# -*- coding: utf-8 -*-
"""API and implementations for loading templates from different data
sources.
"""
import os
import sys
import weakref
from hashlib import sha1
from os import path
from types import ModuleType

from ._compat import abc
from ._compat import fspath
from ._compat import iteritems
from ._compat import string_types
from .exceptions import TemplateNotFound
from .utils import internalcode
from .utils import open_if_exists


def split_template_path(template):
 """Split a path into segments and perform a sanity check. If it detects
 '..' in the path it will raise a `TemplateNotFound` error.
 """
 pieces = []
 for piece in template.split("/"):
 if (
 path.sep in piece
 or (path.altsep and path.altsep in piece)
 or piece == path.pardir
 ):
 raise TemplateNotFound(template)
 elif piece and piece != ".":
 pieces.append(piece)
 return pieces


class BaseLoader(object):
 """Baseclass for all loaders. Subclass this and override `get_source` to
 implement a custom loading mechanism. The environment provides a
 `get_template` method that calls the loader's `load` method to get the
 :class:`Template` object.

 A very basic example for a loader that looks up templates on the file
 system could look like this::

 from jinja2 import BaseLoader, TemplateNotFound
 from os.path import join, exists, getmtime

 class MyLoader(BaseLoader):

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

 def get_source(self, environment, template):
 path = join(self.path, template)
 if not exists(path):
 raise TemplateNotFound(template)
 mtime = getmtime(path)
 with file(path) as f:
 source = f.read().decode('utf-8')
 return source, path, lambda: mtime == getmtime(path)
 """

 #: if set to `False` it indicates that the loader cannot provide access
 #: to the source of templates.
 #:
 #: .. versionadded:: 2.4
 has_source_access = True

 def get_source(self, environment, template):
 """Get the template source, filename and reload helper for a template.
 It's passed the environment and template name and has to return a
 tuple in the form ``(source, filename, uptodate)`` or raise a
 `TemplateNotFound` error if it can't locate the template.

 The source part of the returned tuple must be the source of the
 template as unicode string or a ASCII bytestring. The filename should
 be the name of the file on the filesystem if it was loaded from there,
 otherwise `None`. The filename is used by python for the tracebacks
 if no loader extension is used.

 The last item in the tuple is the `uptodate` function. If auto
 reloading is enabled it's always called to check if the template
 changed. No arguments are passed so the function must store the
 old state somewhere (for example in a closure). If it returns `False`
 the template will be reloaded.
 """
 if not self.has_source_access:
 raise RuntimeError(
 "%s cannot provide access to the source" % self.__class__.__name__
 )
 raise TemplateNotFound(template)

 def list_templates(self):
 """Iterates over all templates. If the loader does not support that
 it should raise a :exc:`TypeError` which is the default behavior.
 """
 raise TypeError("this loader cannot iterate over all templates")

 @internalcode
 def load(self, environment, name, globals=None):
 """Loads a template. This method looks up the template in the cache
 or loads one by calling :meth:`get_source`. Subclasses should not
 override this method as loaders working on collections of other
 loaders (such as :class:`PrefixLoader` or :class:`ChoiceLoader`)
 will not call this method but `get_source` directly.
 """
 code = None
 if globals is None:
 globals = {}

 # first we try to get the source for this template together
 # with the filename and the uptodate function.
 source, filename, uptodate = self.get_source(environment, name)

 # try to load the code from the bytecode cache if there is a
 # bytecode cache configured.
 bcc = environment.bytecode_cache
 if bcc is not None:
 bucket = bcc.get_bucket(environment, name, filename, source)
 code = bucket.code

 # if we don't have code so far (not cached, no longer up to
 # date) etc. we compile the template
 if code is None:
 code = environment.compile(source, name, filename)

 # if the bytecode cache is available and the bucket doesn't
 # have a code so far, we give the bucket the new code and put
 # it back to the bytecode cache.
 if bcc is not None and bucket.code is None:
 bucket.code = code
 bcc.set_bucket(bucket)

 return environment.template_class.from_code(
 environment, code, globals, uptodate
 )


class FileSystemLoader(BaseLoader):
 """Loads templates from the file system. This loader can find templates
 in folders on the file system and is the preferred way to load them.

 The loader takes the path to the templates as string, or if multiple
 locations are wanted a list of them which is then looked up in the
 given order::

 >>> loader = FileSystemLoader('/path/to/templates')
 >>> loader = FileSystemLoader(['/path/to/templates', '/other/path'])

 Per default the template encoding is ``'utf-8'`` which can be changed
 by setting the `encoding` parameter to something else.

