"""Run tests in the farm subdirectory.  Designed for nose."""

import filecmp, fnmatch, glob, os, shutil, sys

try:
    import subprocess
except ImportError:
    subprocess = None


def test_farm(clean_only=False):
    """A test-generating function for nose to find and run."""
    for fname in glob.glob("test/farm/*/*.py"):
        case = FarmTestCase(fname, clean_only)
        yield (case,)


class FarmTestCase(object):
    """A test case from the farm tree.
    
    Tests are short Python script files, often called run.py:
    
        copy("src", "out")
        run('''
            coverage -x white.py
            coverage -a white.py
            ''', rundir="out")
        compare("out", "gold", "*,cover")
        clean("out")

    Verbs (copy, run, compare, clean) are methods in this class.  FarmTestCase
    has options to allow various uses of the test cases (normal execution,
    cleaning-only, or run and leave the results for debugging).
    
    """
    def __init__(self, runpy, clean_only=False, dont_clean=False):
        """Create a test case from a run.py file.
        
        `clean_only` means that only the clean() action is executed.
        `dont_clean` means that the clean() action is not executed.
        
        """
        self.description = runpy
        self.dir, self.runpy = os.path.split(runpy)
        self.clean_only = clean_only
        self.dont_clean = dont_clean

    def cd(self, newdir):
        """Change the current directory, and return the old one."""
        cwd = os.getcwd()
        os.chdir(newdir)
        return cwd

    def __call__(self):
        """Execute the test from the run.py file.
        
        """
        cwd = self.cd(self.dir)

        # Prepare a dictionary of globals for the run.py files to use.
        fns = "copy run runfunc compare contains doesnt_contain clean".split()
        if self.clean_only:
            glo = dict([(fn, self.noop) for fn in fns])
            glo['clean'] = self.clean
        else:
            glo = dict([(fn, getattr(self, fn)) for fn in fns])
            if self.dont_clean:
                glo['clean'] = self.noop
        
        try:
            execfile(self.runpy, glo)
        finally:
            self.cd(cwd)

    def run_fully(self):
        """Run as a full test case, with setUp and tearDown."""
        self.setUp()
        try:
            self()
        finally:
            self.tearDown()

    def fnmatch_list(self, files, filepattern):
        """Filter the list of `files` to only those that match `filepattern`.
        
        If `filepattern` is None, then return the entire list of files.
        
        Returns a list of the filtered files.
        
        """
        if filepattern:
            files = [f for f in files if fnmatch.fnmatch(f, filepattern)]
        return files

    def setUp(self):
        """Test set up, run by nose before __call__."""

        # Modules should be importable from the current directory.
        self.old_syspath = sys.path[:]
        sys.path.insert(0, '')
    
    def tearDown(self):
        """Test tear down, run by nose after __call__."""
        # Make sure no matter what, the test is cleaned up.
        if not self.dont_clean:
            self.clean_only = True
            self()

        # Restore the original sys.path
        sys.path = self.old_syspath

    # Functions usable inside farm run.py files
    
    def noop(self, *args, **kwargs):
        """A no-op function to stub out run, copy, etc, when only cleaning."""
        pass
    
    def copy(self, src, dst):
        """Copy a directory."""

        if os.path.exists(dst):
            shutil.rmtree(dst)
        shutil.copytree(src, dst)

    def run(self, cmds, rundir="src", outfile=None):
        """Run a list of commands.
        
        `cmds` is a string, commands separated by newlines.
        `rundir` is the directory in which to run the commands.
        `outfile` is a filename to redirect stdout to.
        
        """
        cwd = self.cd(rundir)
        try:
            for cmd in cmds.split("\n"):
                if not cmd.strip():
                    continue
                if subprocess:
                    proc = subprocess.Popen(cmd, shell=True, 
                              stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                              stderr=subprocess.STDOUT)
                    retcode = proc.wait()
                    output = proc.stdout.read()
                else:
                    _, stdouterr = os.popen4(cmd)
                    output = stdouterr.read()
                    retcode = 0 # Can't tell if the process failed.
                print output,
                if outfile:
                    open(outfile, "a+").write(output)
                if retcode:
                    raise Exception("command exited abnormally")
        finally:
            self.cd(cwd)

    def runfunc(self, fn, rundir="src"):
        """Run a function.
        
        `fn` is a callable.
        `rundir` is the directory in which to run the function.
        
