require 'active_record'
require 'csv'
require 'ferry/version'
# require 'progressbar'
require 'yaml'

module Ferry
  class Exporter

    def which_db_env
      ARGV[1]
    end

    def switch_to_db_type
      ARGV[2]
    end

    def to_csv
      info = YAML::load(IO.read("config/database.yml"))
      db_type = info[which_db_env||"production"]["adapter"]



      #issues:
      #   csv placement in directory:  do we want it in the lib?
      #   the case where dev/test dbs are different from production db (sqlite for dev/test, pg for prod??)
      #   empty ARGs
      #   ARGs with invalid values


      case db_type
      when "sqlite3"
        puts "operating with sqlite3"

        if(which_db_env)
          homedir = "lib/ferry_to_csv_#{which_db_env}"
          ActiveRecord::Base.establish_connection(adapter: db_type, database: info[which_db_env]['database'])
          puts "connected to #{which_db_env} env db"
          FileUtils.mkdir homedir unless Dir[homedir].present?
          puts "exporting tables to #{homedir}"
          # sqlite_pbar = ProgressBar.new("sqlite_to_csv", 100)
          ActiveRecord::Base.connection.tables.each do |model|
            full_table = ActiveRecord::Base.connection.execute("SELECT * FROM #{model};")
            # do not create a csv for an empty table
            if !full_table[0].nil?
              CSV.open("#{homedir}/#{model}.csv", "w") do |csv|
                size = full_table[0].length / 2
                keys = full_table[0].keys.first(size)
                #first row contains column names
                csv << keys
                full_table.each do |row|
                  csv << row.values_at(*keys)
                  # sqlite_pbar.inc
                end
              end
            end
          end
        else #no db_env is specified
          info.keys.each do |environment|

            if(environment == 'default')  #in Rails 4.1+ environments inherit from default, which does not have database so we will not include it
              next
            end

            homedir = "lib/ferry_to_csv_#{environment}"
            ActiveRecord::Base.establish_connection(adapter: db_type, database: info[environment]['database'])  #connect to sqlite3 file
            puts "connected to #{environment} env db"
            FileUtils.mkdir homedir unless Dir[homedir].present?
            puts "exporting tables to #{homedir}"
            # sqlite_pbar = ProgressBar.new("sqlite_to_csv", 100)
            ActiveRecord::Base.connection.tables.each do |model|                                #for each model in the db
              full_table = ActiveRecord::Base.connection.execute("SELECT * FROM #{model};")    #get all the records
              if !full_table[0].nil?
                CSV.open("#{homedir}/#{model}.csv", "w") do |csv|
                  size = full_table[0].length / 2
                  keys = full_table[0].keys.first(size)
                  #first row contains column names
                  csv << keys
                  full_table.each do |row|
                    csv << row.values_at(*keys)
                    # sqlite_pbar.inc
                  end
                end
              end
            end
          end
        end

      when "postgresql"
        puts "operating with postgres"

        if(which_db_env)
          homedir = "lib/ferry_to_csv_#{which_db_env}"
          ActiveRecord::Base.establish_connection(
            adapter:  'postgresql', 
            host:     info[which_db_env]['host'] || 'localhost', 
            username: info[which_db_env]['username'], 
            password: info[which_db_env]['password'], 
            database: info[which_db_env]['database'], 
            encoding: info[which_db_env]['encoding']
          )
          puts "connected to #{which_db_env} env db"
          FileUtils.mkdir homedir unless Dir[homedir].present?
          puts "exporting tables to #{homedir}"
          # psql_pbar = ProgressBar.new("psql_to_csv", 100)
          ActiveRecord::Base.connection.tables.each do |model|
            full_table = ActiveRecord::Base.connection.execute("SELECT * FROM #{model};")
            # do not create a csv for an empty table
            if full_table.num_tuples > 0
              CSV.open("#{homedir}/#{model}.csv", "w") do |csv|
                size = full_table[0].length / 2
                keys = full_table[0].keys.first(size)
                #first row contains column names
                csv << keys
                full_table.each do |row|
                  csv << row.values_at(*keys)
                  # psql_pbar.inc
                end
              end
            end
          end
        else
          info.keys.each do |environment|

            if(environment == 'default')  #in Rails 4.1+ environments inherit from default, which does not have database so we will not include it
              next
            end
            homedir = "lib/ferry_to_csv_#{environment}"

