97 lines
2.3 KiB
Elixir
97 lines
2.3 KiB
Elixir
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defmodule TodoServer do
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use GenServer
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def start do
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GenServer.start(__MODULE__, nil)
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end
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def add_entry(pid, entry) do
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GenServer.cast(pid, {:add_entry, entry})
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end
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def delete_entry(pid, entry_id) do
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GenServer.cast(pid, {:delete_entry, entry_id})
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end
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def update_entry(pid, entry_id, updater_fun) do
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GenServer.cast(pid, {:update_entry, entry_id, updater_fun})
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end
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def entries(pid, date) do
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GenServer.call(pid, {:entries, date})
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end
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@impl true
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def init(_) do
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{:ok, TodoList.new()}
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end
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@impl true
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def handle_cast({:add_entry, entry}, state) do
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{:noreply, TodoList.add_entry(state, entry)}
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end
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@impl true
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def handle_cast({:delete_entry, entry_id}, state) do
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{:noreply, TodoList.delete_entry(state, entry_id)}
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end
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@impl true
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def handle_cast({:update_entry, entry_id, updater_fun}, state) do
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{:noreply, TodoList.update_entry(state, entry_id, updater_fun)}
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end
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@impl true
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def handle_call({:entries, date}, _, state) do
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{:reply, TodoList.entries(state, date), state}
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end
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end
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defmodule TodoList do
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defstruct auto_id: 1, entries: %{}
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def new(), do: %TodoList{}
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def add_entry(todo_list, entry) do
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entry = Map.put(entry, :id, todo_list.auto_id)
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new_entries =
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Map.put(
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todo_list.entries,
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todo_list.auto_id,
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entry
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)
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%TodoList{todo_list | entries: new_entries, auto_id: todo_list.auto_id + 1}
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end
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def entries(todo_list, date) do
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todo_list.entries
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|> Stream.filter(fn {_, entry} -> entry.date == date end)
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|> Enum.map(fn {_, entry} -> entry end)
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end
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def update_entry(todo_list, %{} = new_entry) do
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update_entry(todo_list, new_entry.id, fn _ -> new_entry end)
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end
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def update_entry(todo_list, entry_id, updater_fun) do
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case Map.fetch(todo_list.entries, entry_id) do
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:error ->
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todo_list
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{:ok, old_entry} ->
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old_entry_id = old_entry.id
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# Make sure that the result of the updater is a map and the
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# id remains unchanged.
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new_entry = %{id: ^old_entry_id} = updater_fun.(old_entry)
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new_entries = Map.put(todo_list.entries, new_entry.id, new_entry)
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%TodoList{todo_list | entries: new_entries}
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end
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end
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def delete_entry(todo_list, entry_id) do
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%TodoList{todo_list | entries: Map.delete(todo_list.entries, entry_id)}
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end
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end
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