 To follow symbolic links, set the *followlinks* parameter to ``True``::

 >>> loader = FileSystemLoader('/path/to/templates', followlinks=True)

 .. versionchanged:: 2.8
 The ``followlinks`` parameter was added.
 """

 def __init__(self, searchpath, encoding="utf-8", followlinks=False):
 if not isinstance(searchpath, abc.Iterable) or isinstance(
 searchpath, string_types
 ):
 searchpath = [searchpath]

 # In Python 3.5, os.path.join doesn't support Path. This can be
 # simplified to list(searchpath) when Python 3.5 is dropped.
 self.searchpath = [fspath(p) for p in searchpath]

 self.encoding = encoding
 self.followlinks = followlinks

 def get_source(self, environment, template):
 pieces = split_template_path(template)
 for searchpath in self.searchpath:
 filename = path.join(searchpath, *pieces)
 f = open_if_exists(filename)
 if f is None:
 continue
 try:
 contents = f.read().decode(self.encoding)
 finally:
 f.close()

 mtime = path.getmtime(filename)

 def uptodate():
 try:
 return path.getmtime(filename) == mtime
 except OSError:
 return False

 return contents, filename, uptodate
 raise TemplateNotFound(template)

 def list_templates(self):
 found = set()
 for searchpath in self.searchpath:
 walk_dir = os.walk(searchpath, followlinks=self.followlinks)
 for dirpath, _, filenames in walk_dir:
 for filename in filenames:
 template = (
 os.path.join(dirpath, filename)[len(searchpath) :]
 .strip(os.path.sep)
 .replace(os.path.sep, "/")
 )
 if template[:2] == "./":
 template = template[2:]
 if template not in found:
 found.add(template)
 return sorted(found)


class PackageLoader(BaseLoader):
 """Load templates from python eggs or packages. It is constructed with
 the name of the python package and the path to the templates in that
 package::

 loader = PackageLoader('mypackage', 'views')

 If the package path is not given, ``'templates'`` is assumed.

 Per default the template encoding is ``'utf-8'`` which can be changed
 by setting the `encoding` parameter to something else. Due to the nature
 of eggs it's only possible to reload templates if the package was loaded
 from the file system and not a zip file.
 """

 def __init__(self, package_name, package_path="templates", encoding="utf-8"):
 from pkg_resources import DefaultProvider
 from pkg_resources import get_provider
 from pkg_resources import ResourceManager

 provider = get_provider(package_name)
 self.encoding = encoding
 self.manager = ResourceManager()
 self.filesystem_bound = isinstance(provider, DefaultProvider)
 self.provider = provider
 self.package_path = package_path

 def get_source(self, environment, template):
 pieces = split_template_path(template)
 p = "/".join((self.package_path,) + tuple(pieces))

 if not self.provider.has_resource(p):
 raise TemplateNotFound(template)

 filename = uptodate = None

 if self.filesystem_bound:
 filename = self.provider.get_resource_filename(self.manager, p)
 mtime = path.getmtime(filename)

 def uptodate():
 try:
 return path.getmtime(filename) == mtime
 except OSError:
 return False

 source = self.provider.get_resource_string(self.manager, p)
 return source.decode(self.encoding), filename, uptodate

 def list_templates(self):
 path = self.package_path

 if path[:2] == "./":
 path = path[2:]
 elif path == ".":
 path = ""

 offset = len(path)
 results = []

 def _walk(path):
 for filename in self.provider.resource_listdir(path):
 fullname = path + "/" + filename

 if self.provider.resource_isdir(fullname):
 _walk(fullname)
 else:
 results.append(fullname[offset:].lstrip("/"))

 _walk(path)
 results.sort()
 return results


class DictLoader(BaseLoader):
 """Loads a template from a python dict. It's passed a dict of unicode
 strings bound to template names. This loader is useful for unittesting:

 >>> loader = DictLoader({'index.html': 'source here'})

 Because auto reloading is rarely useful this is disabled per default.
 """

 def __init__(self, mapping):
 self.mapping = mapping

 def get_source(self, environment, template):
 if template in self.mapping:
 source = self.mapping[template]
 return source, None, lambda: source == self.mapping.get(template)
 raise TemplateNotFound(template)

 def list_templates(self):
 return sorted(self.mapping)


class FunctionLoader(BaseLoader):
 """A loader that is passed a function which does the loading. The
 function receives the name of the template and has to return either
 an unicode string with the template source, a tuple in the form ``(source,
 filename, uptodatefunc)`` or `None` if the template does not exist.

