Claudio Ortolina
83 lines
2.1 KiB
Elixir
83 lines
2.1 KiB
Elixir
defmodule MusicLibraryWeb.AssetController do
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use MusicLibraryWeb, :controller
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alias MusicLibrary.Assets
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alias MusicLibrary.Assets.{Cache, Image, Transform}
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# 1 year in seconds
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@cache_duration 60 * 60 * 24 * 365
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def show(conn, %{"transform_payload" => payload}) do
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format = pick_format(conn)
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transform = Transform.decode!(payload)
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case cached_get(payload, transform, format) do
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nil ->
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not_found(conn)
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content when is_binary(content) ->
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case get_req_header(conn, "if-none-match") do
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[^payload] -> extend_cache(conn)
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_ -> respond_with_cache(conn, content, format, payload)
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end
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end
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end
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defp cached_get(payload, transform, format) do
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case Cache.get(payload, format) do
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:not_found ->
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if asset = Assets.get(transform.hash) do
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image_data =
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if transform.width do
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# TODO: find a way to cache computation, or pre-compute thumb and store it
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{:ok, data} = Image.resize(asset.content, transform.width, format)
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data
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else
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{:ok, data} = Image.convert(asset.content, asset.format, format)
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data
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end
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Cache.set(payload, format, image_data)
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image_data
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end
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{:found, content} ->
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content
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end
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end
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defp pick_format(conn) do
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accept =
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case get_req_header(conn, "accept") do
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[] -> ""
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[value] -> value
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end
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if String.contains?(accept, "image/webp") do
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"image/webp"
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else
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"image/jpeg"
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end
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end
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defp not_found(conn) do
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conn
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|> put_status(:not_found)
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|> text("Not found")
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end
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defp extend_cache(conn) do
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conn
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|> put_resp_header("cache-control", "public, max-age=#{@cache_duration}")
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|> send_resp(304, "")
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end
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defp respond_with_cache(conn, data, format, etag) do
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conn
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|> put_resp_content_type(format, "utf-8")
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|> put_resp_header("cache-control", "public, max-age=#{@cache_duration}")
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|> put_resp_header("etag", etag)
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|> send_resp(200, data)
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end
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end
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