#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import sys
import argparse
import re

# parse arguments and return arguments list.
def get_args():
    parser = argparse.ArgumentParser(
    formatter_class=argparse.RawDescriptionHelpFormatter,
    description="""\
Parse meta connect syntax. Default output is stdout.

sample)
__code code0(struct Data data1, ...){
    goto code1(data1, data2, ...);
    \t|
    \tV
__code code0(struct Context* context, struct Data data1, ...){
    goto meta_code1(context, data1, data2, ..., Code1);
    """)
    parser.add_argument('input_file',\
                        nargs=None,\
                        type=str,\
                        help='input file path.')
    parser.add_argument('-o', dest='output',\
                        nargs=1,\
                        type=str,\
                        metavar='<file>',\
                        help='write output to <file>')
                        
    return parser.parse_args()

# parse input file and create meta connection list
def parse_meta_syntax(lines,file):
    comment_out = False
    caller_name = ''
    isMetaOrStub = False
    defaultMetaIsNotExist = True
    for i,l in enumerate(lines):

        regexed_l = re.search(r"[a-zA-Z0-9_]+ *\(",l)

        # get caller code segment name
        if re.search(r"^ *__code",l) is not None:
            isMetaOrStub = False
            caller_name = regexed_l.group(0).rstrip('(')
            if caller_name == 'meta':
                defaultMetaIsNotExist = False
            if re.search(r"^ *meta_*|stub$",caller_name) is not None: # meta code segment or stub
                isMetaOrStub = True
                file.write(l)
            elif re.search(r"struct Context\* context",l) is None:
                file.write("/*-- generated by script */\n")
                file.write('// '+l)
                file.write('__code {0:s}(struct Context* context{1:s}) {{\n'.format(caller_name,get_args_from_line(l)))
            else:
                file.write(l)
        elif not isMetaOrStub and regexed_l is not None and re.search(r"^ *goto",l):
            callee_name = regexed_l.group(0).rstrip('(')
            if callee_name == 'start_code' or re.match('meta_|meta$',callee_name):
                file.write(l)
            elif re.search(r"\(context", l) is None:
                file.write("/*-- connected by script */\n")
                file.write('// '+l)
                meta_name = 'meta_'+caller_name if cs_search(lines, 'meta_'+callee_name) else 'meta'
                file.write("goto {0:s}(context{1:s}, {2:s});\n".format(meta_name, get_args_from_line(l),\
                                                                        callee_name.capitalize()))
            else:
                file.write(l)
        else:
            file.write(l)
    if defaultMetaIsNotExist:
        create_default_metacs(file)

def create_default_metacs(file):
    file.write('''
__code meta(struct Context* context, enum Code next) {
    goto (context->code[next])(context);
}
    ''')

def get_args_from_line(line):
    args = line.split('(')[1].rsplit(')')[0].strip()
    args = ', ' + args if args else ''
    return args
    

def create_stub(file,name):
    file.write('''__code {0:s}_stub(struct Context* context) {{
    goto {0:s}(context'''.format(name))

    file.write(');\n}\n')

# search meta code segment.
# Find it :  __code meta_'name'
def cs_search(lines, name):
    for l in lines:
        if re.search(r"^ *__code {0:s}\(".format(name),l) is not None:
            return True
    return False

def main():
    args = get_args()
    output = sys.stdout
    try:
        f = open(args.input_file,'r')
    except IOError:
        print("cannot open file %s" % input_file)
    if args.output is not None:
        try:
            output = open(args.output[0],'w')
        except IOError:
            print("cannot open file %s" % args.output)
    lines = f.readlines()
    connect_list = parse_meta_syntax(lines, output)
main()