# -*- coding: utf-8 -*-

"""

This file contains a set of functions for matching values which may be written in different formats
e.g.
0.1uF = 100n (different suffix specified, one has missing unit)
0R1 = 0.1Ohm (Unit replaces decimal, different units)

"""

import re

PREFIX_MICRO = [u"μ","u","micro"]
PREFIX_MILLI = ["milli","m"]
PREFIX_NANO = ["nano","n"]
PREFIX_PICO = ["pico","p"]
PREFIX_KILO = ["kilo","k"]
PREFIX_MEGA = ["mega","meg"]
PREFIX_GIGA = ["giga","g"]

#All prefices
PREFIX_ALL = PREFIX_PICO + PREFIX_NANO + PREFIX_MICRO + PREFIX_MILLI + PREFIX_KILO + PREFIX_MEGA + PREFIX_GIGA

#Common methods of expressing component units 
UNIT_R = ["r","ohms","ohm",u"Ω"]
UNIT_C = ["farad","f"]
UNIT_L = ["henry","h"]

UNIT_ALL = UNIT_R + UNIT_C + UNIT_L

"""
Return a simplified version of a units string, for comparison purposes
"""
def getUnit(unit):

    if not unit: return None
    
    unit = unit.lower()
    
    if unit in UNIT_R: return "R"
    if unit in UNIT_C: return "F"
    if unit in UNIT_L: return "H"

    return None

"""
Return the (numerical) value of a given prefix
"""
def getPrefix(prefix):

    if not prefix: return 1
    
    prefix = prefix.lower()
    
    if prefix in PREFIX_PICO: return 1.0e-12
    if prefix in PREFIX_NANO: return 1.0e-9
    if prefix in PREFIX_MICRO: return 1.0e-6
    if prefix in PREFIX_MILLI: return 1.0e-3
    if prefix in PREFIX_KILO: return 1.0e3
    if prefix in PREFIX_MEGA: return 1.0e6
    if prefix in PREFIX_GIGA: return 1.0e9

    return 1

def groupString(group): #return a reg-ex string for a list of values
    return "|".join(group)

def matchString():
    return "^([0-9\.]+)(" + groupString(PREFIX_ALL) + ")*(" + groupString(UNIT_ALL) + ")*(\d*)$"


"""
Return a normalized value and units for a given component value string
e.g. compMatch("10R2") returns (10, R)
e.g. compMatch("3.3mOhm") returns (0.0033, R)
"""
def compMatch(component):

    #remove any commas
    component = component.strip().replace(",","").lower()

    match = matchString()

    result = re.search(match, component)

    if not result: return None

    if not len(result.groups()) == 4: return None

    value,prefix,units,post = result.groups()

    #special case where units is in the middle of the string
    #e.g. "0R05" for 0.05Ohm
    #in this case, we will NOT have a decimal
    #we will also have a trailing number

    if post and "." not in value:
        try:
            value = float(int(value))
            postValue = float(int(post)) / (10 ** len(post))
            value = value * 1.0 + postValue
        except:
            return None

    try:
        val = float(value)
    except:
        return None

    val = "{0:.15f}".format(val * 1.0 * getPrefix(prefix))

    return (val, getUnit(units))

def componentValue(valString):

    result = compMatch(valString)

    if not result:
        return valString #return the same string back
        
    if not len(result) == 2: #result length is incorrect
        return valString

    (val, unit) = result

    return val

#compare two values
def compareValues(c1, c2):
    r1 = compMatch(c1)
    r2 = compMatch(c2)

    if not r1 or not r2: return False

    (v1, u1) = r1
    (v2, u2) = r2

    if v1 == v2:
        #values match
        if u1 == u2: return True #units match
        if not u1: return True #no units for component 1
        if not u2: return True #no units for component 2

    return False