Filters a list of Blogit.Models.Post structs using a map of meta fields to filter by and/or search query to match to their contents and/or titles.

The params parameter supports zero or more of the following keys:

• "author" - Used to filter Blogit.Models.Post structs by their .meta.author field.
• "category" - Used to filter Blogit.Models.Post structs by their .meta.category field.
• "tags" - Used to filter Blogit.Models.Post structs by their .meta.tags field. The value for this key should a string of comma separated tags.
• "year" - Used to filter Blogit.Models.Post by their .meta.year field.
• "month" - Used to filter Blogit.Models.Post by their .meta.month field.
• "q" - A query to filter Blogit.Models.Post structs by their content or title. Support text in double quotes in order to search for phrases.

If the map contains other keys, they'll be ignored.

Examples

iex> alias Blogit.Models.Post.Meta
iex> posts = [
...>   %Blogit.Models.Post{
...>     name: "one", raw: "", html: "",
...>     meta: %Meta{author: "meddle", category: "Primary"}
...>   },
...>   %Blogit.Models.Post{
...>     name: "two", raw: "", html: "",
...>     meta: %Meta{author: "valo", category: "Secondary"}
...>   },
...>   %Blogit.Models.Post{
...>     name: "three", raw: "", html: "",
...>     meta: %Meta{author: "Reductions", category: "Other"}
...>   },
...>   %Blogit.Models.Post{
...>     name: "four", raw: "", html: "",
...>     meta: %Meta{author: "meddle", category: "Other"}
...>   }
...> ]
iex> filter = %{"author" => "meddle"}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
["one", "four"]
iex> filter = %{"category" => "Other"}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
["three", "four"]

iex> alias Blogit.Models.Post.Meta
iex> posts = [
...>   %Blogit.Models.Post{
...>     name: "one", raw: "", html: "",
...>     meta: %Meta{tags: ["one", "едно", "super"]}
...>   },
...>   %Blogit.Models.Post{
...>     name: "two", raw: "", html: "",
...>     meta: %Meta{tags: ["two", "две", "super"]}
...>   }
...> ]
iex> filter = %{"tags" => "super, one"}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
["one"]

iex> alias Blogit.Models.Post.Meta
iex> posts = [
...>   %Blogit.Models.Post{
...>     name: "one", raw: "", html: "",
...>     meta: %Meta{year: "2017", month: "4"}
...>   },
...>   %Blogit.Models.Post{
...>     name: "two", raw: "", html: "",
...>     meta: %Meta{year: "2016", month: "4"}
...>   },
...>   %Blogit.Models.Post{
...>     name: "three", raw: "", html: "",
...>     meta: %Meta{year: "2017", month: "3"}
...>   }
...> ]
iex> filter = %{"year" => "2017"}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
["one", "three"]
iex> filter = %{"month" => "4"}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
["one", "two"]
iex> filter = %{"month" => "4", "year" => "2017"}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
["one"]

iex> alias Blogit.Models.Post.Meta
iex> posts = [
...>   %Blogit.Models.Post{
...>     name: "one", raw: "Something about Processes - stuff", html: "",
...>     meta: %Meta{author: "meddle", title: "Processes"}
...>   },
...>   %Blogit.Models.Post{
...>     name: "two", raw: "Modules contain functions!", html: "",
...>     meta: %Meta{author: "valo", title: "Modules And Functions"}
...>   },
...>   %Blogit.Models.Post{
...>     name: "three", raw: "Mix is one of the coolest things", html: "",
...>     meta: %Meta{author: "Reductions", title: "Mix And Tests"}
...>   },
...>   %Blogit.Models.Post{
...>     name: "four", raw: "Linked things make difference", html: "",
...>     meta: %Meta{author: "meddle", title: "Processes And Links"}
...>   }
...> ]
iex> filter = %{"q" => "Process"}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
["one", "four"]
iex> filter = %{"q" => "Tests"}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
["three"]
iex> filter = %{"q" => ~s("coolest things")}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
["three"]
iex> filter = %{"q" => ~s("coolest things"), "author" => "meddle"}
iex> filtered = Blogit.Logic.Search.filter_by_params(posts, filter)
iex> filtered |> Enum.map(fn (post) -> post.name end)
[]