import re

# comparison regex
_FULL_ = r"\d+\s*[<>=]+\s*\w+\s*[<>=]+\s*\d+"


# Helper functions
def search_songs(searchterm, cache):
    def match_song(song, term):
        term = term.lower()
        values = [song['title_orig'], song['title_en']]
        values.extend([i for tpl in [(a['name_orig'], a['name_en']) for a in song['artists']] for i in tpl])
        if song['source']:
            values.extend([song['source']['name_orig'], song['source']['name_en']])
        for field in values:
            if term in field.lower():
                return True
        return False
    return [song for song in cache if match_song(song, searchterm)]


def parse_difficulty(term):
    if isinstance(term, str):
        term.lower()
    if   term in [0, 'e', 'k', 'easy', 'kantan']:
        return 'd_kantan'
    elif term in [1, 'n', 'f', 'normal', 'futsuu']:
        return 'd_futsuu'
    elif term in [2, 'h', 'm', 'hard', 'muzukashii', 'muzu']:
        return 'd_muzukashii'
    elif term in [3, 'o', 'extreme', 'oni']:
        return 'd_oni'
    elif term in [4, 'u', 'extra', 'ura']:
        return 'd_ura'
    else:
        return None


def parse_comparison(data):
    digits    = [int(d) for d in re.findall(r"\d+", data) ]
    operators = re.findall(r"[<>=]+", data)
    assert(len(digits) == len(operators))

    # Handle shortened expressions
    if not re.match(_FULL_, data):
        if operators[0] == digits[0]: # digit = operator or vice versa
            return digits[0]
        if data.index(str(digits[0])) < data.index(operators[0]): # digit < x
           digits.append(10)
           operators.append("<=")
        else: # x < digit
           digits.insert(0, 1)
           operators.insert(0, "<=")

    # Someone tried to do something funky like d > x < d OR d < x > d
    if (any( x in ("<", "<=") for x in operators) and
        any( x in (">", ">=") for x in operators)):
        if operators[0] in (">", ">="): # range from 0 to lowest
            low = min(digits)
            op  = operators[digits.index(low)]
            if op in ("<=", ">="): # Soft boundaries: +1 (will be cut at range)
                low += 1
            return list(range(1,low))
        else: # range from 10 to highest
            high = max(digits)
            op  = operators[digits.index(high)]
            if op in ("<", ">"): # Hard boundaries: +1
                high += 1
            return list(range(high, 11))

    # Adjust
    if   operators[0] == "<": digits[0] += 1
    elif operators[0] == ">": digits[0] -= 1
    elif operators[0] == "=": return [digits[0]]
    if   operators[1] == "<": digits[1] -= 1
    elif operators[1] == ">": digits[1] += 1
    elif operators[1] == "=": return [digits[1]]
    if digits[0] > digits[1]:
        digits = list(reversed(digits))
    return list(range(digits[0], digits[1]+1))