str:
            import subprocess
            cp = subprocess.run(['pwdx', str(pid)], capture_output=True)
            if cp.returncode != 0:
                raise ValueError(f'Failed to find cwd of process with pid: {pid}')
            ans = cp.stdout.decode('utf-8', 'replace').split()[1]
            return os.path.realpath(ans, strict=True)
    else:
        def cwd_of_process(pid: int) -> str:
            # We use realpath instead of readlink to match macOS behavior where
            # the underlying OS API returns real paths.
            ans = f'/proc/{pid}/cwd'
            return os.path.realpath(ans, strict=True)

    def _environ_of_process(pid: int) -> str:
        with open(f'/proc/{pid}/environ', 'rb') as f:
            return f.read().decode('utf-8')

    def process_group_map() -> DefaultDict[int, list[int]]:
        ans: DefaultDict[int, list[int]] = defaultdict(list)
        for x in os.listdir('/proc'):
            try:
                pid = int(x)
            except Exception:
                continue
            try:
                with open(f'/proc/{x}/stat', 'rb') as f:
                    raw = f.read().decode('utf-8')
            except OSError:
                continue
            try:
                q = int(raw.split(' ', 5)[4])
            except Exception:
                continue
            ans[q].append(pid)
        return ans

    def abspath_of_exe(pid: int) -> str:
        return os.path.realpath(f'/proc/{pid}/exe', strict=True)


@run_once
def checked_terminfo_dir() -> str | None:
    return terminfo_dir if os.path.isdir(terminfo_dir) else None


class CachedProcessData:

    cached_result: DefaultDict[int, list[int]] | None = None
    cache_active: bool = False
    cache_at: float = 0
    ttl: float = 1

    def process_group_map(self) -> DefaultDict[int, list[int]]:
        if self.cached_result is None or not self.cache_active:
            try:
                self.cached_result = process_group_map()
            except Exception:
                self.cached_result = defaultdict(list)
            self.cache_at = monotonic()
        return self.cached_result

    def processes_in_group(self, grp: int) -> list[int]:
        return self.process_group_map()[grp]

    def clear_cache(self) -> None:
        self.cached_result = None
        self.cache_at = 0

    def start_caching(self, refresh: bool = False) -> bool:
        prev, self.cache_active = self.cache_active, True
        if refresh or monotonic() - self.cache_at > self.ttl:
            self.clear_cache()
        return prev

    def stop_caching(self, prev: bool) -> None:
        self.cache_active = prev


process_data_cache = CachedProcessData()
processes_in_group = process_data_cache.processes_in_group


@contextmanager
def cached_process_data() -> Generator[None, None, None]:
    orig = process_data_cache.start_caching(refresh=True)
    try:
        yield
    finally:
        process_data_cache.stop_caching(orig)


def session_id(pids: Iterable[int]) -> int:
    for pid in pids:
        with suppress(OSError):
            if (sid := os.getsid(pid)) > -1:
                return sid
    return -1

def parse_environ_block(data: str) -> dict[str, str]:
    """Parse a C environ block of environment variables into a dictionary."""
    # The block is usually raw data from the target process.  It might contain
    # trailing garbage and lines that do not look like assignments.
    ret: dict[str, str] = {}
    pos = 0

    while True:
        next_pos = data.find("\0", pos)
        # nul byte at the beginning or double nul byte means finish
        if next_pos <= pos:
            break
        # there might not be an equals sign
        equal_pos = data.find("=", pos, next_pos)
        if equal_pos > pos:
            key = data[pos:equal_pos]
            value = data[equal_pos + 1:next_pos]
            ret[key] = value
        pos = next_pos + 1

    return ret


def environ_of_process(pid: int) -> dict[str, str]:
    return parse_environ_block(_environ_of_process(pid))