 >>> def load_template(name):
 ... if name == 'index.html':
 ... return '...'
 ...
 >>> loader = FunctionLoader(load_template)

 The `uptodatefunc` is a function that is called if autoreload is enabled
 and has to return `True` if the template is still up to date. For more
 details have a look at :meth:`BaseLoader.get_source` which has the same
 return value.
 """

 def __init__(self, load_func):
 self.load_func = load_func

 def get_source(self, environment, template):
 rv = self.load_func(template)
 if rv is None:
 raise TemplateNotFound(template)
 elif isinstance(rv, string_types):
 return rv, None, None
 return rv


class PrefixLoader(BaseLoader):
 """A loader that is passed a dict of loaders where each loader is bound
 to a prefix. The prefix is delimited from the template by a slash per
 default, which can be changed by setting the `delimiter` argument to
 something else::

 loader = PrefixLoader({
 'app1': PackageLoader('mypackage.app1'),
 'app2': PackageLoader('mypackage.app2')
 })

 By loading ``'app1/index.html'`` the file from the app1 package is loaded,
 by loading ``'app2/index.html'`` the file from the second.
 """

 def __init__(self, mapping, delimiter="/"):
 self.mapping = mapping
 self.delimiter = delimiter

 def get_loader(self, template):
 try:
 prefix, name = template.split(self.delimiter, 1)
 loader = self.mapping[prefix]
 except (ValueError, KeyError):
 raise TemplateNotFound(template)
 return loader, name

 def get_source(self, environment, template):
 loader, name = self.get_loader(template)
 try:
 return loader.get_source(environment, name)
 except TemplateNotFound:
 # re-raise the exception with the correct filename here.
 # (the one that includes the prefix)
 raise TemplateNotFound(template)

 @internalcode
 def load(self, environment, name, globals=None):
 loader, local_name = self.get_loader(name)
 try:
 return loader.load(environment, local_name, globals)
 except TemplateNotFound:
 # re-raise the exception with the correct filename here.
 # (the one that includes the prefix)
 raise TemplateNotFound(name)

 def list_templates(self):
 result = []
 for prefix, loader in iteritems(self.mapping):
 for template in loader.list_templates():
 result.append(prefix + self.delimiter + template)
 return result


class ChoiceLoader(BaseLoader):
 """This loader works like the `PrefixLoader` just that no prefix is
 specified. If a template could not be found by one loader the next one
 is tried.

 >>> loader = ChoiceLoader([
 ... FileSystemLoader('/path/to/user/templates'),
 ... FileSystemLoader('/path/to/system/templates')
 ... ])

 This is useful if you want to allow users to override builtin templates
 from a different location.
 """

 def __init__(self, loaders):
 self.loaders = loaders

 def get_source(self, environment, template):
 for loader in self.loaders:
 try:
 return loader.get_source(environment, template)
 except TemplateNotFound:
 pass
 raise TemplateNotFound(template)

 @internalcode
 def load(self, environment, name, globals=None):
 for loader in self.loaders:
 try:
 return loader.load(environment, name, globals)
 except TemplateNotFound:
 pass
 raise TemplateNotFound(name)

 def list_templates(self):
 found = set()
 for loader in self.loaders:
 found.update(loader.list_templates())
 return sorted(found)


class _TemplateModule(ModuleType):
 """Like a normal module but with support for weak references"""


class ModuleLoader(BaseLoader):
 """This loader loads templates from precompiled templates.

 Example usage:

 >>> loader = ChoiceLoader([
 ... ModuleLoader('/path/to/compiled/templates'),
 ... FileSystemLoader('/path/to/templates')
 ... ])

 Templates can be precompiled with :meth:`Environment.compile_templates`.
 """

 has_source_access = False

 def __init__(self, path):
 package_name = "_jinja2_module_templates_%x" % id(self)

 # create a fake module that looks for the templates in the
 # path given.
 mod = _TemplateModule(package_name)

 if not isinstance(path, abc.Iterable) or isinstance(path, string_types):
 path = [path]

 mod.__path__ = [fspath(p) for p in path]

 sys.modules[package_name] = weakref.proxy(
 mod, lambda x: sys.modules.pop(package_name, None)
 )

 # the only strong reference, the sys.modules entry is weak
 # so that the garbage collector can remove it once the
 # loader that created it goes out of business.
 self.module = mod
 self.package_name = package_name

 @staticmethod
 def get_template_key(name):
 return "tmpl_" + sha1(name.encode("utf-8")).hexdigest()

 @staticmethod
 def get_module_filename(name):
 return ModuleLoader.get_template_key(name) + ".py"

 @internalcode
 def load(self, environment, name, globals=None):
 key = self.get_template_key(name)
 module = "%s.%s" % (self.package_name, key)
 mod = getattr(self.module, module, None)
 if mod is None:
 try:
 mod = __import__(module, None, None, ["root"])
 except ImportError:
 raise TemplateNotFound(name)

 # remove the entry from sys.modules, we only want the attribute
 # on the module object we have stored on the loader.
 sys.modules.pop(module, None)

 return environment.template_class.from_module_dict(
 environment, mod.__dict__, globals
 )