style_base.typ

#import "types.typ": *

#let _ex_style(name, elem, styler, pred) = {
  let ex_style = (elem, makeup) => {
    let style = if t_check(TMakeup, makeup) {
      makeup.style 
    } else {
      makeup
    }
    if type(style) == "string" {
      panic(sytle)
    }
    if name != none and name in style {
      styler(elem, style)
    } else {
      panic("missing '" + name + "' in style definition")
    }
  }
  let precedence = makeup => {
    let style = if t_check(TMakeup, makeup) {
      makeup.style 
    } else {
      makeup
    }
    if name != none and name in style {
      pred(style)
    } else {
      panic("missing '" + name + "' in style definition")
    }
  }
  let style = (fn: ex_style, precedence: precedence)
  if t_check(TElem, elem) {
    elem.styles.push(style)
    elem
  } else if type(elem) == "array" {
    elem.flatten().map(e => if t_check(TElem, e) { 
      e.styles.push(style)
      e
    } else {
      (value: e, styles: (style,))
    })
  } else {
    (value: elem, styles: (style,))
  }
}

#let _choose_styler(style, names, def_fmt, style_name) = {
  let s = style
  let style_stack = ()
  for name in names {
    if name in s {
      s = s.at(name)
      style_stack.push(s)
    } else {
      break
    }
  }
  while style_stack.len() > 0 {
    let style = style_stack.pop()
    if style_name in style {
      return style.at(style_name)
    }
  }
  def_fmt
}

#let elem(value, ..names, style: none, style_name: "style") = _ex_style(
  names.pos().at(0),
  value,
  (elem, _style) => {
    let default_styler = if style != none { style } else { i=>repr(i) }
    let styler = _choose_styler(_style, names.pos(), default_styler, style_name)
    styler(elem)
  },
  style => _choose_styler(style, names.pos(), 0, "precedence")
)

#let eval_line(elem, makeup) = elem.flatten().map(e =>
  if t_check(TElem, e) {
    if e.styles.len() == 0 {
      e.value
    } else {
      let first_style = e.styles.at(0)
      let ex_prec = first_style.precedence
      let acc = (fn: first_style.fn, prec: ex_prec(makeup))
      let chosen_style = e.styles.slice(1).fold(acc, (acc, style_def) => {
        let ex_precedence = style_def.precedence
        let precedence = ex_precedence(makeup)
        if precedence > acc.prec {
          (fn: style_def.fn, prec: precedence)
        } else {
          acc
        }
      })
      let styler = chosen_style.fn
      if t_check(TGroupStart, e.value) {
        (start_style: v => styler(v, makeup.style), ..e.value)
      } else if t_check(TGroupEnd, e.value) {
        (end_style: v => styler(v, makeup.style), ..e.value)
      } else {
        styler(e.value, makeup)
      }
    }
  } else {
    e
  }
)


#let sp = " "
#let join(elems, sep) = if elems.len() == 0 {()} else if elems.len() == 1 { elems.at(0) } else { range(elems.len()*2-1).map(i => if calc.even(i) {elems.at(int(i/2))} else {sep}) }
#let ge = (value: (group: none), styles: ())
#let gs(fn, use_start: false, use_end: false) = (value: (group: fn, use_start: use_start, use_end: use_end), styles: ())

#let pipe(..fns) = s => {
  let _s = s

  for fn in fns.pos() {
    let r = fn(_s)
    // first element, if successful, second the value
    if type(r) == "array" {
      // if successful, stop otherwise continue
      if r.at(0) {
        return r.at(1)
      }
    } else {
      _s = r
    }
  }
  _s
}
#let _if(cond, ..fns) = s => {
  if cond(s) {
    let p = pipe(..fns)
    p(s)
  } else {
    s
  }
}

#let _if_else(cond, ..fns) = s => {
  if cond(s) {
    let p = pipe(..fns)
    (true, p(s))
  } else {
    (false, none)
  }
}

#let if_string(..fns) = _if(s => type(s) == "string", ..fns)
#let if_number(..fns) = _if(s => type(s) == "integer" or type(s) == "float", ..fns)
#let if_string_else(..fns) = _if_else(s => type(s) == "string", ..fns)
#let if_number_else(..fns) = _if_else(s => type(s) == "integer" or type(s) == "float", ..fns)