def process_env(env: Mapping[str, str] | None = None) -> dict[str, str]:
    ans = dict(os.environ if env is None else env)
    ssl_env_var = getattr(sys, 'kitty_ssl_env_var', None)
    if ssl_env_var is not None:
        ans.pop(ssl_env_var, None)
    ans.pop('XDG_ACTIVATION_TOKEN', None)
    ans.pop('VTE_VERSION', None)  # Used by the stupid VTE shell integration script that is installed system wide, sigh
    ans.pop('KITTY_SI_RUN_COMMAND_AT_STARTUP', None)
    return ans


def default_env() -> dict[str, str]:
    ans: dict[str, str] | None = getattr(default_env, 'env', None)
    if ans is None:
        return process_env()
    return ans


def set_default_env(val: dict[str, str] | None = None) -> None:
    env = process_env().copy()
    has_lctype = False
    if val:
        has_lctype = 'LC_CTYPE' in val
        env.update(val)
    setattr(default_env, 'env', env)
    setattr(default_env, 'lc_ctype_set_by_user', has_lctype)


def set_LANG_in_default_env(val: str) -> None:
    default_env().setdefault('LANG', val)


def openpty() -> tuple[int, int]:
    master, slave = os.openpty()  # Note that master and slave are in blocking mode
    os.set_inheritable(slave, True)
    os.set_inheritable(master, False)
    fast_data_types.set_iutf8_fd(master, True)
    return master, slave


@run_once
def getpid() -> str:
    return str(os.getpid())


@run_once
def base64_terminfo_data() -> str:
    return (b'b64:' + fast_data_types.base64_encode(fast_data_types.terminfo_data(), True)).decode('ascii')


class ProcessDesc(TypedDict):
    cwd: str | None
    pid: int
    cmdline: Sequence[str] | None


child_counter = count()


class Child:

    child_fd: int | None = None
    pid: int | None = None
    forked = False

    def __init__(
        self,
        argv: Sequence[str],
        cwd: str,
        stdin: bytes | None = None,
        env: dict[str, str] | None = None,
        cwd_from: Optional['CwdRequest'] = None,
        is_clone_launch: str = '',
        add_listen_on_env_var: bool = True,
        hold: bool = False,
        pass_fds: tuple[int, ...] = (),
        remote_control_fd: int = -1,
        hold_after_ssh: bool = False,
        startup_command_via_shell_integration: Sequence[str] | str = (),
    ):
        self.is_clone_launch = is_clone_launch
        self.id = next(child_counter)
        self.add_listen_on_env_var = add_listen_on_env_var
        self.argv = list(argv)
        self.pass_fds = pass_fds
        self.remote_control_fd = remote_control_fd
        if cwd_from:
            try:
                cwd = cwd_from.modify_argv_for_launch_with_cwd(self.argv, env, hold_after_ssh=hold_after_ssh) or cwd
            except Exception as err:
                log_error(f'Failed to read cwd of {cwd_from} with error: {err}')
        else:
            cwd = os.path.expandvars(os.path.expanduser(cwd or os.getcwd()))
        self.cwd = os.path.abspath(cwd)
        self.stdin = stdin
        self.env = env or {}
        self.startup_command_via_shell_integration = startup_command_via_shell_integration
        self.final_env:dict[str, str] = {}
        self.is_default_shell = bool(self.argv and self.argv[0] == shell_path)
        self.should_run_via_run_shell_kitten = is_macos and self.is_default_shell
        self.hold = hold

