diff --git a/VERSION b/VERSION
index 05b19b1..7deb86f 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.0.4
\ No newline at end of file
+0.7.1
\ No newline at end of file
diff --git a/python_terraform/__init__.py b/python_terraform/__init__.py
index 9abb999..d9067ac 100644
--- a/python_terraform/__init__.py
+++ b/python_terraform/__init__.py
@@ -3,180 +3,186 @@ import os
 import json
 import logging
 
+from python_terraform.tfstate import Tfstate
+
 log = logging.getLogger(__name__)
 
 
 class Terraform:
-    def __init__(self, targets=None, state='terraform.tfstate', variables=None):
+    """
+    Wrapper of terraform command line tool
+    https://www.terraform.io/
+    """
+
+    def __init__(self, working_dir=None,
+                 targets=None,
+                 state=None,
+                 variables=None,
+                 parallelism=None,
+                 var_file=None):
+        self.working_dir = working_dir
+        self.state = state
         self.targets = [] if targets is None else targets
         self.variables = dict() if variables is None else variables
-        
-        self.state_filename = state
-        self.state_data = dict()
-        self.parallelism = 50
+        self.parallelism = parallelism
+        self.terraform_bin_path = 'terraform'
+        self.var_file = var_file
+        self.input = False
 
-    def apply(self, targets=None, variables=None, **kargs):
+        # store the tfstate data
+        self.tfstate = dict()
+
+    def apply(self,
+              working_dir=None,
+              no_color=True,
+              **kwargs):
         """
         refer to https://terraform.io/docs/commands/apply.html
-        :param variables: variables in dict type
-        :param targets: targets in list
+        :param working_dir: working folder
+        :param no_color: Disables output with coloring.
         :returns return_code, stdout, stderr
         """
-        variables = self.variables if variables is None else variables
-        targets = self.targets if targets is None else targets
+        if not working_dir:
+            working_dir = self.working_dir
 
-        parameters = []
-        parameters += self._generate_targets(targets)
-        parameters += self._generate_var_string(variables)
-        parameters += self._gen_param_string(kargs)
+        option_dict = dict()
+        option_dict['state'] = self.state
+        option_dict['target'] = self.targets
+        option_dict['var'] = self.variables
+        option_dict['var_file'] = self.var_file
+        option_dict['parallelism'] = self.parallelism
+        if no_color:
+            option_dict['no_color'] = ''
+        option_dict['input'] = self.input
 
-        parameters = \
-            ['terraform', 'apply', '-state=%s' % self.state_filename] + parameters
+        option_dict.update(kwargs)
 
-        cmd = ' '.join(parameters)
-        return self._run_cmd(cmd)
+        args = [working_dir] if working_dir else []
 
-    def _gen_param_string(self, kargs):
-        params = []
-        for key, value in kargs.items():
-            if value:
-                params += ['-%s=%s' % (key, value)]
-            else:
-                params += ['-%s' % key]
-        return params
+        ret, out, err = self.cmd('apply', *args, **option_dict)
 
-    def _run_cmd(self, cmd):
-        log.debug('command: ' + cmd)
+        if ret != 0:
+            raise RuntimeError(err)
 
