#!/usr/bin/env python
"""
Test script to verify WriteOff form validation prevents over-listing.
This tests that WriteOffForm.clean() prevents creating WriteOff with quantity > batch.quantity
"""

import os
import sys
import django

# Setup Django
sys.path.insert(0, 'myproject')
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'myproject.settings')
django.setup()

from inventory.forms import WriteOffForm
from inventory.models import WriteOff, StockBatch, Warehouse, Product
from django.core.exceptions import ValidationError

print("=" * 70)
print("Testing WriteOff Validation")
print("=" * 70)

# Create test data
warehouse = Warehouse.objects.filter(is_active=True).first()
if not warehouse:
    print("ERROR: No active warehouse found. Please create one first.")
    sys.exit(1)

product = Product.objects.filter(tenant=warehouse.tenant).first()
if not product:
    print("ERROR: No product found. Please create one first.")
    sys.exit(1)

# Create a batch with 2 items
batch = StockBatch.objects.create(
    product=product,
    warehouse=warehouse,
    quantity=2,
    cost_price=100.0,
    is_active=True
)

print(f"\n✓ Created StockBatch with quantity=2")
print(f"  Product: {product.name}")
print(f"  Warehouse: {warehouse.name}")
print(f"  Batch ID: {batch.id}")

# Test 1: Valid WriteOff (quantity = batch.quantity)
print("\n" + "=" * 70)
print("Test 1: Valid WriteOff with quantity=2 (equal to batch quantity)")
print("=" * 70)

form_data = {
    'batch': batch.id,
    'quantity': 2,
    'reason': 'damage',
    'document_number': 'DOC001',
    'notes': 'Test valid writeoff'
}

form = WriteOffForm(data=form_data)
if form.is_valid():
    print("✓ PASS: Form is valid (quantity <= batch.quantity)")
else:
    print(f"✗ FAIL: Form should be valid but has errors: {form.errors}")

# Test 2: Invalid WriteOff (quantity > batch.quantity)
print("\n" + "=" * 70)
print("Test 2: Invalid WriteOff with quantity=3 (exceeds batch quantity=2)")
print("=" * 70)

form_data = {
    'batch': batch.id,
    'quantity': 3,
    'reason': 'damage',
    'document_number': 'DOC002',
    'notes': 'Test invalid writeoff - should be rejected'
}

form = WriteOffForm(data=form_data)
if not form.is_valid():
    print("✓ PASS: Form validation correctly rejects over-listing")
    for field, errors in form.errors.items():
        for error in errors:
            print(f"  Error: {error}")
else:
    print("✗ FAIL: Form should reject quantity > batch.quantity")

# Test 3: Invalid WriteOff (quantity = 0)
print("\n" + "=" * 70)
print("Test 3: Invalid WriteOff with quantity=0 (should be > 0)")
print("=" * 70)

form_data = {
    'batch': batch.id,
    'quantity': 0,
    'reason': 'damage',
    'document_number': 'DOC003',
    'notes': 'Test zero quantity'
}

form = WriteOffForm(data=form_data)
if not form.is_valid():
    print("✓ PASS: Form validation correctly rejects zero quantity")
    for field, errors in form.errors.items():
        for error in errors:
            print(f"  Error: {error}")
else:
    print("✗ FAIL: Form should reject quantity <= 0")

# Cleanup
batch.delete()
print("\n" + "=" * 70)
print("Test completed successfully!")
print("=" * 70)