#!/usr/bin/env python
import os, re, sys
from subprocess import Popen, PIPE, STDOUT

_can_debug = os.system('which gdb > /dev/null 2>&1') == 0

def can_debug():
    global _can_debug
    return _can_debug

class Debugger(object):
    frame_begin_re = re.compile('^\032\032frame-begin ([^ ]+) ([^ ]+)$')
    source_re = re.compile('^\032\032source (.+)$')
    def __init__(self, cmd='gdb', args=[]):
        self.pipe = None
        self.cmd = cmd
        self.args = [cmd, '--annotate=3']
        self.args.extend(args)
        self.start()

        #gdb state
        self.prompt = None
        self.path   = None
        self.line   = None
        self.char   = None
        self.middle = None
        self.addr   = None
        self.breaks = []
        
    def start(self):
        assert self.pipe is None
        cmd = ' '.join(self.args)
        self.pipe = Popen(cmd, shell=True, stdin=PIPE, stdout=PIPE, stderr=STDOUT)
    def stop(self):
        self.pipe.stdin.close()
        self.pipe.stdout.close()
        self.pipe = None
    def restart(self):
        self.stop()
        self.start()

    def _readline(self):
        line = self.pipe.stdout.readline()
        if line:
            return line[:-1]
        else:
            return None
    def _assertline(self, s):
        l = self._readline()
        assert l == s, repr(l)

    def run(self):
        while True:
            line = self._readline()
            if line is None:
                break
            if line.startswith('\032\032'):
                if line == '\032\032starting':
                    pass
                elif line == '\032\032stopped':
                    pass
                elif line.startswith('\032\032frame-begin'):
                    m = self.frame_begin_re.match(line)
                    assert m
                elif line.startswith('\032\032source'):
                    m = self.source_re.match(line)
                    assert m
                    fields      = m.group(1).split(':')
                    self.path   = fields[0]
                    self.line   = int(fields[1])
                    self.char   = int(fields[2])
                    self.middle = fields[3]
                    self.addr   = fields[4]
                    print "SOURCE %r, line %d (%s)" % (self.path, self.line, self.addr)
                elif line == '\032\032pre-prompt':
                    self.prompt = self._readline()
                    print 'PROMPT: %r' % self.prompt
                    self._assertline('\032\032prompt')
                    self.pipe.stdin.write(sys.stdin.readline())
                    self._assertline('')
                    self._assertline('\032\032post-prompt')
                else:
                    print 'CMD %r' % line
            elif line:
                print line

if __name__ == "__main__":
    args = sys.argv[1:]
    d = Debugger(args=args)
    d.run()