-        p = subprocess.Popen(
-            cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
+    def generate_cmd_string(self, cmd, *args, **kwargs):
+        """
+        for any generate_cmd_string doesn't written as public method of terraform
+
+        examples:
+        1. call import command,
+        ref to https://www.terraform.io/docs/commands/import.html
+        --> generate_cmd_string call:
+                terraform import -input=true aws_instance.foo i-abcd1234
+        --> python call:
+                tf.generate_cmd_string('import', 'aws_instance.foo', 'i-abcd1234', input=True)
+
+        2. call apply command,
+        --> generate_cmd_string call:
+                terraform apply -var='a=b' -var='c=d' -no-color the_folder
+        --> python call:
+                tf.generate_cmd_string('apply', the_folder, no_color='', var={'a':'b', 'c':'d'})
+
+        :param cmd: command and sub-command of terraform, seperated with space
+                    refer to https://www.terraform.io/docs/commands/index.html
+        :param args: argument other than options of a command
+        :param kwargs: same as kwags in method 'cmd'
+        :return: string of valid terraform command
+        """
+        cmds = cmd.split()
+        cmds = [self.terraform_bin_path] + cmds
+
+        for k, v in kwargs.items():
+            if '_' in k:
+                k = k.replace('_', '-')
+
+            if type(v) is list:
+                for sub_v in v:
+                    cmds += ['-{k}={v}'.format(k=k, v=sub_v)]
+                continue
+
+            if type(v) is dict:
+                for sub_k, sub_v in v.items():
+                    cmds += ["-{k}='{var_k}={var_v}'".format(k=k,
+                                                             var_k=sub_k,
+                                                             var_v=sub_v)]
+                continue
+
+            # simple flag,
+            if v == '':
+                cmds += ['-{k}'.format(k=k)]
+                continue
+
+            if not v:
+                continue
+
+            if type(v) is bool:
+                v = 'true' if v else 'false'
+
+            cmds += ['-{k}={v}'.format(k=k, v=v)]
+
+        cmds += args
+        cmd = ' '.join(cmds)
+        return cmd
+
+    def cmd(self, cmd, *args, **kwargs):
+        """
+        run a terraform command, if success, will try to read state file
+        :param cmd: command and sub-command of terraform, seperated with space
+                    refer to https://www.terraform.io/docs/commands/index.html
+        :param args: argument other than options of a command
+        :param kwargs:  any option flag with key value other than variables,
+                if there's a dash in the option name, use under line instead of dash, ex -no-color --> no_color
+                if it's a simple flag with no value, value should be empty string
+                if it's a boolean value flag, assign True or false
+                if it's a flag could be used multiple times, assign list to it's value
+                if it's a "var" variable flag, assign dictionary to it
+                if a value is None, will skip this option
+        :return: ret_code, out, err
+        """
+        cmd_string = self.generate_cmd_string(cmd, *args, **kwargs)
+        log.debug('command: {c}'.format(c=cmd_string))
+
+        p = subprocess.Popen(cmd_string, stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE, shell=True)
         out, err = p.communicate()
         ret_code = p.returncode
-        log.debug('output: ' + out)
+        log.debug('output: {o}'.format(o=out))
 
         if ret_code == 0:
-            log.debug('error: ' + err)
             self.read_state_file()
-        return ret_code, out, err
+        else:
+            log.warn('error: {e}'.format(e=err))
+        return ret_code, out.decode('utf-8'), err.decode('utf-8')
 
-    def destroy(self, targets=None, variables=None, **kwargs):
-        variables = self.variables if variables is None else variables
-        targets = self.targets if targets is None else targets
+    def output(self, name):
+        """
+        https://www.terraform.io/docs/commands/output.html
+        :param name: name of output
+        :return: output value
+        """
+        ret, out, err = self.cmd('output', name, json='')
 
-        parameters = []
-        parameters += self._generate_targets(targets)
-        parameters += self._generate_var_string(variables)
+        if ret != 0:
+            return None
+        out = out.lstrip()
 
-        parameters = \
-            ['terraform', 'destroy', '-force', '-state=%s' % self.state_filename] + \
-            parameters
-        cmd = ' '.join(parameters)
-        return self._run_cmd(cmd)
+        output_dict = json.loads(out)
+        return output_dict['value']
 
-    def refresh(self, targets=None, variables=None):
-        variables = self.variables if variables is None else variables
-        targets = self.targets if targets is None else targets
-
-        parameters = []
-        parameters += self._generate_targets(targets)
-        parameters += self._generate_var_string(variables)
-        parameters = \
-            ['terraform', 'refresh', '-state=%s' % self.state_filename] + \
-            parameters
-        cmd = ' '.join(parameters)
-        return self._run_cmd(cmd)
-
-    def read_state_file(self):
+    def read_state_file(self, file_path=None):
         """
         read .tfstate file
+        :param file_path: relative path to working dir
         :return: states file in dict type
         """
-        if os.path.exists(self.state_filename):
-            with open(self.state_filename) as f:
-                json_data = json.load(f)
-            self.state_data = json_data
-            log.debug("state_data=%s" % str(self.state_data))
-            return json_data
 
