#!/usr/bin/env python

# The MIT License (MIT)
#
# Copyright (c) 2018 Sunaina Pai
#
# 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.


"""Make static website/blog with Python."""


import os
import shutil
import re
import glob
import sys
import json
import datetime
import optparse

try:
    import markdown
    has_markdown = True
except ImportError as err:
    print(f'Could not import markdown: {err}. Markdown cannot be rendered!')
    has_markdown = False

def fread(filename):
    """Read file and close the file."""
    with open(filename, 'r') as f:
        return f.read()


def fwrite(filename, text):
    """Write content to file and close the file."""
    basedir = os.path.dirname(filename)
    if not os.path.isdir(basedir):
        os.makedirs(basedir)

    with open(filename, 'w') as f:
        f.write(text)


def log(msg, *args):
    """Log message with specified arguments."""
    sys.stderr.write(msg.format(*args) + '\n')


def truncate(text, words=25):
    """Remove tags and truncate text to the specified number of words."""
    return ' '.join(re.sub('(?s)<.*?>', ' ', text).split()[:words])


def read_headers(text):
    """Parse headers in text and yield (key, value, end-index) tuples."""
    for match in re.finditer(r'\s*<!--\s*(.+?)\s*:\s*(.+?)\s*-->\s*|.+', text):
        if not match.group(1):
            break
        yield match.group(1), match.group(2), match.end()


def rfc_2822_format(date_str):
    """Convert yyyy-mm-dd date string to RFC 2822 format date string."""
    d = datetime.datetime.strptime(date_str, '%Y-%m-%d')
    return d.strftime('%a, %d %b %Y %H:%M:%S +0000')


def read_content(filename):
    """Read content and metadata from file into a dictionary."""
    # Read file content.
    text = fread(filename)

    # Read metadata and save it in a dictionary.
    date_slug = os.path.basename(filename).split('.')[0]
    match = re.search(r'^(?:(\d\d\d\d-\d\d-\d\d)-)?(.+)$', date_slug)
    content = {
        'date': match.group(1) or '1970-01-01',
        'slug': match.group(2),
    }

    # Read headers.
    end = 0
    for key, val, end in read_headers(text):
        content[key] = val

    # Separate content from headers.
    text = text[end:]

    # Convert Markdown content to HTML.
    if filename.endswith(('.md', '.mkd', '.mkdn', '.mdown', '.markdown')):
        if _test == 'ImportError':
            raise ImportError('Error forced by test')
        if has_markdown:
            text = markdown.markdown(text, extensions=['codehilite', 'fenced_code'])
        else:
            log('WARNING: Cannot render Markdown in {}: python-markdown not available', filename)

    # Update the dictionary with content and RFC 2822 date.
    content.update({
        'content': text,
        'rfc_2822_date': rfc_2822_format(content['date'])
    })

    return content


def render(template, **params):
    """Replace placeholders in template with values from params."""
    def handle_variable(match):
        var = match.group(1).strip()
        if match.group(1).startswith("template "):
            import_name = var[7:]
            import_ = fread(import_name)
            return render(import_, **params)
        elif var.startswith("for_each "):
            args = var.split(" ")[1:]
            attribute_name = args[0]
            template_name = args[1]

            template_ = fread(template_name)
            templates = []
            for val in params.get(attribute_name, []):
                templates.append(render(template_, **params, item=val))
            return "\n".join(templates)
        elif var.startswith("item."):
            return str(params["item"].get(var[5:], match.group(0)))
        elif var.startswith("template_if_empty "):
            # {{ template_if_empty <param> <template if param is empty> <otherwise> }}
            args = var[17:].split(" ")[1:]
            value = params["item"].get(args[0][5:], "") if args[0].startswith("item.") else params.get(args[0], "")
            template_name = args[1] if value == "" else args[2]
            template_ = fread(template_name)
            return render(template_, **params)
        else:
            if not var in params:
                print("Did not find variable '%s'!" % var)
                return match.group(0)
            
            return params[var]

    return re.sub(r'{{\s*([^}]+)\s*}}',
                  handle_variable,
                  template)


def make_pages(src, dst, layout, **params):
    """Generate pages from page content."""
    items = []

    for src_path in glob.glob(src):
        content = read_content(src_path)
        page_params = dict(params, **content)
        
        # Check if reading specific params was requested
        if 'params' in content:
            page_params.update(**json.loads(open(content['params'], 'r').read()))

        page_params['file_name'] = os.path.basename(src_path)
            
