import re

# Keycmd format which includes the markup for the cursor.
KEYCMD_FORMAT = "%s<span @cursor_style>%s</span>%s"
MODCMD_FORMAT = "<span> %s </span>"


def escape(str):
    for char in ['\\', '@']:
        str = str.replace(char, '\\'+char)

    return str


def uzbl_escape(str):
    return "@[%s]@" % escape(str) if str else ''


class Keylet(object):
    '''Small per-instance object that tracks characters typed.'''

    def __init__(self):
        # Modcmd tracking
        self.modcmd = ''
        self.is_modcmd = False

        # Keycmd tracking
        self.keycmd = ''
        self.cursor = 0

        self.modmaps = {}
        self.ignores = {}


    def get_keycmd(self):
        '''Get the keycmd-part of the keylet.'''

        return self.keycmd


    def get_modcmd(self):
        '''Get the modcmd-part of the keylet.'''

        if not self.is_modcmd:
            return ''

        return self.modcmd


    def modmap_key(self, key):
        '''Make some obscure names for some keys friendlier.'''

        if key in self.modmaps:
            return self.modmaps[key]

        elif key.endswith('_L') or key.endswith('_R'):
            # Remove left-right discrimination and try again.
            return self.modmap_key(key[:-2])

        else:
            return key


    def key_ignored(self, key):
        '''Check if the given key is ignored by any ignore rules.'''

        for (glob, match) in self.ignores.items():
            if match(key):
                return True

        return False


    def __repr__(self):
        '''Return a string representation of the keylet.'''

        l = []
        if self.is_modcmd:
            l.append('modcmd=%r' % self.get_modcmd())

        if self.keycmd:
            l.append('keycmd=%r' % self.get_keycmd())

        return '<keylet(%s)>' % ', '.join(l)


def add_modmap(uzbl, key, map):
    '''Add modmaps.

    Examples:
        set modmap = request MODMAP
        @modmap <Control> <Ctrl>
        @modmap <ISO_Left_Tab> <Shift-Tab>
        ...

    Then:
        @bind <Shift-Tab> = <command1>
        @bind <Ctrl>x = <command2>
        ...

    '''

    assert len(key)
    modmaps = uzbl.keylet.modmaps

    modmaps[key.strip('<>')] = map.strip('<>')
    uzbl.event("NEW_MODMAP", key, map)


def modmap_parse(uzbl, map):
    '''Parse a modmap definiton.'''

    split = [s.strip() for s in map.split(' ') if s.split()]

    if not split or len(split) > 2:
        raise Exception('Invalid modmap arugments: %r' % map)

    add_modmap(uzbl, *split)


def add_key_ignore(uzbl, glob):
    '''Add an ignore definition.

    Examples:
        set ignore_key = request IGNORE_KEY
        @ignore_key <Shift>
        @ignore_key <ISO_*>
        ...
    '''

    assert len(glob) > 1
    ignores = uzbl.keylet.ignores

    glob = "<%s>" % glob.strip("<> ")
    restr = glob.replace('*', '[^\s]*')
    match = re.compile(restr).match

    ignores[glob] = match
    uzbl.event('NEW_KEY_IGNORE', glob)


def clear_keycmd(uzbl, *args):
    '''Clear the keycmd for this uzbl instance.'''

    k = uzbl.keylet
    k.keycmd = ''
    k.cursor = 0
    del uzbl.config['keycmd']
    uzbl.event('KEYCMD_CLEARED')


def clear_modcmd(uzbl):
    '''Clear the modcmd for this uzbl instance.'''

    k = uzbl.keylet
    k.modcmd = ''
    k.is_modcmd = False

    del uzbl.config['modcmd']
    uzbl.event('MODCMD_CLEARED')


def clear_current(uzbl):
    '''Clear the modcmd if is_modcmd else clear keycmd.'''

    if uzbl.keylet.is_modcmd:
        clear_modcmd(uzbl)

    else:
        clear_keycmd(uzbl)


def update_event(uzbl, modstate, k, execute=True):
    '''Raise keycmd & modcmd update events.'''