        """
        
        cwd = self.cd(rundir)
        try:
            fn()
        finally:
            self.cd(cwd)

    def compare(self, dir1, dir2, filepattern=None, size_within=0,
            left_extra=False, right_extra=False
            ):
        """Compare files matching `filepattern` in `dir1` and `dir2`.
        
        `dir2` is interpreted as a prefix, with Python version numbers appended
        to find the actual directory to compare with. "foo" will compare against
        "foo_v241", "foo_v24", "foo_v2", or "foo", depending on which directory
        is found first.
        
        `size_within` is a percentage delta for the file sizes.  If non-zero,
        then the file contents are not compared (since they are expected to
        often be different), but the file sizes must be within this amount.
        For example, size_within=10 means that the two files' sizes must be
        within 10 percent of each other to compare equal.
        
        `left_extra` true means the left directory can have extra files in it
        without triggering an assertion.  `right_extra` means the right
        directory can.
        
        An assertion will be raised if the directories fail one of their
        matches.
        
        """
        # Search for a dir2 with a version suffix.
        version_suff = ''.join(map(str, sys.version_info[:3]))
        while version_suff:
            trydir = dir2 + '_v' + version_suff
            if os.path.exists(trydir):
                dir2 = trydir
                break
            version_suff = version_suff[:-1]

        assert os.path.exists(dir1), "Left directory missing: %s" % dir1
        assert os.path.exists(dir2), "Right directory missing: %s" % dir2
            
        dc = filecmp.dircmp(dir1, dir2)
        diff_files = self.fnmatch_list(dc.diff_files, filepattern)
        left_only = self.fnmatch_list(dc.left_only, filepattern)
        right_only = self.fnmatch_list(dc.right_only, filepattern)
        
        if size_within:
            # The files were already compared, use the diff_files list as a
            # guide for size comparison.
            wrong_size = []
            for f in diff_files:
                left = open(os.path.join(dir1, f), "rb").read()
                right = open(os.path.join(dir2, f), "rb").read()
                size_l, size_r = len(left), len(right)
                big, little = max(size_l, size_r), min(size_l, size_r)
                if (big - little) / float(little) > size_within/100.0:
                    # print "%d %d" % (big, little)
                    # print "Left: ---\n%s\n-----\n%s" % (left, right)
                    wrong_size.append(f)
            assert not wrong_size, "File sizes differ: %s" % wrong_size
        else:
            # filecmp only compares in binary mode, but we want text mode.  So
            # look through the list of different files, and compare them
            # ourselves.
            text_diff = []
            for f in diff_files:
                left = open(os.path.join(dir1, f), "r").read()
                right = open(os.path.join(dir2, f), "r").read()
                if left != right:
                    text_diff.append(f)
            assert not text_diff, "Files differ: %s" % text_diff

        if not left_extra:
            assert not left_only, "Files in %s only: %s" % (dir1, left_only)
        if not right_extra:
            assert not right_only, "Files in %s only: %s" % (dir2, right_only)

    def contains(self, filename, *strlist):
        """Check that the file contains all of a list of strings.
        
        An assert will be raised if one of the arguments in `strlist` is
        missing in `filename`.
        
        """
        text = open(filename, "r").read()
        for s in strlist:
            assert s in text, "Missing content in %s: %r" % (filename, s)

    def doesnt_contain(self, filename, *strlist):
        """Check that the file contains none of a list of strings.
        
        An assert will be raised if any of the strings in strlist appears in
        `filename`.
        
        """
        text = open(filename, "r").read()
        for s in strlist:
            assert s not in text, "Forbidden content in %s: %r" % (filename, s)

    def clean(self, cleandir):
        """Clean `cleandir` by removing it and all its children completely."""
        if os.path.exists(cleandir):
            shutil.rmtree(cleandir)

def main():
    """Command-line access to test_farm.
    
    Commands:
    
    run testcase    - Run a single test case.
    out testcase    - Run a test case, but don't clean up, to see the output.
    clean           - Clean all the output for all tests.
        
    """
    op = sys.argv[1]
    if op == 'run':
        # Run the test for real.
        case = FarmTestCase(sys.argv[2])
        case.run_fully()
    elif op == 'out':
        # Run the test, but don't clean up, so we can examine the output.
        case = FarmTestCase(sys.argv[2], dont_clean=True)
        case.run_fully()
    elif op == 'clean':
        # Run all the tests, but just clean.
        for test in test_farm(clean_only=True):
            test[0].run_fully()
    else:
        print "Need an operation: run, out, clean"
    
# So that we can run just one farm run.py at a time.
if __name__ == '__main__':
    main()
