#!/usr/bin/env python
import sys, os, re
"""Utility for substituting parameters in files in a specific folder.

Create an instance and invoke the process method
    targetDir = the directory to target
    parametersName = file name of the properties file to use (without extension)

For example:
    targetDir = /home/myapp/
    templateDir = /home/myapp_template/
        Example file = /home/myapp_template/somedir/config.py
        Containing:
        config = {'someKey' : '@someKey@', 'abc' : '@hi@'}
    parametersDir = /home/myapp_params/
        For local dev = /home/myapp_params/local.properties
        Containing:
        someKey=someValue
        For production = /home/myapp_params/production.properties
        Containing:
        someKey=someOtherValue
        hi=Bye!

    Invoking Pants with '/home/myapp/ local' will create a directory 'somedir'
    in /home/myapp/ (if it doesn't exist) and a file 'config.py' with all
    parameters (all alphanumeric characters and dots in between 2 '@') replaced
    by the corresponding values, supplied in local.properties. The resulting
    content of /home/myapp/somedir/config.py:
        config = {'someKey' : 'someValue', 'abc' : '@hi@'}
    The '@hi@' parameters isn't replaced, because there's no entry for 'hi'
    in the properties file.

    Doing the same thing afterwards for '/home/myapp/ production', results in
    the following content of /home/myapp/somedir/config.py:
        config = {'someKey' : 'someOtherValue', 'abc' : 'Bye!'}
"""
class Pants:

    def __init__(self):
        self.__parameters = {}
        self.__ignorePatterns = [r'\.svn.*']
        self.__ignorePatterns = [re.compile(elem) for elem in self.__ignorePatterns]

    def process(self, targetDir, parametersName):
        targetDirFull = os.path.abspath(targetDir)
        'Preparing ' + targetDirFull + ' for ' + parametersName
        self.__readParameters(targetDirFull, parametersName)
        (targetDirPath, targetDir) = os.path.split(targetDirFull)
        templateDirFull = os.path.join(targetDirPath, targetDir + '_template')
        listing = os.listdir(templateDirFull)
        for listed in listing:
            processListed = True
            for regex in self.__ignorePatterns:
                if (regex.match(listed)):
                    processListed = False
                    continue
            if processListed:
                self.__processTemplate(os.path.join(templateDirFull, listed), os.path.join(targetDirFull, listed))

    def __processTemplate(self, src, target):
        if (os.path.isdir(src)):
            listing = os.listdir(src)
            for listed in listing:
                processListed = True
                for regex in self.__ignorePatterns:
                    if (regex.match(listed)):
                        processListed = False
                        continue
                if processListed:
                    self.__processTemplate(os.path.join(src, listed), os.path.join(target, listed))
        else:
            print 'Processing ' + src
            f = open(src, 'r')
            template = f.read();
            f.close();
            (target_dir, target_file) = os.path.split(target)
            if not os.path.exists(target_dir):
                print 'Creating ' + target_dir
                os.makedirs(target_dir)
            f = open(target, 'w')
            f.write(re.sub(r'@([\w|\\.]*)@', self.__getParameter, template))
            f.close()

    def __getParameter(self, matchobj):
        match = matchobj.group(1)
        if match in self.__parameters:
            return self.__parameters[match]
        return '@' + match + '@'

    def __readParameters(self, targetDirFull, parametersName):
        (targetDirPath, targetDir) = os.path.split(targetDirFull)
        parametersDirFull = os.path.join(targetDirPath, targetDir + '_params')
        f = open(os.path.join(parametersDirFull, parametersName + '.properties'), 'r')
        params = f.read().split('\n')
        self.__parameters = {}
        for param in params:
            (property, x, value) = param.partition('=')
            self.__parameters[property] = value


if len(sys.argv) < 3:
    print 'Supply the path to the folder that should be targeted and the target environment'
else:
    p = Pants()
    p.process(sys.argv[1], sys.argv[2])