132 lines
3.5 KiB
Elixir
132 lines
3.5 KiB
Elixir
defmodule Frenzy.Task.FetchFavicon do
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require Logger
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use Task
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alias Frenzy.{HTTP, Repo, Feed}
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def start_link(feed) do
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Task.start_link(__MODULE__, :run, [feed])
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end
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def run(feed) do
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Logger.metadata(favicon_task_id: generate_task_id())
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site_url =
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case feed.site_url do
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url when is_binary(url) ->
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url
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_ ->
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%URI{URI.parse(feed.feed_url) | path: nil, query: nil, fragment: nil} |> URI.to_string()
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end
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Logger.debug("Fetching favicon for #{site_url}")
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case fetch_favicon_from_webpage(site_url) do
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{:ok, favicon_data} ->
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changeset = Feed.changeset(feed, %{favicon: favicon_data})
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{:ok, _feed} = Repo.update(changeset)
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{:error, reason} ->
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Logger.info("Couldn't fetch favicon for #{site_url}: #{reason}")
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favicon_uri =
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%{URI.parse(site_url) | path: "/favicon.ico", query: nil, fragment: nil}
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|> URI.to_string()
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Logger.info("Trying default path: #{favicon_uri}")
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case fetch_favicon_data(favicon_uri, site_url) do
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{:ok, favicon_data} ->
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changeset = Feed.changeset(feed, %{favicon: favicon_data})
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{:ok, _feed} = Repo.update(changeset)
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{:error, reason} ->
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Logger.info("Couldn't fetch default /favicon.ico for #{site_url}: #{reason}")
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end
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end
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end
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defp fetch_favicon_from_webpage(url) when is_binary(url) do
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case HTTP.get(url) do
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{:ok, %HTTPoison.Response{body: body}} ->
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extract_favicon(url, body)
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{:error, _reason} = err ->
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err
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end
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end
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defp fetch_favicon_from_webpage(_), do: {:error, "URL must be a string"}
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defp extract_favicon(page_url, body) do
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html_tree = Floki.parse(body)
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case Floki.find(html_tree, "link[rel=icon]") do
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[] ->
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{:error, "No element matching link[rel=icon]"}
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links ->
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links
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|> Enum.find(fn link ->
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link
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|> Floki.attribute("type")
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|> Enum.map(&String.downcase/1)
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|> Enum.any?(&(&1 == "image/png"))
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|> case do
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false ->
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link
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|> Floki.attribute("href")
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# bad hack for missing type attr
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|> Enum.any?(&String.contains?(&1, ".png"))
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true ->
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true
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end
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# todo: support more image types
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end)
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|> case do
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nil ->
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{:error, "No link[rel=icon] with type of image/png"}
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# todo: try requesting /favicon.ico
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link ->
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link
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|> Floki.attribute("href")
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|> List.first()
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|> fetch_favicon_data(page_url)
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end
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end
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end
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defp fetch_favicon_data(favicon_url, site_url) when is_binary(favicon_url) do
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# handle relative URIs, set default scheme if not provided
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absolute_url =
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favicon_url
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|> URI.parse()
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|> HTTP.resolve_uri(URI.parse(site_url))
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case HTTP.get(absolute_url) do
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{:ok, %HTTPoison.Response{body: body}} ->
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{:ok, "data:image/png;base64,#{Base.encode64(body)}"}
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{:error, _reason} = err ->
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err
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end
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end
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defp fetch_favicon_data(_, _), do: {:error, "No or invalid href for link"}
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# from https://github.com/elixir-plug/plug/blob/v1.8.3/lib/plug/request_id.ex#L60
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defp generate_task_id() do
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binary = <<
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System.system_time(:nanosecond)::64,
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:erlang.phash2({node(), self()}, 16_777_216)::24,
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:erlang.unique_integer()::32
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>>
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Base.url_encode64(binary)
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end
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end
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