import os, popen2
import cache

_speller   = None
_can_spell = os.system('which ispell > /dev/null 2>&1') == 0

def can_spell():
    global _can_spell
    return _can_spell
def get_speller():
    global _speller
    return _speller

class Speller(object):
    def __init__(self, cmd='ispell'):
        self.pipe = None
        self.cache = cache.CacheDict()
        self.cmd = cmd
        self.start()

    def start(self):
        assert self.pipe is None
        self.pipe = popen2.Popen3('%s -a' % self.cmd, 'rw')
        self.pipe.childerr.close()
        self.pipe.fromchild.readline()

    def stop(self):
        self.pipe.tochild.close()
        self.pipe.fromchild.close()
        self.pipe = None

    def restart(self):
        self.stop()
        self.start()

    def flush(self, word):
        if word in self.cache:
            del self.cache[word]

    def check(self, word, caps=False, title=True):
        # here are some quick checks:
        # 1. zero-length words
        # 2. all-caps word
        # 3. words whose first letter is capitalized
        if len(word) == 0:
            return True
        elif not caps and word.isupper():
            return True
        elif not title and word[0].isupper():
            return True

        result = False
        if word in self.cache:
            result = self.cache[word]
        else:
            if self.pipe.poll() >= 0:
                self.pipe = None
                self.start()
            self.pipe.tochild.write("%s\n" % (word))
            self.pipe.tochild.flush()
            l = self.pipe.fromchild.readline()
            if l.startswith("*") or l.startswith("+") or l.startswith("-"):
                result = True
            while True:
                l = self.pipe.fromchild.readline()
                if l == "\n":
                    break
            self.cache[word] = result
        return result

    def learn(self, word):
        if self.pipe.poll() >= 0:
            self.pipe = None
            self.start()
        self.pipe.tochild.write("*%s\n" % (word))
        self.pipe.tochild.flush()
        self.flush(word)

if _can_spell:
    _speller = Speller()