    keycmd, modcmd = k.get_keycmd(), ''.join(modstate) + k.get_modcmd()

    if k.is_modcmd:
        logger.debug('modcmd_update, %s' % modcmd)
        uzbl.event('MODCMD_UPDATE', modstate, k)

    else:
        logger.debug('keycmd_update, %s' % keycmd)
        uzbl.event('KEYCMD_UPDATE', modstate, k)

    if uzbl.config.get('modcmd_updates', '1') == '1':
        new_modcmd = ''.join(modstate) + k.get_modcmd()
        if not new_modcmd or not k.is_modcmd:
            del uzbl.config['modcmd']

        elif new_modcmd == modcmd:
            uzbl.config['modcmd'] = MODCMD_FORMAT % uzbl_escape(modcmd)

    if uzbl.config.get('keycmd_events', '1') != '1':
        return

    new_keycmd = k.get_keycmd()
    if not new_keycmd:
        del uzbl.config['keycmd']

    elif new_keycmd == keycmd:
        # Generate the pango markup for the cursor in the keycmd.
        curchar = keycmd[k.cursor] if k.cursor < len(keycmd) else ' '
        chunks = [keycmd[:k.cursor], curchar, keycmd[k.cursor+1:]]
        value = KEYCMD_FORMAT % tuple(map(uzbl_escape, chunks))

        uzbl.config['keycmd'] = value


def inject_str(str, index, inj):
    '''Inject a string into string at at given index.'''

    return "%s%s%s" % (str[:index], inj, str[index:])


def parse_key_event(uzbl, key):
    ''' Build a set from the modstate part of the event, and pass all keys through modmap '''
    keylet = uzbl.keylet

    modstate, key = splitquoted(key)
    modstate = set(['<%s>' % keylet.modmap_key(k) for k in modstate.split('|') if k])
    
    key = keylet.modmap_key(key)
    return modstate, key


def key_press(uzbl, key):
    '''Handle KEY_PRESS events. Things done by this function include:

    1. Ignore all shift key presses (shift can be detected by capital chars)
    2. In non-modcmd mode:
         a. append char to keycmd
    3. If not in modcmd mode and a modkey was pressed set modcmd mode.
    4. Keycmd is updated and events raised if anything is changed.'''

    k = uzbl.keylet
    modstate, key = parse_key_event(uzbl, key)
    k.is_modcmd = any(not k.key_ignored(m) for m in modstate)

    logger.debug('key press modstate=%s' % str(modstate))
    if key.lower() == 'space' and not k.is_modcmd and k.keycmd:
        k.keycmd = inject_str(k.keycmd, k.cursor, ' ')
        k.cursor += 1

    elif not k.is_modcmd and len(key) == 1:
        if uzbl.config.get('keycmd_events', '1') != '1':
            # TODO, make a note on what's going on here
            k.keycmd = ''
            k.cursor = 0
            del uzbl.config['keycmd']
            return

        k.keycmd = inject_str(k.keycmd, k.cursor, key)
        k.cursor += 1

    elif len(key) == 1:
        k.modcmd += key

    else:
        if not k.key_ignored('<%s>' % key):
            modstate.add('<%s>' % key)
            k.is_modcmd = True

    update_event(uzbl, modstate, k)


def key_release(uzbl, key):
    '''Respond to KEY_RELEASE event. Things done by this function include:

    1. If in a mod-command then raise a MODCMD_EXEC.
    2. Update the keycmd uzbl variable if anything changed.'''
    k = uzbl.keylet
    modstate, key = parse_key_event(uzbl, key)

    if len(key) > 1:
        if k.is_modcmd:
            uzbl.event('MODCMD_EXEC', modstate, k)

        clear_modcmd(uzbl)


def set_keycmd(uzbl, keycmd):
    '''Allow setting of the keycmd externally.'''

    k = uzbl.keylet
    k.keycmd = keycmd
    k.cursor = len(keycmd)
    update_event(uzbl, set(), k, False)


def inject_keycmd(uzbl, keycmd):
    '''Allow injecting of a string into the keycmd at the cursor position.'''

