# Represents a person in an address book.
class Contact

  @@people = []
  attr_accessor :name, :email, :id

  def initialize(id, name, email)
    @id = id
    @name = name
    @email = email
  end

  # allows for upserting into contacts
  def save
    check = self.class.connect.exec_params('SELECT * FROM contacts WHERE id = $1', [id])
    if check.cmd_tuples == 0
      res = self.class.connect.exec_params(
        'INSERT INTO contacts (name, email) VALUES ($1, $2) RETURNING id;',
        [name, email]
        )
      self.id = res[0]['id']

    else
      self.class.connect.exec_params('UPDATE contacts SET name = $1, email = $2 WHERE id = $3::int;', [name, email, id])
    end
  end

  # allows for deleting from contacts
  def destroy
    res = self.class.connect.exec_params('DELETE FROM contacts WHERE id = $1::int', [id])
  end

  # Provides functionality for managing a list of Contacts in a database.
  class << self

    def connect
      PG.connect(
        host: 'localhost',
        dbname: 'contact_list',
        user: 'development',
        password: 'development')
    end

    # Returns an Array of Contacts loaded from the database.
    def all
      res = connect.exec_params('SELECT * FROM contacts;')
      list_contacts(res)
    end

    # Creates a new contact, adding it to the database, returning the new contact.
    def create(name, email)
      raise DuplicateEmailError, "Duplicate email, cannot create this person" if all.detect {|contact| contact.email == email}
      new_person = Contact.new(nil, name, email)
      new_person.save
      new_person
    end

    # Returns the contact with the specified id. If no contact has the id, returns nil.
    def find(id)
      res = connect.exec_params("SELECT * FROM contacts WHERE id = $1::int LIMIT 1;", [id])
      return nil if res.cmd_tuples == 0
      Contact.new(res[0]['id'], res[0]['name'], res[0]['email'])
    end

    # Returns an array of contacts who match the given term.
    def search(term)
      res = connect.exec_params(
        "SELECT * FROM contacts WHERE email LIKE concat('%', $1::text, '%') OR name LIKE concat('%', $1::text, '%');",
        [term]
        )
      list_contacts(res)
    end

    # Iterates over PG Result object and populates class variable @@people with relevant contacts
    def list_contacts(res)
      res.each do |contact|
        @@people << Contact.new(contact['id'].to_i, contact['name'], contact['email'])
      end
      @@people
    end
  end
end

class DuplicateEmailError < StandardError
end