Create a script/module for import/export of articles/categories in MijoShop (Opencart)

We need a script/module in MijoShop (Opencart 1.5.5.1 integrated into Joomla 2.5) to easily export and import articles and categories. = Processes: -- Import: 1. Via Backend (MijoShop in Joomla), the user can upload a file with the data to be imported 2. User selects, whether to delete all existing records or not. If not, new records are added and existing ones updated with the data from the file. 3. The Script validates the fields and headers with the fields in the DB, to make sure that they match 4. If necessary, the user can map header-fields in the file to fields in the DB. This selection should be stored for future imports. 5. Perform import and give feedback to user -- Export: 1. Via Backend (MijoShop in Joomla), the user can generate and download a file with the exported data. = Requirements: - File to import/export must be in the format CSV or Excel (preferably Excel, but CSV should do if that is easier for you); The file must be readable in Excel without having to adjust anything in the data/Excel-configuration (encoding, separators etc.). - If a row cannot be imported, it must be skipped and the import continued at the next line - After the job is run, the user must receive a log/feedback about the status, how many rows imported successfully, how many (and which ones) failed and possibly why they failed - The script must be able to handle thousands of rows in the file (>10'000) with all relevant information. The memory_limit in PHP is set to 256MB. - If the script fails or runs into a timeout, it should continue where it left off. - Support for OpenCart multi-language environment (no hardcoded strings in the script), article-/category-data can be multi-lingual. = General: - We have an import/export module that might help as a starting point. The problem is that with thousands of articles it runs out of memory and it always deletes all articles/categories before importing, plus fields are not verified before import. - We can provide a development environment with an existing shop for you to test in our environment. We look forward to hearing from you!