// tools/hako_check/rules/rule_missing_entrypoint.hako — HC014: Missing Entrypoint
// Detect when no entrypoint (Main.main or main) exists in the analyzed code.

static box RuleMissingEntrypointBox {
  method apply_ir(ir, path, out) {
    local entrypoints = ir.get("entrypoints")
    if entrypoints == null { return 0 }

    local methods = ir.get("methods")
    if methods == null || methods.size() == 0 {
      // No methods at all - definitely missing entrypoint
      out.push("[HC014] missing entrypoint (Main.main or main)")
      return out.size()
    }

    // Check if any entrypoint exists
    local found = 0
    local ei = 0
    while ei < entrypoints.size() {
      local ep = entrypoints.get(ei)
      if me._has_entrypoint_method(methods, ep) == 1 {
        found = 1
        break
      }
      ei = ei + 1
    }

    // If no entrypoint found, report error
    if found == 0 {
      out.push("[HC014] missing entrypoint (Main.main or main)")
    }

    return out.size()
  }

  _has_entrypoint_method(methods, ep_name) {
    // Check if method starting with ep_name exists
    // e.g., "Main.main" matches "Main.main/0", "Main.main/1", etc.
    // "main" matches "main/0", etc.
    local mi = 0
    while mi < methods.size() {
      local m = methods.get(mi)
      if m == null { mi = mi + 1; continue }

      // Check exact match with arity suffix
      // ep_name can be "Main.main" or "main"
      local len = ep_name.length()
      if m.length() >= len + 2 {
        local prefix = m.substring(0, len)
        if prefix == ep_name {
          // Check if followed by "/" (arity separator)
          local next_char = m.substring(len, len+1)
          if next_char == "/" { return 1 }
        }
      }
      mi = mi + 1
    }
    return 0
  }
}

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