import copy # needed in examples of functions that modify input dict

from typing import TextIO

from constants import $($ID$,$ HEADLINE, LISTED, FEATURES, LOC, DESC, END, SEP,

LocType, ListingValueType, ListingType, BookSysType$)$

EXAMPLE$\_$BOOK$\_$SYS $=\{$

$\text{'}137\text{'}$: $\{$

'identifier': $\text{'}137\text{'},$

'headline': 'Beautiful $4-$bedroom home on lakeside',

'listed': $\text{'}2024-07-17\text{'},$

'features': $[\text{'}4$ bedroom', $\text{'}3$ bath', 'Pool'$],$

'location': $(\text{'}$New York', 'USA'$),$

'description': $\text{'}\text{'}\text{'}$This is a beautiful $4-$bedroom, $3-$bath detached house

with an outdoor pool.$\text{'}\text{'}\text{'}\},$

$\text{'}001\text{'}$: $\{$

'identifier': $\text{'}001\text{'},$

'headline': 'House',

'listed': None,

'features': $[\text{'}$clean$\text{'}],$

'location': $(\text{'}$Hamilton$\text{'},$ 'Canada'$),$

'description': None$\},$

$\text{'}05\text{'}$: $\{$

'identifier': $\text{'}05\text{'},$

'headline': 'Stunning lakeside cottage$\text{'},$

'listed': $\text{'}2021-02-08\text{'},$

'features': $[],$

'location': $(\text{'}$Oxford$\text{'},\text{'}$UK$\text{'}),$

'description': 'This is lakeside!$\text{'}\}$

$\}$

EXAMPLE$\_$BY$\_$COUNTRY $=\{$

'USA': $[\text{'}137\text{'}],$

'Canada': $[\text{'}001\text{'}],$

$\text{'}$UK$\text{'}$: $[\text{'}05\text{'}]$

$\}$

# We provide the header and docstring for this function to get you

# started and to demonstrate that there are no docstring examples in

# functions that read from files.

def read$\_$book$\_$sys$\_$file$($book$\_$sys$\_$file: TextIO$)->$ BookSysType:

$"""$Return a dict containing all booking system info in 'book$\_$sys$\_$file'.

Precondition: 'book$\_$sys$\_$file' is open for reading

'book$\_$sys$\_$file' is in the format described in the handout

$"""$

pass

# We provide the header and PART of a docstring for this function to

# get you started and to demonstrate the use of example data.

def make$\_$country$\_$to$\_$listings$($

book$\_$sys: BookSysType$)->$ dict$[$str$,$ list$[$str$]]$:

$"""$Return a dict that maps each country to a list of IDs of listings in

that country based on the information in booking system data 'book$\_$sys$\text{'}.$

$>>>$ make$\_$country$\_$to$\_$listings$($EXAMPLE$\_$BOOK$\_$SYS$)==$ EXAMPLE$\_$BY$\_$COUNTRY

True

$"""$

pass

# We provide the header and PART of a docstring for this function to

# get you started and to demonstrate the use of function deepcopy in

# examples that modify input data.

def keep$\_$complete$\_$listings$($book$\_$sys: BookSysType$)->$ None:

$"""$Update the booking system data 'book$\_$sys$\text{'}$ so that it only contains

listings that are not missing any information.

$>>>$ book$\_$sys$\_$copy $=$ copy.deepcopy$($EXAMPLE$\_$BOOK$\_$SYS$)$

$>>>$ keep$\_$complete$\_$listings$($book$\_$sys$\_$copy$)$

$>>>$ book$\_$sys$\_$copy $==\{\text{'}137\text{'}$: EXAMPLE$\_$BOOK$\_$SYS$[\text{'}137\text{'}]\}$

True

$"""$

pass

if $\_\_$name$\_\_==\text{'}\_\_$main$\_\_\text{'}$:

import doctest

doctest.testmod$()$

# uncomment to test with example data files

# with open$(\text{'}$example$\_$data.txt$\text{'})$ as example$\_$data:

# RESULT $=$ read$\_$book$\_$sys$\_$file$($example$\_$data$)$

# print$(\text{'}$Did we produce a correct dict? $\text{'},$ RESULT $==$ EXAMPLE$\_$BOOK$\_$SYS$)$

# uncomment to work with a larger data set

# with open$(\text{'}$data$.$txt$\text{'})$ as data$\_$txt:

# EXAMPLE $=$ read$\_$book$\_$sys$\_$file$($data$\_$txt$)$

# EXAMPLE$\_$COUNTRY$\_$TO$\_$LISTING $=$ make$\_$country$\_$to$\_$listings$($EXAMPLE$)$

# EXAMPLE$\_$MOST$\_$POPULAR$\_$COUNTRIES $=$ get$\_$most$\_$popular$\_$countries$($EXAMPLE$)$

# print$($EXAMPLE$\_$MOST$\_$POPULAR$\_$COUNTRIES$)$