"""Contains library functions"""
import os
from git.test.lib import *
import shutil
import tempfile

from git.db import (
                        GitCmdObjectDB,
                        GitDB
                    )

from git import (
    Repo
    )

#{ Invvariants
k_env_git_repo = "GIT_PYTHON_TEST_GIT_REPO_BASE"
#} END invariants


#{ Utilities
def resolve_or_fail(env_var):
    """:return: resolved environment variable or raise EnvironmentError"""
    try:
        return os.environ[env_var]
    except KeyError:
        raise EnvironmentError("Please set the %r envrionment variable and retry" % env_var)
    # END exception handling

#} END utilities


#{ Base Classes 

class TestBigRepoR(TestBase):
    """TestCase providing access to readonly 'big' repositories using the following 
    member variables:
    
    * gitrorepo
    
     * Read-Only git repository - actually the repo of git itself
     
    * puregitrorepo
    
     * As gitrepo, but uses pure python implementation
    """
     
    #{ Invariants
    head_sha_2k = '235d521da60e4699e5bd59ac658b5b48bd76ddca'
    head_sha_50 = '32347c375250fd470973a5d76185cac718955fd5'
    #} END invariants 
    
    @classmethod
    def setUp(cls):
        super(TestBigRepoR, cls).setUp()
        repo_path = resolve_or_fail(k_env_git_repo)
        cls.gitrorepo = Repo(repo_path, odbt=GitCmdObjectDB)
        cls.puregitrorepo = Repo(repo_path, odbt=GitDB)


class TestBigRepoRW(TestBigRepoR):
    """As above, but provides a big repository that we can write to.
    
    Provides ``self.gitrwrepo`` and ``self.puregitrwrepo``"""
    
    @classmethod
    def setUp(cls):
        super(TestBigRepoRW, cls).setUp()
        dirname = tempfile.mktemp()
        os.mkdir(dirname)
        cls.gitrwrepo = cls.gitrorepo.clone(dirname, shared=True, bare=True, odbt=GitCmdObjectDB)
        cls.puregitrwrepo = Repo(dirname, odbt=GitDB)
    
    @classmethod
    def tearDownAll(cls):
        shutil.rmtree(cls.gitrwrepo.working_dir)
        
#} END base classes
