#!/usr/bin/env python
"""
Environment data class abstraction that is usable as an executable module

```bash
python -m rsconnect.environment
```
"""
import collections
import datetime
import json
import locale
import os
import re
import subprocess
import sys

try:
    import typing
    from typing import Optional
except ImportError:
    typing = None

version_re = re.compile(r"\d+\.\d+(\.\d+)?")
conda_version_re = re.compile(r"^(?:\s*-\s*)?python=(\d+\.\d+(?:\.\d+)?)", re.MULTILINE)
exec_dir = os.path.dirname(sys.executable)


Environment = collections.namedtuple(
    "Environment", ("conda", "contents", "error", "filename", "locale", "package_manager", "pip", "python", "source",),
)


def MakeEnvironment(
    conda=None,  # type: Optional[str]
    contents="",  # type: Optional[str]
    error=None,  # type: Optional[str]
    filename="",  # type: Optional[str]
    locale="",  # type: Optional[str]
    package_manager="",  # type: Optional[str]
    pip=None,  # type: Optional[str]
    python=None,  # type: Optional[str]
    source=None,  # type: Optional[str]
):
    return Environment(conda, contents, error, filename, locale, package_manager, pip, python, source)


class EnvironmentException(Exception):
    pass


def detect_environment(dirname, force_generate=False, conda_mode=False, conda=None):
    # type: (str, bool, bool, typing.Optional[str]) -> Environment
    """Determine the python dependencies in the environment.

    `pip freeze` will be used to introspect the environment unless `conda_mode` is
    set to `True`.  In that case, an attempt will be made to use Conda to introspect
    the environment.

    :param: dirname Directory name
    :param: force_generate Force the generation of an environment
    :param: conda_mode inspect the environment assuming Conda
    :return: a dictionary containing the package spec filename and contents if successful,
    or a dictionary containing `error` on failure.
    """
    conda = get_conda(conda)

    if conda_mode and conda:
        if force_generate:
            result = conda_env_export(conda)
        else:
            result = output_file(dirname, "environment.yml", "conda") or conda_env_export(conda)
    else:
        if force_generate:
            result = pip_freeze()
        else:
            result = output_file(dirname, "requirements.txt", "pip") or pip_freeze()

    if result is not None:
        if conda_mode and result["package_manager"] != "conda":
            return MakeEnvironment(
                error=(
                    'Conda was requested but no activated Conda environment was found. See "conda activate '
                    '--help" for more information.'
                )
            )

        result["python"] = get_python_version(MakeEnvironment(**result))
        result["pip"] = get_version("pip")
        if conda:
            result["conda"] = get_conda_version(conda)
        result["locale"] = get_default_locale()

    return MakeEnvironment(**result)


def get_conda(conda=None):
    """get_conda tries to find the conda executable if we're in
    a conda environment. If not, or if we cannot find the executable,
    return None.
    :returns: conda string path to conda or None.
    """
    if os.environ.get("CONDA_PREFIX", None) is None and conda is None:
        return None
    else:
        return conda or os.environ.get("CONDA_EXE", None)


def get_python_version(environment):
    # type: (Environment) -> str
    if environment.package_manager == "conda":
        versions = conda_version_re.findall(environment.contents)
        if len(versions) > 0:
            version = versions[0]
            if version.count(".") == 1:
                version = version + ".0"
            return version

    v = sys.version_info
    return "%d.%d.%d" % (v[0], v[1], v[2])


def get_conda_version(conda):
    try:
        args = [conda, "-V"]
        proc = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True,)
        stdout, stderr = proc.communicate()
        match = version_re.search(stdout or stderr)
        if match:
            return match.group()
        msg = "Failed to get version of conda from the output of: %s - standard output: %s; standard error: %s" % (
            " ".join(args),
            stdout,
            stderr,
        )
        raise EnvironmentException(msg)
    except Exception as exception:
        raise EnvironmentException("Error getting conda version: %s" % str(exception))


