import os
import re
import glob
import simplejson as json
import mistune

import app.settings.app_cfg as cfg
import app.site.s3 as s3

renderer = mistune.Renderer(escape=False)
markdown = mistune.Markdown(renderer=renderer)

def fix_images(lines, s3_path):
  """
  do our own tranformation of the markdown around images to handle wide images etc
  lines: markdown lines
  """
  real_lines = []
  block = "\n\n".join(lines)
  for line in block.split("\n"):
    if "![" in line:
      line = line.replace('![', '')
      alt_text, tail = line.split('](', 1)
      url, tail = tail.split(')', 1)
      if ':' in alt_text:
        tail, alt_text = alt_text.split(':', 1)
      img_tag = "<img src='{}' alt='{}'>".format(s3_path + url, alt_text.replace("'", ""))
      if len(alt_text):
        line = "<div class='image'>{}<div class='caption'>{}</div></div>".format(img_tag, alt_text)
      else:
        line = "<div class='image'>{}</div>".format(img_tag, alt_text)
    real_lines.append(line)
  return "\n".join(real_lines)

def format_section(lines, s3_path, type=''):
  """
  format a normal markdown section
  """
  if len(lines):
    lines = fix_images(lines, s3_path)
    if type:
      return "<section class='{}'>{}</section>".format(type, markdown(lines))
    else:
      return "<section>" + markdown(lines) + "</section>"
  return ""

def format_metadata(section):
  """
  format a metadata section (+ key: value pairs)
  """
  meta = []
  for line in section.split('\n'):
    key, value = line[2:].split(': ', 1)
    meta.append("<div><div class='gray'>{}</div><div>{}</div></div>".format(key, value))
  return "<section><div class='meta'>{}</div></section>".format(''.join(meta)) 

def format_applet(section, s3_path):
  # print(section)
  payload = section.strip('```').strip().strip('```').strip().split('\n')
  applet = {}
  print(payload)
  if ': ' in payload[0]:
    command, opt = payload[0].split(': ')
  else:
    command = payload[0]
    opt = None
  if command == 'python' or command == 'javascript' or command == 'code':
    return format_section([ section ], s3_path)
  if command == '':
    return ''

  applet['command'] = command
  if opt:
    applet['opt'] = opt
  if command == 'load_file':
    if opt[0:4] != 'http':
      applet['opt'] = s3_path + opt
  if len(payload) > 1:
    applet['fields'] = payload[1:]
  return "<section class='applet_container'><div class='applet' data-payload='{}'></div></section>".format(json.dumps(applet))

def parse_markdown(sections, s3_path, skip_h1=False):
  """
  parse page into sections, preprocess the markdown to handle our modifications
  """
  groups = []
  current_group = []
  for section in sections:
    if skip_h1 and section.startswith('# '):
      continue
    elif section.strip().startswith('```'):
      groups.append(format_section(current_group, s3_path))
      current_group = []
      current_group.append(section)
      if section.strip().endswith('```'):
        groups.append(format_applet("\n\n".join(current_group), s3_path))
        current_group = []
    elif section.strip().endswith('```'):
      current_group.append(section)
      groups.append(format_applet("\n\n".join(current_group), s3_path))
      current_group = []
    elif section.startswith('+ '):
      groups.append(format_section(current_group, s3_path))
      groups.append(format_metadata(section))
      current_group = []
    elif '![fullwidth:' in section:
      groups.append(format_section(current_group, s3_path))
      groups.append(format_section([section], s3_path, type='fullwidth'))
      current_group = []
    elif '![wide:' in section:
      groups.append(format_section(current_group, s3_path))
      groups.append(format_section([section], s3_path, type='wide'))
      current_group = []
    elif '![' in section:
      groups.append(format_section(current_group, s3_path))
      groups.append(format_section([section], s3_path, type='images'))
      current_group = []
    else:
      current_group.append(section)
  groups.append(format_section(current_group, s3_path))
  content = "".join(groups)
  return content

def parse_research_index(research_posts):
  """
  Generate an index file for the research pages
  """
  content = "<div class='research_index'>"
  for post in research_posts:
    s3_path = s3.make_s3_path(cfg.S3_SITE_PATH, post['path'])
    if 'image' in post:
      post_image = s3_path + post['image']
    else:
      post_image = 'data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=='
    row = "<a href='{}'><section class='wide'><img src='{}' alt='Research post' /><section><h1>{}</h1><h2>{}</h2></section></section></a>".format(
      post['path'],
      post_image,
      post['title'],
      post['tagline'])
    content += row
  content += '</div>'
  return content

def read_metadata(fn):
  """
  Read in read a markdown file and extract the metadata
  """
  with open(fn, "r") as file:
    data = file.read()
    data = data.replace("\n ", "\n")
    if "\n" in data:
      data = data.replace("\r", "")
    else:
      data = data.replace("\r", "\n")
    sections = data.split("\n\n")
  return parse_metadata(fn, sections)

default_metadata = {
  'status': 'published',
  'title': 'Untitled Page',
  'desc': '',
  'slug': '',
  'published': '2018-12-31',
  'updated': '2018-12-31',
  'authors': 'Adam Harvey',
  'sync': 'true',
  'tagline': '',
}

def parse_metadata_section(metadata, section):
  """
  parse a metadata key: value pair
  """
  for line in section.split("\n"):
    if ': ' not in line:
      continue
    key, value = line.split(': ', 1)
    metadata[key.lower()] = value

def parse_metadata(fn, sections):
  """
  parse the metadata headers in a markdown file
  (everything before the second ---------)
  also generates appropriate urls for this page :)
  """
  found_meta = False
  metadata = {}
  valid_sections = []
  for section in sections:
    if not found_meta and ': ' in section:
      found_meta = True
      parse_metadata_section(metadata, section)
      continue
    if '-----' in section:
      continue
    if found_meta:
      valid_sections.append(section)

  if 'title' not in metadata:
    print('warning: {} has no title'.format(fn))
  for key in default_metadata:
    if key not in metadata:
      metadata[key] = default_metadata[key]

  basedir = os.path.dirname(fn.replace(cfg.DIR_SITE_CONTENT, ''))
  basename = os.path.basename(fn)
  if basedir == '/':
    metadata['path'] = '/'
    metadata['url'] = '/'
  elif basename == 'index.md':
    metadata['path'] = basedir + '/'
    metadata['url'] = metadata['path']
  else:
    metadata['path'] = basedir + '/'
    metadata['url'] = metadata['path'] + basename.replace('.md', '') + '/'

  if metadata['status'] == 'published|draft|private':
    metadata['status'] = 'published'

  metadata['sync'] = metadata['sync'] != 'false'

  metadata['author_html'] = '<br>'.join(metadata['authors'].split(','))

  return metadata, valid_sections

def read_research_post_index():
  """
  Generate an index of the research (blog) posts
  """
  return read_post_index('research')

def read_datasets_index():
  """
  Generate an index of the datasets
  """
  return read_post_index('datasets')

def read_post_index(basedir):
  """
  Generate an index of posts
  """
  posts = []
  for fn in sorted(glob.glob('../site/content/{}/*/index.md'.format(basedir))):
    metadata, valid_sections = read_metadata(fn)
    if metadata is None or metadata['status'] == 'private' or metadata['status'] == 'draft':
      continue
    posts.append(metadata)
  if not len(posts):
    posts.append({
      'title': 'Placeholder',
      'slug': 'placeholder',
      'date': 'Placeholder',
      'url': '/',
    })
  return posts