bones73k/lib/bones73k_web/views/pagination.ex

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Elixir
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defmodule Bones73kWeb.Pagination do
def generate_page_list(_, total_pages) when total_pages < 5,
do: 1..total_pages |> Enum.to_list()
def generate_page_list(current, total_pages),
do: first_half(1, current) ++ [current] ++ second_half(current, total_pages)
defp first_half(first, current) do
prev = current - 1
cond do
first == current -> []
prev <= first -> [first]
prev - first > 2 -> [first, -1, prev]
true -> first..prev |> Enum.to_list()
end
end
defp second_half(current, last) do
next = current + 1
cond do
last == current -> []
next >= last -> [last]
last - next > 2 -> [next, -1, last]
true -> next..last |> Enum.to_list()
end
end
end