from django.conf import settings

import codecs
import logging; log = logging.getLogger('qmsk_www_pages.pages')
import os, os.path

class Tree (object):
    @classmethod
    def lookup (cls, parts):
        path = settings.QMSK_WWW_PAGES_DIR

        for part in parts:
            if part.startswith('.'):
                # evil
                return None
            
            if not part:
                continue
        
            path = os.path.join(path, part)

            if not os.path.exists(path):
                return None
            
            if not os.path.isdir(path):
                return None
        
        return cls(path, parts)

    def __init__ (self, path, parts):
        self.path = path
        self.parts = parts

    def page (self, name):
        """
            Scans through tree looking for a matching page.
            
            Returns Page.
        """

        page_type = None

        for filename in os.listdir(self.path):
            if filename.startswith('.'):
                continue
            
            if '.' not in filename:
                continue

            file_name, file_type = filename.rsplit('.', 1)
            path = os.path.join(self.path, filename)

            if not file_name:
                continue

            if file_name != name:
                continue
            
            # page_name matches
            page_type = TYPES.get(file_type)

            if not page_type:
                continue

            return page_type(
                path    = path,
                name    = name,
                tree    = self,
            )

class Page (object):
    ENCODING = 'utf-8'

    @classmethod
    def lookup (cls, page):
        """
            Lookup a Page from disk.

            Returns None if there is no such page.
        """
        
        log.info("page=%r", page)

        if page:
            parts = page.split('/')
        else:
            parts = [ ]
            
        if parts:
            page_name = parts.pop(-1)
            tree_parts = parts
        else:
            page_name = ''
            tree_parts = []

        if not page_name:
            page_name = 'index'

        # scan dir
        tree = Tree.lookup(tree_parts)

        if not tree:
            return None

        # scan page
        page = tree.page(page_name)

        if not page:
            return None

        return page

    def __init__ (self, path, name, tree, encoding=ENCODING):
        self.path = path
        self.name = name
        self.tree = tree
        self.encoding = encoding

    def open (self):
        return codecs.open(self.path, encoding=self.encoding)

    def breadcrumb (self):
        path = []

        for part in self.tree.parts + [ self.name ]:
            path.append(part)

            yield '/'.join(path), part

    def render (self, request):
        raise NotImplementedError()

class HTML_Page (Page):
    def render (self, request):
        return self.open().read()

TYPES = {
    'html':         HTML_Page,
}