    def get_final_env(self) -> tuple[dict[str, str], bool]:
        from kitty.options.utils import DELETE_ENV_VAR
        env = default_env().copy()
        opts = fast_data_types.get_options()
        boss = fast_data_types.get_boss()
        if is_macos and env.get('LC_CTYPE') == 'UTF-8' and not getattr(sys, 'kitty_run_data').get(
                'lc_ctype_before_python') and not getattr(default_env, 'lc_ctype_set_by_user', False):
            del env['LC_CTYPE']
        env.update(self.env)
        env['TERM'] = opts.term
        env['COLORTERM'] = 'truecolor'
        env['KITTY_PID'] = getpid()
        env['KITTY_PUBLIC_KEY'] = boss.encryption_public_key
        if self.remote_control_fd > -1:
            env['KITTY_LISTEN_ON'] = f'fd:{self.remote_control_fd}'
        elif self.add_listen_on_env_var and boss.listening_on:
            env['KITTY_LISTEN_ON'] = boss.listening_on
        else:
            env.pop('KITTY_LISTEN_ON', None)
        env.pop('KITTY_STDIO_FORWARDED', None)
        if self.cwd:
            # needed in case cwd is a symlink, in which case shells
            # can use it to display the current directory name rather
            # than the resolved path
            env['PWD'] = self.cwd
        if opts.terminfo_type == 'path':
            tdir = checked_terminfo_dir()
            if tdir:
                env['TERMINFO'] = tdir
        elif opts.terminfo_type == 'direct':
            env['TERMINFO'] = base64_terminfo_data()
        env['KITTY_INSTALLATION_DIR'] = kitty_base_dir
        self.unmodified_argv = list(self.argv)
        if not self.should_run_via_run_shell_kitten and 'disabled' not in opts.shell_integration:
            from .shell_integration import modify_shell_environ
            modify_shell_environ(opts, env, self.argv)
        env = {k: v for k, v in env.items() if v is not DELETE_ENV_VAR}
        if self.is_clone_launch:
            env['KITTY_IS_CLONE_LAUNCH'] = self.is_clone_launch
            self.is_clone_launch = '1'  # free memory
        else:
            env.pop('KITTY_IS_CLONE_LAUNCH', None)
        must_run_startup_command_via_kitten = False
        if self.startup_command_via_shell_integration:
            if isinstance(self.startup_command_via_shell_integration, str):
                env['KITTY_SI_RUN_COMMAND_AT_STARTUP'] = self.startup_command_via_shell_integration
            else:
                from .shell_integration import join
                scmd = self.argv or resolved_shell(fast_data_types.get_options())
                try:
                    env['KITTY_SI_RUN_COMMAND_AT_STARTUP'] = join(scmd[0], self.startup_command_via_shell_integration)
                except Exception:
                    must_run_startup_command_via_kitten = True  # unknown shell
        return env, must_run_startup_command_via_kitten

