require 'rails_helper'
require_dependency 'migration/column_dropper'

RSpec.describe Migration::ColumnDropper do
  def has_column?(table, column)
    DB.exec(<<~SQL, table: table, column: column) == 1
      SELECT 1
      FROM INFORMATION_SCHEMA.COLUMNS
      WHERE
        table_schema = 'public' AND
        table_name = :table AND
        column_name = :column
    SQL
  end

  describe ".execute_drop" do
    let(:columns) { %w{junk junk2} }

    before do
      columns.each do |column|
        DB.exec("ALTER TABLE topics ADD COLUMN #{column} int")
      end
    end

    after do
      columns.each do |column|
        DB.exec("ALTER TABLE topics DROP COLUMN IF EXISTS #{column}")
      end
    end

    it "drops the columns" do
      Migration::ColumnDropper.execute_drop("topics", columns)

      columns.each do |column|
        expect(has_column?('topics', column)).to eq(false)
      end
    end
  end

  describe '.mark_readonly' do
    let(:table_name) { "table_with_readonly_column" }

    before do
      DB.exec <<~SQL
      CREATE TABLE #{table_name} (topic_id INTEGER, email TEXT);

      INSERT INTO #{table_name} (topic_id, email)
      VALUES (1, 'something@email.com');
      SQL

      Migration::ColumnDropper.mark_readonly(table_name, 'email')
    end

    after do
      ActiveRecord::Base.connection.reset!

      DB.exec <<~SQL
      DROP TABLE IF EXISTS #{table_name};
      DROP FUNCTION IF EXISTS #{Migration::BaseDropper.readonly_function_name(table_name, 'email')} CASCADE;
      SQL
    end

    it 'should be droppable' do
      Migration::ColumnDropper.execute_drop(table_name, ['email'])

      expect(has_trigger?(Migration::BaseDropper.readonly_trigger_name(
        table_name, 'email'
      ))).to eq(false)

      expect(has_column?(table_name, 'email')).to eq(false)
    end

    it 'should prevent updates to the readonly column' do
      begin
        DB.exec <<~SQL
        UPDATE #{table_name}
        SET email = 'testing@email.com'
        WHERE topic_id = 1;
        SQL
      rescue PG::RaiseException => e
        [
          "Discourse: email in #{table_name} is readonly",
          'discourse_functions.raise_table_with_readonly_column_email_readonly()'
        ].each do |message|
          expect(e.message).to include(message)
        end
      end
    end

    it 'should allow updates to the other columns' do
      DB.exec <<~SQL
      UPDATE #{table_name}
      SET topic_id = 2
      WHERE topic_id = 1
      SQL

      expect(
        ActiveRecord::Base.exec_sql("SELECT * FROM #{table_name};").values
      ).to include([2, "something@email.com"])
    end

    it 'should prevent insertions to the readonly column' do
      expect do
        ActiveRecord::Base.connection.raw_connection.exec <<~SQL
        INSERT INTO #{table_name} (topic_id, email)
        VALUES (2, 'something@email.com');
        SQL
      end.to raise_error(
        PG::RaiseException,
        /Discourse: email in table_with_readonly_column is readonly/
      )
    end

    it 'should allow insertions to the other columns' do
      DB.exec <<~SQL
      INSERT INTO #{table_name} (topic_id)
      VALUES (2);
      SQL

      expect(
        DB.query_single("SELECT topic_id FROM #{table_name} WHERE topic_id = 2")
      ).to eq([2])
    end
  end
end