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Assignments/assignment4.exs

+#Part 1
+
+
+#Declare a keyword list that contains name of the color and color html value.
+#Add at least 10 colors to the keyword list
+#Create a loop that asks user the color name or color html value.
+#If entered text begins with '#', print the corresponding color name.
+#Otherwise print the corresponding html color value.
+#If neither is found in keyword list, exit the loop.
+
+
+
+
+#this was a bit harder, as creating a working loop took a lot of time.
+#as a result the structure of the code became a bit complex
+
+defmodule ColorMatcher do
+  @colors [ #keywordlist is declared here
+    {:azure, "#F0FFFF"},
+    {:coral, "#FF7F50"},
+    {:indigo, "#4B0082"},
+    {:navy, "#000080"},
+    {:orchid, "#DA70D6"},
+    {:silver, "#C0C0C0"},
+    {:teal, "#008080"},
+    {:thistle, "#D8BFD8"},
+    {:wheat, "#F5DEB3"},
+    {:white, "#FFFFFF"}
+  ]
+
+  defp find_color(input) do #this function tries to find the color that user gave
+    input_trim = String.trim(input) #whitespaces etc. get trimmed off the given user input
+
+    case String.starts_with?(input_trim, "#") do #the case checks whether input starts with "#" or not
+      true -> find_by_html_value(input_trim) #if it starts with "#", it calls a function to find the color by value
+      false -> find_by_color_name(input_trim) #if it does not, it calls a function to find the color by name
+    end
+  end
+
+  defp find_by_html_value(html_value) do
+    case Enum.find(@colors, fn {_name, value} -> value == html_value end) do #case to find a matching HMTL value
+      {name, _} -> #if match is found, color name is printed and true is returned
+        IO.puts("Color name for #{html_value}: #{name}")
+        true
+      nil -> false #if not, false is returned
+    end
+  end
+
+  defp find_by_color_name(color_name) do
+    case Enum.find(@colors, fn {name, _value} -> name == String.to_atom(color_name) end) do
+      {_, value} -> #if match found, color value is printed and true is returned
+        IO.puts("HTML value for #{color_name}: #{value}")
+        true
+      nil -> false #if not, return false
+    end
+  end
+
+  def start_loop() do #this function initiates color match finder loop
+    do_while(fn -> loop() end)
+  end
+
+  #loop's operating principles are defined in this function
+  defp loop() do
+    IO.puts("Enter a color name or HTML value:")
+    input = IO.gets("") |> String.trim() #user's input is taken here and trimmed of whitespaces etc.
+
+    case input do 
+      _ ->
+        case find_color(input) do #checking if a match is found for the user's input
+          true -> :continue
+          false -> #if there is no match, loop is exited
+            IO.puts("No matching color found. Exiting.")
+            :ok
+        end
+    end
+  end
+
+  defp do_while(block) do #this function executes block in the loop until :continue is not returned
+    case block.() do
+      :continue -> do_while(block)
+      _ -> :ok
+    end
+  end
+end
+
+ColorMatcher.start_loop() #calls the start_loop function of the ColorMatcher module
+
+
+
+
+
+#Part 2
+
+
+#Declare a map that contains book ISBN as a key and book name as a value.
+#Add at least 5 books into the map
+#Create a loop that reads commands from the user:
+#list lists all books in the map.
+#search ISBN searches a book with specified ISBN and prints book info.
+#add ISBN,NAME adds new book into the map.
+#remove ISBN removes book with ISBN if found on map.
+#quit exits the loop.
+
+
+defmodule BookMap do #a module with a map of books within
+  @books %{
+    "ISBN1234567890" => "The Great Gatsby",
+    "ISBN0987654321" => "To Kill a Mockingbird",
+    "ISBN5678901234" => "1984",
+    "ISBN9876543210" => "Harry Potter and the Sorcerer's Stone",
+    "ISBN5432109876" => "The Catcher in the Rye"
+  }
+
+  def main do  #loop function is called with the map of books given
+    loop(@books)
+  end
+
+  def loop(books) do #this loop works as a main that reads user's commands and executes them
+    IO.puts("Enter a command (list, search ISBN(give only number), add [ISBN] [NAME], remove ISBN(give only number), quit):")
+    command = String.downcase(IO.gets(""))
+
+    case String.split(command, ~r/\s+/, trim: true) do
+      ["list"] -> list_books(books) #gives a list of the books
+      ["search", raw_isbn] -> search_book(books, raw_isbn) #searches book with isbn number
+      ["add" | rest] -> add_book(books, rest) #adds a new book into map
+      ["remove", isbn] -> loop(Map.delete(books, "ISBN" <> isbn)) #removes book from map
+      ["quit"] -> IO.puts("Goodbye!") #quits loop
+      _ -> IO.puts("Invalid command. Try again."); loop(books) #in case of invalid command
+    end
+  end
+
+  def list_books(books) do #function that lists books
+    IO.puts("List of Books:")
+    Enum.each(books, fn {isbn, name} -> IO.puts("#{isbn}: #{name}") end)
+    loop(books)
+  end
+
+  def search_book(books, raw_isbn) do #function that searches book
+    normalized_isbn = "ISBN" <> String.replace_prefix(raw_isbn, "ISBN", "") #to make search easier, prefix is replaced
+    case Map.get(books, normalized_isbn) do
+      nil -> IO.puts("Book not found.")
+      name -> IO.puts("Book found: #{normalized_isbn}: #{name}")
+    end
+    loop(books) #calling back to loop
+  end
+
+  defp add_book(books, [isbn | name_parts]) do #adds books to map
+    name = Enum.join(name_parts, " ")
+    loop(Map.put(books, "ISBN" <> isbn, name))
+  end
+
+  defp add_book(books, _) do
+    IO.puts("Invalid add command. Try again.")
+    loop(books) #calling back to loop
+  end
+end
+
+BookMap.main()