--
-- (C) 2020-23 - ntop.org
--
local dirs = ntop.getDirs()
package.path = dirs.installdir .. "/scripts/lua/modules/pools/?.lua;" .. package.path

require "lua_utils"
local json = require "dkjson"
local rest_utils = require "rest_utils"
local tracker = require("tracker")

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

local import_export_rest_utils = {}

import_export_rest_utils.IMPORT_EXPORT_JSON_VERSION = "1.0"

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

-- @brief Add an envelope to the module configurations
function import_export_rest_utils.pack(modules)
    local rc = rest_utils.consts.success.ok
    local envelope = {}

    -- Add a version to the envelope to track the dump version
    envelope.version = import_export_rest_utils.IMPORT_EXPORT_JSON_VERSION

    -- Add the configuration of all provided module
    envelope.modules = modules

    return envelope
end

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

-- @brief Decode the configuration in json format
-- and handle the envelope. Return the list of
-- configurations for all the modules to be imported. 
function import_export_rest_utils.unpack(json_conf)

    -- Decode the json
    if json_conf == nil then
        return nil
    end

    local envelope = json.decode(json_conf)

    -- Check the envelope format and version
    if not envelope or not envelope.version == nil or envelope.version ~=
        import_export_rest_utils.IMPORT_EXPORT_JSON_VERSION then
        return nil
    end

    return envelope.modules
end

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

-- @brief Import the configuration for a list of (provided)
-- module instances
function import_export_rest_utils.import(items)
    local rc = rest_utils.consts.success.ok
    local list = {}

    for _, module in ipairs(items) do
        local res = module.instance:import(module.conf)
        if res.err then

            -- DEBUG
            -- tprint(module.name.." failure ")
            -- tprint(res)

            rc = res.err
        end
        list[#list] = module.name
    end

    rest_utils.answer(rc)

    -- TRACKER HOOK
    tracker.log('import', {
        modules = list
    })
end

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

-- @brief Export the configuration for a list of (provided) module instances
function import_export_rest_utils.export(instances, is_download, return_envelope)
    local rc = rest_utils.consts.success.ok
    local modules = {}
    local list = {}
    local missing_modules = {}

    -- Build the list of configurations for each module
    for name, instance in pairs(instances) do
        local conf = instance:export()
        if not conf then
            rc = rest_utils.consts.err.internal_error
            missing_modules[#missing_modules + 1] = name
        else
            modules[name] = conf
            list[#list] = name
        end
    end

    local envelope = import_export_rest_utils.pack(modules)

    -- This if is to keep the compatibility with old code
    if return_envelope then
        -- return the configuration
        return envelope
    else
        -- send a rest response
        if is_download then
            -- Download as file

            if rc ~= rest_utils.consts.success.ok then
                traceError(TRACE_ERROR, TRACE_CONSOLE,
                    "Failure exporting configuration for " .. table.concat(missing_modules, ", "))
            end

            sendHTTPContentTypeHeader('application/json', 'attachment; filename="configuration.json"')
            print(json.encode(envelope, nil))
        else
            -- Send as REST answer
            rest_utils.answer(rc, envelope)
        end

        -- TRACKER HOOK
        tracker.log('export', {
            modules = list
        })
    end
end

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

-- @brief Reset the configuration for a list of (provided) module instances
function import_export_rest_utils.reset(instances)
    local rc = rest_utils.consts.success.ok
    local list = {}

    for name, instance in pairs(instances) do
        instance:reset()
        list[#list] = name
    end

    rest_utils.answer(rc)

    -- TRACKER HOOK
    tracker.log('reset', {
        modules = list
    })
end

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

return import_export_rest_utils
