Procurement Models
==================

Material
--------

Catalog of materials used in EV charger installations.

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   :header-rows: 1
   :widths: 20 20 20 40

   * - Field
     - Type
     - Constraints
     - Description
   * - id
     - UUIDField
     - PK, default=uuid4
     - Primary key
   * - name
     - CharField(200)
     - not null
     - Material name
   * - sku
     - CharField(50)
     - unique
     - Stock keeping unit code
   * - category
     - CharField(50)
     - choices: ``charger``, ``cable``, ``mounting``, ``electrical``, ``misc``
     - Material category
   * - unit
     - CharField(20)
     - choices: ``piece``, ``meter``, ``kg``, ``set``
     - Unit of measurement
   * - description
     - TextField
     - blank
     - Detailed description

MaterialStock
-------------

Inventory levels per material per zone.

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   :header-rows: 1
   :widths: 20 20 20 40

   * - Field
     - Type
     - Constraints
     - Description
   * - id
     - UUIDField
     - PK, default=uuid4
     - Primary key
   * - material
     - ForeignKey(Material)
     - not null, on_delete=CASCADE
     - Material reference
   * - zone
     - ForeignKey(Zone)
     - not null, on_delete=PROTECT
     - Stock location zone
   * - quantity_available
     - IntegerField
     - not null, >=0
     - Current available stock
   * - reorder_level
     - IntegerField
     - default=5
     - Threshold for reorder alerts
   * - updated_at
     - DateTimeField
     - auto_now
     - Last stock update

**Unique constraint**: ``(material, zone)``

MaterialAllocation
------------------

Records material reserved or dispatched for a specific installation.

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 40

   * - Field
     - Type
     - Constraints
     - Description
   * - id
     - UUIDField
     - PK, default=uuid4
     - Primary key
   * - installation
     - ForeignKey(Installation)
     - not null, on_delete=CASCADE
     - Target installation
   * - material
     - ForeignKey(Material)
     - not null, on_delete=PROTECT
     - Allocated material
   * - quantity
     - IntegerField
     - not null, >0
     - Quantity allocated
   * - allocated_by
     - ForeignKey(User)
     - not null, on_delete=PROTECT
     - Procurement staff who allocated
   * - status
     - CharField(20)
     - choices: ``allocated``, ``dispatched``, ``delivered``, ``returned``
     - Allocation lifecycle state
   * - allocated_at
     - DateTimeField
     - auto_now_add
     - Allocation timestamp

ProcurementRequest
------------------

Request to procure materials locally when zone stock is insufficient.

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 40

   * - Field
     - Type
     - Constraints
     - Description
   * - id
     - UUIDField
     - PK, default=uuid4
     - Primary key
   * - installation
     - ForeignKey(Installation)
     - not null, on_delete=CASCADE
     - For which installation
   * - material
     - ForeignKey(Material)
     - not null, on_delete=PROTECT
     - What material is needed
   * - quantity
     - IntegerField
     - not null, >0
     - Quantity needed
   * - vendor
     - ForeignKey(Vendor)
     - nullable, on_delete=SET_NULL
     - Local vendor if identified
   * - status
     - CharField(20)
     - choices: ``requested``, ``approved``, ``ordered``, ``received``, ``cancelled``
     - Request lifecycle state
   * - estimated_cost
     - DecimalField(10,2)
     - nullable
     - Expected cost before ordering
   * - actual_cost
     - DecimalField(10,2)
     - nullable
     - Final cost after receiving
   * - requested_by
     - ForeignKey(User)
     - not null, on_delete=PROTECT
     - Who created the request
   * - created_at
     - DateTimeField
     - auto_now_add
     - Request creation timestamp

Vendor
------

Local suppliers for material procurement.

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 40

   * - Field
     - Type
     - Constraints
     - Description
   * - id
     - UUIDField
     - PK, default=uuid4
     - Primary key
   * - name
     - CharField(200)
     - not null
     - Vendor business name
   * - phone
     - CharField(15)
     - not null
     - Contact number
   * - zone
     - ForeignKey(Zone)
     - not null, on_delete=PROTECT
     - Vendor's operating zone
   * - upi_id
     - CharField(100)
     - nullable
     - UPI/QR payment identifier
   * - bank_account
     - CharField(20)
     - nullable
     - Bank account number
   * - bank_ifsc
     - CharField(15)
     - nullable
     - Bank IFSC code
   * - is_active
     - BooleanField
     - default=True
     - Whether vendor is active

**Note**: At least one payment method (``upi_id`` or ``bank_account`` + ``bank_ifsc``) should be provided, enforced at the application level.