require "sequel"
require "sequel/extensions/migration"
require "uri"

require "pliny/utils"

namespace :db do
  desc "Run database migrations"
  task :migrate do
    next if Dir["./db/migrate/*.rb"].empty?
    database_urls.each do |database_url|
      db = Sequel.connect(database_url)
      Sequel::Migrator.apply(db, "./db/migrate")
      puts "Migrated `#{name_from_uri(database_url)}`"
    end
    disconnect
  end

  desc "Rollback the database"
  task :rollback do
    next if Dir["./db/migrate/*.rb"].empty?
    database_urls.each do |database_url|
      db = Sequel.connect(database_url)
      Sequel::Migrator.apply(db, "./db/migrate", -1)
      puts "Rolled back `#{name_from_uri(database_url)}`"
    end
    disconnect
  end

  desc "Nuke the database (drop all tables)"
  task :nuke do
    database_urls.each do |database_url|
      db = Sequel.connect(database_url)
      db.tables.each do |table|
        db.run(%{DROP TABLE "#{table}" CASCADE})
      end
      puts "Nuked `#{name_from_uri(database_url)}`"
    end
    disconnect
  end

  desc "Seed the database with data"
  task :seed do
    if File.exist?('./db/seeds.rb')
      database_urls.each do |database_url|
        Sequel.connect(database_url)
        load 'db/seeds.rb'
      end
      disconnect
    end
  end

  desc "Reset the database"
  task :reset => [:nuke, :migrate, :seed]

  desc "Create the database"
  task :create do
    database_urls.each do |database_url|
      db = Sequel.connect("#{postgres_location_from_uri(database_url)}/postgres")
      exists = false
      name = name_from_uri(database_url)
      begin
        db.run(%{CREATE DATABASE "#{name}"})
      rescue Sequel::DatabaseError
        raise unless $!.message =~ /already exists/
        exists = true
      end
      puts "Created `#{name}`" if !exists
    end
    disconnect
  end

  desc "Drop the database"
  task :drop do
    database_urls.each do |database_url|
      db = Sequel.connect("#{postgres_location_from_uri(database_url)}/postgres")
      name = name_from_uri(database_url)
      db.run(%{DROP DATABASE IF EXISTS "#{name}"})
      puts "Dropped `#{name}`"
    end
    disconnect
  end

  namespace :schema do
    desc "Load the database schema"
    task :load do
      if File.exists?("./db/schema.sql")
        schema = File.read("./db/schema.sql")
        database_urls.each do |database_url|
          db = Sequel.connect(database_url)
          db.run(schema)
          puts "Loaded `#{name_from_uri(database_url)}`"
        end
        disconnect
      else
        puts "Skipped schema load, schema.sql not present"
      end
    end

    desc "Dump the database schema"
    task :dump do
      file = File.join("db", "schema.sql")
      database_url = database_urls.first
      `pg_dump -i -s -x -O -f #{file} #{database_url}`

      schema = File.read(file)
      # filter all COMMENT ON EXTENSION, only owners and the db
      # superuser can execute these, making it impossible to just
      # replay such statements in certain production databases
      schema.gsub!(/^COMMENT ON EXTENSION.*\n/, "")

      # add migrations used to compose this schema
      db = Sequel.connect(database_urls.first)
      if db.table_exists?(:schema_migrations)
        db[:schema_migrations].each do |migration|
          schema << db[:schema_migrations].insert_sql(migration) + ";\n"
        end
      end
      disconnect

      File.open(file, "w") { |f| f.puts schema }
      puts "Dumped `#{name_from_uri(database_url)}` to #{file}"
    end

    desc "Merges migrations into schema and removes them"
    task :merge => ["db:setup", "db:schema:dump"] do
      FileUtils.rm Dir["./db/migrate/*.rb"]
      puts "Removed migrations"
    end
  end

  desc "Setup the database"
  task :setup => [:drop, :create, "schema:load", :migrate, :seed]

  private

  def disconnect
    Sequel::DATABASES.each { |db| db.disconnect }
    Sequel::DATABASES.clear
  end

  def database_urls
    if ENV["DATABASE_URL"]
      [ENV["DATABASE_URL"]]
    else
      %w(.env .env.test).map { |env_file|
        env_path = "./#{env_file}"
        if File.exists?(env_path)
          Pliny::Utils.parse_env(env_path)["DATABASE_URL"]
        else
          nil
        end
      }.compact
    end
  end

  def name_from_uri(uri)
    URI.parse(uri).path[1..-1]
  end

  def postgres_location_from_uri(uri)
    p = URI.parse(uri)
    p.path = ""
    p.to_s
  end
end