    def fork(self) -> int | None:
        if self.forked:
            return None
        opts = fast_data_types.get_options()
        self.forked = True
        master, slave = openpty()
        stdin, self.stdin = self.stdin, None
        ready_read_fd, ready_write_fd = os.pipe()
        os.set_inheritable(ready_write_fd, False)
        os.set_inheritable(ready_read_fd, True)
        if stdin is not None:
            stdin_read_fd, stdin_write_fd = os.pipe()
            os.set_inheritable(stdin_write_fd, False)
            os.set_inheritable(stdin_read_fd, True)
        else:
            stdin_read_fd = stdin_write_fd = -1
        self.final_env, must_run_startup_command_via_kitten = self.get_final_env()
        self.initial_termios_state = termios.tcgetattr(master)
        argv = list(self.argv)
        cwd = self.cwd
        pass_fds = self.pass_fds
        if self.remote_control_fd > -1:
            pass_fds += self.remote_control_fd,
        if self.should_run_via_run_shell_kitten or must_run_startup_command_via_kitten:
            # bash will only source ~/.bash_profile if it detects it is a login
            # shell (see the invocation section of the bash man page), which it
            # does if argv[0] is prefixed by a hyphen see
            # https://github.com/kovidgoyal/kitty/issues/247
            # it is apparently common to use ~/.bash_profile instead of the
            # more correct ~/.bashrc on macOS to setup env vars, so if
            # the default shell is used prefix argv[0] by '-'
            #
            # it is arguable whether graphical terminals should start shells
            # in login mode in general, there are at least a few Linux users
            # that also make this incorrect assumption, see for example
            # https://github.com/kovidgoyal/kitty/issues/1870
            # xterm, urxvt, konsole and gnome-terminal do not do it in my
            # testing.
            import shlex
            ksi = ' '.join(opts.shell_integration)
            if ksi == 'invalid':
                ksi = 'enabled'
            argv = [kitten_exe(), 'run-shell', '--shell', shlex.join(argv), '--shell-integration', ksi]
            if must_run_startup_command_via_kitten:
                argv.extend(self.startup_command_via_shell_integration)
            if is_macos and not pass_fds and not opts.forward_stdio:
                # In addition for getlogin() to work we need to run the shell
                # via the /usr/bin/login wrapper, sigh.
                # And login on macOS looks for .hushlogin in CWD instead of
                # HOME, bloody idiotic so we cant cwd when running it.
                # https://github.com/kovidgoyal/kitty/issues/6511
                # login closes inherited file descriptors so dont use it when
                # forward_stdio or pass_fds are used.
                import pwd
                user = pwd.getpwuid(os.geteuid()).pw_name
                if cwd:
                    argv.append('--cwd=' + cwd)
                    cwd = os.path.expanduser('~')
                argv = ['/usr/bin/login', '-f', '-l', '-p', user] + argv
        self.final_exe = final_exe = which(argv[0]) or argv[0]
        self.final_argv0 = argv[0]
        if self.hold:
            argv = cmdline_for_hold(argv)
            final_exe = argv[0]
        env = tuple(f'{k}={v}' for k, v in self.final_env.items())
        pid = fast_data_types.spawn(
            final_exe, cwd, tuple(argv), env, master, slave, stdin_read_fd, stdin_write_fd,
            ready_read_fd, ready_write_fd, tuple(handled_signals), kitten_exe(), opts.forward_stdio, pass_fds)
        os.close(slave)
        self.pid = pid
        self.child_fd = master
        if stdin is not None:
            os.close(stdin_read_fd)
            fast_data_types.thread_write(stdin_write_fd, stdin)
        os.close(ready_read_fd)
        self.terminal_ready_fd = ready_write_fd
        if self.child_fd is not None:
            os.set_blocking(self.child_fd, False)
        if not is_macos:
            ppid = getpid()
            try:
                fast_data_types.systemd_move_pid_into_new_scope(pid, f'kitty-{ppid}-{self.id}.scope', f'kitty child process: {pid} launched by: {ppid}')
            except NotImplementedError:
                pass
            except OSError as err:
                log_error("Could not move child process into a systemd scope: " + str(err))
        return pid

    def __del__(self) -> None:
        fd = getattr(self, 'terminal_ready_fd', -1)
        if fd > -1:
            os.close(fd)
        self.terminal_ready_fd = -1

    def mark_terminal_ready(self) -> None:
        os.close(self.terminal_ready_fd)
        self.terminal_ready_fd = -1

    def cmdline_of_pid(self, pid: int) -> list[str]:
        try:
            ans = cmdline_of_pid(pid)
        except Exception:
            ans = []
        if pid == self.pid and (not ans):
            ans = list(self.argv)
        return ans

    def process_desc(self, pid: int) -> ProcessDesc:
        ans: ProcessDesc = {'pid': pid, 'cmdline': None, 'cwd': None}
        with suppress(Exception):
            ans['cmdline'] = self.cmdline_of_pid(pid)
        with suppress(Exception):
            ans['cwd'] = cwd_of_process(pid) or None
        return ans

    @property
    def foreground_processes(self) -> list[ProcessDesc]:
        if self.child_fd is None:
            return []
        try:
            pgrp = os.tcgetpgrp(self.child_fd)
            foreground_processes = processes_in_group(pgrp) if pgrp >= 0 else []
            return [self.process_desc(x) for x in foreground_processes]
        except Exception:
            return []

