from django.db import models

# Create your models here.
from django.db import models
from django.contrib.auth.models import User
from django.utils import timezone
import re
from human_resource.models import StaffProfile

from system_administration.models import CompanyBranch, CompanyProfile


class Warehouse(models.Model):
    company_branch = models.ForeignKey(
        CompanyBranch, null=True, on_delete=models.SET_NULL, related_name="branch_warehouses")
    warehouse_name = models.CharField(max_length=50, default="", unique=True)
    warehouse_location = models.CharField(
        max_length=50, default="",)
    warehouse_capacity = models.CharField(
        max_length=12, default="0",)  # capacity in square feet
    warehouse_contact_phone = models.CharField(
        max_length=25, default="", blank=False)
    warehouse_description = models.CharField(
        max_length=500, default="", blank=True)
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="warehouse_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="warehouse_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)

# created by warehouse staff at the main branch


class Category(models.Model):
    category_name = models.CharField(max_length=50, default="",)
    category_description = models.CharField(
        max_length=500, default="", blank=True)
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="category_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="category_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)

    class Meta:
        # ordering= ("first_name", "last_name",)
        verbose_name = "Category"
        verbose_name_plural = "Categories"


# created by warehouse staff at the main branch
class Product(models.Model):
    category = models.ForeignKey(
        Category, null=True, on_delete=models.SET_NULL, related_name="category_products")
    product_name = models.CharField(max_length=50, default="",)
    stock_keeping_unit = models.CharField(
        max_length=20, default="", unique=True)
    measurement_choices = [
        ("kilowatts", "Kilowatts"), ("piece", "Piece"), ("box", "Box"), ("pallet", "Pallet"), ("metre", "Metre"), ("kg", "Kg"), ("litre", "Litre"), ("other", "Other"), ("not_selected", "Not Selected")]
    unit_of_measurement = models.CharField(
        max_length=20, choices=measurement_choices, default="not_selected",)
    product_description = models.CharField(
        max_length=500, default="", blank=True)
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="product_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="product_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)
    timestamp = models.DateTimeField(default=timezone.now)

    def save(self, *args, **kwargs):
        if not self.pk:
            # numberReg = re.sub(
            #     r'[^0-9]', '', self.timestamp.strftime('%Y-%m-%d %H:%M:%S'))
            numberReg = re.sub(
                r'[^0-9]', '', self.timestamp.strftime('%Y-%d %H:%M:%S'))
            self.stock_keeping_unit = 'SKU' + numberReg
        super().save(*args, **kwargs)


class Inventory(models.Model):  # inventory is unique for every branch
    product = models.ForeignKey(
        Product, null=True, on_delete=models.SET_NULL, related_name="product_inventories")
    warehouse = models.ForeignKey(
        Warehouse, null=True, on_delete=models.SET_NULL, related_name="warehouse_inventories")
    quantity = models.CharField(max_length=15, default="0",)
    minimum_stock_level = models.CharField(max_length=15, default="0",)
    inventory_description = models.CharField(
        max_length=500, default="", blank=True)
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="inventory_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="inventory_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)

    class Meta:
        # ordering= ("first_name", "last_name",)
        verbose_name = "Inventory"
        verbose_name_plural = "Inventories"


class InventoryFinancialYearOpening(models.Model):
    inventory = models.ForeignKey(
        Inventory, null=True, on_delete=models.SET_NULL, related_name="inventory_financial_year_opening_values")
    financial_year = models.CharField(max_length=7, default="", blank=True)
    opening_quantity = models.CharField(max_length=20, default="0", blank=True)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)


class StockTransaction(models.Model):
    stock_transaction_number = models.CharField(
        max_length=50, unique=True, default="")
    source_warehouse = models.ForeignKey(
        Warehouse, null=True, on_delete=models.SET_NULL, related_name="source_warehouse_stock_transactions")
    recipient_warehouse = models.ForeignKey(
        Warehouse, null=True, on_delete=models.SET_NULL, related_name="recipient_warehouse_stock_transactions")
    transaction_type_choices = [
        ("in_bound", "Inbound"), ("out_bound", "Outbound"), ("not_selected", "Not Selected")]
    transaction_type = models.CharField(
        max_length=20, choices=transaction_type_choices, default="not_selected",)
    transaction_description = models.CharField(
        max_length=500, default="", blank=True)
    stock_transaction_reference = models.CharField(
        max_length=50, default="", blank=True)  # will store the stock order number or sales order number that the stock transaction is fullfilling
    stock_transaction_added_to_inventory = models.BooleanField(
        default=False)  # turned True only for inbound after they are received
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="stock_transaction_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="stock_transaction_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)
    timestamp = models.DateTimeField(default=timezone.now)

    class Meta:
        # ordering= ("first_name", "last_name",)
        verbose_name = "Stock Transaction"
        verbose_name_plural = "Stock Transactions"

