#!/usr/bin/env python3

# http://inamidst.com/saxo/
# Created by Sean B. Palmer

import re
import saxo

r_parens = re.compile(r"(\s*)\(\s*(.*?)\s*\)")
r_stringified = re.compile(r'"stringified":\s"([^"]+)"')
r_superscript = re.compile(r"\^\(?(-?[0-9]+)\)?")

@saxo.pipe
def wa(arg):
    page = saxo.request(
        "http://www.wolframalpha.com/input/",
        follow=True,
        query={
            "asynchronous": "false",
            "i": arg
        })

    simples = {
        r"\/": "/",
        r"\'": "'",
        "": "",
        " °": "°",
        "~~": " ~",
        "~~ ": " ~"
    }

    patterns = {
        r"\\n( *\| *)?": ", ",
        r"~~ *\(": "~(",
        r"[ \t]+": " ",
        r"([0-9]{12})[0-9]+": r"\g<1>"
    }

    def parentheses(text):
        def replacement(match):
            pre = " " if match.group(1) else ""
            content = match.group(2)
            return pre + "(" + content + ")"
        return r_parens.sub(replacement, text)

    def superscript(text):
        super = {"0": "⁰", "1": "¹", "2": "²", "3": "³", "4": "⁴",
            "5": "⁵", "6": "⁶", "7": "⁷","8": "⁸", "9": "⁹", "-": "⁻"}

        def replacement(match):
            characters = []
            for character in match.group(1):
                characters.append(super.get(character, character))
            return "".join(characters)
        return r_superscript.sub(replacement, text)

    def pretty(text):
        for key, value in simples.items():
            text = text.replace(key, value)

        for key, value in patterns.items():
            text = re.sub(key, value, text)

        text = re.sub(r"[ \t]+\|[ \t]+", ": ", text)
        text = parentheses(text)
        return superscript(text)

    first = ""
    items = []

    expression = ""
    expressions = []

    for i, stringified in enumerate(r_stringified.findall(page["text"])):
        exp = pretty(stringified)
        if not i:
            expression = exp[:]
        else:
            if exp.startswith(expression):
                exp = exp[len(expression):].lstrip(" =")
            expressions.append(exp)

    sep = "; "

    limit = 400

    if not expression:
        return "No results found"

    text = expression + " = "
    for exp in expressions:
        if len((text + exp + sep).encode("utf-8")) > limit:
            break

        text += exp + sep
    return text.rstrip(sep)