class TrustyCms::ExtensionMigrator

def assume_migrated_upto_version(version)
  version = version.to_i
  sm_table = self.class.schema_migrations_table_name
  migrated = self.class.get_all_versions
  versions = Dir["#{@migrations_path}/[0-9]*_*.rb"].map do |filename|
    filename.split('/').last.split('_').first.to_i
  end
  unless migrated.include?(version)
    ActiveRecord::Base.connection.execute "INSERT INTO #{sm_table} (version) VALUES (#{sanitize(quote(version_string(version)))})"
  end
  inserted = Set.new
  (versions - migrated).each do |v|
    if inserted.include?(v)
      raise "Duplicate migration #{v}. Please renumber your migrations to resolve the conflict."
    elsif v < version
      ActiveRecord::Base.connection.execute "INSERT INTO #{sm_table} (version) VALUES (#{sanitize(quote(version_string(v)))})"
      inserted << v
    end
  end
end

def extension_name
  self.class.extension.extension_name
end

def get_all_versions
  ActiveRecord::Base.connection.select_values("SELECT version FROM #{sanitize(schema_migrations_table_name)}").
    select { |version| version.starts_with?("#{@extension.extension_name}-") }.
    map { |version| version.sub("#{@extension.extension_name}-", '').to_i }.sort
end

def initialize(direction, migrations_path, target_version = nil)
  super
  initialize_extension_schema_migrations
  initialize_received_migrations
end

def initialize_extension_schema_migrations
  current_version = ActiveRecord::Base.connection.select_value("SELECT schema_version FROM extension_meta WHERE name = #{sanitize(quote(extension_name))}")
  if current_version
    assume_migrated_upto_version(current_version.to_i)
    ActiveRecord::Base.connection.delete("DELETE FROM extension_meta WHERE name = #{sanitize(quote(extension_name))}")
  end
end

def initialize_received_migrations
  if donors = self.class.extension.migrates_from
    donors.each do |extension_name, until_migration|
      replaced = ActiveRecord::Base.connection.select_values("SELECT version FROM #{sanitize(ActiveRecord::Migrator.schema_migrations_table_name)} WHERE version LIKE '#{extension_name}-%'").map { |v| v.sub(/^#{extension_name}\-/, '').to_i }
      replaced.delete_if { |v| v > until_migration.to_i } if until_migration
      assume_migrated_upto_version(replaced.max) if replaced.any?
    end
  end
end

def migrate(target_version = nil)
  super extension.migrations_path, target_version
end

def migrate_extensions
  []
end

def quote(s)
  ActiveRecord::Base.connection.quote(s)
end

def version_string(version)
  "#{extension_name}-#{version}"
end