// tools/hako_check/rules/rule_dead_static_box.hako — HC012: Dead Static Box
// Detect static boxes that are never referenced from any code path.
// Excludes Main box (entry point) and boxes referenced in calls.

static box RuleDeadStaticBoxBox {
  // Local int_to_str helper (avoids using alias issues)
  _itoa(n) {
    local v = 0 + n
    if v == 0 { return "0" }
    local out = ""
    local digits = "0123456789"
    local tmp = ""
    loop (v > 0) {
      local d = v % 10
      tmp = digits.substring(d, d+1) + tmp
      v = v / 10
    }
    out = tmp
    return out
  }

  method apply_ir(ir, path, out) {
    local boxes = ir.get("boxes")
    if boxes == null { return 0 }

    local calls = ir.get("calls")
    if calls == null { return 0 }

    // Collect all box names that are referenced in calls
    local referenced_boxes = new MapBox()
    local ci = 0
    while ci < calls.size() {
      local call = calls.get(ci)
      if call == null { ci = ci + 1; continue }
      local to = call.get("to")
      if to != null {
        // Extract box name from qualified call (e.g., "Box.method/0" -> "Box")
        local dot = to.indexOf(".")
        if dot > 0 {
          local box_name = to.substring(0, dot)
          referenced_boxes.set(box_name, "1")
        }
      }
      ci = ci + 1
    }

    // Check each box
    local bi = 0
    while bi < boxes.size() {
      local box_info = boxes.get(bi)
      if box_info == null { bi = bi + 1; continue }

      local name = box_info.get("name")
      if name == null { bi = bi + 1; continue }

      local is_static = box_info.get("is_static")

      // Skip Main box (entry point)
      if name == "Main" { bi = bi + 1; continue }

      // Only check static boxes
      if is_static == null || is_static == 0 { bi = bi + 1; continue }

      // Check if box is referenced - if not in map, it returns "[map/missing]" StringBox
      local ref_check = referenced_boxes.get(name)

      // If ref_check is null or doesn't equal "1", box is unreferenced
      if ref_check == null || ref_check != "1" {
        // Box is never referenced - report error
        // Line precision: prefer span_line from AST intake if present
        local line = box_info.get("span_line")
        if line == null { line = 1 }
        out.push("[HC012] dead static box (never referenced): " + name + " :: path:" + me._itoa(line))
      }

      bi = bi + 1
    }
    return out.size()
  }
}

static box RuleDeadStaticBoxMain { method main(args) { return 0 } }