#!/usr/bin/env python3
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'''
Helper methods & common code for the uorb message templates msg.{cpp,h}.em

Another positive effect of having the code here, is that this file will get
precompiled and thus message generation will be much faster
'''

import os
import errno
import re

import genmsg.msgs


type_map = {
    'int8': 'int8_t',
    'int16': 'int16_t',
    'int32': 'int32_t',
    'int64': 'int64_t',
    'uint8': 'uint8_t',
    'uint16': 'uint16_t',
    'uint32': 'uint32_t',
    'uint64': 'uint64_t',
    'float32': 'float',
    'float64': 'double',
    'bool': 'bool',
    'char': 'char',
}

type_map_short = {
    # We use some range outside of alpha-numeric and special characters.
    # This needs to match with orb_get_c_type()
    'int8': '\\x82',
    'int16': '\\x83',
    'int32': '\\x84',
    'int64': '\\x85',
    'uint8': '\\x86',
    'uint16': '\\x87',
    'uint32': '\\x88',
    'uint64': '\\x89',
    'float32': '\\x8a',
    'float64': '\\x8b',
    'bool': '\\x8c',
    'char': '\\x8d',
}

type_serialize_map = {
    'int8': 'int8_t',
    'int16': 'int16_t',
    'int32': 'int32_t',
    'int64': 'int64_t',
    'uint8': 'uint8_t',
    'uint16': 'uint16_t',
    'uint32': 'uint32_t',
    'uint64': 'uint64_t',
    'float32': 'float',
    'float64': 'double',
    'bool': 'bool',
    'char': 'char',
}

type_idl_map = {
    'bool': 'boolean',
    'byte': 'octet',
    'char': 'char',
    'int8': 'octet',
    'uint8': 'octet',
    'int16': 'short',
    'uint16': 'unsigned short',
    'int32': 'long',
    'uint32': 'unsigned long',
    'int64': 'long long',
    'uint64': 'unsigned long long',
    'float32': 'float',
    'float64': 'double',
    'string': 'string',
}

msgtype_size_map = {
    'int8': 1,
    'int16': 2,
    'int32': 4,
    'int64': 8,
    'uint8': 1,
    'uint16': 2,
    'uint32': 4,
    'uint64': 8,
    'float32': 4,
    'float64': 8,
    'bool': 1,
    'char': 1,
}

type_printf_map = {
    'int8': '%d',
    'int16': '%d',
    'int32': '%" PRId32 "',
    'int64': '%" PRId64 "',
    'uint8': '%u',
    'uint16': '%u',
    'uint32': '%" PRIu32 "',
    'uint64': '%" PRIu64 "',
    'float32': '%.4f',
    'float64': '%.6f',
    'bool': '%u',
    'char': '%c',
}


def bare_name(msg_type):
    """
    Get bare_name from <dir>/<bare_name>[x] format
    """
    bare = msg_type
    if '/' in msg_type:
        # removing prefix
        bare = (msg_type.split('/'))[1]
    # removing suffix
    return bare.split('[')[0]


def sizeof_field_type(field):
    """
    Get size of a field, used for sorting
    """
    bare_name_str = bare_name(field.type)
    if bare_name_str in msgtype_size_map:
        return msgtype_size_map[bare_name_str]
    return 0  # this is for non-builtin types: sort them at the end


def get_children_fields(base_type, search_path):
    (package, name) = genmsg.names.package_resource_name(base_type)
    tmp_msg_context = genmsg.msg_loader.MsgContext.create_default()
    spec_temp = genmsg.msg_loader.load_msg_by_type(
        tmp_msg_context, '%s/%s' % (package, name), search_path)
    return spec_temp.parsed_fields()


def get_message_fields_str_for_message_hash(msg_fields, search_path):
    """
    Get all fields (including for nested types) in the form of:
'''
uint64 timestamp
uint8 esc_count
uint8 esc_online_flags
EscReport[8] esc
uint64 timestamp
uint32 esc_errorcount
int32 esc_rpm
float32 esc_voltage
uint16 failures
int8 esc_power
'''
    """
    all_fields_str = ''
    for field in msg_fields:
        if field.is_header:
            continue

        type_name = field.type
        # detect embedded types
        sl_pos = type_name.find('/')
        if sl_pos >= 0:
            type_name = type_name[sl_pos + 1:]

        all_fields_str += type_name + ' ' + field.name + '\n'

