prep

01_recap.rb

[1, 2, 3, "hello"] # Array
"hello" # String
5 # Integer
1.356 # Float
(1..10) # Range
true # boolean
nil # Nil

# box/container to store stuff/data
# so it can be used again
first_name = "rui"
last_name = "freitas"

# this is a recipe
# or a set of instructions
#.               string,    string
def full_name(first_name, last_name)
  # concatenation
  # first_name.capitalize + " " + last_name.capitalize
  # interpolation
  "#{first_name.capitalize} #{last_name.capitalize}"
end

# here i am preparin the meal
#.          "rui"        "freitas"
puts full_name(first_name, last_name)

02_students.rb

#                  0.       1.      2.        3
students =     [ "Peter", "Mary", "George", "Emma" ]
#                 0.       1.     2.         3
student_ages = [ 24     , 25    , 22      ,  20    ]
# length is 4

"Peter is 24 years of age"

# for i in (0...students.length)
#   name = students[i]
#   age = student_ages[i]
#   puts "#{name} is #{age} years of age"
# end

students.each_with_index do |student, index|
  age = student_ages[index]
  name = student
  puts "#{name} is #{age} years of age"
end

# students << "John"


students = {
  "Peter" => 24,
  "Mary" => 25,
  "George" => 22,
  "Emma" => 20
}

# students["Peter"]

03_lisbon.rb

lisbon = {
  "country" => "Portugal",
  "population" => 504718
}

puts lisbon.class
puts lisbon.size
p lisbon

# CRUD
# Arrays
# students = ["Peter", "Mary"]
# C: students << "John"
# R: students[1]
# U: students[0] = "Susan"
# D: students.delete_at(2)

# hashes CRUD
# Create
lisbon["monuments"] = ["Torre de Belém", "Castelo de S. Jorge"]
p lisbon

# Reading
puts lisbon["monuments"]

# Updating
lisbon["population"] = 600000
p lisbon

# the value is an array
# so i can use array methods
lisbon["monuments"] << "Ponte 25 de Abril"
p lisbon
lisbon["monuments"][1] = "Estádio da Luz"
p lisbon

# Delete
lisbon.delete("monuments")
p lisbon

04_iterating.rb

lisbon = {
  "country" => "Portugal",
  "population" => 504718
}

lisbon.each do |key, value|
  puts "The value of #{key} is #{value}"
end

london = {}
# lisbon has two key/value pairs
# puts lisbon.size == 0
puts lisbon.empty?
puts london.empty?

puts "======= KEYS"
puts lisbon.key?("country")
puts lisbon.key?("monuments")
# return an array with keys
p lisbon.keys

puts "===== VALUES"
# return an array with values
p lisbon.values

05_hash_map.rb

students = {
  "Peter" => 24,
  "Mary" => 25,
  "George" => 22,
  "Emma" => 20
}

mapped_students = students.map do |name, age|
  "#{name} is #{age} years old."
end

# Array
p mapped_students.class

# Each
aged_students = students.each do |key, value|
  students[key] = value + 1
end
p aged_students

06_count.rb

students = {
  "Peter" => 24,
  "Mary" => 25,
  "George" => 22,
  "Emma" => 20
}

# => returns an integer
count_22 = students.count do |_key, age|
  age <= 22
end

four_letter = students.count do |name, _age|
  name.length == 4
end

p count_22
p four_letter

07_symbols.rb

# keys as strings
paris = {
  "country" => "France",
  "population" => 2211000
}

# keys as symbols
london = {
  country: "England",
  population: 8308000
}
puts london[:country]

08_last_argument.rb

require "byebug"
#. opening content closing
# <div>Hello</div>
# <a href="www.lewagon.com">Click me!</a>
# <h1 class="title" id="main_heading">Welcome!</h1>

def tag(tag_name, content, attributes = {})
  attr_string = ""
  attributes.each do |name, value|
    attr_string += " #{name}=\"#{value}\""
  end
  "<#{tag_name}#{attr_string}>#{content}</#{tag_name}>"
end


puts tag("div", "Hello")
attributes = {
  href: "www.lewagon.com"
}
puts tag("a", "Click me!", attributes)
attributes = {
  class: "title",
  id: "main_heading",
}
puts tag("h1", "Welcome!", attributes)

09_csv.rb

require "csv"

file = "cities.csv"

cities = []
CSV.foreach(file) do |row|
  city = {
    name: row[0],
    population: row[1],
    monument: row[2]
  }
  cities << city
end

p cities

10_api.rb

require "byebug"
require "json"
require "open-uri"

puts "What's your Github username?"
username = gets.chomp

url = "https://api.github.com/users/#{username}"

response = open(url).read
json = JSON.parse(response)
first_name = json["name"].split.first
public_repos = json["public_repos"]

puts "#{first_name} has #{public_repos} public repos!"