--
-- (C) 2013-26 - ntop.org
--
local dirs = ntop.getDirs()
package.path = dirs.installdir .. "/scripts/lua/modules/?.lua;" .. package.path

local TABLE_NAME = "hourly_asn"
local flow_data_historical = {}

-- ###################################################

-- Helper used just to correctly format the Limit clause
local function buildLimitClause(query_info)
   local limit_keys = query_info.limit_query or {}
   local formatted_limit_query = "LIMIT "

   if not limit_keys or (table.len(limit_keys) == 0) then
      formatted_limit_query = ""
   end

   -- Multiple limit allowed only in Historical, just skip all except the first limit
   if not isHistorical then
      limit_keys = { limit_keys[1] }
   end

   for index, num_limit in pairs(limit_keys) do
      formatted_limit_query = string.format("%s%s", formatted_limit_query, num_limit)
      if index ~= #limit_keys then
	 -- Add the separator
	 formatted_limit_query = string.format("%s, ", formatted_limit_query)
      end
   end

   return formatted_limit_query
end

-- ###################################################

-- Helper used just to correctly format the order by clause
local function buildOrderByClause(query_info)
   local order_by_keys = query_info.order_by_query or {}
   local formatted_order_by_query = "ORDER BY "

   if not order_by_keys or (table.len(order_by_keys) == 0) then
      formatted_order_by_query = ""
   end

   -- Multiple order by allowed only in Historical, just skip all except the first order by
   if not isHistorical then
      order_by_keys = { order_by_keys[1] }
   end

   -- ###### ORDER BY ######
   for index, order_by_info in pairs(order_by_keys) do
      formatted_order_by_query =
	 string.format("%s%s %s", formatted_order_by_query, order_by_info.key, tostring(order_by_info.value))
      if index ~= #order_by_keys then
	 -- Add the separator
	 formatted_order_by_query = string.format("%s, ", formatted_order_by_query)
      end
   end

   return formatted_order_by_query
end

-- ###################################################

-- Helper used just to correctly format the where clause
local function buildSelectClause(query_info)
   local select_keys = query_info.select_query
   local formatted_select_query = "SELECT "

   -- ###### SELECT ######
   for index, select_info in pairs(select_keys) do
      formatted_select_query = string.format("%s%s", formatted_select_query, select_info.key)
      if select_info.rename then
	 -- Add the AS if requested
	 formatted_select_query = string.format("%s AS %s", formatted_select_query, select_info.rename)
      end
      if index ~= #select_keys then
	 -- Add the separator
	 formatted_select_query = string.format("%s, ", formatted_select_query)
      end
   end

   return formatted_select_query
end

-- ###################################################

-- Helper used just to correctly format the group by clause
local function buildGroupByClause(query_info)
   local select_keys = query_info.select_query
   local formatted_group_by = "GROUP BY "

   -- ###### GROUP BY ######
   for index, select_keys_info in pairs(select_keys) do
      if select_keys_info.is_key then
	 formatted_group_by =
	    string.format("%s%s", formatted_group_by, (select_keys_info.rename or select_keys_info.key))
	 -- Add the separator
	 formatted_group_by = string.format("%s, ", formatted_group_by)
      end
   end

   formatted_group_by = formatted_group_by:sub(1, -3)

   return formatted_group_by
end

-- ###################################################

-- Helper used just to correctly format the where clause
local function buildWhereClause(query_info)
   local where_keys = query_info.where_query or {}
   local formatted_where_query = "WHERE "

   -- First of all add the basic filters (ifid and epoch) to the where
   if query_info.basic_filters then
      local basic_filters = query_info.basic_filters
      -- IFID
      if basic_filters.ifid then
	 formatted_where_query =
	    string.format("%sINTERFACE_ID=%s AND ", formatted_where_query, tostring(basic_filters.ifid))
      end
      if basic_filters.epoch_begin then
	 formatted_where_query =
	    string.format("%sFIRST_SEEN>=%s AND ", formatted_where_query, tostring(basic_filters.epoch_begin))
      end
      if basic_filters.epoch_end then
	 formatted_where_query = string.format(
	    "%sFIRST_SEEN<=%u AND LAST_SEEN<=%s AND ",
	    formatted_where_query,
	    tostring(basic_filters.epoch_end),
	    tostring(basic_filters.epoch_end)
	 )
      end
   end

   -- Now format the others where
   for index, where_info in pairs(where_keys) do
      -- It means that there is an array of keys that needs to be put in an OR condition
      if where_info.or_condition then
	 formatted_where_query = formatted_where_query .. "("
	 for _, info in pairs(where_info.key) do
	    formatted_where_query =
	       string.format("%s%s%s%s OR ", formatted_where_query, info.key, info.operator, tostring(info.value))
	 end
	 formatted_where_query = formatted_where_query:sub(1, -4)
	 formatted_where_query = formatted_where_query .. ")"
      else
	 formatted_where_query = string.format(
	    "%s%s%s%s AND ",
	    formatted_where_query,
	    where_info.key,
	    where_info.operator,
	    tostring(where_info.value)
	 )
      end
   end

   -- Remove the last "AND " string alwais added
   if not isEmptyString(formatted_where_query) and formatted_where_query:sub(-5) == " AND " then
      formatted_where_query = formatted_where_query:sub(1, -5)
   end

   return formatted_where_query
end

-- ###################################################

function flow_data_historical.retrieveFlowData(query_info)
   local results = nil
   local error_code = nil
   -- Handle the select first
   local isHistorical = not query_info.basic_info
      or isEmptyString(query_info.basic_info.epoch_begin)
      or isEmptyString(query_info.basic_info.epoch_end)

   -- In case no select keys are requested return empty -> error
   if not query_info.select_query then
      traceError(TRACE_ERROR, TRACE_CONSOLE, "No SELECT keys provided\n")
      return {}
   end

   local select_query = buildSelectClause(query_info)
   local group_by_query = buildGroupByClause(query_info)
   local where_query = buildWhereClause(query_info)
   local order_by_query = buildOrderByClause(query_info)
   local limit_query = buildLimitClause(query_info)

   local query =
      string.format("%s FROM %s %s %s %s %s", select_query, TABLE_NAME, where_query, group_by_query, order_by_query, limit_query)

   if isHistorical and hasClickHouseSupport() then
      results, error_code = interface.execSQLQuery(query)
   else
      results, error_code = interface.execInMemoryQuery(query)
   end

   return results or {}
end

-- ###################################################

return flow_data_historical