import os
import sys
import django
from django.test import Client
from django.core.files.uploadedfile import SimpleUploadedFile
from decimal import Decimal

# Set up Django environment
sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'config.settings')
django.setup()

from django.conf import settings
if 'testserver' not in settings.ALLOWED_HOSTS:
    settings.ALLOWED_HOSTS.append('testserver')

from django.contrib.auth.models import User
from expenses.models import Project, Category, Vendor, Expense, Document, SystemSetting, CurrencyEnum, TaxTypeEnum, ApprovalStatusEnum

def run_test():
    print("=" * 60)
    print("EFINTEL ERP — Expense Creation Flow Integration Test")
    print("=" * 60)

    # 1. Setup client and login
    print("Step 1: Setting up Django test Client & Authenticating...")
    client = Client()
    admin_user = User.objects.filter(username='admin').first()
    if not admin_user:
        print("Admin user 'admin' not found in database. Creating user...")
        admin_user = User.objects.create_superuser('admin', 'admin@example.com', 'admin')
        print("Admin user created successfully.")
    
    client.force_login(admin_user)
    print(f"Authenticated successfully as: {admin_user.username} (ID: {admin_user.id})")

    # Fetch required objects
    print("\nFetching Project (PRY-101) and Category (1201)...")
    project = Project.objects.filter(code='PRY-101').first()
    if not project:
        raise ValueError("Project PRY-101 not found! Please run project seed scripts first.")
    print(f"Found Project: {project.code} - '{project.name}' (ID: {project.id})")

    category = Category.objects.filter(code='1201').first()
    if not category:
        raise ValueError("Category 1201 not found! Please run category seed scripts first.")
    print(f"Found Category: {category.code} - '{category.name}' (ID: {category.id})")

    # Fetch/create SystemSetting to get exchange rate
    setting, created = SystemSetting.objects.get_or_create(id=1, defaults={'usd_exchange_rate': 950.0})
    usd_rate = setting.usd_exchange_rate
    print(f"System setting exchange rate is: {usd_rate}")

    # Prepare Mock Files
    print("\nPreparing mock evidence files for upload...")
    file1 = SimpleUploadedFile("receipt1.pdf", b"pdf content mock", content_type="application/pdf")
    file2 = SimpleUploadedFile("receipt2.png", b"png content mock", content_type="image/png")

    # 2. Prepare POST data
    print("\nStep 2: Preparing POST request data for '/gastos/nuevo/'...")
    post_data = {
        'project': project.id,
        'category': category.id,
        'amount_clp': '2.500.000',
        'tax_type': TaxTypeEnum.IVA_19,
        'tax_amount_clp': '475.000',  # 19% of 2.500.000
        'total_amount_clp': '2.975.000', # 2.500.000 + 475.000
        'currency': CurrencyEnum.CLP,
        'responsible_person': admin_user.id,
        'date': '2026-08-21',
        'description': 'Servicios de consultoría de prototipado rápido y PCBs',
        'new_vendor_rut': '77.888.999-5',
        'new_vendor_name': 'CONEXIONES SPA',
        'toggle-new-vendor': 'on',
        'region': 'Región Metropolitana',
        'comuna': 'Santiago',
        'receipt': [file1, file2],
    }

    # Clean existing data to avoid conflicts and guarantee clean assertion
    print("Cleaning any existing vendor/expense with target RUT to avoid duplication conflicts...")
    Vendor.objects.filter(rut='77.888.999-5').delete()

    # 3. Execute POST request
    print("\nStep 3: Executing POST request to '/gastos/nuevo/'...")
    response = client.post('/gastos/nuevo/', post_data, follow=False)