    def save(self, *args, **kwargs):
        if not self.pk:
            numberReg = re.sub(
                r'[^0-9]', '', self.timestamp.strftime('%Y-%m-%d %H:%M:%S'))
            self.stock_transaction_number = "ST"+numberReg
        super().save(*args, **kwargs)


class StockTransactionInstance(models.Model):
    product = models.ForeignKey(
        Product, null=True, on_delete=models.SET_NULL, related_name="product_stock_transactions")
    quantity = models.CharField(max_length=15, default="0",)
    stock_transaction = models.ForeignKey(
        StockTransaction, null=True, on_delete=models.SET_NULL, related_name="stock_transaction_instances")
    # purchase_requisition_items_purchased = models.BooleanField(default=False)


class Equipment(models.Model):
    warehouse = models.ForeignKey(
        Warehouse, null=True, on_delete=models.SET_NULL, related_name="warehouse_equipment")
    equipment_name = models.CharField(max_length=100, default="",)
    equipment_serial_number = models.CharField(
        max_length=50, default="", blank=True)
    equipment_description = models.CharField(
        max_length=500, default="", blank=True)
    status_choices = [
        ("operational", "Operational"), ("under_maintenance", "Under Maintenance"), ("decommisioned", "Decommisioned"), ("not_selected", "Not Selected")]
    status = models.CharField(
        max_length=20, choices=status_choices, default="not_selected",)
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="equipment_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="equipment_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)


# only applicable to the main warehouse
class PurchaseRequisition(models.Model):
    warehouse = models.ForeignKey(
        Warehouse, null=True, on_delete=models.SET_NULL, related_name="warehouse_purchase_requisitions")
    purchase_requisition_number = models.CharField(
        max_length=50, unique=True, default="")
    purchase_requisition_description = models.CharField(
        max_length=500, default="", blank=True)
    purchase_requisition_approved = models.BooleanField(
        default=False)  # approved by finance/accountant
    purchase_requisition_rejected = models.BooleanField(default=False)
    rejection_reason = models.CharField(max_length=500, default="", blank=True)
    specifications = models.TextField(default="", blank=True)
    approved_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL,
        related_name="purchase_requisitions_approved_by")
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="purchase_requisitions_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="purchase_requisitions_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)
    timestamp = models.DateTimeField(default=timezone.now)

    class Meta:
        # ordering= ("first_name", "last_name",)
        verbose_name = "Purchase Requisition"
        verbose_name_plural = "Purchase Requisitions"

    def save(self, *args, **kwargs):
        if not self.pk:
            numberReg = re.sub(
                r'[^0-9]', '', self.timestamp.strftime('%Y-%m-%d %H:%M:%S'))
            self.purchase_requisition_number = "PR"+numberReg
        super().save(*args, **kwargs)


# only applicable to the main warehouse
class PurchaseRequisitionInstance(models.Model):
    product = models.ForeignKey(
        Product, null=True, on_delete=models.SET_NULL, related_name="product_purchase_requisitions")
    purchase_requisition = models.ForeignKey(
        PurchaseRequisition, null=True, on_delete=models.SET_NULL, related_name="purchase_requisition_instances")
    quantity = models.CharField(max_length=15, default="0",)
    purchase_requisition_items_purchased = models.BooleanField(default=False)
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="purchase_requisition_instances_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="purchase_requisition_instances_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)


class PurchaseRequisitionDocument(models.Model):
    DOCUMENT_TYPES = [
        ('justification', 'Justification'),
        ('specification', 'Specification'),
        ('supporting', 'Supporting Document'),
    ]
    purchase_requisition = models.ForeignKey(
        PurchaseRequisition, null=True, on_delete=models.CASCADE,
        related_name='documents')
    document_name = models.CharField(max_length=200, default='')
    document_type = models.CharField(max_length=50, default='supporting')
    content_type = models.CharField(max_length=120, default='application/octet-stream')
    file_data_base64 = models.TextField(default='', blank=True)
    uploaded_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL,
        related_name='purchase_requisition_documents_uploaded')
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)


# only made by subsidiary warehouses to their respective procurement department
class StockRequisition(models.Model):
    warehouse = models.ForeignKey(
        Warehouse, null=True, on_delete=models.SET_NULL, related_name="warehouse_stock_requisitions")
    stock_requisition_number = models.CharField(
        max_length=50, unique=True, default="")
    stock_requisition_description = models.CharField(
        max_length=500, default="", blank=True)
    # approved by the h.o.d of the respective procurement department
    stock_requisition_approved = models.BooleanField(default=False)
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="stock_requisitions_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="stock_requisitions_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)
    timestamp = models.DateTimeField(default=timezone.now)

    def save(self, *args, **kwargs):
        if not self.pk:
            numberReg = re.sub(
                r'[^0-9]', '', self.timestamp.strftime('%Y-%m-%d %H:%M:%S'))
            self.stock_requisition_number = "ST"+numberReg
        super().save(*args, **kwargs)