    @property
    def background_processes(self) -> list[ProcessDesc]:
        if self.child_fd is None:
            return []
        try:
            foreground_process_group_id = os.tcgetpgrp(self.child_fd)
            if foreground_process_group_id < 0:
                return []
            gmap = process_group_map()

            sid = session_id(gmap.get(foreground_process_group_id, ()))
            if sid < 0:
                return []
            ans: list[ProcessDesc] = []
            for grp_id, pids in gmap.items():
                if grp_id != foreground_process_group_id and session_id(pids) == sid:
                    ans.extend(map(self.process_desc, pids))
            return ans
        except Exception:
            return []

    @property
    def cmdline(self) -> list[str]:
        try:
            assert self.pid is not None
            return self.cmdline_of_pid(self.pid) or list(self.argv)
        except Exception:
            return list(self.argv)

    @property
    def foreground_cmdline(self) -> list[str]:
        try:
            assert self.pid_for_cwd is not None
            return self.cmdline_of_pid(self.pid_for_cwd) or self.cmdline
        except Exception:
            return self.cmdline

    @property
    def environ(self) -> dict[str, str]:
        try:
            assert self.pid is not None
            return environ_of_process(self.pid) or self.final_env.copy()
        except Exception:
            return self.final_env.copy()

    @property
    def current_cwd(self) -> str | None:
        with suppress(Exception):
            assert self.pid is not None
            return cwd_of_process(self.pid)
        return None

    def get_pid_for_cwd(self, oldest: bool = False) -> int | None:
        with suppress(Exception):
            assert self.child_fd is not None
            pgrp = os.tcgetpgrp(self.child_fd)
            foreground_processes = processes_in_group(pgrp) if pgrp >= 0 else []
            if foreground_processes:
                # there is no easy way that I know of to know which process is the
                # foreground process in this group from the users perspective,
                # so we assume the one with the highest PID is as that is most
                # likely to be the newest process. This situation can happen
                # for example with a shell script such as:
                # #!/bin/bash
                # cd /tmp
                # vim
                # With this script , the foreground process group will contain
                # both the bash instance running the script and vim.
                return min(foreground_processes) if oldest else max(foreground_processes)
        return self.pid

    @property
    def pid_for_cwd(self) -> int | None:
        return self.get_pid_for_cwd()

    def get_foreground_cwd(self, oldest: bool = False) -> str | None:
        with suppress(Exception):
            pid = self.get_pid_for_cwd(oldest)
            if pid is not None:
                return cwd_of_process(pid) or None
        return None

    def get_foreground_exe(self, oldest: bool = False) -> str | None:
        with suppress(Exception):
            pid = self.get_pid_for_cwd(oldest)
            if pid is not None:
                c = cmdline_of_pid(pid)
                if c:
                    return c[0]
        return None

    @property
    def foreground_cwd(self) -> str | None:
        return self.get_foreground_cwd()

    @property
    def foreground_environ(self) -> dict[str, str]:
        pid = self.pid_for_cwd
        if pid is not None:
            with suppress(Exception):
                return environ_of_process(pid)
        pid = self.pid
        if pid is not None:
            with suppress(Exception):
                return environ_of_process(pid)
        return {}

    def send_signal_for_key(self, key_num: bytes) -> bool:
        import signal
        if self.child_fd is None:
            return False
        t = termios.tcgetattr(self.child_fd)
        if not t[3] & termios.ISIG:
            return False
        cc = t[-1]
        if key_num == cc[termios.VINTR]:
            s: signal.Signals = signal.SIGINT
        elif key_num == cc[termios.VSUSP]:
            s = signal.SIGTSTP
        elif key_num == cc[termios.VQUIT]:
            s = signal.SIGQUIT
        else:
            return False
        pgrp = os.tcgetpgrp(self.child_fd)
        os.killpg(pgrp, s)
        return True

    def reset_termios_state(self, when: int = termios.TCSANOW) -> None:
        if (s := getattr(self, 'initial_termios_state', None)) and self.child_fd is not None:
            try:
                termios.tcsetattr(self.child_fd, when, s)
            except OSError:
                pass
