class Combustion::Database::Migrate

def self.call
  new.call
end

def base_migration_paths
  if migrator.respond_to?(:migrations_paths)
    migrator.migrations_paths
  else
    Array("db/migrate/")
  end
end

def call
  ar_gate = Combustion::VersionGate.new("activerecord")
  if ar_gate.call(">= 5.2")
    migration_context.migrate
  elsif ar_gate.call(">= 3.1")
    migrator.migrate paths, nil
  else
    paths.each { |path| migrator.migrate path, nil }
  end
end

def engine_migration_paths
  migration_paths = Rails.application.paths["db/migrate"].to_a
  if engine_paths_exist_in?(migration_paths)
    migration_paths
  else
    base_migration_paths + migration_paths
  end
end

def engine_path
  Rails.application.root.sub(::Combustion.path, "")
end

def engine_paths_exist_in?(paths)
  paths.include?(engine_path.join("db/migrate").to_s)
end

def migration_context
  if ActiveRecord::MigrationContext.instance_method(:initialize).arity <= 1
    ActiveRecord::MigrationContext.new paths
  else
    ActiveRecord::MigrationContext.new(
      paths, ActiveRecord::Base.connection.schema_migration
    )
  end
end

def migrator
  @migrator ||= ActiveRecord::Migrator
end

def paths
  (engine_migration_paths + [File.join(Rails.root, "db/migrate")]).uniq
end