class StockRequisitionInstance(models.Model):
    product = models.ForeignKey(
        Product, null=True, on_delete=models.SET_NULL, related_name="product_stock_requisitions")
    stock_requisition = models.ForeignKey(
        StockRequisition, null=True, on_delete=models.SET_NULL, related_name="stock_requisition_instances")
    quantity = models.CharField(max_length=15, default="0",)
    stock_requisition_items_delivered = models.BooleanField(default=False)
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="stock_requisition_instances_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="stock_requisition_instances_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)


class StockReservation(models.Model):
    """Created by sales staff to reserve stock; approved/rejected by warehouse staff."""
    reservation_number = models.CharField(max_length=50, unique=True, default="")
    warehouse = models.ForeignKey(
        Warehouse, null=True, on_delete=models.SET_NULL, related_name="warehouse_stock_reservations")
    reservation_description = models.CharField(max_length=500, default="", blank=True)
    STATUS_CHOICES = [
        ("pending", "Pending"),
        ("approved", "Approved"),
        ("rejected", "Rejected"),
        ("expired", "Expired"),
        ("fulfilled", "Fulfilled"),
        ("released", "Released"),
    ]
    status = models.CharField(max_length=20, choices=STATUS_CHOICES, default="pending")
    expiry_date = models.DateTimeField(null=True, blank=True)
    rejection_reason = models.CharField(max_length=500, default="", blank=True)
    requested_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="staff_stock_reservations")
    approved_or_rejected_by = models.ForeignKey(
        StaffProfile, null=True, blank=True, on_delete=models.SET_NULL, related_name="staff_handled_reservations")
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="reservation_created_by")
    last_updated_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="reservation_last_updated_by")
    recycle_bin = models.BooleanField(default=False)
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)
    timestamp = models.DateTimeField(default=timezone.now)

    class Meta:
        verbose_name = "Stock Reservation"
        verbose_name_plural = "Stock Reservations"

    def save(self, *args, **kwargs):
        if not self.pk:
            numberReg = re.sub(r'[^0-9]', '', self.timestamp.strftime('%Y-%m-%d %H:%M:%S'))
            self.reservation_number = "RSV" + numberReg
        super().save(*args, **kwargs)


class StockReservationInstance(models.Model):
    stock_reservation = models.ForeignKey(
        StockReservation, null=True, on_delete=models.CASCADE, related_name="reservation_instances")
    product = models.ForeignKey(
        Product, null=True, on_delete=models.SET_NULL, related_name="product_reservations")
    quantity_requested = models.CharField(max_length=15, default="0")
    created_on = models.DateTimeField(auto_now_add=True)
    last_updated_on = models.DateTimeField(auto_now=True)


class StockMovement(models.Model):
    """Immutable audit log of every change to a product's on-hand quantity in a
    warehouse — a stock ledger / kardex. One row per quantity change, recording
    the before/after balance, the signed change, the cause, the source document,
    and who made it. Never edited or deleted; corrections are new movements."""
    MOVEMENT_TYPES = [
        ("receipt", "Receipt (Inbound)"),
        ("issue", "Issue (Outbound)"),
        ("requisition_issue", "Requisition Issue"),
        ("adjustment", "Manual Adjustment"),
        ("reversal", "Transaction Reversal"),
        ("opening", "Opening Balance"),
    ]
    inventory = models.ForeignKey(
        Inventory, null=True, on_delete=models.SET_NULL, related_name="stock_movements")
    product = models.ForeignKey(
        Product, null=True, on_delete=models.SET_NULL, related_name="stock_movements")
    warehouse = models.ForeignKey(
        Warehouse, null=True, on_delete=models.SET_NULL, related_name="stock_movements")
    movement_type = models.CharField(
        max_length=30, choices=MOVEMENT_TYPES, default="adjustment")
    quantity_before = models.DecimalField(max_digits=18, decimal_places=3, default=0)
    quantity_change = models.DecimalField(max_digits=18, decimal_places=3, default=0)
    quantity_after = models.DecimalField(max_digits=18, decimal_places=3, default=0)
    reference = models.CharField(max_length=100, default="", blank=True)
    stock_transaction = models.ForeignKey(
        StockTransaction, null=True, blank=True, on_delete=models.SET_NULL, related_name="stock_movements")
    notes = models.CharField(max_length=500, default="", blank=True)
    created_by = models.ForeignKey(
        StaffProfile, null=True, on_delete=models.SET_NULL, related_name="stock_movements_created")
    created_on = models.DateTimeField(auto_now_add=True)

    class Meta:
        ordering = ("-created_on", "-id")
        verbose_name = "Stock Movement"
        verbose_name_plural = "Stock Movements"

    def __str__(self):
        product_name = self.product.product_name if self.product else "?"
        return f"{self.movement_type} {self.quantity_change} {product_name}"