        if sl_pos >= 0: # nested type, add all nested fields
            children_fields = get_children_fields(field.base_type, search_path)
            all_fields_str += get_message_fields_str_for_message_hash(children_fields, search_path)

    return all_fields_str


def hash_32_fnv1a(data: str):
    hash_val = 0x811c9dc5
    prime = 0x1000193
    for i in range(len(data)):
        value = ord(data[i])
        hash_val = hash_val ^ value
        hash_val *= prime
        hash_val &= 0xffffffff
    return hash_val


def get_message_hash(msg_fields, search_path):
    """
    Get a 32 bit message hash over all fields
    """
    all_fields_str = get_message_fields_str_for_message_hash(msg_fields, search_path)
    return hash_32_fnv1a(all_fields_str)


def add_padding_bytes(fields, search_path):
    """
    Add padding fields before the embedded types, at the end and calculate the
    struct size
    returns a tuple with the struct size and padding at the end
    """
    struct_size = 0
    align_to = 8  # this is always 8, because of the 64bit timestamp
    i = 0
    padding_idx = 0
    while i < len(fields):
        field = fields[i]
        if not field.is_header:
            a_pos = field.type.find('[')
            array_size = 1
            if field.is_array:
                array_size = field.array_len
            if field.is_builtin:
                field.sizeof_field_type = sizeof_field_type(field)
            else:
                # embedded type: may need to add padding
                num_padding_bytes = align_to - (struct_size % align_to)
                if num_padding_bytes != align_to:
                    padding_field = genmsg.Field('_padding' + str(padding_idx),
                                                 'uint8[' + str(num_padding_bytes) + ']')
                    padding_idx += 1
                    padding_field.sizeof_field_type = 1
                    struct_size += num_padding_bytes
                    fields.insert(i, padding_field)
                    i += 1
                children_fields = get_children_fields(
                    field.base_type, search_path)
                field.sizeof_field_type, unused = add_padding_bytes(children_fields,
                                                                    search_path)
            struct_size += field.sizeof_field_type * array_size
        i += 1

    # add padding at the end (necessary for embedded types)
    num_padding_bytes = align_to - (struct_size % align_to)
    if num_padding_bytes == align_to:
        num_padding_bytes = 0
    else:
        padding_field = genmsg.Field('_padding' + str(padding_idx),
                                     'uint8[' + str(num_padding_bytes) + ']')
        padding_idx += 1
        padding_field.sizeof_field_type = 1
        struct_size += num_padding_bytes
        fields.append(padding_field)
    return (struct_size, num_padding_bytes)


def convert_type(spec_type, use_short_type=False):
    """
    Convert from msg type to C type
    """
    bare_type = spec_type
    if '/' in spec_type:
        # removing prefix
        bare_type = (spec_type.split('/'))[1]

    msg_type, is_array, array_length = genmsg.msgs.parse_type(bare_type)
    c_type = msg_type
    if use_short_type and msg_type in type_map_short:
        c_type = type_map_short[msg_type]
    elif msg_type in type_map:
        c_type = type_map[msg_type]
    else:
        c_type = re.sub(r'(?<!^)(?=[A-Z])', '_', c_type).lower() # PascalCase to snake_case

    if is_array:
        return c_type + "[" + str(array_length) + "]"

    return c_type


def print_field_def(field):
    """
    Print the C type from a field
    """

    # check if there are any upper case letters in the field name
    assert not any(a.isupper()
                   for a in field.name), "%r field contains uppercase letters" % field.name

    type_name = field.type
    # detect embedded types
    sl_pos = type_name.find('/')
    type_appendix = ''
    type_prefix = ''
    if (sl_pos >= 0):
        type_name = type_name[sl_pos + 1:]
        type_name = re.sub(r'(?<!^)(?=[A-Z])', '_', type_name).lower() # PascalCase to snake_case
        type_prefix = 'struct '
        type_appendix = '_s'

    # detect arrays
    a_pos = type_name.find('[')
    array_size = ''
    if (a_pos >= 0):
        # field is array
        array_size = type_name[a_pos:]
        type_name = type_name[:a_pos]

    if type_name in type_map:
        # need to add _t: int8 --> int8_t
        type_px4 = type_map[type_name]
    else:
        type_px4 = type_name

    comment = ''
    if field.name.startswith('_padding'):
        comment = ' // required for logger'

    print(('\t%s%s%s %s%s;%s' % (type_prefix, type_px4, type_appendix, field.name,
                                 array_size, comment)))