import math
from collections import namedtuple
from .armor import NoArmor, NoShield, HeavyArmor
from .features import (UnarmoredDefenseMonk, UnarmoredDefenseBarbarian,
                       DraconicResilience, Defense, FastMovement,
                       UnarmoredMovement, GiftOfTheDepths, RemarkableAthelete,
                       SeaSoul, JackOfAllTrades)
from math import ceil


def findattr(obj, name):
    """Similar to builtin getattr(obj, name) but more forgiving to
    whitespace and capitalization.
    
    """
    # Come up with several options
    py_name = name.replace('-', '_').replace(' ', '_').replace("'", "")
    camel_case = "".join([s.capitalize() for s in py_name.split('_')])
    if hasattr(obj, py_name):
        # Direct lookup
        attr = getattr(obj, py_name)
    elif hasattr(obj, camel_case):
        # CamelCase lookup
        attr = getattr(obj, camel_case)
    else:
        raise AttributeError(f'{obj} has no attribute {name}')
    return attr


def mod_str(modifier):
    """Converts a modifier to a string, eg 2 -> '+2'."""
    return '{:+d}'.format(modifier)
    if modifier == 0:
        return str(modifier)
    else:
        return '{:+}'.format(modifier)


AbilityScore = namedtuple('AbilityScore',
                          ('value', 'modifier', 'saving_throw'))


class Ability():
    ability_name = None
    
    def __init__(self, default_value=10):
        self.default_value = default_value
    
    def __set_name__(self, character, name):
        self.ability_name = name
    
    def _check_dict(self, obj):
        if not hasattr(obj, '_ability_scores'):
            # No ability score dictionary exists
            obj._ability_scores = {
                self.ability_name: self.default_value
            }
        elif self.ability_name not in obj._ability_scores.keys():
            # ability score dictionary exists but doesn't have this ability
            obj._ability_scores[self.ability_name] = self.default_value
    
    def __get__(self, character, Character):
        self._check_dict(character)
        score = character._ability_scores[self.ability_name]
        modifier = math.floor((score - 10) / 2)
        # Check for proficiency
        saving_throw = modifier
        if self.ability_name is not None and hasattr(character, 'saving_throw_proficiencies'):
            is_proficient = (self.ability_name in character.saving_throw_proficiencies)
            if is_proficient:
                saving_throw += character.proficiency_bonus
        # Create the named tuple
        value = AbilityScore(modifier=modifier, value=score, saving_throw=saving_throw)
        return value
    
    def __set__(self, character, val):
        self._check_dict(character)
        character._ability_scores[self.ability_name] = val
        self.value = val


class Skill():
    """An ability-based skill, such as athletics."""
    
    def __init__(self, ability):
        self.ability_name = ability
    
    def __set_name__(self, character, name):
        self.skill_name = name.lower().replace('_', ' ')
        self.character = character
    
    def __get__(self, character, owner):
        ability = getattr(character, self.ability_name)
        modifier = ability.modifier
        # Check for proficiency
        is_proficient = self.skill_name in character.skill_proficiencies
        if is_proficient:
            modifier += character.proficiency_bonus
        elif character.has_feature(JackOfAllTrades):
            modifier += character.proficiency_bonus // 2
        elif character.has_feature(RemarkableAthelete):
            if self.ability_name.lower() in ('strength',
                                             'dexterity', 'constitution'):
                modifier += ceil(character.proficienc_bonus / 2.)
        
        # Check for expertise
        is_expert = self.skill_name in character.skill_expertise
        if is_expert:
            modifier += character.proficiency_bonus
        return modifier


class ArmorClass():
    """
    The Armor Class of a character
    """

    def __get__(self, char, Character):
        armor = char.armor or NoArmor()
        ac = armor.base_armor_class
        shield = char.shield or NoShield()
        ac += shield.base_armor_class
        # calculate and apply modifiers
        if armor.dexterity_mod_max is None:
            ac += char.dexterity.modifier
        else:
            ac += min(char.dexterity.modifier, armor.dexterity_mod_max)
        # Compute feature-specific additions
        if any([isinstance(f, UnarmoredDefenseMonk) for f in char.features]):
            if (isinstance(armor, NoArmor) and isinstance(shield, NoShield)):
                ac += char.wisdom.modifier
        if any([isinstance(f, UnarmoredDefenseBarbarian) for f in char.features]):
            if isinstance(armor, NoArmor):
                ac += char.constitution.modifier
        if any([isinstance(f, DraconicResilience) for f in char.features]):
            if isinstance(armor, NoArmor):
                ac += 3
        if any([isinstance(f, Defense) for f in char.features]):
            if not isinstance(armor, NoArmor):
                ac += 1
        # Check if any magic items add to AC
        for mitem in char.magic_items:
            if hasattr(mitem, 'ac_bonus'):
                ac += mitem.ac_bonus
        return ac
        

class Speed():
    """
    The speed of a character
    """

    def __get__(self, char, Character):
        speed = char.race.speed
        other_speed = ''
        if isinstance(speed, str):
            other_speed = speed[2:]
            speed = int(speed[:2])  # ignore other speeds, like fly
        if any([isinstance(f, FastMovement) for f in char.features]):
            if not isinstance(char.armor, HeavyArmor):
                speed += 10
        if isinstance(char.armor, NoArmor) or (char.armor is None):
            for f in char.features:
                if isinstance(f, UnarmoredMovement):
                    speed += f.speed_bonus
        if any([isinstance(f, GiftOfTheDepths) for f in char.features]):
            if 'swim' not in other_speed:
                other_speed += ' ({:d} swim)'.format(speed)
        if any([isinstance(f, SeaSoul) for f in char.features]):
            if 'swim' not in other_speed:
                other_speed += ' (30 swim)'
        return '{:d}{:s}'.format(speed, other_speed)