"""
mbed SDK
Copyright (c) 2017 ARM Limited

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
"""

import re
import os
import binascii
from mbed_host_tests import BaseHostTest, event_callback


class TestDataParser(object):
    """
    parser for mbedtls test data files.
    """

    def __init__(self):
        """
        Constructor
        """
        self.tests = []

    def parse(self, data_file):
        """

        """
        with open(data_file, 'r') as f:
            self.__parse(f)

    @staticmethod
    def __escaped_split(str, ch):
        """
        """
        if len(ch) > 1:
            raise ValueError('Expected split character. Found string!')
        out = []
        part = ''
        escape = False
        for i in range(len(str)):
            if not escape and str[i] == ch:
                out.append(part)
                part = ''
            else:
                part += str[i]
                escape = not escape and str[i] == '\\'
        if len(part):
            out.append(part)
        return out

    def __parse(self, file):
        """
        """
        for line in file:
            line = line.strip()
            if len(line) == 0:
                continue
            # Read test name
            name = line

            # Check dependencies
            deps = []
            line = file.next().strip()
            m = re.search('depends_on\:(.*)', line)
            if m:
                deps = [int(x) for x in m.group(1).split(':')]
                line = file.next().strip()

            # Read test vectors
            line = line.replace('\\n', '\n')
            parts = self.__escaped_split(line, ':')
            function = int(parts[0])
            x = parts[1:]
            l = len(x)
            assert l % 2 == 0, "Number of test arguments should be even: %s" % line
            args = [(x[i * 2], x[(i * 2) + 1]) for i in range(len(x)/2)]
            self.tests.append((name, function, deps, args))

    def get_test_data(self):
        """
        """
        return self.tests


class MbedTlsTest(BaseHostTest):
    """
    Event handler for mbedtls unit tests. This script is loaded at run time
    by htrun while executing mbedtls unit tests.
    """
    # From suites/helpers.function
    DEPENDENCY_SUPPORTED = 0
    KEY_VALUE_MAPPING_FOUND = DEPENDENCY_SUPPORTED
    DISPATCH_TEST_SUCCESS = DEPENDENCY_SUPPORTED

    KEY_VALUE_MAPPING_NOT_FOUND = -1
    DEPENDENCY_NOT_SUPPORTED = -2
    DISPATCH_TEST_FN_NOT_FOUND = -3
    DISPATCH_INVALID_TEST_DATA = -4
    DISPATCH_UNSUPPORTED_SUITE = -5

    def __init__(self):
        """
        """
        super(MbedTlsTest, self).__init__()
        self.tests = []
        self.test_index = -1
        self.dep_index = 0
        self.error_str = dict()
        self.error_str[self.DEPENDENCY_SUPPORTED] = 'DEPENDENCY_SUPPORTED'
        self.error_str[self.KEY_VALUE_MAPPING_NOT_FOUND] = 'KEY_VALUE_MAPPING_NOT_FOUND'
        self.error_str[self.DEPENDENCY_NOT_SUPPORTED] = 'DEPENDENCY_NOT_SUPPORTED'
        self.error_str[self.DISPATCH_TEST_FN_NOT_FOUND] = 'DISPATCH_TEST_FN_NOT_FOUND'
        self.error_str[self.DISPATCH_INVALID_TEST_DATA] = 'DISPATCH_INVALID_TEST_DATA'
        self.error_str[self.DISPATCH_UNSUPPORTED_SUITE] = 'DISPATCH_UNSUPPORTED_SUITE'

    def setup(self):
        """
        """
        binary_path = self.get_config_item('image_path')
        script_dir = os.path.split(os.path.abspath(__file__))[0]
        suite_name = os.path.splitext(os.path.basename(binary_path))[0]
        data_file = ".".join((suite_name, 'data'))
        data_file = os.path.join(script_dir, '..', 'mbedtls', suite_name, data_file)
        if os.path.exists(data_file):
            self.log("Running tests from %s" % data_file)
            parser = TestDataParser()
            parser.parse(data_file)
            self.tests = parser.get_test_data()
            self.print_test_info()
        else:
            self.log("Data file not found: %s" % data_file)
            self.notify_complete(False)

    def print_test_info(self):
        """
        """
        self.log('{{__testcase_count;%d}}' % len(self.tests))
        for name, _, _, _ in self.tests:
            self.log('{{__testcase_name;%s}}' % name)

    @staticmethod
    def align_32bit(b):
        """
        4 byte aligns byte array.