-        return dict()
-
-    def is_any_aws_instance_alive(self):
-        self.refresh()
-        if not os.path.exists(self.state_filename):
-            log.debug("can't find %s " % self.state_data)
-            return False
-
-        self.read_state_file()
-        try:
-            main_module = self._get_main_module()
-            for resource_key, info in main_module['resources'].items():
-                if 'aws_instance' in resource_key:
-                    log.debug("%s is found when read state" % resource_key)
-                    return True
-            log.debug("no aws_instance found in resource key")
-            return False
-        except KeyError as err:
-            log.debug(str(err))
-            return False
-        except TypeError as err:
-            log.debug(str(err))
-            return False
-
-    def _get_main_module(self):
-        return self.state_data['modules'][0]
-
-    def get_aws_instances(self):
-        instances = dict()
-
-        try:
-            main_module = self._get_main_module()
-            for resource_key, info in main_module['resources'].items():
-                if 'aws_instance' in resource_key:
-                    instances[resource_key] = info
-        except KeyError:
-            return instances
-        except TypeError:
-            return instances
-
-        return instances
-
-    def get_aws_instance(self, resource_name):
-        """
-        :param resource_name:
-            name of terraform resource, make source count is attached
-        :return: return None if not exist, dict type if exist
-        """
-        try:
-            return self.get_aws_instances()[resource_name]
-        except KeyError:
-            return None
-
-    def get_output_value(self, output_name):
-        """
-
-        :param output_name:
-        :return:
-        """
-        try:
-            main_module = self._get_main_module()
-            return main_module['outputs'][output_name]
-        except KeyError:
-            return None
-
-    @staticmethod
-    def _generate_var_string(d):
-        str_t = []
-        for k, v in d.iteritems():
-            str_t += ['-var'] + ["%s=%s" % (k, v)]
-
-        return str_t
-
-    @staticmethod
-    def _generate_targets(targets):
-        str_t = []
-        for t in targets:
-            str_t += ['-target=%s' % t]
-        return str_t
+        if not file_path:
+            file_path = self.state
 
+        if not file_path:
+            file_path = 'terraform.tfstate'
 
+        if self.working_dir:
+            file_path = os.path.join(self.working_dir, file_path)
 
