#!/usr/bin/env python
# coding: utf-8

# ##A Demonstration of how one can use Python to select chapters of a Ebook based on their POV in title.
# 
#  - The is is a simple demonstration, it only catches the basic case
#  - You'll likely need to customise it on a per-book basis
#  - For demonstration, I am using a particular ebook containing the first for books of George R.R. Matrin's Song of Ice and Fire
#  - It is your responsibility to ensure the legality of this in your local
# 

# ----------------------
# 
# ####The Libraries
# We are using python3 today, but this code should work almost without change in python2. To libraries are required.
# 
#  - [ebooklib](https://github.com/aerkalov/ebooklib) is for reading and writing the epubs as a whole -- they are basically Zip Archieves
#  - [BeautifulSoup](http://www.crummy.com/software/BeautifulSoup/bs4/doc/) is for reading the HTML files within them
# 
# Both can be installed with `pip`.
# 
# We are also going to use the standard library component:
# 
#  - [re](https://docs.python.org/3/library/re.html) for regular expressions 

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import ebooklib
from ebooklib import epub
from bs4 import BeautifulSoup
import re


# ##What to Keep:
# ebooklib.epub breaks the epub up into items. These are files with in the zip archieve.
# Generally most booked have one item (ie file), per chapter. That is the case for our book.
# 
# Of these items, there are three catagories of  item we want to keep:
#     
# - items that are not chapters at all -- these could be pictures, or metadata or something else. we don't know.
# - chapters that are universal, eg the prologue, the dedication or the appendix.
# - chapter's  that are about the character we are interested in

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def is_not_chapter(item):
    return item.get_type() != ebooklib.ITEM_DOCUMENT


# #####Recognising univeral chapters
# All the normal chapted in out case are named along the lines of: `b01-c01` for book 1 (as it is a complation) chapter 1. Special chapters like the appendix don't follow this pattern. We can check for it with a regex

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def is_univeral_chapter(chapter):
    return not re.match("(b\d\d.c\d\d)",chapter.get_id())


# ##Is it about our character?
# 
# In this particular book all the character names are in the chapter headings.
# However it does represent them in two different ways. In some sections it is with a `<h1>` element, in others in is in a `<p class="ct">` element. We'll check for both. 
# 
# Notice this function is a higher order function that returns a function. That makes it work nice with filter -- useful for testing, if you've already stripped down to just the normal chapters.
# 
# `filter(is_character("JON"), chapters)`

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def is_character(name):
    def inner(chapter):
        soup = BeautifulSoup(chapter.get_content())
        heading_matchers = [lambda: soup.find_all('h1'),
                            lambda: soup.find_all(class_='ct')
                           ]
        headings=[]
        for matcher in heading_matchers:
            headings = matcher()
            if len(headings)>0: break
        else:
            return False
        
        assert(len(headings)==1)
        heading = headings[0]
        chapter_character_name = heading.text.strip()
        return chapter_character_name == name
        
    return inner


# ###Bring our conditions together
# Another higher order function, again to make it work with `filter`.
# In this case it is a closure.

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def keep_item(character_name):
    is_our_charatacter = is_character(character_name)
    def inner(item):
        return (is_not_chapter(item) 
                or is_univeral_chapter(item) 
                or is_our_charatacter(item))
    return inner
        
    


# ###Combine it all, with a read and a write
# Also we'll modify the title, don't want to get them confused.
# There is also a helper function below to workout the new filename

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def rewrite_book_by_character(filename, character):
    book = epub.read_epub(filename)
    book.items = list(filter(keep_item(character), book.items))
    book.title+=": " + character + "POVs_ONLY"
    
    new_filename = get_new_filename(filename,character)
    epub.write_epub(new_filename, book, {})
    return new_filename

def get_new_filename(filename,character):
    import os.path
    filename_base, ext = os.path.splitext(filename)
    new_filename = filename_base +"_" + character+"_ONLY"+ext
    return new_filename


# ##Git it a go

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from IPython.display import FileLink
filename = rewrite_book_by_character('asoiaf01-04.epub', "JON")
FileLink(filename)


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# ####The MIT License (MIT)
# 
# Copyright (c) 2015 Lyndon White
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

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