#!/usr/bin/env python
# Character map generator
#
# Copyright (C) 2012-2018 Nirenjan Krishnan (nirenjan@nirenjan.org)
#
# SPDX-License-Identifier: GPL-2.0-only WITH Classpath-exception-2.0
"""
Generator script to parse character mapping
for the X52/X52 Pro MFD
"""

import sys
import re

AUTOGEN_HEADER = """
/*
 * Autogenerated character map file for Saitek X52 Pro
 * Generated from %s
 */

#include "x52_char_map.h"

"""


class MapTable(object):
    """
    Defines a MapTable entry, with each entry storing the value seen so far,
    the type of the entry, and the value, if it's a value node.
    """
    # Empty list
    root = [None] * 256

    def __init__(self, value_so_far, map_value=None):
        self.next_level = [None] * 256
        self.value_so_far = value_so_far
        self.map_value = map_value

    def output_nodes(self):
        """
        Output the individual nodes
        """
        output_lines = []
        output_count = 0
        for node in self.next_level:
            if node is not None:
                output_lines.extend(node.output_nodes())
                output_count += 1

        if output_count != 0:
            struct_header = 'static struct map_entry table_%x[64] = {' % \
                            self.value_so_far
            output_lines.append(struct_header)

            for node_index in range(0, 256):
                node = self.next_level[node_index]
                if node is not None:
                    output_lines.append(self.dump_entry_line(0x80, node_index,
                                                             node.value_so_far,
                                                             node.map_value))

            output_lines.extend(['};', ''])

        return output_lines

    @staticmethod
    def dump_entry_line(offset, node_index, value_so_far, map_value):
        """
        Dump the array entry for the current node
        """
        if map_value is None:
            node_entry_line = '\t[0x%02x] = { table_%x, TYPE_POINTER, 0 },' % \
                (node_index - offset, value_so_far)
        else:
            node_entry_line = '\t[0x%02x] = { NULL, TYPE_ENTRY, 0x%02x },' % \
                (node_index - offset, map_value)

        return node_entry_line

    @classmethod
    def add_to_table(cls, input_val, map_val):
        """
        Add a map value to the lookup table
        """
        try:
            uchr = unichr(input_val)
        except NameError:
            # Python 3 doesn't have unichr, but chr should work
            uchr = chr(input_val)

        utf8_str = uchr.encode('utf-8')
        # Python2 returns the encoded result as a string, wheras
        # Python3 returns the result as a bytearray. Converting
        # the string (or bytearray) into a bytearray ensures that
        # this can be run in both Python2 and Python3
        utf8_vals = [c for c in bytearray(utf8_str)]

        value_so_far = 0
        level = cls.root
        for index, char in enumerate(utf8_vals):
            value_so_far = (value_so_far << 8) | char
            if index < (len(utf8_vals) - 1):
                node = level[char]
                if node is None:
                    node = cls(value_so_far)
                    level[char] = node

                level = level[char].next_level
            else:
                node = cls(value_so_far, map_val)
                level[char] = node

    @classmethod
    def output_table_as_list(cls):
        """
        Output the map table as a list of lines
        """
        output_lines = []
        for node in cls.root:
            if node is not None:
                output_lines.extend(node.output_nodes())

        output_lines.append('struct map_entry map_root[256] = {')

        for node_index in range(0, 256):
            node = cls.root[node_index]
            if node is not None:
                output_lines.append(cls.dump_entry_line(0x0, node_index,
                                                        node.value_so_far,
                                                        node.map_value))

        output_lines.extend(['};', ''])

        return output_lines


class LineFormatError(ValueError):
    """
    Error class for parser
    """

def parse_line(data):
    """
    Parse a line containing a mapping descriptor. The mapping descriptor
    must start with a hexadecimal unicode code point, followed by either a
    single character, or a hexadecimal integer that corresponds to the map
    value.
    """
    # Strip off comments
    data = re.sub(re.compile('#.*$'), '', data)

    # Strip off leading and trailing whitespace
    data = data.strip()

    # If the line is empty, it is a comment line
    if len(data) == 0:
        return None, None

    # Find the code point and the target value
    try:
        code_point, target = data.strip().split()
    except ValueError:
        # Raised when there are either too many, or not enough values in
        # the string
        raise LineFormatError('Invalid descriptor format "%s"' % data)

    # Convert the string to its equivalent numeric value
    try:
        code_point = int(code_point, 0)
    except ValueError:
        raise LineFormatError('Invalid code point "%s"' % code_point)

    # Check if the target is a single character
    if len(target) == 1:
        target = ord(target)
    else:
        # Try parsing the target as an integer
        try:
            target = int(target, 0)
        except ValueError:
            raise LineFormatError('Invalid map value "%s"' % target)

    return code_point, target

if __name__ == "__main__":
    if len(sys.argv) != 3:
        sys.stderr.write('Usage: %s <input-map> <output-c-file>\n' %
                         sys.argv[0])
        sys.exit(1)

    with open(sys.argv[1], 'r') as infile:
        for line in infile:
            src, dst = parse_line(line)
            if src is not None:
                MapTable.add_to_table(src, dst)

    with open(sys.argv[2], 'w') as outfile:
        outfile.write(AUTOGEN_HEADER % sys.argv[1])

        for line in MapTable.output_table_as_list():
            outfile.write(line + '\n')