# coding: utf-8

import pymses.utils.constants as cst


def parse_exp_unit(u):
    splitted = u.split("^")
    name_u = cst.Unit.from_name(splitted[0]).latex
    exp = ""
    if len(splitted) > 1:
        exp = "$^{" + str(splitted[1]) + "}$"
    return name_u + exp


def convert_exp(number, digits=4):
    # Split string as [coeff, exponent]
    splitted = "{num:.{digits}g}".format(num=number, digits=digits).split("e")
    # If no need of scientific notation (low number of digits)
    if len(splitted) == 1:
        return "${}$".format(splitted[0])
    else:
        coeff = splitted[0]
        exp = splitted[1]
        exp_str = "10^{" + str(int(exp)) + "}"
        if float(coeff) == 1.0:
            return "$" + exp_str + "$"
        else:
            return "${}\\times {}$".format(coeff, exp_str)


def unit_str(unit, base=None, prefix=""):
    if unit == cst.none:
        return ""
    elif not base is None:
        coeff = unit.express(base)
        return unit_str(base, prefix=convert_exp(coeff) + " ")
    elif len(unit.latex) > 0:
        if ("." in unit.latex or "^" in unit.latex) and not "$" in unit.latex:
            base_str = ".".join(map(parse_exp_unit, unit.name.split(".")))
            return r" [{}{}]".format(prefix, base_str)
        else:
            return r" [{}{}]".format(prefix, unit.latex)
    elif len(unit.name) > 0:
        try:
            base_str = ".".join(map(parse_exp_unit, unit.name.split(".")))
            u_str = r" [{}{}]".format(prefix, base_str)
        except:
            u_str = r" [{}{}]".format(prefix, unit.name)
        return u_str
    else:
        base_str = ".".join(
            map(parse_exp_unit, unit._decompose_base_units().split("."))
        )
        return r" [{}{} {}]".format(prefix, unit.coeff, base_str)


cst.Msun_pc3 = cst.create_unit(
    "Msun.pc^-3", base_unit=cst.Msun / cst.pc ** 3, descr="Density"
)

cst.Msun_pc3 = cst.create_unit(
    "Msun.pc^-3", base_unit=cst.Msun / cst.pc ** 3, descr="Density"
)

cst.ssfr = cst.create_unit(
    "Msun.yr^-1.pc^-2",
    base_unit=cst.Msun / cst.year / cst.pc ** 2,
    descr="Surfacic SFR",
    latex="M$_{\odot}$.yr$^{-1}$.pc$^{-2}$",
)