    # 4. Verify results
    print("\nStep 4: Verifying results...")
    
    # 4.1 Response Status and Redirect
    status_code = response.status_code
    location = response.get('Location', '')
    print(f"  [Assertion 1] Response Status Code: {status_code} (Expected: 302)")
    print(f"  [Assertion 1] Redirect Location: {location} (Expected: /gastos/)")
    assert status_code == 302, f"Expected status code 302, got {status_code}"
    assert '/gastos/' in location, f"Expected redirect to '/gastos/', got '{location}'"
    print("  => Response redirect validation: PASSED")

    # 4.2 New Vendor creation
    vendor = Vendor.objects.filter(rut='77.888.999-5').first()
    assert vendor is not None, "Vendor was not created!"
    print(f"  [Assertion 2] Vendor Created: RUT={vendor.rut}, Name='{vendor.name}' (Expected: 'CONEXIONES SPA')")
    assert vendor.name == 'CONEXIONES SPA', f"Expected name 'CONEXIONES SPA', got '{vendor.name}'"
    print("  => Vendor DB validation: PASSED")

    # 4.3 New Expense creation
    expense = Expense.objects.filter(vendor=vendor, date='2026-08-21').first()
    assert expense is not None, "Expense was not created!"
    print(f"  [Assertion 3] Expense Created with net amount={expense.amount_clp} CLP (Expected: 2500000.00 CLP)")
    assert expense.amount_clp == Decimal('2500000.00'), f"Expected net amount 2500000.00, got {expense.amount_clp}"
    print("  => Expense DB amount validation: PASSED")

    # 4.4 Associated Document verification
    documents = list(expense.documents.all())
    print(f"  [Assertion 4] Associated Documents Count: {len(documents)} (Expected: 2)")
    assert len(documents) == 2, f"Expected 2 documents, found {len(documents)}"
    filenames = [os.path.basename(doc.file.name) for doc in documents]
    print(f"  [Assertion 4] Document filenames in DB: {filenames} (Expected containing 'receipt1.pdf' and 'receipt2.png')")
    assert any("receipt1" in fn and fn.endswith(".pdf") for fn in filenames), "receipt1.pdf not found in documents"
    assert any("receipt2" in fn and fn.endswith(".png") for fn in filenames), "receipt2.png not found in documents"
    print("  => Documents validation: PASSED")

    # 4.5 USD conversion calculation
    expected_usd = Decimal('2500000.00') / usd_rate
    print(f"  [Assertion 5] Expense USD Amount in DB: {expense.amount_usd} (Expected: {expected_usd})")
    assert abs(expense.amount_usd - expected_usd) < Decimal('0.01'), f"USD conversion mismatch: DB={expense.amount_usd}, Expected={expected_usd}"
    print("  => USD exchange rate conversion validation: PASSED")

    # 5. Test bank transfer export
    print("\nStep 5: Testing 'export_bank_transfer_csv' endpoint...")
    # Change expense status to SOLICITADO_FINANZAS to make sure it is exported
    expense.approval_status = ApprovalStatusEnum.SOLICITADO_FINANZAS
    expense.save()

    export_response = client.get('/gastos/exportar/transferencias/')
    print(f"  [Assertion 6] Export Status Code: {export_response.status_code} (Expected: 200)")
    assert export_response.status_code == 200, f"Expected 200, got {export_response.status_code}"
    
    # Decode using utf-8-sig to automatically handle BOM if present, or manually assert it
    content_raw = export_response.content
    assert content_raw.startswith(b'\xef\xbb\xbf'), "BOM bytes not found at the start of CSV!"
    content_str = content_raw.decode('utf-8')
    assert 'RUT Proveedor' in content_str, "CSV header mismatch!"
    assert 'CONEXIONES SPA' in content_str, "CONEXIONES SPA should be present in the export!"
    print("  => Bank Transfer CSV validation: PASSED")

    print("\n" + "=" * 60)
    print("🎉 ALL INTEGRATION VALIDATION STEPS PASSED SUCCESSFULLY! 🎉")
    print("=" * 60)

if __name__ == '__main__':
    try:
        run_test()
    except Exception as e:
        import traceback
        traceback.print_exc()
        sys.exit(1)