from __future__ import unicode_literals

import os
import sys
import shutil
import tempfile
import textwrap
import contextlib

try:
    from contextlib import ExitStack
except ImportError:
    from contextlib2 import ExitStack

try:
    import pathlib
except ImportError:
    import pathlib2 as pathlib


__metaclass__ = type


@contextlib.contextmanager
def tempdir():
    tmpdir = tempfile.mkdtemp()
    sys.path[:0] = [tmpdir]
    try:
        yield pathlib.Path(tmpdir)
    finally:
        sys.path.remove(tmpdir)
        shutil.rmtree(tmpdir)


@contextlib.contextmanager
def save_cwd():
    orig = os.getcwd()
    try:
        yield
    finally:
        os.chdir(orig)


@contextlib.contextmanager
def tempdir_as_cwd():
    with tempdir() as tmp:
        with save_cwd():
            os.chdir(str(tmp))
            yield tmp


class SiteDir:
    @staticmethod
    @contextlib.contextmanager
    def site_dir():
        with tempdir() as tmp:
            sys.path[:0] = [str(tmp)]
            yield tmp

    def setUp(self):
        self.fixtures = ExitStack()
        self.addCleanup(self.fixtures.close)
        self.site_dir = self.fixtures.enter_context(self.site_dir())


class DistInfoPkg(SiteDir):
    files = {
        "distinfo_pkg-1.0.0.dist-info": {
            "METADATA": """
                Name: distinfo-pkg
                Author: Steven Ma
                Version: 1.0.0
                Requires-Dist: wheel >= 1.0
                Requires-Dist: pytest; extra == 'test'
                """,
            "RECORD": "mod.py,sha256=abc,20\n",
            "entry_points.txt": """
                [entries]
                main = mod:main
            """
            },
        "mod.py": """
            def main():
                print("hello world")
            """,
        }

    def setUp(self):
        super(DistInfoPkg, self).setUp()
        build_files(DistInfoPkg.files, self.site_dir)


class EggInfoPkg(SiteDir):
    files = {
        "egginfo_pkg.egg-info": {
            "PKG-INFO": """
                Name: egginfo-pkg
                Author: Steven Ma
                License: Unknown
                Version: 1.0.0
                Classifier: Intended Audience :: Developers
                Classifier: Topic :: Software Development :: Libraries
                """,
            "SOURCES.txt": """
                mod.py
                egginfo_pkg.egg-info/top_level.txt
            """,
            "entry_points.txt": """
                [entries]
                main = mod:main
            """,
            "requires.txt": """
                wheel >= 1.0; python_version >= "2.7"
                [test]
                pytest
            """,
            "top_level.txt": "mod\n"
            },
        "mod.py": """
            def main():
                print("hello world")
            """,
        }

    def setUp(self):
        super(EggInfoPkg, self).setUp()
        build_files(EggInfoPkg.files, prefix=self.site_dir)


class LocalPackage:
    def setUp(self):
        self.fixtures = ExitStack()
        self.addCleanup(self.fixtures.close)
        self.fixtures.enter_context(tempdir_as_cwd())
        build_files(EggInfoPkg.files)


def build_files(file_defs, prefix=pathlib.Path()):
    """
    Build a set of files/directories, as described by the
    file_defs dictionary.
    Each key/value pair in the dictionary is interpreted as
    a filename/contents
    pair. If the contents value is a dictionary, a directory
    is created, and the
    dictionary interpreted as the files within it, recursively.
    For example:
    {"README.txt": "A README file",
     "foo": {
        "__init__.py": "",
        "bar": {
            "__init__.py": "",
        },
        "baz.py": "# Some code",
     }
    }
    """
    for name, contents in file_defs.items():
        full_name = prefix / name
        if isinstance(contents, dict):
            full_name.mkdir()
            build_files(contents, prefix=full_name)
        else:
            if isinstance(contents, bytes):
                with full_name.open('wb') as f:
                    f.write(contents)
            else:
                with full_name.open('w') as f:
                    f.write(DALS(contents))


def DALS(str):
    "Dedent and left-strip"
    return textwrap.dedent(str).lstrip()
