# Value to string conversion

# This file's encoding must be UTF-8Y with BOM so Python will auto-detect UTF-8

import locale

import re

import strings

import util

locale.setlocale(locale.LC_ALL, '') # needed to initialize locale

##### String parsing

def clean_numeric(val):

    '''Removes embedded whitespace. e.g "1, 000"'''

    return re.sub(r'(?<=[,.]) +', r'', val)

def str2int(val): return locale.atoi(clean_numeric(val))

def str2float(val): return locale.atof(clean_numeric(val))

##### Value formatting

def format_str(format, val):

    return locale.format_string(format, val, grouping=True)

def int2str(val): return format_str('%d', val)

def float2str(val): return format_str('%f', val)

def to_percent(val, sig_figs=2):

    if val >= 1: sig_figs += 1

    return format_str('%#.'+str(sig_figs)+'g', val*100)+'%'

def to_si(val, sig_figs=3):

    '''Adds SI prefix to value'''

    prefix = ''

    if val < 1: prefix = 'm'; val *= 1000

    return format_str('%#.'+str(sig_figs)+'g', val)+' '+prefix

##### Units

class MissingUnitsException(Exception):

    def __init__(self, value):

        Exception.__init__(self, 'Value has no units: '+value)

def std_units(units):

    if units == None: return units

    else: return strings.remove_suffix('.', units) # for abbr ending in '.'

    # TODO: deal with '"° and abbrs

def parse_units(value):

    '''@return tuple (number float, units str|None)'''

    number = value

    units = None

    if not value.isdigit(): # optimization to avoid regexp for simple cases

        match = re.match(ur'(?i)^\s*(.*?\d\.?)\s*([a-z\'"°][\w.*/^-]*?)?\s*$',

            value)

        if match: # has units

            number, units = match.groups()

            units = std_units(util.none_if(units, u''))

    return (str2float(number), units)

def cleanup_units(value, default_units=None):

    '''Cleans up units so the number is separated from the units by one space.

    @param default_units Units to add if value has no units. If None, raises

        MissingUnitsException if value has no units.

    '''

    number, units = parse_units(value)

    if units == None:

        if default_units != None: units = default_units

        else: raise MissingUnitsException(value)

    return str(number)+' '+units