142 lines
4.0 KiB
Elixir
142 lines
4.0 KiB
Elixir
defmodule Frenzy.Pipeline.FilterEngine do
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def validate_filter(filter) when is_map(filter) do
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cond do
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not is_map(filter) ->
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{:error, "filter must be a map"}
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not (Map.has_key?(filter, "mode") and is_binary(filter["mode"]) and
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filter["mode"] in ["accept", "reject"]) ->
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{:error, "mode must be a string, either 'accept' or 'reject'"}
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not (Map.has_key?(filter, "score") and is_integer(filter["score"])) ->
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{:error, "score must be an integer"}
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not (Map.has_key?(filter, "rules") and is_list(filter["rules"])) ->
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{:error, "rules must be a list of rules"}
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true ->
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validate_rules(filter)
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end
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end
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def validate_rules(%{"rules" => rules} = filter) do
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case validate_rules(rules) do
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{:ok, rules} ->
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{:ok, Map.put(filter, "rules", rules)}
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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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def validate_rules(rules) when is_list(rules) do
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rules
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|> Enum.with_index()
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|> Enum.reduce_while({:ok, []}, fn {rule, index}, {:ok, new_rules} ->
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case validate_rule(rule) do
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{:ok, rule} ->
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{:cont, {:ok, [rule | new_rules]}}
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{:error, reason} ->
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{:halt, {:error, "invalid rule #{index}: #{reason}"}}
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end
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end)
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end
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def validate_rules(_rules), do: {:error, "rules must be a list"}
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@rule_modes ~W[contains_string contains_string_case_sensitive matches_regex]
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@rule_properties ~W[url title author content]
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def validate_rule(rule) do
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cond do
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not is_map(rule) ->
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{:error, "rule must be a map"}
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not (Map.has_key?(rule, "mode") and is_binary(rule["mode"]) and
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rule["mode"] in @rule_modes) ->
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rule_modes_text = Enum.map_join(@rule_modes, ", ", &"'#{&1}'")
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{:error, "mode property must be a string, one of #{rule_modes_text}"}
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not (Map.has_key?(rule, "property") and is_binary(rule["property"]) and
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rule["property"] in @rule_properties) ->
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rule_props_text = Enum.map_join(@rule_properties, ", ", &"'#{&1}'")
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{:error, "property property must be a string, one of #{rule_props_text}"}
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not (Map.has_key?(rule, "param") and is_binary(rule["param"])) ->
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{:error, "param property must be a string"}
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not (Map.has_key?(rule, "weight") and is_integer(rule["weight"])) ->
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{:error, "weight property must be an integer"}
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true ->
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{:ok, rule}
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end
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end
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def test(%{"mode" => mode, "score" => score, "rules" => rules}, item_params) do
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item_score =
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rules
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|> Enum.filter(&test_rule(&1, item_params))
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|> Enum.map(& &1["weight"])
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|> Enum.sum()
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matches = item_score >= score
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case {mode, matches} do
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{"accept", true} ->
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true
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{"reject", false} ->
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true
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_ ->
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false
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end
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end
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def test_rule(
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%{"mode" => mode, "property" => property, "param" => param},
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item_params
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) do
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with prop_value <- get_property(item_params, property),
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true <- is_binary(prop_value),
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true <- matches(prop_value, mode, param) do
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true
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else
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_ ->
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false
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end
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end
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defp matches(value, "contains_string", param) do
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String.contains?(String.downcase(value), String.downcase(param))
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end
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defp matches(value, "contains_string_case_sensitive", param) do
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String.contains?(value, param)
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end
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defp matches(value, "matches_regex", param) do
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{:ok, regex} = Regex.compile(param, "i")
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String.match?(value, regex)
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end
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defp get_property(item_params, "url"), do: item_params.url
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defp get_property(item_params, "title"), do: item_params.title
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defp get_property(item_params, "author"), do: item_params.author
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defp get_property(%{content: content, content_type: type}, "content")
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when type in ["text/plain", "text/gemini"],
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do: content
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defp get_property(%{content: content, content_type: "text/html"}, "content") do
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content
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|> Floki.parse()
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|> Floki.text()
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end
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defp get_property(_item_params, _property), do: {:error, "invalid property"}
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end
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