B2B and B2C System

An B2B & B2C e-commerce. The Overview: We have providers (vendors). Each provider have a lot of products and each product has an "base price" and an "SAP code" One provider can have many costumers. Each costumer have one or more contracts Each contract have one or more "constructions" vinculated. One construction have just one contract. But, for the visual, the construction is the focus (the customer enter in the system to manage their constructions) Each customer have one or more purchaser (the "buyers") and can have approvers (not obrigatory) Each approver can be in one or more constructions and each construction can have more than one approver... If the construction have approvers, the approvers will have levels for the purchases.. Example: For the purchases bellow $2.000,00, the approver of level 1 will say "ok" or "rejected" For the purchases above $2.000,00, the approver of level 1 needs give the "ok" and the approver of level 2 too (if the approver of level 1 give the "ok", but the approver of level 2 don't give, the request is "rejected") And this rule continues for each approver vinculated to construction (if the construction have only one approver, its "ok" is enough.), but if the construction have no approvers, each buy is automatically "approved". Each contract has one or more itens (the itens of the provider), but not necessary all itens and each item in the contract has an "Number of Item"... (that representate the ítem in the contract, ever starting by 1 for each new contract) And each contract has one or more imposts (for example: ICMS and IPI) The tax of each impost can variate for each State (so, in São Paulo, the ICMS is 18%, in Rondônia, the ICMS is 17%), but all them needs have an "base tax" (so, for pattern, the ICMS is 18% and I just modify that value in some specifics contracts) When one "buyer" enter in the system, he have to choose for what the construction he will buy... Needs to have acess to historic of buys and to the course of the opened buys (the pendent and the rejected). There's no payment forms, when the buyer finish the buy, she goes right to approver. When an buy is approved by all approvers, she goes to provider and integrate with SAP system. --- Important: - The system needs to integrate with SAP (just the buy) - The system needs to have suport to internacionalization (pt-br) - All involved with the process needs to receive e-mails (the buyer, the approver and, when an solicitation is finished, the provider... the cliente receive e-mail for each integration with sistem) ---