console.py

#!/usr/bin/python3

"""
A module that defines the command line interpreter for AirBnB project
"""

import re
import cmd
import json
import shlex
from models import storage
from models.user import User
from models.city import City
from models.place import Place
from models.state import State
from models.review import Review
from models.amenity import Amenity
from models.base_model import BaseModel


class HBNBCommand(cmd.Cmd):
    """
    Entry point of the command line interpreter
    """
    prompt = '(hbnb) '
    __classes = {
        'User': User,
        'City': City,
        'Place': Place,
        'State': State,
        'Review': Review,
        'Amenity': Amenity,
        'BaseModel': BaseModel
    }

    def parseline(self, line):
        """Parse the line into a command name and a string containing
        the arguments.  Returns a tuple containing (command, args, line).
        'command' and 'args' may be None if the line couldn't be parsed.
        """
        line = self.__parseline(line)
        return super().parseline(line)

    def emptyline(self):
        """Overrides parent method
        Prevents the execution of the last command, on empty line input
        """
        pass

    def do_create(self, arg):
        """usage: create <Model>
        Creates an instance of Model
        """
        args = shlex.split(arg)
        self.__validateArgs('create', args)
        if len(args) > 0 and args[0] in self.__classes:
            newBaseModel = self.__classes[args[0]]
            new = newBaseModel()
            storage.save()
            print(new.id)

    def do_show(self, arg):
        """usage: show <Model> <id>
        Shows an obj of type Model with id
        """
        args = shlex.split(arg)
        result = self.__validateArgs('show', args)
        if type(result) == list:
            [objs, key] = result
            print(objs.get(key, ''))

    def do_destroy(self, arg):
        """usage: destroy <Model> <id>
        Deletes an obj of type Model with id
        """
        args = shlex.split(arg)
        result = self.__validateArgs('destroy', args)
        if type(result) == list:
            [objs, key] = result
            objs.pop(key, None)
            storage.save()

    def __all(self, arg):
        """Prints all string representation of
        all instances based or not on the class name
        Attr:
            arg (str): string or arguments
        """
        args = shlex.split(arg)
        model = None
        if len(args) > 0:
            if not (self.__classes.get(args[0], None)):
                return print('** class doesn\'t exist **')
            model = args[0]
        obList = [str(v) for v in (storage.all()).values()]
        if model:
            match = '[{}]'.format(model)
            obList = list(filter(lambda s: s.startswith(match), obList))
        return (obList)

    def do_all(self, arg):
        """usage: all [Model] | <Model>.all()
        Prints all instances (of Model only if specified)
        """
        hall = self.__all(arg)
        if hall is not None:
            print(hall)

    def do_count(self, arg):
        """usage: <Model>.count()
        Prints the number of instances of Model
        """
        count = self.__all(arg)
        if count is not None:
            print(len(count))

    def __updateMePlease(self, obj, args):
        """Checks if update inputs are valid
        Attr:
            obj (BaseModel): instance to be updated
            args (list): list of passed arguments
        Return:
            (str): error message
            (None): if no parameters are valid and all set.
        """
        args = (args).replace("'", '"')
        try:
            params = json.loads(args)
        except Exception:
            params = {"None": "None"}
        for key, value in params.items():
            if key == "None":
                return print('** attribute name missing **')
            if value == "None":
                return print('** value missing **')
            if len(key) > 0:
                setattr(obj, key, value)
                obj.save()

    def do_update(self, arg):
        """usage: update <Model> <id> <field> <value>
        or <Model>.update(<id>, ["<field>", "<value>] | [{<field>: <value>}])
        Updates field to value of an obj of type Model with id
        """
        args = shlex.split(arg)
        result = self.__validateArgs('update', args)
        if type(result) != list:
            return
        [objs, key] = result
        newargs = args + ['None', 'None', 'None']
        [three, four] = newargs[2:4]
        if three.startswith('{') and three.endswith('}'):
            newargs[2] = three
        else:
            four = four if four.isnumeric() else '"{}"'.format(four)
            newargs[2] = '{"' + three + '": ' + four + '}'
        obj = objs.get(key, None)
        self.__updateMePlease(obj, newargs[2])

    def do_quit(self, arg):
        """Quit command to exit the program"""
        return True

    def do_EOF(self, arg):
        """Exits the interpreter"""
        return True

    def __validateArgs(self, query, args):
        """Validates given parameters
        Attr:
            query (str): action to be performed
            args (list): list of parameters
        Return:
            None: on valid inputs
            (str): on invalid inputs
        """
        actions = ['create', 'destroy', 'show', 'update']
        if len(args) < 1:
            return print('** class name missing **')
        if not (self.__classes.get(args[0], None)):
            return print('** class doesn\'t exist **')
        if query in actions[1:]:
            if len(args) < 2:
                return print('** instance id missing **')
            key = '.'.join(args[:2])
            objs = storage.all()
            if objs.get(key, None):
                return [objs, key]
            return print('** no instance found **')
        return None

    def __parseline(self, line):
        """Parse command like:
        <Model>.<action>([[*args], [**kwargs]]) to native formats
        """
        newLine = line.strip()
        args = re.search(r'\(.*?\)', newLine)
        if args is not None:
            params = args.group().strip('()')
            curls = re.search(r'\{(.*?)\}', params)
            if curls:
                items = curls.group()
                try:
                    uid = shlex.split(params[:curls.span()[0]])[0].strip(",")
                except IndexError:
                    uid = ""
                newargs = '{} \'{}\''.format(uid, items.replace("'", '"'))
            else:
                newargs = params.split(',')
                newargs = " ".join(newargs) or ""
            action = shlex.split(newLine[:args.span()[0]])[0].split(".")
            if len(action) == 2:
                line = "{} {} {}".format(action[1], action[0], newargs.strip())
        return line


if __name__ == '__main__':
    HBNBCommand().cmdloop()