student.rb

require 'sqlite3'
require 'debugger'

DB = SQLite3::Database.new("studentbody.db")

create_students_table_sql = <<SQL
CREATE TABLE students
(
id INTEGER PRIMARY KEY,
first_name TEXT,
last_name TEXT,
email TEXT,
twitter TEXT,
facebook TEXT,
photo TEXT
);
SQL

# r
# Student.find(1) #=> <#Student>

class Student
  def self.table_name
    "#{self.to_s.downcase}s"
  end

  def self.column_names
    @column_names ||= DB.execute("PRAGMA table_info([students])").map do |column_info|
      column_info[1].downcase.to_sym
    end
  end

  def self.columns_for_sql
    self.column_names[1..-1].join(",")
  end

  self.column_names.each do |column|
    attr_accessor column

    define_singleton_method "find_by_#{column}" do |value|
      result = DB.execute("SELECT * FROM #{self.table_name} WHERE #{column} = ?", value)
      initialize_from_db(result)
    end
  end

  # for each column name
  # define a method called find_by_#colum_name
  # and then somehow use that column to construct the where clause


  def self.find(id)

    result = DB.execute("SELECT * FROM students WHERE id = ?", id)

    initialize_from_db(result)
    # load the student's data from the database
    # instantiate a new student
    # set that students attributes wtih values from the datbase
  end

  def self.initialize_from_db(result)
    Student.new.tap do |s|
      self.column_names.each_with_index do |column_name, i|
        s.send("#{column_name}=", result.flatten[i])
      end
    end
  end

  def save
    if new_record?
      sql = "INSERT INTO students (#{self.class.columns_for_sql}) VALUES
        (#{place_holders})"
      puts sql
      DB.execute(sql, attributes.values)
    else
      # for each column name I need a column = value
       sql = "UPDATE students SET #{set_clause} WHERE id = #{id}"
       puts sql
       DB.execute(sql, attributes.values)
    end
  end

  def new_record?
    id ? false : true
  end

  private
    def set_clause
      attributes.keys.collect{|k|
        "#{k} = ?"
      }.join(",")
    end



    def place_holders
      attributes.collect{"?"}.join(",")
    end

    def attributes
      self.class.column_names[1..-1].inject({}) do |attributes, column|
        attributes[column] = self.send(column)
        attributes
      end
    end
end

debugger
@avi = Student.find(1)


# @student = Student.new
# @student.first_name = "Avi"
# @student.save