// loop_normalize_macro.nyash
// MVP: identity expansion with (json, ctx) signature.
// Next steps: normalize `loop(cond){ body }` into carrier-based LoopForm.

static box MacroBoxSpec {
  static function name() { return "LoopNormalize" }

  static function expand(json, ctx) {
    // MVP normalizer: detect Loop nodes with canonical key order
    // "kind":"Loop","condition":<json>,"body":[ ... ] and rewrite them
    // into a normalized form using JsonBuilder (keys ordered as condition/body).

    local JB = include "apps/lib/json_builder.nyash"

    // helpers
    local s = json
    local out = ""
    local i = 0

    // parse a JSON string starting at i (supports objects, arrays, strings, numbers, true/false/null)
    function parse_value(s, i) {
      local n = s.length()
      if i >= n { return ["", i] }
      local ch = s.substring(i, i+1)
      // string
      if ch == "\"" {
        local j = i + 1
        loop(j < n) {
          local c = s.substring(j, j+1)
          if c == "\\" { j = j + 2; continue }
          if c == "\"" { j = j + 1; break }
          j = j + 1
        }
        return [s.substring(i, j), j]
      }
      // object
      if ch == "{" {
        local depth = 1
        local j = i + 1
        local in_str = false
        loop(j < n && depth > 0) {
          local c = s.substring(j, j+1)
          if c == "\"" {
            // toggle string (respect escape)
            local k = j - 1
            local esc = false
            if k >= 0 && s.substring(k, k+1) == "\\" { esc = true }
            if !esc { in_str = !in_str }
            j = j + 1
            continue
          }
          if !in_str {
            if c == "{" { depth = depth + 1 }
            else if c == "}" { depth = depth - 1 }
          }
          j = j + 1
        }
        return [s.substring(i, j), j]
      }
      // array
      if ch == "[" {
        local depth = 1
        local j = i + 1
        local in_str = false
        loop(j < n && depth > 0) {
          local c = s.substring(j, j+1)
          if c == "\"" {
            local k = j - 1
            local esc = false
            if k >= 0 && s.substring(k, k+1) == "\\" { esc = true }
            if !esc { in_str = !in_str }
            j = j + 1
            continue
          }
          if !in_str {
            if c == "[" { depth = depth + 1 }
            else if c == "]" { depth = depth - 1 }
          }
          j = j + 1
        }
        return [s.substring(i, j), j]
      }
      // number/true/false/null: read until delimiter
      local j = i
      loop(j < n) {
        local c = s.substring(j, j+1)
        if c == "," || c == "]" || c == "}" || c == "\n" || c == "\r" || c == "\t" || c == " " { break }
        j = j + 1
      }
      return [s.substring(i, j), j]
    }

    // pattern tokens
    local t_kind_loop = "\"kind\":\"Loop\""
    local t_cond = "\"condition\":"
    local t_body = "\"body\":"

    loop(i < s.length()) {
      // try to detect a Loop object start
      if i + 6 < s.length() && s.substring(i, i+1) == "{" {
        // look ahead inside this object to see if it begins with kind:Loop
        local val = parse_value(s, i)
        local obj = val.get(0)
        local endi = val.get(1)

        // quick check: contains kind:"Loop"
        local pos_kind = obj.indexOf(t_kind_loop)  // assume Nyash has indexOf? If not, manual scan fallback below
        if pos_kind == null {
          // Fallback manual contains
          local found = 0
          local k = 0
          loop(k + t_kind_loop.length() <= obj.length()) {
            if obj.substring(k, k + t_kind_loop.length()) == t_kind_loop { found = 1; break }
            k = k + 1
          }
          if found == 0 {
            out = out + obj
            i = endi
            continue
          }
        }

        // Now attempt to parse condition and body assuming canonical order
        // Find condition token within object string
        local oj = 0
        local pos_c = -1
        loop(oj + t_cond.length() <= obj.length()) {
          if obj.substring(oj, oj + t_cond.length()) == t_cond { pos_c = oj + t_cond.length(); break }
          oj = oj + 1
        }
        local pos_b = -1
        local kk = 0
        loop(kk + t_body.length() <= obj.length()) {
          if obj.substring(kk, kk + t_body.length()) == t_body { pos_b = kk + t_body.length(); break }
          kk = kk + 1
        }
        if pos_c >= 0 && pos_b >= 0 {
          // extract values
          local cond_pair = parse_value(obj, pos_c)
          local cond_json = cond_pair.get(0)
          // move after condition to find body array
          // ensure we re-scan from pos_b to robustly pick body
          local body_pair = parse_value(obj, pos_b)
          local body_json = body_pair.get(0)
          // if body_json is not array, keep identity
          if body_json.substring(0,1) == "[" {
            // decompose body array into elements
            local elems = []
            // strip [ ... ]
            local inner = body_json.substring(1, body_json.length()-1)
            // split top-level JSON elements (respect nesting)
            local p = 0
            local n = inner.length()
            local in_str = false
            local depth_obj = 0
            local depth_arr = 0
            local start = 0
            loop(p < n) {
              local c = inner.substring(p, p+1)
              if c == "\"" {
                // toggle string unless escaped
                local k2 = p - 1
                local esc2 = false
                if k2 >= 0 && inner.substring(k2, k2+1) == "\\" { esc2 = true }
                if !esc2 { in_str = !in_str }
              } else if !in_str {
                if c == "{" { depth_obj = depth_obj + 1 }
                else if c == "}" { depth_obj = depth_obj - 1 }
                else if c == "[" { depth_arr = depth_arr + 1 }
                else if c == "]" { depth_arr = depth_arr - 1 }
                else if c == "," && depth_obj == 0 && depth_arr == 0 {
                  elems.push(inner.substring(start, p))
                  start = p + 1
                }
              }
              p = p + 1
            }
            if start < n { elems.push(inner.substring(start, n)) }

            // trim spaces of elements (simple)
            local t = 0
            loop(t < elems.length()) {
              local e = elems.get(t)
              // naive trim
              local a = 0
              local b = e.length()
              loop(a < b && (e.substring(a,a+1)==" " || e.substring(a,a+1)=="\n" || e.substring(a,a+1)=="\t" || e.substring(a,a+1)=="\r")) { a = a + 1 }
              loop(b > a && (e.substring(b-1,b)==" " || e.substring(b-1,b)=="\n" || e.substring(b-1,b)=="\t" || e.substring(b-1,b)=="\r")) { b = b - 1 }
              elems.set(t, e.substring(a,b))
              t = t + 1
            }

            // rebuild Loop via JsonBuilder (canonical key order)
            local loop_norm = JB.loop_(cond_json, elems)
            out = out + loop_norm
            i = endi
            continue
          }
        }
        // fallback: copy as-is if parsing failed
        out = out + obj
        i = endi
        continue
      }
      // default: copy through one char
      out = out + s.substring(i, i+1)
      i = i + 1
    }
    return out
  }
}