# Copyright (C) 2011-2012  Patrick Totzke <patricktotzke@gmail.com>
# This file is released under the GNU GPL, version 3 or a later revision.
# For further details see the COPYING file
import re
import os
import glob
import logging
import argparse

import alot.commands as commands
from alot.buffers import EnvelopeBuffer
from alot.settings import settings
from alot.utils.booleanaction import BooleanAction


class Completer(object):
    """base class for completers"""
    def complete(self, original, pos):
        """returns a list of completions and cursor positions for the
        string original from position pos on.

        :param original: the string to complete
        :type original: str
        :param pos: starting position to complete from
        :type pos: int
        :returns: pairs of completed string and cursor position in the
                  new string
        :rtype: list of (str, int)
        """
        return list()

    def relevant_part(self, original, pos, sep=' '):
        """
        calculates the subword in a `sep`-splitted list of substrings of
        `original` that `pos` is ia.n
        """
        start = original.rfind(sep, 0, pos) + 1
        end = original.find(sep, pos - 1)
        if end == -1:
            end = len(original)
        return original[start:end], start, end, pos - start


class StringlistCompleter(Completer):
    """completer for a fixed list of strings"""

    def __init__(self, resultlist):
        """
        :param resultlist: strings used for completion
        :type resultlist: list of str
        """
        self.resultlist = resultlist

    def complete(self, original, pos):
        pref = original[:pos]
        return [(a, len(a)) for a in self.resultlist if a.startswith(pref)]


class MultipleSelectionCompleter(Completer):
    """
    Meta-Completer that turns any Completer into one that deals with a list of
    completion strings using the wrapped Completer.
    This allows for example to easily construct a completer for comma separated
    recipient-lists using a :class:`ContactsCompleter`.
    """

    def __init__(self, completer, separator=', '):
        """
        :param completer: completer to use for individual substrings
        :type completer: Completer
        :param separator: separator used to split the completion string into
                          substrings to be fed to `completer`.
        :type separator: str
        """
        self._completer = completer
        self._separator = separator

    def relevant_part(self, original, pos):
        """
        calculates the subword of `original` that `pos` is in
        """
        start = original.rfind(self._separator, 0, pos)
        if start == -1:
            start = 0
        else:
            start = start + len(self._separator)
        end = original.find(self._separator, pos - 1)
        if end == -1:
            end = len(original)
        return original[start:end], start, end, pos - start

    def complete(self, original, pos):
        mypart, start, end, mypos = self.relevant_part(original, pos)
        res = []
        for c, p in self._completer.complete(mypart, mypos):
            newprefix = original[:start] + c
            if not original[end:].startswith(self._separator):
                newprefix += self._separator
            res.append((newprefix + original[end:], len(newprefix)))
        return res


class QueryCompleter(Completer):
    """completion for a notmuch query string"""
    def __init__(self, dbman):
        """
        :param dbman: used to look up avaliable tagstrings
        :type dbman: :class:`~alot.db.DBManager`
        """
        self.dbman = dbman
        abooks = settings.get_addressbooks()
        self._abookscompleter = AbooksCompleter(abooks, addressesonly=True)
        self._tagcompleter = TagCompleter(dbman)
        self.keywords = ['tag', 'from', 'to', 'subject', 'attachment',
                         'is', 'id', 'thread', 'folder']

    def complete(self, original, pos):
        mypart, start, end, mypos = self.relevant_part(original, pos)
        myprefix = mypart[:mypos]
        m = re.search('(tag|is|to|from):(\w*)', myprefix)
        if m:
            cmd, params = m.groups()
            cmdlen = len(cmd) + 1  # length of the keyword part incld colon
            if cmd in ['to', 'from']:
                localres = self._abookscompleter.complete(mypart[cmdlen:],
                                                          mypos - cmdlen)
            else:
                localres = self._tagcompleter.complete(mypart[cmdlen:],
                                                        mypos - cmdlen)
            resultlist = []
            for ltxt, lpos in localres:
                newtext = original[:start] + cmd + ':' + ltxt + original[end:]
                newpos = start + len(cmd) + 1 + lpos
                resultlist.append((newtext, newpos))
            return resultlist
        else:
            matched = filter(lambda t: t.startswith(myprefix), self.keywords)
            resultlist = []
            for keyword in matched:
                newprefix = original[:start] + keyword + ':'
                resultlist.append((newprefix + original[end:], len(newprefix)))
            return resultlist


class TagCompleter(StringlistCompleter):
    """complete a tagstring"""

    def __init__(self, dbman):
        """
        :param dbman: used to look up avaliable tagstrings
        :type dbman: :class:`~alot.db.DBManager`
        """
        resultlist = dbman.get_all_tags()
        StringlistCompleter.__init__(self, resultlist)


