#!/usr/bin/env python

"""
Provides some import hooks to allow Cheetah's .tmpl files to be imported
directly like Python .py modules.

To use these:
  import Cheetah.ImportHooks
  Cheetah.ImportHooks.install()
"""

import sys
import os.path
import types
try:
    import builtins as builtin
except ImportError:  # PY2
    import __builtin__ as builtin
import imp
from threading import RLock
import string
import traceback
import types

from Cheetah import ImportManager
from Cheetah.ImportManager import DirOwner
from Cheetah.Compiler import Compiler
from Cheetah.convertTmplPathToModuleName import convertTmplPathToModuleName

_installed = False

##################################################
## HELPER FUNCS

_cacheDir = []
def setCacheDir(cacheDir):
    global _cacheDir
    _cacheDir.append(cacheDir)

##################################################
## CLASSES

class CheetahDirOwner(DirOwner):
    _lock = RLock()
    _acquireLock = _lock.acquire
    _releaseLock = _lock.release

    templateFileExtensions = ('.tmpl',)

    def getmod(self, name):
        self._acquireLock()
        try:
            mod = DirOwner.getmod(self, name)
            if mod:
                return mod

            for ext in self.templateFileExtensions:
                tmplPath =  os.path.join(self.path, name + ext)
                if os.path.exists(tmplPath):
                    try:
                        return self._compile(name, tmplPath)
                    except:
                        # @@TR: log the error
                        exc_txt = traceback.format_exc()
                        exc_txt ='  '+('  \n'.join(exc_txt.splitlines()))
                        raise ImportError(
                            'Error while compiling Cheetah module'
                        ' %(name)s, original traceback follows:\n%(exc_txt)s'%locals())
            ##
            return None

        finally:
            self._releaseLock()

    def _compile(self, name, tmplPath):
        ## @@ consider adding an ImportError raiser here
        code = str(Compiler(file=tmplPath, moduleName=name,
                            mainClassName=name))
        if _cacheDir:
            __file__ = os.path.join(_cacheDir[0],
                                    convertTmplPathToModuleName(tmplPath)) + '.py'
            try:
                open(__file__, 'w').write(code)
            except OSError:
                ## @@ TR: need to add some error code here
                traceback.print_exc(file=sys.stderr)
                __file__ = tmplPath
        else:
            __file__ = tmplPath
        co = compile(code+'\n', __file__, 'exec')

        mod = types.ModuleType(name)
        mod.__file__ = co.co_filename
        if _cacheDir:
            mod.__orig_file__ = tmplPath # @@TR: this is used in the WebKit
                                         # filemonitoring code
        mod.__co__ = co
        return mod


##################################################
## FUNCTIONS

def install(templateFileExtensions=('.tmpl',)):
    """Install the Cheetah Import Hooks"""

    global _installed
    if not _installed:
        CheetahDirOwner.templateFileExtensions = templateFileExtensions
        try:
            import builtins as builtin
        except ImportError:  # PY2
            import __builtin__ as builtin
        if isinstance(builtin.__import__, types.BuiltinFunctionType):
            global __oldimport__
            __oldimport__ = builtin.__import__
            ImportManager._globalOwnerTypes.insert(0, CheetahDirOwner)
            #ImportManager._globalOwnerTypes.append(CheetahDirOwner)
            global _manager
            _manager=ImportManager.ImportManager()
            _manager.setThreaded()
            _manager.install()

def uninstall():
    """Uninstall the Cheetah Import Hooks"""
    global _installed
    if not _installed:
        try:
            import builtins as builtin
        except ImportError:  # PY2
            import __builtin__ as builtin
        if isinstance(builtin.__import__, types.MethodType):
            builtin.__import__ = __oldimport__
            global _manager
            del _manager

if __name__ == '__main__':
    install()