def get_default_locale(locale_source=locale.getdefaultlocale):
    result = ".".join([item or "" for item in locale_source()])
    return "" if result == "." else result


def get_version(module):
    try:
        args = [sys.executable, "-m", module, "--version"]
        proc = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True,)
        stdout, stderr = proc.communicate()
        match = version_re.search(stdout)
        if match:
            return match.group()

        msg = "Failed to get version of '%s' from the output of: %s" % (module, " ".join(args),)
        raise EnvironmentException(msg)
    except Exception as exception:
        raise EnvironmentException("Error getting '%s' version: %s" % (module, str(exception)))


def output_file(dirname, filename, package_manager):
    """Read an existing package spec file.

    Returns a dictionary containing the filename and contents
    if successful, None if the file does not exist,
    or a dictionary containing 'error' on failure.
    """
    try:
        path = os.path.join(dirname, filename)
        if not os.path.exists(path):
            return None

        with open(path, "r") as f:
            data = f.read()

        data = "\n".join([line for line in data.split("\n") if "rsconnect" not in line])

        return {
            "filename": filename,
            "contents": data,
            "source": "file",
            "package_manager": package_manager,
        }
    except Exception as exception:
        raise EnvironmentException("Error reading %s: %s" % (filename, str(exception)))


def pip_freeze():
    """Inspect the environment using `pip freeze`.

    Returns a dictionary containing the filename
    (always 'requirements.txt') and contents if successful,
    or a dictionary containing 'error' on failure.
    """
    try:
        proc = subprocess.Popen(
            [sys.executable, "-m", "pip", "list", "--format=freeze"],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            universal_newlines=True,
        )

        pip_stdout, pip_stderr = proc.communicate()
        pip_status = proc.returncode
    except Exception as exception:
        raise EnvironmentException("Error during pip freeze: %s" % str(exception))

    if pip_status != 0:
        msg = pip_stderr or ("exited with code %d" % pip_status)
        raise EnvironmentException("Error during pip freeze: %s" % msg)

    pip_stdout = "\n".join([line for line in pip_stdout.split("\n") if "rsconnect" not in line])

    pip_stdout = (
        "# requirements.txt generated by rsconnect-python on " + str(datetime.datetime.utcnow()) + "\n" + pip_stdout
    )

    return {
        "filename": "requirements.txt",
        "contents": pip_stdout,
        "source": "pip_freeze",
        "package_manager": "pip",
    }


def conda_env_export(conda):
    """Inspect the environment using `conda env export`
    :param: conda path to the `conda` tool
    :return: dictionary containing the key "environment.yml" and the data inside
    """
    try:
        proc = subprocess.Popen(
            [conda, "env", "export"], stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True,
        )
        conda_stdout, conda_stderr = proc.communicate()
        conda_status = proc.returncode
    except Exception as exception:
        raise EnvironmentException("Error during conda env export: %s" % str(exception))

    if conda_status != 0:
        msg = conda_stderr or ("exited with code %d" % conda_status)
        raise EnvironmentException("Error during conda env export: %s" % msg)

    return {
        "filename": "environment.yml",
        "contents": conda_stdout,
        "source": "conda_env_export",
        "package_manager": "conda",
    }


def main():
    """
    Run `detect_environment` and dump the result as JSON.
    """
    try:
        if len(sys.argv) < 2:
            raise EnvironmentException("Usage: %s [-fc] DIRECTORY" % sys.argv[0])
        # directory is always the last argument
        directory = sys.argv[len(sys.argv) - 1]
        flags = ""
        force_generate = False
        conda_mode = False
        if len(sys.argv) > 2:
            flags = sys.argv[1]
        if "f" in flags:
            force_generate = True
        if "c" in flags:
            conda_mode = True
        json.dump(
            detect_environment(directory, force_generate, conda_mode)._asdict(), sys.stdout, indent=4,
        )
    except EnvironmentException as exception:
        json.dump(dict(error=str(exception)), sys.stdout, indent=4)


if __name__ == "__main__":
    main()