+        self.tfstate = Tfstate.load_file(file_path)
diff --git a/python_terraform/tfstate.py b/python_terraform/tfstate.py
new file mode 100644
index 0000000..81e26a5
--- /dev/null
+++ b/python_terraform/tfstate.py
@@ -0,0 +1,31 @@
+import json
+import os
+import logging
+
+log = logging.getLogger(__name__)
+
+
+class Tfstate(object):
+    def __init__(self, data=None):
+        self.tfstate_file = None
+        self.native_data = data
+        if data:
+            self.__dict__ = data
+
+    @staticmethod
+    def load_file(file_path):
+        """
+        Read the tfstate file and load its contents, parses then as JSON and put the result into the object
+        """
+        log.debug('read data from {0}'.format(file_path))
+        if os.path.exists(file_path):
+            with open(file_path) as f:
+                json_data = json.load(f)
+
+            tf_state = Tfstate(json_data)
+            tf_state.tfstate_file = file_path
+            return tf_state
+
+        log.warn('{0} is not exist'.format(file_path))
+
+        return Tfstate()
\ No newline at end of file
diff --git a/setup.cfg b/setup.cfg
new file mode 100644
index 0000000..5e40900
--- /dev/null
+++ b/setup.cfg
@@ -0,0 +1,2 @@
+[wheel]
+universal = 1
diff --git a/setup.py b/setup.py
index 3c4bbe0..de4e272 100644
--- a/setup.py
+++ b/setup.py
@@ -38,8 +38,8 @@ setup(
         # 'Development Status :: 1 - Planning',
         # 'Development Status :: 2 - Pre-Alpha',
         # 'Development Status :: 3 - Alpha',
-        'Development Status :: 4 - Beta',
-        # 'Development Status :: 5 - Production/Stable',
+        # 'Development Status :: 4 - Beta',
+        'Development Status :: 5 - Production/Stable',
         # 'Development Status :: 6 - Mature',
         # 'Development Status :: 7 - Inactive',
         'Environment :: Console',
diff --git a/test/__init__.py b/test/__init__.py
deleted file mode 100644
index e69de29..0000000
diff --git a/test/apply_tf/test.tf b/test/apply_tf/test.tf
new file mode 100644
index 0000000..c247514
--- /dev/null
+++ b/test/apply_tf/test.tf
@@ -0,0 +1,8 @@
+variable "test_var" {}
+
+provider "archive" {
+}
+
+output "test_output" {
+  value = "${var.test_var}"
+}
\ No newline at end of file
diff --git a/test/test.tf b/test/aws_tf/test.tf
similarity index 50%
rename from test/test.tf
rename to test/aws_tf/test.tf
index 6219dce..1e79483 100644
--- a/test/test.tf
+++ b/test/aws_tf/test.tf
@@ -10,15 +10,4 @@ provider "aws" {
 resource "aws_instance" "ubuntu-1404" {
   ami = "ami-9abea4fb"
   instance_type = "t2.micro"
-  security_groups = ["terraform-salty-splunk"]
-  tags {
-    Name = "python-terraform-test"
-  }
-//  key_name = "${aws_key_pair.key.key_name}"
-//  connection {
-//    type = "ssh"
-//    user = "ubuntu"
-//    key_file = "${var.key_path}"
-//    timeout = "10m"
-//  }
 }
\ No newline at end of file
diff --git a/test/test_terraform.py b/test/test_terraform.py
index 6fbdd32..e0c8bb9 100644
--- a/test/test_terraform.py
+++ b/test/test_terraform.py
@@ -1,15 +1,83 @@
 from python_terraform import Terraform
+import pytest
+import os
+import logging
+import re
+
+logging.basicConfig(level=logging.DEBUG)
+
+ACCESS_KEY = os.environ['PACKER_access_key']
+SECRET_KEY = os.environ['PACKER_secret_key']
+
+STRING_CASES = [
+     [
+         lambda x: x.generate_cmd_string('apply', 'the_folder',
+                                         no_color='',
+                                         var={'a': 'b', 'c': 'd'}),
+         "terraform apply -var='a=b' -var='c=d' -no-color the_folder"
+     ],
+     [
+         lambda x: x.generate_cmd_string('push', 'path',
+                                         var={'a': 'b'}, vcs=True,
+                                         token='token',
+                                         atlas_address='url'),
+         "terraform push -var='a=b' -vcs=true -token=token -atlas-address=url path"
+     ],
+ ]
+
+CMD_CASES = [
+    ['method', 'expected_output'],
+    [
+        [
+            lambda x: x.cmd('plan', 'aws_tf', no_color='', var={'access_key': ACCESS_KEY, 'secret_key': SECRET_KEY}) ,
+            'Plan: 1 to add, 0 to change, 0 to destroy'
+        ]
+    ]
+]
 
 
 class TestTerraform:
-    def test_apply_and_destory(self):
+    def teardown_method(self, method):
+        """ teardown any state that was previously setup with a setup_method
+        call.
+        """
+
+        def purge(dir, pattern):
+            for f in os.listdir(dir):
+                if re.search(pattern, f):
+                    if os.path.isfile(f):
+                        os.remove(os.path.join(dir, f))
+
+        purge('.', '.tfstate')
+
+    @pytest.mark.parametrize([
+                 "method", "expected"
+             ], STRING_CASES)
+    def test_generate_cmd_string(self, method, expected):
         tf = Terraform()
-        ret_code, out, err = tf.apply()
+        result = method(tf)
 
-        print out
-        print err
-        # assert ret_code, 0
+        strs = expected.split()
+        for s in strs:
+            assert s in result
 
-        ret_code, out, err = tf.destroy()
+    @pytest.mark.parametrize(*CMD_CASES)
+    def test_cmd(self, method, expected_output):
+        tf = Terraform()
+        ret, out, err = method(tf)
+        assert expected_output in out
+        assert ret == 0
 
-        assert ret_code, 0
+    def test_state_data(self):
+        tf = Terraform(working_dir='test_tfstate_file')
+        tf.read_state_file()
+        assert tf.tfstate.modules[0]['path'] == ['root']
+
+    def test_apply(self):
+        tf = Terraform(working_dir='apply_tf', variables={'test_var': 'test'})
+        tf.apply(var={'test_var': 'test2'})
+
+    def test_get_output(self):
+        tf = Terraform(working_dir='apply_tf', variables={'test_var': 'test'})
+        tf.apply()
+        assert tf.output('test_output') == 'test'