class TagsCompleter(MultipleSelectionCompleter):
    """completion for a comma separated list of tagstrings"""

    def __init__(self, dbman):
        """
        :param dbman: used to look up avaliable tagstrings
        :type dbman: :class:`~alot.db.DBManager`
        """
        self._completer = TagCompleter(dbman)
        self._separator = ','


class ContactsCompleter(MultipleSelectionCompleter):
    """completes contacts from given address books"""
    def __init__(self, abooks, addressesonly=False):
        """
        :param abooks: used to look up email addresses
        :type abooks: list of :class:`~alot.account.AddresBook`
        :param addressesonly: only insert address, not the realname of the
                              contact
        :type addressesonly: bool
        """
        self._completer = AbooksCompleter(abooks, addressesonly=addressesonly)
        self._separator = ', '


class AbooksCompleter(Completer):
    """completes a contact from given address books"""
    def __init__(self, abooks, addressesonly=False):
        """
        :param abooks: used to look up email addresses
        :type abooks: list of :class:`~alot.account.AddresBook`
        :param addressesonly: only insert address, not the realname of the
                              contact
        :type addressesonly: bool
        """
        self.abooks = abooks
        self.addressesonly = addressesonly

    def complete(self, original, pos):
        if not self.abooks:
            return []
        prefix = original[:pos]
        res = []
        for abook in self.abooks:
            res = res + abook.lookup(prefix)
        if self.addressesonly:
            returnlist = [(email, len(email)) for (name, email) in res]
        else:
            returnlist = []
            for name, email in res:
                if name:
                    newtext = "%s <%s>" % (name, email)
                else:
                    newtext = email
                returnlist.append((newtext, len(newtext)))
        return returnlist


class ArgparseOptionCompleter(Completer):
    """completes option parameters for a given argparse.Parser"""
    def __init__(self, parser):
        """
        :param parser: the option parser we look up parameter and  choices from
        :type parser: `argparse.ArgumentParser`
        """
        self.parser = parser
        self.actions = parser._optionals._actions

    def complete(self, original, pos):
        pref = original[:pos]

        res = []
        for act in self.actions:
            if '=' in pref:
                optionstring = pref[:pref.rfind('=') + 1]
                # get choices
                if 'choices' in act.__dict__:
                    # TODO: respect prefix
                    choices = act.choices or []
                    res = res + [optionstring + a for a in choices]
            else:
                for optionstring in act.option_strings:
                    if optionstring.startswith(pref):
                        # append '=' for options that await a string value
                        if isinstance(act, argparse._StoreAction) or\
                         isinstance(act, BooleanAction):
                            optionstring += '='
                        res.append(optionstring)

        return [(a, len(a)) for a in res]


class AccountCompleter(StringlistCompleter):
    """completes users' own mailaddresses"""

    def __init__(self):
        resultlist = settings.get_main_addresses()
        StringlistCompleter.__init__(self, resultlist)


class CommandCompleter(Completer):
    """completes commands"""

    def __init__(self, mode):
        """
        :param mode: mode identifier
        :type mode: str
        """
        self.mode = mode

    def complete(self, original, pos):
        #TODO refine <tab> should get current querystring
        commandprefix = original[:pos]
        logging.debug('original="%s" prefix="%s"' % (original, commandprefix))
        cmdlist = commands.COMMANDS['global'].copy()
        cmdlist.update(commands.COMMANDS[self.mode])
        matching = [t for t in cmdlist if t.startswith(commandprefix)]
        return [(t, len(t)) for t in matching]


class CommandLineCompleter(Completer):
    """completion for commandline"""

    def __init__(self, dbman, mode, currentbuffer=None):
        """
        :param dbman: used to look up avaliable tagstrings
        :type dbman: :class:`~alot.db.DBManager`
        :param mode: mode identifier
        :type mode: str
        :param currentbuffer: currently active buffer. If defined, this will be
                              used to dynamically extract possible completion
                              strings
        :type currentbuffer: :class:`~alot.buffers.Buffer`
        """
        self.dbman = dbman
        self.mode = mode
        self.currentbuffer = currentbuffer
        self._commandcompleter = CommandCompleter(mode)
        self._querycompleter = QueryCompleter(dbman)
        self._tagcompleter = TagCompleter(dbman)
        abooks = settings.get_addressbooks()
        self._contactscompleter = ContactsCompleter(abooks)
        self._pathcompleter = PathCompleter()

    def complete(self, line, pos):
        words = line.split(' ', 1)

        res = []
        if pos <= len(words[0]):  # we complete commands
            for cmd, cpos in self._commandcompleter.complete(line, pos):
                newtext = ('%s %s' % (cmd, ' '.join(words[1:])))
                res.append((newtext, cpos + 1))
        else:
            cmd, params = words
            localpos = pos - (len(cmd) + 1)
            parser = commands.lookup_parser(cmd, self.mode)
            # set 'res' - the result set of matching completionstrings
            # depending on the current mode and command

