import urlparse
import mimetypes

from fs.errors import FSError
from fs.path import basename, pathsplit

from datetime import datetime

try:
    from mako.template import Template
except ImportError:
    print "Requires mako templates http://www.makotemplates.org/"
    raise


class Request(object):
    """Very simple request object"""
    def __init__(self, environ, start_response):
        self.environ = environ
        self.start_response = start_response
        self.path = environ.get('PATH_INFO')


class WSGIServer(object):
    """Light-weight WSGI server that exposes an FS"""

    def __init__(self, serve_fs, indexes=True, dir_template=None, chunk_size=16*1024*1024):

        if dir_template is None:
            from dirtemplate import template as dir_template

        self.serve_fs = serve_fs
        self.indexes = indexes
        self.chunk_size = chunk_size

        self.dir_template = Template(dir_template)

    def __call__(self, environ, start_response):

        request = Request(environ, start_response)

        if not self.serve_fs.exists(request.path):
            return self.serve_404(request)

        if self.serve_fs.isdir(request.path):
            if not self.indexes:
                return self.serve_404(request)
            return self.serve_dir(request)
        else:
            return self.serve_file(request)


    def serve_file(self, request):
        """Serve a file, guessing a mime-type"""
        path = request.path
        serving_file = None
        try:
            serving_file = self.serve_fs.open(path, 'rb')
        except Exception, e:
            if serving_file is not None:
                serving_file.close()
            return self.serve_500(request, str(e))

        mime_type = mimetypes.guess_type(basename(path))[0] or b'text/plain'
        file_size = self.serve_fs.getsize(path)
        headers = [(b'Content-Type', bytes(mime_type)),
                   (b'Content-Length', bytes(file_size))]

        def gen_file():
            chunk_size = self.chunk_size
            read = serving_file.read
            try:
                while 1:
                    data = read(chunk_size)
                    if not data:
                        break
                    yield data
            finally:
                serving_file.close()

        request.start_response(b'200 OK',
                               headers)
        return gen_file()

    def serve_dir(self, request):
        """Serve an index page"""
        fs = self.serve_fs
        isdir = fs.isdir
        path = request.path
        dirinfo = fs.listdirinfo(path, full=True, absolute=True)
        entries = []

        for p, info in dirinfo:
            entry = {}
            entry['path'] = p
            entry['name'] = basename(p)
            entry['size'] = info.get('size', 'unknown')
            entry['created_time'] = info.get('created_time')
            if isdir(p):
                entry['type'] = 'dir'
            else:
                entry['type'] = 'file'

            entries.append(entry)

        # Put dirs first, and sort by reverse created time order
        no_time = datetime(1970, 1, 1, 1, 0)
        entries.sort(key=lambda k:(k['type'] == 'dir', k.get('created_time') or no_time), reverse=True)

        # Turn datetime to text and tweak names
        for entry in entries:
            t = entry.get('created_time')
            if t and hasattr(t, 'ctime'):
                entry['created_time'] = t.ctime()
            if entry['type'] == 'dir':
                entry['name'] += '/'

        # Add an up dir link for non-root
        if path not in ('', '/'):
            entries.insert(0, dict(name='../', path='../', type="dir", size='', created_time='..'))

        # Render the mako template
        html = self.dir_template.render(**dict(fs=self.serve_fs,
                                               path=path,
                                               dirlist=entries)).encode('utf-8')
        request.start_response(b'200 OK', [(b'Content-Type', b'text/html'),
                                           (b'Content-Length', b'%i' % len(html))])

        return [html]


    def serve_404(self, request, msg='Not found'):
        """Serves a Not found page"""
        request.start_response(b'404 NOT FOUND', [(b'Content-Type', b'text/html')])
        return [msg]

    def serve_500(self, request, msg='Unable to complete request'):
        """Serves an internal server error page"""
        request.start_response(b'500 INTERNAL SERVER ERROR', [(b'Content-Type', b'text/html')])
        return [msg]


def serve_fs(fs, indexes=True):
    """Serves an FS object via WSGI"""
    application = WSGIServer(fs, indexes)
    return application