            ActiveRecord::Base.establish_connection(
              adapter:  'postgresql', 
              host:     info[environment]['host'] || 'localhost', 
              username: info[environment]['username'], 
              password: info[environment]['password'], 
              database: info[environment]['database'], 
              encoding: info[environment]['encoding']
            )
            puts "connected to #{environment} env db"
            FileUtils.mkdir homedir unless Dir[homedir].present?
            puts "exporting tables to #{homedir}"
            # psql_pbar = ProgressBar.new("psql_to_csv", 100)
            ActiveRecord::Base.connection.tables.each do |model|
              full_table = ActiveRecord::Base.connection.execute("SELECT * FROM #{model};")
              # do not create a csv for an empty table
              if full_table.num_tuples > 0
                CSV.open("#{homedir}/#{model}.csv", "w") do |csv|
                  size = full_table[0].length / 2
                  keys = full_table[0].keys.first(size)
                  #first row contains column names
                  csv << keys
                  full_table.each do |row|
                    csv << row.values_at(*keys)
                    # psql_pbar.inc
                  end
                end
              end
            end
          end
        end
      when "mysql2"
        puts "operating with mysql2"

        if(which_db_env)
          homedir = "lib/ferry_to_csv_#{which_db_env}"

          ActiveRecord::Base.establish_connection(    #this may not work on default rails if production db is not created (must run rake db:create:all)
            adapter:  'mysql2',
            host:     info[which_db_env]['host'] || 'localhost', 
            username: info[which_db_env]['username'], 
            password: info[which_db_env]['password'], 
            database: info[which_db_env]['database']
          )
          puts "connected to #{which_db_env} env db"
          FileUtils.mkdir homedir unless Dir[homedir].present?
          puts "exporting tables to #{homedir}"
          # psql_pbar = ProgressBar.new("psql_to_csv", 100)

          ActiveRecord::Base.connection.tables.each do |model|                              #for each model in the db
            columns = ActiveRecord::Base.connection.execute("SELECT `COLUMN_NAME` FROM `INFORMATION_SCHEMA`.`COLUMNS` WHERE `TABLE_SCHEMA`= '#{info[which_db_env]['database']}' AND `TABLE_NAME`='#{model}';")
            CSV.open("#{homedir}/#{model}.csv", "w") do |csv|

              col_names=[]
              columns.each do |col|
                col_names.append(col[0])  #append the column names to an array, makes for good formatting
              end
              csv << col_names  #first csv row is of column names

              full_table = ActiveRecord::Base.connection.execute("SELECT * FROM #{model};")
              full_table.each do |row|
                csv << row  #not sure if this will hold, but no 'values_at' method exists
                # psql_pbar.inc
              end
            end
          end
        else
          info.keys.each do |environment|

            if(environment == 'default')  #in Rails 4.1+ environments inherit from default, which does not have database so we will not include it
              next
            end

            homedir = "lib/ferry_to_csv_#{environment}"

              ActiveRecord::Base.establish_connection(    #this may not work on default rails if production db is not created (must run rake db:create:all)
                adapter:  'mysql2',
                host:     info[environment]['host'] || 'localhost', 
                username: info[environment]['username'], 
                password: info[environment]['password'], 
                database: info[environment]['database']
              )
            puts "connected to #{environment} env db"
            FileUtils.mkdir homedir unless Dir[homedir].present?
            puts "exporting tables to #{homedir}"
            # psql_pbar = ProgressBar.new("psql_to_csv", 100)

            ActiveRecord::Base.connection.tables.each do |model|                              #for each model in the db
              columns = ActiveRecord::Base.connection.execute("SELECT `COLUMN_NAME` FROM `INFORMATION_SCHEMA`.`COLUMNS` WHERE `TABLE_SCHEMA`= '#{info[environment]['database']}' AND `TABLE_NAME`='#{model}';")
              CSV.open("#{homedir}/#{model}.csv", "w") do |csv|

                col_names=[]
                columns.each do |col|
                  col_names.append(col[0])  #append the column names to an array, makes for good formatting
                end
                csv << col_names  #first csv row is of column names

                full_table = ActiveRecord::Base.connection.execute("SELECT * FROM #{model};")
                full_table.each do |row|
                  csv << row  #not sure if this will hold, but no 'values_at' method exists
                  # psql_pbar.inc
                end
              end
            end
          end
        end  
      when "mongo"
        puts "mongo is currently not supported"
      else
        puts "Unknown db type or no database associated with this application."
      end
    end

    def to_new_db_type
      info = YAML::load(IO.read("config/database.yml"))
      current_db_type = info[which_db_env]["adapter"]
      puts "switching the #{which_db_env} database's adapter"
      puts "current_db_type: #{current_db_type}"
      puts "to_new_db_type: #{switch_to_db_type}"

      # check for dependencies
      # if dependencies exist - install them
      # create new connection
      # transfer old db into new connection
      # drop old connection
      # update the config file
      # profit
    end

  end
end