class ActiveRow

# File lib/active_row.rb, line 60
def self.create(attr_hash)
  CSV.open(table_path, 'a+') do |csv| # a+ => append to document
    # concatenate an array of values [1, 'text', 'username']
    csv << CSV::Row.new(attr_hash.keys, attr_hash.values).fields
  end
  self.new(attr_hash)
end

# File lib/active_row.rb, line 25
def self.find(id = nil)
  csv_table = CSV.table(table_path, converters: CONVERTERS)
  csv_row = csv_table.find { |row| row.field(:id) == id }
  csv_row ? self.new(csv_row.to_hash) : nil
end

# File lib/active_row.rb, line 36
def self.find_by(attr_hash)
  csv_table = CSV.table(table_path, converters: CONVERTERS)
  # Find the row where values in the CSV::Row are
  # equal to the values of the attributes that were provided
  csv_row = csv_table.find { |row| row.values_at(*attr_hash.keys) == attr_hash.values}
  csv_row ? self.new(csv_row.to_hash) : nil
end

# File lib/active_row.rb, line 14
def self.table_directory
  "./tables/"
end

# File lib/active_row.rb, line 10
def self.table_name
  "#{self.name.downcase}s"
end

# File lib/active_row.rb, line 18
def self.table_path
  "#{self.table_directory}#{self.table_name}.csv"
end

# File lib/active_row.rb, line 126
def attributes
  attrs = {}
  instance_variables.each { |instance_variable|
    # Convert the instariable to a string, removing the @ (instance notation), and convert back to a symbol
    attrs[instance_variable.to_s[1..-1].to_sym] = instance_variable_get(instance_variable)
  }
  attrs
end

# File lib/active_row.rb, line 135
def attributes=(new_attributes)
  new_attributes.each { |key, value| instance_variable_set(key, value) }
  attributes
end

# File lib/active_row.rb, line 98
def destroy
  csv_table = CSV.table(table_path, converters: CONVERTERS)
  # Delete the row from the table if it is equivalent to the receiving instance.
  csv_table.delete_if do |row|
    row == CSV::Row.new(attributes.keys, attributes.values)
  end

  # Write the csv_table to a file, replacing the original
  File.open(table_path, 'w') do |f| # w => write-only
    f.write(csv_table.to_csv)
  end

  # Get the file's contents and close it
  file = File.open(table_path, 'rb')
  contents = file.read
  file.close

  # If all rows but the header have been deleted...
  if contents.lines.count < 2
     # then ensure the headers are still there.
     File.open(table_path, 'w') do |f| # w => write-only
      f.write(attributes.keys.map(&:to_s).join(','))
    end
  end
  self.freeze
end

# File lib/active_row.rb, line 45
def save
  attr_hash = self.attributes
  if self.class.find_by(attr_hash)
    return false
  else
    self.class.create(attr_hash)
    return true
  end
end

# File lib/active_row.rb, line 73
def update(attr_hash)
  # Prevent update of id field
  attr_hash.reject! { |k, v| k == :id || k == "id" }
  csv_table = CSV.table(table_path, converters: CONVERTERS)
  old_row = csv_table.find { |row| row.field(:id) == id }
  new_row = CSV::Row.new(old_row.headers, old_row.fields)

  # Assign new values to the row by param name (which should be a field name)
  attr_hash.each { |k, v| new_row[k] = v }
  # Delete the old_row
  csv_table = CSV.table(table_path, converters: CONVERTERS)
  csv_table.delete_if do |row|
    row == old_row
  end
  csv_table << new_row
  # Write the csv_table to a file, replacing the original
  File.open(table_path, 'w') do |f| # w => write-only
    f.write(csv_table.to_csv)
  end
  # Note: AR returns true if successful, false if not.
  # If AR is successful, it updates the receiving instance's attributes.
  # This returns a new instance with the variables on success.
  new_row ? self.class.new(new_row.to_hash) : false
end