// tools/hako_check/rules/rule_top_level_local.hako — HC018: Top-level local in prelude
// Detects top-level `local` statements (outside of methods/boxes), which are cleanup omissions.

static box RuleTopLevelLocalBox {
  method apply(text, path, out) {
    if text == null { return 0 }

    local lines = me._split_lines(text)
    local i = 0
    local in_box = 0
    local in_method = 0
    local brace_depth = 0

    while i < lines.size() {
      local ln = lines.get(i)
      local trimmed = me._trim(ln)

      // Track context: are we inside a box or method?
      if trimmed.indexOf("box ") == 0 || trimmed.indexOf("static box ") == 0 {
        in_box = 1
      }
      if in_box == 1 && (trimmed.indexOf("method ") >= 0 || trimmed.indexOf("birth(") >= 0) {
        in_method = 1
      }

      // Track brace depth
      local j = 0
      while j < trimmed.length() {
        local ch = trimmed.substring(j, j+1)
        if ch == "{" { brace_depth = brace_depth + 1 }
        if ch == "}" {
          brace_depth = brace_depth - 1
          if brace_depth == 0 {
            in_method = 0
            in_box = 0
          }
        }
        j = j + 1
      }

      // Check for top-level local (not inside method, not a comment)
      if trimmed.indexOf("local ") == 0 {
        if in_method == 0 && me._is_comment(trimmed) == 0 {
          out.push("[HC018] top-level local declaration (not allowed): " + path + ":" + me._itoa(i+1))
        }
      }

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

  _trim(s) {
    if s == null { return "" }
    local start = 0
    local end = s.length()

    // Trim leading whitespace
    while start < end {
      local ch = s.substring(start, start+1)
      if ch == " " || ch == "\t" { start = start + 1 } else { break }
    }

    // Trim trailing whitespace
    while end > start {
      local ch = s.substring(end-1, end)
      if ch == " " || ch == "\t" || ch == "\n" || ch == "\r" { end = end - 1 } else { break }
    }

    return s.substring(start, end)
  }

  _is_comment(s) {
    if s == null { return 0 }
    local trimmed = me._trim(s)
    if trimmed.indexOf("//") == 0 { return 1 }
    return 0
  }

  _split_lines(s) {
    local arr = new ArrayBox()
    if s == null { return arr }
    local n = s.length()
    local last = 0
    local i = 0
    loop(i < n) {
      local ch = s.substring(i, i+1)
      if ch == "\n" {
        arr.push(s.substring(last, i))
        last = i + 1
      }
      i = i + 1
    }
    if last <= n { arr.push(s.substring(last)) }
    return arr
  }

  _itoa(n) {
    local v = 0 + n
    if v == 0 { return "0" }
    local out = ""
    local digits = "0123456789"
    local tmp = ""
    while v > 0 {
      local d = v % 10
      tmp = digits.substring(d, d+1) + tmp
      v = v / 10
    }
    out = tmp
    return out
  }
}

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