# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: 2025 DBVisor

defmodule Mix.Tasks.Sql.Create do
  use Mix.Task
  @moduledoc since: "0.5.0"

  @opts [strict: [pool: [:string, :keep], quiet: :boolean], aliases: [p: :pool, q: :quiet]]

  @shortdoc "Create a database for each pool"
  def run(args) do
    {opts, _} = OptionParser.parse!(args, @opts)
    app = Mix.Project.config()[:app]
    Application.load(app)
    Mix.Task.run("app.config", args)
    pools = Application.get_env(:sql, :pools)
    only = opts |> Keyword.take([:pool]) |> Keyword.values |> Enum.map(&String.to_atom/1)
    pools = if only != [] do
              Enum.reject(pools, &elem(&1, 0) in only)
            else
              pools
            end
    for {name, config} <- pools do
      state = struct(SQL.Pool, [{:name, name}|config])
      {:ok, pid} = state.adapter.start(maintiance(state))
      Process.put(SQL.Conn, pid)
      execute(opts, state)
      Process.exit(pid, :normal)
    end
  end

  defp maintiance(%{adapter: SQL.Adapters.Postgres}=state) do
    state
    |> Map.put(:database, "postgres")
    |> Map.put_new(:encoding, "UTF8")
  end

  defp create(%{adapter: SQL.Adapters.Postgres, database: database}=state) do
    Enum.reduce(~w[encoding template lc_ctype lc_collate lc_time timezone]a, "create database #{database}", fn key, acc ->
      right = Map.get(state, key)
      left = String.upcase("#{key}")
      case is_binary(right) do
        false -> acc
        true when key == :template -> <<acc::binary, ?\s, left::binary, ?=, right::binary>>
        true when key == :timezone -> <<acc::binary, ?\s, left::binary, right::binary>>
        true -> <<acc::binary, ?\s, left::binary, ?=, ?', right::binary, ?'>>
      end
    end)
  end

  defp execute(opts, %{adapter: SQL.Adapters.Postgres, name: name, database: database}=state) do
    case Enum.to_list(SQL.parse("select count(*)::int4 from pg_database where datname::text = '#{database}'")) do
      [[0]] ->
        try do
          [] = Enum.to_list(SQL.parse(create(state)))
          if !opts[:quit], do: Mix.shell().info("The database for #{name} has been created")
        catch
          e ->
          Mix.raise("The database for #{name} couldn't be created: #{e.message}")
        end
      [[1]] ->
        if !opts[:quit], do: Mix.shell().info("The database for #{name} has already been created")
    end
  end
end