#!/usr/bin/env python3
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# <pep8 compliant>

import argparse
import functools
import shutil
import pathlib
import subprocess
import sys
import tempfile
import unittest


def with_tempdir(wrapped):
    """Creates a temporary directory for the function, cleaning up after it returns normally.

    When the wrapped function raises an exception, the contents of the temporary directory
    remain available for manual inspection.

    The wrapped function is called with an extra positional argument containing
    the pathlib.Path() of the temporary directory.
    """

    @functools.wraps(wrapped)
    def decorator(*args, **kwargs):
        dirname = tempfile.mkdtemp(prefix='blender-alembic-test')
        try:
            retval = wrapped(*args, pathlib.Path(dirname), **kwargs)
        except:
            print('Exception in %s, not cleaning up temporary directory %s' % (wrapped, dirname))
            raise
        else:
            shutil.rmtree(dirname)
        return retval

    return decorator


class AbstractAlembicTest(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        import re

        parser = argparse.ArgumentParser()
        parser.add_argument('--blender', required=True)
        parser.add_argument('--testdir', required=True)
        parser.add_argument('--alembic-root', required=True)
        args, _ = parser.parse_known_args()

        cls.blender = args.blender
        cls.testdir = pathlib.Path(args.testdir)
        cls.alembic_root = pathlib.Path(args.alembic_root)

        # 'abcls' outputs ANSI colour codes, even when stdout is not a terminal.
        # See https://github.com/alembic/alembic/issues/120
        cls.ansi_remove_re = re.compile(rb'\x1b[^m]*m')

        # 'abcls' array notation, like "name[16]"
        cls.abcls_array = re.compile(r'^(?P<name>[^\[]+)(\[(?P<arraysize>\d+)\])?$')

    def run_blender(self, filepath: str, python_script: str, timeout: int=300) -> str:
        """Runs Blender by opening a blendfile and executing a script.

        Returns Blender's stdout + stderr combined into one string.

        :param filepath: taken relative to self.testdir.
        :param timeout: in seconds
        """

        blendfile = self.testdir / filepath

        command = (
            self.blender,
            '--background',
            '-noaudio',
            '--factory-startup',
            '--enable-autoexec',
            str(blendfile),
            '-E', 'CYCLES',
            '--python-exit-code', '47',
            '--python-expr', python_script,
        )

        proc = subprocess.run(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                              timeout=timeout)
        output = proc.stdout.decode('utf8')
        if proc.returncode:
            self.fail('Error %d running Blender:\n%s' % (proc.returncode, output))

        return output

    def abcprop(self, filepath: pathlib.Path, proppath: str) -> dict:
        """Uses abcls to obtain compound property values from an Alembic object.

        A dict of subproperties is returned, where the values are just strings
        as returned by abcls.

        The Python bindings for Alembic are old, and only compatible with Python 2.x,
        so that's why we can't use them here, and have to rely on other tooling.
        """
        import collections

        abcls = self.alembic_root / 'bin' / 'abcls'

        command = (str(abcls), '-vl', '%s%s' % (filepath, proppath))
        proc = subprocess.run(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                              timeout=30)

        coloured_output = proc.stdout
        output = self.ansi_remove_re.sub(b'', coloured_output).decode('utf8')

        if proc.returncode:
            self.fail('Error %d running abcls:\n%s' % (proc.returncode, output))

        # Mapping from value type to callable that can convert a string to Python values.
        converters = {
            'bool_t': int,
            'uint8_t': int,
            'int32_t': int,
            'float64_t': float,
            'float32_t': float,
        }

        result = {}

        # Ideally we'd get abcls to output JSON, see https://github.com/alembic/alembic/issues/121
        lines = collections.deque(output.split('\n'))
        while lines:
            info = lines.popleft()
            if not info:
                continue
            proptype, valtype_and_arrsize, name_and_extent = info.split()

            # Parse name and extent
            m = self.abcls_array.match(name_and_extent)
            if not m:
                self.fail('Unparsable name/extent from abcls: %s' % name_and_extent)
            name, extent = m.group('name'), m.group('arraysize')

            if extent != '1':
                self.fail('Unsupported extent %s for property %s/%s' % (extent, proppath, name))

            # Parse type
            m = self.abcls_array.match(valtype_and_arrsize)
            if not m:
                self.fail('Unparsable value type from abcls: %s' % valtype_and_arrsize)
            valtype, scalarsize = m.group('name'), m.group('arraysize')

            # Convert values
            try:
                conv = converters[valtype]
            except KeyError:
                self.fail('Unsupported type %s for property %s/%s' % (valtype, proppath, name))

            def convert_single_line(linevalue):
                try:
                    if scalarsize is None:
                        return conv(linevalue)
                    else:
                        return [conv(v.strip()) for v in linevalue.split(',')]
                except ValueError as ex:
                    return str(ex)

            if proptype == 'ScalarProperty':
                value = lines.popleft()
                result[name] = convert_single_line(value)
            elif proptype == 'ArrayProperty':
                arrayvalue = []
                # Arrays consist of a variable number of items, and end in a blank line.
                while True:
                    linevalue = lines.popleft()
                    if not linevalue:
                        break
                    arrayvalue.append(convert_single_line(linevalue))
                result[name] = arrayvalue
            else:
                self.fail('Unsupported type %s for property %s/%s' % (proptype, proppath, name))

        return result

    def assertAlmostEqualFloatArray(self, actual, expect, places=6, delta=None):
        """Asserts that the arrays of floats are almost equal."""

