#!/home/mark/opt/rakudo-star-2014.04/perl6

#
#  This following information is excerpted from Derrick's message and has
#  been slightly reformatted.  Derrick Kearney <derrick@csociety.org>
#  wrote on 2014-04-28 at 17:35:51 GMT:
#
#  In our last meeting we learned about the JSON file format.  I
#  created the sample json file I wanted to use for the first part of
#  the challenge.  I uploaded the file to
#      http://www.csociety.org/~kearneyd/tmp/purduepm_json_challenge_1.json
#  
#  While I sort things out with my system, if you have a bit of extra
#  time, can you write a program that will do the following?
#  
#  1) Read and Parse the JSON file.
#  
#  Read the json file into memory and parse it into data structures that
#  best fit the programming language you are using.  There are 6 data
#  types you need to worry about:
#  
#  Primitive Types:
#  * null
#  * booleans
#  * strings
#  * numbers
#  
#  Structured Types:
#  * arrays
#  * objects
#  
#  More information about the json file format can be found at
#      http://json.org
#  
#  The file represents a dictionary, or hash table, or associative array.
#  
#  There is probably a library available in your programming language,
#  you can use to quickly read and parse the file.  The json.org
#  website has a list of some libraries for popular programming
#  languages.
#  
#  After parsing the file into your language's data structures, you
#  should print the values stored in the data structures to stdout or
#  another file to make sure you are reading the data properly.  Don't
#  just print the file after reading it.
#  
#  
#  2) Fix the JSON file and write it back to disk.
#  
#  Here is where it gets tricky.  Even though the json file was
#  syntactically correct, I made some mistakes in the data that is
#  stored in it.  Here is a summary of what I wanted for each key in
#  the dictionary :
#  
#  (a) null_value should be a json NULL or None value, not a string.
#  (b) boolean_true should be a json true value, not false
#  (c) boolean_false should be a json false value, not true
#  (d) integer_number should be the integer representation of its current
#      value, not the floating point representation (i.e., 3)
#  (e) number_examples -> "not a number" should not even be in the
#      dictionary, lets remove it.
#  (f) in "array", the string "value5" should read "value4" to match "key4"
#  
#  Can you write a program to make these specific changes?  Don't
#  forget to comment your code.  If you find an interesting way of
#  addressing elements inside of the structure, please highlight that
#  in your code.  For example, how would you find the value for "key4"
#  in the file?  If there were multiple dictionary keys named "key4"
#  in the file, how could you make sure you were addressing the
#  correct one?
#  
#  The data in the outputted file should look something like like this:
#  
#  {
#       "null_value": null,
#       "boolean_true": true,
#       "boolean_false": false,
#       "string": "this is my string.",
#       "integer_number": 3,
#       "number_examples": {
#           "positive integer": 9,
#           "negative integer": -1,
#           "float": 2.3,
#           "positive_exponent": 4.35e+58,
#           "negative_exponent": 4.3508e-93
#       },
#       "array": [true,null,["value3"],{"key4":"value4"}]
#  }
#  
#  Note that the order of the keys (null_value, boolean_true,
#  boolean_false, ...) does not matter since the pairs of a json
#  object are unordered.
#  
#  We'll discuss how to perform these actions in the different
#  programming languages people chose to use in the next meeting on
#  May 20, 2014.
#

use v6;

use JSON::Tiny;
use LWP::Simple;

# Read the file.
my $fn = 'http://www.csociety.org/~kearneyd/tmp/purduepm_json_challenge_1.json';
my $text = LWP::Simple.get($fn);
say '';
say 'JSON FILE TEXT READ:';
say $text;

# Quota null because it is a Perl 6 keyword.
$text.=subst(/\,null\,/, ',"null",');
say 'JSON FILE TEXT AFTER REPLACING ,null, WITH ,"null",:';
say "$text";

# Does the file parse ok?
my $t = JSON::Tiny::Grammar.parse($text) ?? 'succeeded' !! 'failed';
say "The JSON parse $t.";

# Get JSON data.
my $from = from-json($text);
my %from = $from;
say '';
say 'FORMATTED HASHED JSON DATA:';
%from.keys.sort.map({say "$_ => %from{$_}"});

#  (a) null_value should be a json NULL or None value, not a string.
%from{'null_value'} = 'NULL';
say '';
say 'There is no documentation for JSON::Tiny, I don\'t';
say 'know what to use for a JSON NULL or None value.';
say 'FORMATTED HASHED JSON DATA AFTER CHANGING null_value FROM null TO NULL:';
%from.keys.sort.map({say "$_ => %from{$_}"});

#  (b) boolean_true should be a json true value, not false
%from{'boolean_true'} = True;
say '';
say 'FORMATTED HASHED JSON DATA AFTER CHANGING boolean_true FROM False TO True:';
%from.keys.sort.map({say "$_ => %from{$_}"});

#  (c) boolean_false should be a json false value, not true
%from{'boolean_false'} = False;
say '';
say 'FORMATTED HASHED JSON DATA AFTER CHANGING boolean_false FROM True TO False:';
%from.keys.sort.map({say "$_ => %from{$_}"});

#  (d) integer_number should be the integer representation of its current
#      value, not the floating point representation (i.e., 3)
%from{'integer_number'} = %from{'integer_number'}.floor();
say '';
say 'FORMATTED HASHED JSON DATA AFTER CHANGING integer_number FROM 3.14159 TO 3:';
%from.keys.sort.map({say "$_ => %from{$_}"});

#  (e) number_examples -> "not a number" should not even be in the
#      dictionary, lets remove it.
%from{'number_examples'}{'not a number'}:delete;
say '';
say 'FORMATTED HASHED JSON DATA AFTER DELETING number_examples -> "not a number":';
%from.keys.sort.map({say "$_ => %from{$_}"});

# (f) in "array", the string "value5" should read "value4" to match "key4"
$from{'array'}[3]{'key4'} = 'value4';
say '';
say 'I cheated by not searching array for the index of the';
say 'hash and instead just used 3 as the index of the hash.';
say 'FORMATTED HASHED JSON DATA AFTER CHANGING value5 TO value4:';
%from.keys.sort.map({say "$_ => %from{$_}"});

my $to = to-json(%from);
say '';
say 'JSON DATA IS NOW:';
say $to;
say '';

# $from = from-json($to);
# say '';
# say 'JSON DATA:';
# say $from;
# say '';
# 

# We're done.
exit 0;