#!/usr/bin/python
# -*- coding: utf-8 -*-
#
# Urwid unicode character processing tables
#    Copyright (C) 2004-2011  Ian Ward
#
#    This library is free software; you can redistribute it and/or
#    modify it under the terms of the GNU Lesser General Public
#    License as published by the Free Software Foundation; either
#    version 2.1 of the License, or (at your option) any later version.
#
#    This library is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
#    Lesser General Public License for more details.
#
#    You should have received a copy of the GNU Lesser General Public
#    License along with this library; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# Urwid web site: http://excess.org/urwid/

import re

from urwid.compat import bytes, B, ord2

SAFE_ASCII_RE = re.compile("^[ -~]*$")
SAFE_ASCII_BYTES_RE = re.compile(B("^[ -~]*$"))

_byte_encoding = None

# GENERATED DATA
# generated from 
# http://www.unicode.org/Public/4.0-Update/EastAsianWidth-4.0.0.txt

widths = [
    (126, 1),
    (159, 0),
    (687, 1),
    (710, 0),
    (711, 1),
    (727, 0),
    (733, 1),
    (879, 0),
    (1154, 1),
    (1161, 0),
    (4347, 1),
    (4447, 2),
    (7467, 1),
    (7521, 0),
    (8369, 1),
    (8426, 0),
    (9000, 1),
    (9002, 2),
    (11021, 1),
    (12350, 2),
    (12351, 1),
    (12438, 2),
    (12442, 0),
    (19893, 2),
    (19967, 1),
    (55203, 2),
    (63743, 1),
    (64106, 2),
    (65039, 1),
    (65059, 0),
    (65131, 2),
    (65279, 1),
    (65376, 2),
    (65500, 1),
    (65510, 2),
    (120831, 1),
    (262141, 2),
    (1114109, 1),
]

# ACCESSOR FUNCTIONS

def get_width( o ):
    """Return the screen column width for unicode ordinal o."""
    global widths
    if o == 0xe or o == 0xf:
        return 0
    for num, wid in widths:
        if o <= num:
            return wid
    return 1

def decode_one( text, pos ):
    """
    Return (ordinal at pos, next position) for UTF-8 encoded text.
    """
    assert isinstance(text, bytes), text
    b1 = ord2(text[pos])
    if not b1 & 0x80: 
        return b1, pos+1
    error = ord("?"), pos+1
    lt = len(text)
    lt = lt-pos
    if lt < 2:
        return error
    if b1 & 0xe0 == 0xc0:
        b2 = ord2(text[pos+1])
        if b2 & 0xc0 != 0x80:
            return error
        o = ((b1&0x1f)<<6)|(b2&0x3f)
        if o < 0x80:
            return error
        return o, pos+2
    if lt < 3:
        return error
    if b1 & 0xf0 == 0xe0:
        b2 = ord2(text[pos+1])
        if b2 & 0xc0 != 0x80:
            return error
        b3 = ord2(text[pos+2])
        if b3 & 0xc0 != 0x80:
            return error
        o = ((b1&0x0f)<<12)|((b2&0x3f)<<6)|(b3&0x3f)
        if o < 0x800:
            return error
        return o, pos+3
    if lt < 4:
        return error
    if b1 & 0xf8 == 0xf0:
        b2 = ord2(text[pos+1])
        if b2 & 0xc0 != 0x80:
            return error
        b3 = ord2(text[pos+2])
        if b3 & 0xc0 != 0x80:
            return error
        b4 = ord2(text[pos+2])
        if b4 & 0xc0 != 0x80:
            return error
        o = ((b1&0x07)<<18)|((b2&0x3f)<<12)|((b3&0x3f)<<6)|(b4&0x3f)
        if o < 0x10000:
            return error
        return o, pos+4
    return error

def decode_one_uni(text, i):
    """
    decode_one implementation for unicode strings
    """
    return ord(text[i]), i+1

def decode_one_right(text, pos):
    """
    Return (ordinal at pos, next position) for UTF-8 encoded text.
    pos is assumed to be on the trailing byte of a utf-8 sequence.
    """
    assert isinstance(text, bytes), text
    error = ord("?"), pos-1
    p = pos
    while p >= 0:
        if ord2(text[p])&0xc0 != 0x80:
            o, next = decode_one( text, p )
            return o, p-1
        p -=1
        if p == p-4:
            return error

def set_byte_encoding(enc):
    assert enc in ('utf8', 'narrow', 'wide')
    global _byte_encoding
    _byte_encoding = enc

def get_byte_encoding():
    return _byte_encoding

def calc_text_pos(text, start_offs, end_offs, pref_col):
    """
    Calculate the closest position to the screen column pref_col in text
    where start_offs is the offset into text assumed to be screen column 0
    and end_offs is the end of the range to search.

    text may be unicode or a byte string in the target _byte_encoding

    Returns (position, actual_col).
    """
    assert start_offs <= end_offs, repr((start_offs, end_offs))
    utfs = isinstance(text, bytes) and _byte_encoding == "utf8"
    unis = not isinstance(text, bytes)
    if unis or utfs:
        decode = [decode_one, decode_one_uni][unis]
        i = start_offs
        sc = 0
        n = 1 # number to advance by
        while i < end_offs:
            o, n = decode(text, i)
            w = get_width(o)
            if w+sc > pref_col: 
                return i, sc
            i = n
            sc += w
        return i, sc