        self.assertEqual(len(actual), len(expect),
                         'Actual array has %d items, expected %d' % (len(actual), len(expect)))

        for idx, (act, exp) in enumerate(zip(actual, expect)):
            self.assertAlmostEqual(act, exp, places=places, delta=delta,
                                   msg='%f != %f at index %d' % (act, exp, idx))


class HierarchicalAndFlatExportTest(AbstractAlembicTest):
    @with_tempdir
    def test_hierarchical_export(self, tempdir: pathlib.Path):
        abc = tempdir / 'cubes_hierarchical.abc'
        script = "import bpy; bpy.ops.wm.alembic_export(filepath='%s', start=1, end=1, " \
                 "renderable_only=True, visible_layers_only=True, flatten=False)" % abc
        self.run_blender('cubes-hierarchy.blend', script)

        # Now check the resulting Alembic file.
        xform = self.abcprop(abc, '/Cube/Cube_002/Cube_012/.xform')
        self.assertEqual(1, xform['.inherits'])
        self.assertAlmostEqualFloatArray(
            xform['.vals'],
            [1.0, 0.0, 0.0, 0.0,
             0.0, 1.0, 0.0, 0.0,
             0.0, 0.0, 1.0, 0.0,
             3.07484, -2.92265, 0.0586434, 1.0]
        )

    @with_tempdir
    def test_flat_export(self, tempdir: pathlib.Path):
        abc = tempdir / 'cubes_flat.abc'
        script = "import bpy; bpy.ops.wm.alembic_export(filepath='%s', start=1, end=1, " \
                 "renderable_only=True, visible_layers_only=True, flatten=True)" % abc
        self.run_blender('cubes-hierarchy.blend', script)

        # Now check the resulting Alembic file.
        xform = self.abcprop(abc, '/Cube_012/.xform')
        self.assertEqual(0, xform['.inherits'])

        self.assertAlmostEqualFloatArray(
            xform['.vals'],
            [0.343134, 0.485243, 0.804238, 0,
             0.0, 0.856222, -0.516608, 0,
             -0.939287, 0.177266, 0.293799, 0,
             1, 3, 4, 1],
        )


class DupliGroupExportTest(AbstractAlembicTest):
    @with_tempdir
    def test_hierarchical_export(self, tempdir: pathlib.Path):
        abc = tempdir / 'dupligroup_hierarchical.abc'
        script = "import bpy; bpy.ops.wm.alembic_export(filepath='%s', start=1, end=1, " \
                 "renderable_only=True, visible_layers_only=True, flatten=False)" % abc
        self.run_blender('dupligroup-scene.blend', script)

        # Now check the resulting Alembic file.
        xform = self.abcprop(abc, '/Real_Cube/Linked_Suzanne/Cylinder/Suzanne/.xform')
        self.assertEqual(1, xform['.inherits'])
        self.assertAlmostEqualFloatArray(
            xform['.vals'],
            [1.0, 0.0, 0.0, 0.0,
             0.0, 1.0, 0.0, 0.0,
             0.0, 0.0, 1.0, 0.0,
             0.0, 2.0, 0.0, 1.0]
        )

    @with_tempdir
    def test_flat_export(self, tempdir: pathlib.Path):
        abc = tempdir / 'dupligroup_hierarchical.abc'
        script = "import bpy; bpy.ops.wm.alembic_export(filepath='%s', start=1, end=1, " \
                 "renderable_only=True, visible_layers_only=True, flatten=True)" % abc
        self.run_blender('dupligroup-scene.blend', script)

        # Now check the resulting Alembic file.
        xform = self.abcprop(abc, '/Suzanne/.xform')
        self.assertEqual(0, xform['.inherits'])

        self.assertAlmostEqualFloatArray(
            xform['.vals'],
            [1.5, 0.0, 0.0, 0.0,
             0.0, 1.5, 0.0, 0.0,
             0.0, 0.0, 1.5, 0.0,
             2.0, 3.0, 0.0, 1.0]
        )


class CurveExportTest(AbstractAlembicTest):
    @with_tempdir
    def test_export_single_curve(self, tempdir: pathlib.Path):
        abc = tempdir / 'single-curve.abc'
        script = "import bpy; bpy.ops.wm.alembic_export(filepath='%s', start=1, end=1, " \
                 "renderable_only=True, visible_layers_only=True, flatten=False)" % abc
        self.run_blender('single-curve.blend', script)

        # Now check the resulting Alembic file.
        abcprop = self.abcprop(abc, '/NurbsCurve/NurbsCurveShape/.geom')
        self.assertEqual(abcprop['.orders'], [4])


if __name__ == '__main__':
    unittest.main(argv=sys.argv[0:1])