from __future__ import annotations

import contextlib
import os
import shlex
import shutil
import tempfile
import textwrap
from collections.abc import Generator
from collections.abc import Sequence

from pre_commit import lang_base
from pre_commit.envcontext import envcontext
from pre_commit.envcontext import PatchesT
from pre_commit.envcontext import UNSET
from pre_commit.prefix import Prefix
from pre_commit.util import cmd_output
from pre_commit.util import win_exe

ENVIRONMENT_DIR = 'renv'
get_default_version = lang_base.basic_get_default_version

_RENV_ACTIVATED_OPTS = (
    '--no-save', '--no-restore', '--no-site-file', '--no-environ',
)


def _execute_r(
        code: str, *,
        prefix: Prefix, version: str, args: Sequence[str] = (), cwd: str,
        cli_opts: Sequence[str],
) -> str:
    with in_env(prefix, version), _r_code_in_tempfile(code) as f:
        _, out, _ = cmd_output(
            _rscript_exec(), *cli_opts, f, *args, cwd=cwd,
        )
    return out.rstrip('\n')


def _execute_r_in_renv(
        code: str, *,
        prefix: Prefix, version: str, args: Sequence[str] = (), cwd: str,
) -> str:
    return _execute_r(
        code=code, prefix=prefix, version=version, args=args, cwd=cwd,
        cli_opts=_RENV_ACTIVATED_OPTS,
    )


def _execute_vanilla_r(
        code: str, *,
        prefix: Prefix, version: str, args: Sequence[str] = (), cwd: str,
) -> str:
    return _execute_r(
        code=code, prefix=prefix, version=version, args=args, cwd=cwd,
        cli_opts=('--vanilla',),
    )


def _read_installed_version(envdir: str, prefix: Prefix, version: str) -> str:
    return _execute_r_in_renv(
        'cat(renv::settings$r.version())',
        prefix=prefix, version=version,
        cwd=envdir,
    )


def _read_executable_version(envdir: str, prefix: Prefix, version: str) -> str:
    return _execute_r_in_renv(
        'cat(as.character(getRversion()))',
        prefix=prefix, version=version,
        cwd=envdir,
    )


def _write_current_r_version(
        envdir: str, prefix: Prefix, version: str,
) -> None:
    _execute_r_in_renv(
        'renv::settings$r.version(as.character(getRversion()))',
        prefix=prefix, version=version,
        cwd=envdir,
    )


def health_check(prefix: Prefix, version: str) -> str | None:
    envdir = lang_base.environment_dir(prefix, ENVIRONMENT_DIR, version)

    r_version_installation = _read_installed_version(
        envdir=envdir, prefix=prefix, version=version,
    )
    r_version_current_executable = _read_executable_version(
        envdir=envdir, prefix=prefix, version=version,
    )
    if r_version_installation in {'NULL', ''}:
        return (
            f'Hooks were installed with an unknown R version. R version for '
            f'hook repo now set to {r_version_current_executable}'
        )
    elif r_version_installation != r_version_current_executable:
        return (
            f'Hooks were installed for R version {r_version_installation}, '
            f'but current R executable has version '
            f'{r_version_current_executable}'
        )

    return None


@contextlib.contextmanager
def _r_code_in_tempfile(code: str) -> Generator[str]:
    """
    To avoid quoting and escaping issues, avoid `Rscript [options] -e {expr}`
    but use `Rscript [options] path/to/file_with_expr.R`
    """
    with tempfile.TemporaryDirectory() as tmpdir:
        fname = os.path.join(tmpdir, 'script.R')
        with open(fname, 'w') as f:
            f.write(_inline_r_setup(textwrap.dedent(code)))
        yield fname


def get_env_patch(venv: str) -> PatchesT:
    return (
        ('R_PROFILE_USER', os.path.join(venv, 'activate.R')),
        ('RENV_PROJECT', UNSET),
    )


@contextlib.contextmanager
def in_env(prefix: Prefix, version: str) -> Generator[None]:
    envdir = lang_base.environment_dir(prefix, ENVIRONMENT_DIR, version)
    with envcontext(get_env_patch(envdir)):
        yield


def _prefix_if_file_entry(
        entry: list[str],
        prefix: Prefix,
        *,
        is_local: bool,
) -> Sequence[str]:
    if entry[1] == '-e' or is_local:
        return entry[1:]
    else:
        return (prefix.path(entry[1]),)


def _rscript_exec() -> str:
    r_home = os.environ.get('R_HOME')
    if r_home is None:
        return 'Rscript'
    else:
        return os.path.join(r_home, 'bin', win_exe('Rscript'))


def _entry_validate(entry: list[str]) -> None:
    """
    Allowed entries:
    # Rscript -e expr
    # Rscript path/to/file
    """
    if entry[0] != 'Rscript':
        raise ValueError('entry must start with `Rscript`.')

    if entry[1] == '-e':
        if len(entry) > 3:
            raise ValueError('You can supply at most one expression.')
    elif len(entry) > 2:
        raise ValueError(
            'The only valid syntax is `Rscript -e {expr}`'
            'or `Rscript path/to/hook/script`',
        )


def _cmd_from_hook(
        prefix: Prefix,
        entry: str,
        args: Sequence[str],
        *,
        is_local: bool,
) -> tuple[str, ...]:
    cmd = shlex.split(entry)
    _entry_validate(cmd)

    cmd_part = _prefix_if_file_entry(cmd, prefix, is_local=is_local)
    return (cmd[0], *_RENV_ACTIVATED_OPTS, *cmd_part, *args)


def install_environment(
        prefix: Prefix,
        version: str,
        additional_dependencies: Sequence[str],
) -> None:
    lang_base.assert_version_default('r', version)

    env_dir = lang_base.environment_dir(prefix, ENVIRONMENT_DIR, version)
    os.makedirs(env_dir, exist_ok=True)
    shutil.copy(prefix.path('renv.lock'), env_dir)
    shutil.copytree(prefix.path('renv'), os.path.join(env_dir, 'renv'))

    r_code_inst_environment = f"""\
        prefix_dir