defmodule Mix.Tasks.Mandrag do
  defmodule Deploy do
    use Mix.Task

    @shortdoc "Deploys an exrm release."

    def run(_) do
      case {initial_deploy?, rel_dir?(location)} do
        {true, _} -> prepare; build; start
        {false, hot?} ->
          build
          Code.ensure_loaded?(Ecto) && update_db
          hot? && hot_upgrade || cold_upgrade
      end
    end

    defp prepare, do: _prepare(location)
    defp build, do: _build(location)

    defp _prepare(:local) do
      ssh "mkdir -p #{name}/run"
    end

    defp _prepare(:remote) do
      ssh "git clone #{repo} #{name}"
      ssh "mkdir #{name}/priv/static"
      ssh "mkdir #{name}/run"
    end

    defp _build(:local) do
      Mix.Task.run "compile"
      Mix.Shell.IO.cmd "npm install"
      Mix.Shell.IO.cmd "node_modules/brunch/bin/brunch build --production"
      Mix.Task.run "phoenix.digest", []
      Mix.Task.run "release", []
    end

    defp _build(:remote) do
      ssh "cd #{name} && git pull"
      scp "config/prod.secret.exs", "#{name}/config/prod.secret.exs"
      ssh "cd #{name} && MIX_ENV=#{Mix.env} mix deps.get"
      ssh "cd #{name} && MIX_ENV=#{Mix.env} mix compile"
      ssh "cd #{name} && npm install"
      ssh "cd #{name} && node_modules/brunch/bin/brunch build --production"
      ssh "cd #{name} && MIX_ENV=#{Mix.env} mix phoenix.digest"
      ssh "cd #{name} && MIX_ENV=#{Mix.env} mix release"
    end

    defp start do
      case location do
        :local ->
          if Code.ensure_loaded?(Ecto) do
            Mix.Task.run "ecto.create", []
            Mix.Task.run "ecto.migrate", []
            Mix.Task.run "run", ["priv/repo/seeds.exs"]
          end
          scp "rel/#{name}/releases/#{version}/#{name}.tar.gz", "#{name}/run/#{name}.tar.gz"
        :remote ->
          if Code.ensure_loaded?(Ecto), do: ssh "cd #{name} && MIX_ENV=#{Mix.env} mix do ecto.create, ecto.migrate, run priv/repo/seeds.exs"
          ssh "cp #{name}/rel/#{name}/releases/#{version}/#{name}.tar.gz #{name}/run"
      end
      ssh "cd #{name}/run && tar xf #{name}.tar.gz && rm #{name}.tar.gz"
      _run("start")
    end

    defp update_db do
      case location do
        :local -> Mix.Task.run "ecto.migrate", []
        :remote -> ssh "cd #{name} && MIX_ENV=#{Mix.env} mix ecto.migrate"
      end
    end

    defp hot_upgrade do
      case location do
        :local ->
          ssh "mkdir #{name}/releases/#{version}"
          scp "rel/#{name}/releases/#{version}/#{name}.tar.gz", "#{name}/releases/#{version}/#{name}.tar.gz"
        :remote ->
          ssh "mkdir #{name}/run/releases/#{version}"
          ssh "cp #{name}/rel/#{name}/releases/#{version}/#{name}.tar.gz #{name}/run/releases/#{version}/"
          scp "config/prod.secret.exs", "#{name}/config/prod.secret.exs"
      end
       _run("upgrade '#{version}'")
    end

    defp cold_upgrade do
      case location do
        :local -> scp "rel/#{name}/releases/#{version}/#{name}.tar.gz", "#{name}/run/#{name}.tar.gz"
        :remote -> ssh "cp #{name}/rel/#{name}/releases/#{version}/#{name}.tar.gz #{name}/run"
      end
      ssh "cd #{name}/run && tar xf #{name}.tar.gz && rm #{name}.tar.gz"
      _run("stop")
      _run("start")
    end

    defp _run(command), do: ssh("#{name}/run/bin/#{name} #{command}")

    defp initial_deploy?, do: ssh("ls #{name} &>/dev/null") != 0
    defp rel_dir?(:remote), do: ssh("ls #{name}/rel/* %>/dev/null") == 0
    defp rel_dir?(:local), do: Mix.Shell.IO.cmd("ls #{name}/rel/* %>/dev/null") == 0

    # ssh helpers
    defp ssh_options, do: "-i#{key} -oStrictHostKeyChecking=no"
    defp ssh(command), do: Mix.Shell.IO.cmd "ssh #{user}@#{host} #{ssh_options} '#{command}'"
    defp scp(source, destination), do: Mix.Shell.IO.cmd "scp #{ssh_options} #{source} #{user}@#{host}:#{destination}"

    # config helpers
    defp location, do: Application.get_env(:mandrag, :build_location)
    defp user, do: Application.get_env(:mandrag, :user)
    defp host, do: Application.get_env(:mandrag, :host)
    defp key, do: Application.get_env(:mandrag, :key)
    defp name, do: Application.get_env(:mandrag, :name)
    defp version, do: Application.get_env(:mandrag, :version)
    defp repo, do: Application.get_env(:mandrag, :repo)
  end
end