        # Populate placeholders in content if content-rendering is enabled.
        if page_params.get('render') == 'yes':
            rendered_content = render(page_params['content'], **page_params)
            page_params['content'] = rendered_content
            content['content'] = rendered_content

        items.append(content)

        dst_path = render(dst, **page_params)
        output = render(layout, **page_params)
        
        log('Rendering {} => {} ...', src_path, dst_path)
        fwrite(dst_path, output)

    return sorted(items, key=lambda x: x['date'], reverse=True)


def make_list(posts, dst, list_layout, item_layout, truncate_posts=True, **params):
    """Generate list page for a blog."""
    items = []
    for post in posts:
        item_params = dict(params, **post)
        if truncate_posts:
            item_params['summary'] = truncate(post['content'])
        else:
            item_params['summary'] = post['content']
        item = render(item_layout, **item_params)
        items.append(item)

    params['content'] = ''.join(items)
    dst_path = render(dst, **params)
    output = render(list_layout, **params)

    log('Rendering list => {} ...', dst_path)
    fwrite(dst_path, output)


def main():
    parser = optparse.OptionParser()
    parser.add_option('-p', '--params', dest='params',
                      help='The params file to load')
    parser.add_option('-b', '--blog', action='store_true', dest='blog',
                      help='Generate a blog')
    parser.add_option('-r', '--rss', action='store_true', dest='rss',
                      help='Generate a RSS feed')
    parser.add_option('--copy-assets', action='store_true', dest='copy_assets',
                      help='Copy assets over')
    parser.add_option('-a', '--assets', action='append', dest='assets', default=['assets'],
                      help='The assets directory to copy')
    parser.add_option('-v', '--variable', action='append', dest='variables',
                      help='Append a variable to the params')
    parser.add_option('-i', '--ignore', action='append', dest='asset_ignores', default=[],
                      help='Ignore a folder when copying the assets')
    parser.add_option('--include', action='append', dest='includes', default=[],
                      help='Include files and folders into the build')
    (options, args) = parser.parse_args()

    # Create a new _site directory from scratch.
    if os.path.isdir('_site'):
        shutil.rmtree('_site')
    if options.copy_assets:
        def ignore(dir_, items):
            full_items = [os.path.join(dir_, i) for i in items]
            intersection = set(full_items).intersection(options.asset_ignores)
            starts = [(item.startswith(i) for i in options.asset_ignores) for item in full_items]

            return list(intersection) + starts
        for asset in options.assets:
            shutil.copytree(asset, '_site/assets', ignore=ignore, dirs_exist_ok=True)

    if options.includes:
        for include in options.includes:
            print(f'Copying {include} => _site/{include} ...')
            if os.path.isfile(include):
                shutil.copy(include, '_site/')
            else:
                shutil.copytree(include, '_site/')

    # Default parameters.
    params = {
        'base_path': '',
        'subtitle': 'Lorem Ipsum',
        'author': 'Admin',
        'site_url': 'http://localhost:8000',
        'current_year': datetime.datetime.now().year
    }

    # If params.json exists, load it.
    if not options.params:
        params_file = 'params.json'
    else:
        params_file = options.params
    if os.path.isfile(params_file):
        params.update(**json.loads(fread(params_file)))

    for variable in (options.variables or []):
        key, val = variable.split('=')
        params[key] = val

    # Load layouts.
    page_layout = fread('layout/page.html')

    # Create site pages.
    for element in os.listdir('content/'):
        if not os.path.isfile('content/' + element):
            continue

        make_pages('content/' + element, '_site/' + element,
                   page_layout, **params)

    if options.blog:
        post_layout = fread('layout/post.html')
        list_layout = fread('layout/list.html')
        item_layout = fread('layout/item.html')

        # Combine layouts to form final layouts.
        post_layout = render(page_layout, content=post_layout)
        list_layout = render(page_layout, content=list_layout)

        # Create blogs.
        blog_posts = make_pages('content/blog/*.md',
                                '_site/{{ slug }}.html',
                                post_layout, blog='blog', **params)

        # Create blog list pages.
        make_list(blog_posts, '_site/index.html',
                  list_layout, item_layout, blog='blog', title=params["blog_title"], description=params["blog_description"], **params)
    
    if options.rss:
        feed_xml = fread('layout/feed.xml')
        item_xml = fread('layout/item.xml')

        # Create RSS feeds.
        make_list(blog_posts, '_site/atom.xml',
                  feed_xml, item_xml, truncate_posts=False, blog='blog', **params)


# Test parameter to be set temporarily by unit tests.
_test = None


if __name__ == '__main__':
    main()