        :return:
        """
        b += bytearray((4 - (len(b))) % 4)

    @staticmethod
    def hex_str_bytes(hex_str):
        """
        Converts Hex string representation to byte array

        :param hex_str:
        :return:
        """
        assert hex_str[0] == '"' and hex_str[len(hex_str) - 1] == '"', \
            "HEX test parameter missing '\"': %s" % hex_str
        hex_str = hex_str.strip('"')
        assert len(hex_str) % 2 == 0, "HEX parameter len should be mod of 2: %s" % hex_str

        b = binascii.unhexlify(hex_str)
        return b

    @staticmethod
    def int32_to_bigendian_bytes(i):
        """
        Coverts i to bytearray in big endian format.

        :param i:
        :return:
        """
        b = bytearray([((i >> x) & 0xff) for x in [24, 16, 8, 0]])
        return b

    def test_vector_to_bytes(self, function_id, deps, parameters):
        """
        Converts test vector into a byte array that can be sent to the target.

        :param function_id:
        :param deps:
        :param parameters:
        :return:
        """
        b = bytearray([len(deps)])
        if len(deps):
            b += bytearray(deps)
        b += bytearray([function_id, len(parameters)])
        for typ, param in parameters:
            if typ == 'int' or typ == 'exp':
                i = int(param)
                b += 'I' if typ == 'int' else 'E'
                self.align_32bit(b)
                b += self.int32_to_bigendian_bytes(i)
            elif typ == 'char*':
                param = param.strip('"')
                i = len(param) + 1  # + 1 for null termination
                b += 'S'
                self.align_32bit(b)
                b += self.int32_to_bigendian_bytes(i)
                b += bytearray(list(param))
                b += '\0'   # Null terminate
            elif typ == 'hex':
                hb = self.hex_str_bytes(param)
                b += 'H'
                self.align_32bit(b)
                i = len(hb)
                b += self.int32_to_bigendian_bytes(i)
                b += hb
        length = self.int32_to_bigendian_bytes(len(b))
        return b, length

    def run_next_test(self):
        """
        Send next test function to the target.

        """
        self.test_index += 1
        self.dep_index = 0
        if self.test_index < len(self.tests):
            name, function_id, deps, args = self.tests[self.test_index]
            self.run_test(name, function_id, deps, args)
        else:
            self.notify_complete(True)

    def run_test(self, name, function_id, deps, args):
        """
        Runs the test.

        :param name:
        :param function_id:
        :param deps:
        :param args:
        :return:
        """
        self.log("Running: %s" % name)

        bytes, length = self.test_vector_to_bytes(function_id, deps, args)
        self.send_kv(length, bytes)

    @staticmethod
    def get_result(value):
        try:
            return int(value)
        except ValueError:
            ValueError("Result should return error number. Instead received %s" % value)
        return 0

    @event_callback('GO')
    def on_go(self, key, value, timestamp):
        self.run_next_test()

    @event_callback("R")
    def on_result(self, key, value, timestamp):
        """
        Handle result.

        """
        int_val = self.get_result(value)
        name, function, deps, args = self.tests[self.test_index]
        self.log('{{__testcase_start;%s}}' % name)
        self.log('{{__testcase_finish;%s;%d;%d}}' % (name, int_val == 0,
                                                     int_val != 0))
        self.run_next_test()

    @event_callback("F")
    def on_failure(self, key, value, timestamp):
        """
        Handles test execution failure. Hence marking test as skipped.

        :param key:
        :param value:
        :param timestamp:
        :return:
        """
        int_val = self.get_result(value)
        name, function, deps, args = self.tests[self.test_index]
        if int_val in self.error_str:
            err = self.error_str[int_val]
        else:
            err = 'Unknown error'
        # For skip status, do not write {{__testcase_finish;...}}
        self.log("Error: %s" % err)
        self.run_next_test()