local DATABASE_VERSION = 0

local private, public = {}, {}
Aux.persistence = public

aux_database = {}

function public.on_load()
	perform_migration(aux_database)
    aux_database.version = DATABASE_VERSION
end

function private.get_dataset_key()
	local realm = GetCVar('realmName')
	local zone = GetMinimapZoneText()
	local faction
    -- TODO use UnitFactionGroup(unit) or race with auctioneer instead to work for all locales
	if zone == 'Gadgetzan' or zone == 'Everlook' or zone == 'Booty Bay' then
		faction = 'Neutral'
	else
		faction = UnitFactionGroup('player')
	end
	return realm..'|'..faction
end

function private.load_dataset()
    local dataset_key = private.get_dataset_key()
    aux_database[dataset_key] = aux_database[dataset_key] or {}
    return aux_database[dataset_key]
end

function load_snapshot()
    local dataset = load_dataset()
    local snapshot = Aux.util.set()
    snapshot.set_data(dataset.snapshot)
    return snapshot
end

function public.load_scan_records(item_key)
    local dataset = private.load_dataset()

    local serialized_records = private.deserialize(dataset[item_key] or '', ';')
    return Aux.util.map(serialized_records, function(serialized_record)
        local time, count, min_price, accumulated_price = private.deserialize(serialized_record, '#')
        return {
            time = time,
            count = count,
            min_price = min_price,
            accumulated_price = accumulated_price,
        }
    end)
end

function public.store_scan_record(item_key, record)
    local dataset = private.load_dataset()
    local serialized_record = private.serialize({ record.time, record.count, record.min_price, record.accumulated_price }, '#')
    local serialized_records = dataset[item_key] or ''
    serialized_records = serialized_records..(serialized_records == '' and '' or ';')..serialized_record
    dataset[item_key] = serialized_records
end

function private.serialize(data, separator)
    local data_string = ''
    for i, datum in ipairs(data) do
        data_string = data_string..(i == 1 and '' or separator)..datum
    end
    return data_string
end

function private.deserialize(data_string, separator)
    if data_string == '' then
        return {}
    end

    local data = {}
    while true do
        local start_index, _ = strfind(data_string, separator, 1, true)
        if start_index then
            tinsert(data, string.sub(data_string, 1, start_index - 1))
            data_string = string.sub(data_string, start_index + 1, strlen(data_string))
        else
            tinsert(data, string.sub(data_string, 1, strlen(data_string)))
            return data
        end
    end
end