            # detect if we are completing optional parameter
            arguments_until_now = params[:localpos].split(' ')
            all_optionals = True
            logging.debug(str(arguments_until_now))
            for a in arguments_until_now:
                logging.debug(a)
                if a and not a.startswith('-'):
                    all_optionals = False
            # complete optional parameter if
            # 1. all arguments prior to current position are optional parameter
            # 2. the parameter starts with '-' or we are at its beginning
            if all_optionals:
                myarg = arguments_until_now[-1]
                start_myarg = params.rindex(myarg)
                beforeme = params[:start_myarg]
                # set up local stringlist completer
                # and let it complete for given list of options
                localcompleter = ArgparseOptionCompleter(parser)
                localres = localcompleter.complete(myarg, len(myarg))
                res = [(beforeme + c, p + start_myarg) for (c, p) in localres]

            # global
            elif cmd == 'search':
                res = self._querycompleter.complete(params, localpos)
            elif cmd == 'help':
                res = self._commandcompleter.complete(params, localpos)
            elif cmd in ['compose']:
                res = self._contactscompleter.complete(params, localpos)
            # search
            elif self.mode == 'search' and cmd == 'refine':
                res = self._querycompleter.complete(params, localpos)
            elif self.mode == 'search' and cmd in ['tag', 'retag', 'untag',
                                                   'toggletags']:
                localcomp = MultipleSelectionCompleter(self._tagcompleter,
                                                       separator=',')
                res = localcomp.complete(params, localpos)
            elif self.mode == 'search' and cmd == 'toggletag':
                localcomp = MultipleSelectionCompleter(self._tagcompleter,
                                                       separator=' ')
                res = localcomp.complete(params, localpos)
            # envelope
            elif self.mode == 'envelope' and cmd == 'set':
                plist = params.split(' ', 1)
                if len(plist) == 1:  # complete from header keys
                    localprefix = params
                    headers = ['Subject', 'To', 'Cc', 'Bcc', 'In-Reply-To']
                    localcompleter = StringlistCompleter(headers)
                    localres = localcompleter.complete(localprefix, localpos)
                    res = [(c, p + 6) for (c, p) in localres]
                else:  # must have 2 elements
                    header, params = plist
                    localpos = localpos - (len(header) + 1)
                    if header.lower() in ['to', 'cc', 'bcc']:

                        # prepend 'set ' + header and correct position
                        def f((completed, pos)):
                            return ('%s %s' % (header, completed),
                                    pos + len(header) + 1)
                        res = map(f, self._contactscompleter.complete(params,
                                                                  localpos))
            elif self.mode == 'envelope' and cmd == 'unset':
                plist = params.split(' ', 1)
                if len(plist) == 1:  # complete from header keys
                    localprefix = params
                    buf = self.currentbuffer
                    if buf:
                        if isinstance(buf, EnvelopeBuffer):
                            available = buf.envelope.headers.keys()
                            localcompleter = StringlistCompleter(available)
                            localres = localcompleter.complete(localprefix,
                                                               localpos)
                            res = [(c, p + 6) for (c, p) in localres]

            elif self.mode == 'envelope' and cmd == 'attach':
                res = self._pathcompleter.complete(params, localpos)
            # thread
            elif self.mode == 'thread' and cmd == 'save':
                res = self._pathcompleter.complete(params, localpos)
            elif self.mode == 'thread' and cmd in ['tag', 'retag', 'untag',
                                                   'toggletags']:
                localcomp = MultipleSelectionCompleter(self._tagcompleter,
                                                       separator=',')
                res = localcomp.complete(params, localpos)

            # prepend cmd and correct position
            res = [('%s %s' % (cmd, t), p + len(cmd) + 1) for (t, p) in res]
        return res


class PathCompleter(Completer):
    """completion for paths"""
    def complete(self, original, pos):
        if not original:
            return [('~/', 2)]
        prefix = os.path.expanduser(original[:pos])

        def escape(path):
            return path.replace('\\', '\\\\').replace(' ', '\ ')

        def deescape(escaped_path):
            return escaped_path.replace('\\ ', ' ').replace('\\\\', '\\')

        def prep(path):
            escaped_path = escape(path)
            return escaped_path, len(escaped_path)

        return map(prep, glob.glob(deescape(prefix) + '*'))