type pseudo = [ `Hover | `Focus | `Focus_within | `Focus_visible | `Active | `Visited | `Target 
  | `Disabled | `Enabled | `Checked | `Indeterminate | `Default | `Required | `Valid | `Invalid
  | `In_range | `Out_of_range | `Placeholder_shown | `Autofill | `Read_only ]

type pseudo_element = [ `Before | `After | `First_line | `First_letter | `Marker | `Selection | `File | `Backdrop | `Placeholder ]

type structural = [ `First | `Last | `Only | `Odd | `Even | `First_of_type | `Last_of_type | `Only_of_type | `Empty | `Root | `Nth of int | `Nth_last of int ]

type group = [ `Group of pseudo | `Peer of pseudo ]

type special = [ `Not of pseudo | `Has of string | `Where of string | `Is of string | `Starting_style | `Inert | `Open | `In of string ]

type t = [
  | `Pseudo of pseudo * Css.t
  | `Pseudo_element of pseudo_element * Css.t
  | `Structural of structural * Css.t
  | `Group of group * Css.t
  | `Special of special * Css.t
]

let pseudo_to_string = function
  | `Hover -> "hover"
  | `Focus -> "focus"
  | `Focus_within -> "focus-within"
  | `Focus_visible -> "focus-visible"
  | `Active -> "active"
  | `Visited -> "visited"
  | `Target -> "target"
  | `Disabled -> "disabled"
  | `Enabled -> "enabled"
  | `Checked -> "checked"
  | `Indeterminate -> "indeterminate"
  | `Default -> "default"
  | `Required -> "required"
  | `Valid -> "valid"
  | `Invalid -> "invalid"
  | `In_range -> "in-range"
  | `Out_of_range -> "out-of-range"
  | `Placeholder_shown -> "placeholder-shown"
  | `Autofill -> "autofill"
  | `Read_only -> "read-only"

let to_class = function
  | `Pseudo (pseudo, classes) -> 
    let prefix = pseudo_to_string pseudo in
    Css.make (prefix ^ ":" ^ Css.to_string classes)
  | `Pseudo_element (`Before, classes) -> Css.make ("before:" ^ Css.to_string classes)
  | `Pseudo_element (`After, classes) -> Css.make ("after:" ^ Css.to_string classes)
  | `Pseudo_element (`First_line, classes) -> Css.make ("first-line:" ^ Css.to_string classes)
  | `Pseudo_element (`First_letter, classes) -> Css.make ("first-letter:" ^ Css.to_string classes)
  | `Pseudo_element (`Marker, classes) -> Css.make ("marker:" ^ Css.to_string classes)
  | `Pseudo_element (`Selection, classes) -> Css.make ("selection:" ^ Css.to_string classes)
  | `Pseudo_element (`File, classes) -> Css.make ("file:" ^ Css.to_string classes)
  | `Pseudo_element (`Backdrop, classes) -> Css.make ("backdrop:" ^ Css.to_string classes)
  | `Pseudo_element (`Placeholder, classes) -> Css.make ("placeholder:" ^ Css.to_string classes)
  | `Structural (`First, classes) -> Css.make ("first:" ^ Css.to_string classes)
  | `Structural (`Last, classes) -> Css.make ("last:" ^ Css.to_string classes)
  | `Structural (`Only, classes) -> Css.make ("only:" ^ Css.to_string classes)
  | `Structural (`Odd, classes) -> Css.make ("odd:" ^ Css.to_string classes)
  | `Structural (`Even, classes) -> Css.make ("even:" ^ Css.to_string classes)
  | `Structural (`First_of_type, classes) -> Css.make ("first-of-type:" ^ Css.to_string classes)
  | `Structural (`Last_of_type, classes) -> Css.make ("last-of-type:" ^ Css.to_string classes)
  | `Structural (`Only_of_type, classes) -> Css.make ("only-of-type:" ^ Css.to_string classes)
  | `Structural (`Empty, classes) -> Css.make ("empty:" ^ Css.to_string classes)
  | `Structural (`Root, classes) -> Css.make ("root:" ^ Css.to_string classes)
  | `Structural (`Nth n, classes) -> Css.make (Printf.sprintf "nth-child(%d):" n ^ Css.to_string classes)
  | `Structural (`Nth_last n, classes) -> Css.make (Printf.sprintf "nth-last-child(%d):" n ^ Css.to_string classes)
  | `Group (`Group pseudo, classes) -> 
    let prefix = pseudo_to_string pseudo in
    Css.make ("group-" ^ prefix ^ ":" ^ Css.to_string classes)
  | `Group (`Peer pseudo, classes) -> 
    let prefix = pseudo_to_string pseudo in
    Css.make ("peer-" ^ prefix ^ ":" ^ Css.to_string classes)
  | `Special (`Not pseudo, classes) -> 
    let prefix = pseudo_to_string pseudo in
    Css.make ("not-" ^ prefix ^ ":" ^ Css.to_string classes)
  | `Special (`Has selector, classes) -> Css.make ("has-[" ^ selector ^ "]:" ^ Css.to_string classes)
  | `Special (`Where selector, classes) -> Css.make ("where-[" ^ selector ^ "]:" ^ Css.to_string classes)
  | `Special (`Is selector, classes) -> Css.make ("is-[" ^ selector ^ "]:" ^ Css.to_string classes)
  | `Special (`Starting_style, classes) -> Css.make ("@starting-style:" ^ Css.to_string classes)
  | `Special (`Inert, classes) -> Css.make ("inert:" ^ Css.to_string classes)
  | `Special (`Open, classes) -> Css.make ("open:" ^ Css.to_string classes)
  | `Special (`In variant, classes) -> Css.make ("in-" ^ variant ^ ":" ^ Css.to_string classes)

let pseudo p classes = `Pseudo (p, classes)
let pseudo_element pe classes = `Pseudo_element (pe, classes)
let structural s classes = `Structural (s, classes)
let group g classes = `Group (g, classes)
let special s classes = `Special (s, classes)

let apply variant_t classes =
  Css.combine (to_class variant_t) classes

let hover classes = Css.make ("hover:" ^ Css.to_string classes)
let focus classes = Css.make ("focus:" ^ Css.to_string classes)
let active classes = Css.make ("active:" ^ Css.to_string classes)
let disabled classes = Css.make ("disabled:" ^ Css.to_string classes)
let first classes = Css.make ("first:" ^ Css.to_string classes)
let last classes = Css.make ("last:" ^ Css.to_string classes)
let odd classes = Css.make ("odd:" ^ Css.to_string classes)
let even classes = Css.make ("even:" ^ Css.to_string classes)
let starting_style classes = Css.make ("@starting-style:" ^ Css.to_string classes)