// pattern_util_box.hako — Shared utilities for MirBuilder lowers

using selfhost.shared.json.utils.json_frag as JsonFragBox
using selfhost.shared.common.string_helpers as StringHelpers

static box PatternUtilBox {
  map_cmp(sym) { if sym=="<" {return "Lt"} if sym==">" {return "Gt"} if sym=="<=" {return "Le"} if sym==">=" {return "Ge"} if sym=="==" {return "Eq"} if sym=="!=" {return "Ne"} return null }
  // Normalize limit for canonical (i < limit) form.
  // When swapped==0, expects op in {'<','<='}; when swapped==1 (Int on lhs, Var on rhs), expects op in {'>','>='}.
  // Returns adjusted limit string or null if unsupported.
  normalize_limit_for_lt(op, swapped, limit_str) {
    local op1 = "" + op
    local ls = "" + limit_str
    if swapped == 0 {
      if op1 == "<" { return ls }
      if op1 == "<=" { return StringHelpers.int_to_str(JsonFragBox._str_to_int(ls) + 1) }
      if op1 == "!=" { return ls } // safe for count(init=0,step=1)
      return null
    } else {
      if op1 == ">" { return ls }
      if op1 == ">=" { return StringHelpers.int_to_str(JsonFragBox._str_to_int(ls) + 1) }
      return null
    }
  }
  find_local_int_before(s, name, before_pos) {
    local pos=0; local last=-1
    loop(true){ local k=JsonFragBox.index_of_from(s, "\"type\":\"Local\"",pos); if k<0||k>=before_pos{break}; local kn=JsonFragBox.index_of_from(s, "\"name\":\"",k); if kn>=0{ local ii=kn+8; local nn=s.length(); local jj=ii; loop(jj<nn){ if s.substring(jj,jj+1)=="\"" {break} jj=jj+1 } if s.substring(ii,jj)==name { last=k } } pos=k+1 }
    if last<0 { return null }
    local ki=s.indexOf("\"type\":\"Int\"",last); if ki<0||ki>=before_pos { return null }
    local kv=s.indexOf("\"value\":",ki); if kv<0 { return null }
    return JsonFragBox.read_int_after(s, kv+8)
  }
  find_local_bool_before(s, name, before_pos) {
    local pos=0; local last=-1
    loop(true){ local k=JsonFragBox.index_of_from(s, "\"type\":\"Local\"",pos); if k<0||k>=before_pos{break}; local kn=JsonFragBox.index_of_from(s, "\"name\":\"",k); if kn>=0{ local ii=kn+8; local nn=s.length(); local jj=ii; loop(jj<nn){ if s.substring(jj,jj+1)=="\"" {break} jj=jj+1 } if s.substring(ii,jj)==name { last=k } } pos=k+1 }
    if last<0 { return null }
    local kb=s.indexOf("\"type\":\"Bool\"",last); if kb<0||kb>=before_pos { return null }
    local kv=s.indexOf("\"value\":",kb); if kv<0 { return null }
    return JsonFragBox.read_bool_after(s, kv+8)
  }
}