    k = uzbl.keylet
    k.keycmd = inject_str(k.keycmd, k.cursor, keycmd)
    k.cursor += len(keycmd)
    update_event(uzbl, set(), k, False)


def append_keycmd(uzbl, keycmd):
    '''Allow appening of a string to the keycmd.'''

    k = uzbl.keylet
    k.keycmd += keycmd
    k.cursor = len(k.keycmd)
    update_event(uzbl, set(), k, False)


def keycmd_strip_word(uzbl, seps):
    ''' Removes the last word from the keycmd, similar to readline ^W '''

    seps = seps or ' '
    k = uzbl.keylet
    if not k.keycmd:
        return

    head, tail = k.keycmd[:k.cursor].rstrip(seps), k.keycmd[k.cursor:]
    rfind = -1
    for sep in seps:
        p = head.rfind(sep)
        if p >= 0 and rfind < p + 1:
            rfind = p + 1
    if rfind == len(head) and head[-1] in seps:
        rfind -= 1
    head = head[:rfind] if rfind + 1 else ''
    k.keycmd = head + tail
    k.cursor = len(head)
    update_event(uzbl, set(), k, False)


def keycmd_backspace(uzbl, *args):
    '''Removes the character at the cursor position in the keycmd.'''

    k = uzbl.keylet
    if not k.keycmd or not k.cursor:
        return

    k.keycmd = k.keycmd[:k.cursor-1] + k.keycmd[k.cursor:]
    k.cursor -= 1
    update_event(uzbl, set(), k, False)


def keycmd_delete(uzbl, *args):
    '''Removes the character after the cursor position in the keycmd.'''

    k = uzbl.keylet
    if not k.keycmd:
        return

    k.keycmd = k.keycmd[:k.cursor] + k.keycmd[k.cursor+1:]
    update_event(uzbl, set(), k, False)


def keycmd_exec_current(uzbl, *args):
    '''Raise a KEYCMD_EXEC with the current keylet and then clear the
    keycmd.'''

    uzbl.event('KEYCMD_EXEC', set(), uzbl.keylet)
    clear_keycmd(uzbl)


def set_cursor_pos(uzbl, index):
    '''Allow setting of the cursor position externally. Supports negative
    indexing and relative stepping with '+' and '-'.'''

    k = uzbl.keylet
    if index == '-':
        cursor = k.cursor - 1

    elif index == '+':
        cursor = k.cursor + 1

    else:
        cursor = int(index.strip())
        if cursor < 0:
            cursor = len(k.keycmd) + cursor + 1

    if cursor < 0:
        cursor = 0

    if cursor > len(k.keycmd):
        cursor = len(k.keycmd)

    k.cursor = cursor
    update_event(uzbl, set(), k, False)


# plugin init hook
def init(uzbl):
    '''Export functions and connect handlers to events.'''

    connect_dict(uzbl, {
        'APPEND_KEYCMD':        append_keycmd,
        'IGNORE_KEY':           add_key_ignore,
        'INJECT_KEYCMD':        inject_keycmd,
        'KEYCMD_BACKSPACE':     keycmd_backspace,
        'KEYCMD_DELETE':        keycmd_delete,
        'KEYCMD_EXEC_CURRENT':  keycmd_exec_current,
        'KEYCMD_STRIP_WORD':    keycmd_strip_word,
        'KEYCMD_CLEAR':         clear_keycmd,
        'KEY_PRESS':            key_press,
        'KEY_RELEASE':          key_release,
        'MOD_PRESS':            key_press,
        'MOD_RELEASE':          key_release,
        'MODMAP':               modmap_parse,
        'SET_CURSOR_POS':       set_cursor_pos,
        'SET_KEYCMD':           set_keycmd,
    })

    export_dict(uzbl, {
        'add_key_ignore':       add_key_ignore,
        'add_modmap':           add_modmap,
        'append_keycmd':        append_keycmd,
        'clear_current':        clear_current,
        'clear_keycmd':         clear_keycmd,
        'clear_modcmd':         clear_modcmd,
        'inject_keycmd':        inject_keycmd,
        'keylet':               Keylet(),
        'set_cursor_pos':       set_cursor_pos,
        'set_keycmd':           set_keycmd,
    })

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