# -*- coding: utf-8 -*-
import StringIO
import hashlib
import sys
import os
import os.path
import fileinput
import logging
logger = logging.getLogger(__name__)

from permission import *
from config import config

class ObjectError(Exception):
    pass;

class Object:
    def __init__(self, name, owner, split_name = True):
        self.hash = name
        self.owner = owner
        if split_name:
            self.object_path = os.path.join(config.root, owner, name[:2], name[2:])
        else:
            self.object_path = os.path.join(config.root, owner, name)

    def exists(self):
        return os.path.exists(self.object_path)

class ObjectReader(Object):
    def __init__(self, hash, owner, split_name = True):
        Object.__init__(self, hash, owner, split_name)
        if not self.exists():
            logger.error("Object {} can't be found for user {}".format(self.hash,
                                                                        self.owner))
            raise ObjectError

    def get_permission(self, user):
        with open(os.path.join(self.object_path, 'permissions'), 'r') as file:
            for line in file:
                name, perm, key = line.split()
                if name == user:
                    return int(perm)
            return None

    def get_key(self, user):
        with open(os.path.join(self.object_path, 'permissions'), 'r') as file:
            for line in file:
                name, perm, key = line.split()
                if name == user:
                    return key
            return None

    def get_permission_key(self, user):
        with open(os.path.join(self.object_path, 'permissions'), 'r') as file:
            for line in file:
                name, perm, key = line.split()
                if name == user:
                    return (int(perm), key)
            return (None, None)

    def get_child_list(self, user):
        perm = self.get_permission(user)
        if not perm & LIST:
            logger.error("User {} doesn't have the list permission for object {}"
                          .format(user, self.hash))
            raise PermissionError

        file = open(os.path.join(self.object_path, 'childs'), 'r')
        result = []
        for line in file:
            name = line.rstrip('\n')
            try:
                child = ObjectReader(name, self.owner)
            except ObjectError:
                logger.error('Object {} doesn\'t exist'.format(name))
            else:
                perm, key = child.get_permission_key(user)
                if perm > 0:
                    result.append((name, perm, key))

        file.close()
        return result

    def get_content(self, user):
        """Return object content and the user key to decrypt it."""
        perm, key = self.get_permission_key(user)
        if not perm & READ :
            logger.error("User {} doesn't have read access to object {}"
                          .format(user, self.hash))
            raise PermissionError
        with open(os.path.join(self.object_path, 'object'), 'r') as file:
            content = file.read()

        return content, key

class ObjectWriter(ObjectReader):
    
    def __init__(self, hash, owner, split_name = True, key = None):
        Object.__init__(self, hash, owner, split_name)
        self.files = ('permissions', 'children', 'object')
        self.__create_skeleton(key)
    
    def __create_skeleton(self, key):
        #new object
        if not self.exists():
            os.makedirs(self.object_path)
            for filename in self.files:
                file = open(os.path.join(self.object_path, filename), "w")
                file.close()
        #give all the permissions to the owner 
        ALLPERM = READ + MODIFY + APPEND + LIST
        self.add_user(self.owner, ALLPERM, key)
            
    def write(self, user, content):
        perm = self.get_permission(user)
        if not perm & MODIFY:
            logger.error("User {} doesn't have the modify permission for object {}"
                          .format(user, self.hash))
            raise PermissionError
        with open(os.path.join(self.object_path, 'object'), "w") as file:
                file.write('{}'.format(content))

    def append(self, user, content, parent):
        parent_object = ObjectReader(parent, self.owner)
        perm = parent_object.get_permission(user)
        if not perm & APPEND:
            logger.error("User {} doesn't have the modify permission for object {}"
                          .format(user, parent))
            raise PermissionError
        with open(os.path.join(self.object_path, 'object'), "w") as file:
            for k, v in content:
                file.write('{} {}\n'.format(k,v))
        #add the child hash to the parent
        with open(os.path.join(parent_object.object_path, 'children'), "a") as file:
            file.write('{} {}\n'.format(self.hash))

    def add_user(self, user, perm, key = None):
        with open(os.path.join(self.object_path, 'permissions'), "a") as file:
            if key:
                file.write('{} {} {}\n'.format(user, perm, key))
            else:
                file.write('{} {} None\n'.format(user, perm, key))
        
if __name__ == '__main__':
    jid = 'thrasibule@alias.im'
    hash = hashlib.sha1(jid).hexdigest()
    config.root = '/var/lib/alias'
    print ObjectReader(hash, jid).get_content(jid)