# app/api/v1/vendor/invoices.py
"""
Vendor invoice management endpoints.

Vendor Context: Uses token_vendor_id from JWT token (authenticated vendor API pattern).
The get_current_vendor_api dependency guarantees token_vendor_id is present.

Endpoints:
- GET /invoices - List vendor invoices
- GET /invoices/{invoice_id} - Get invoice details
- POST /invoices - Create invoice from order
- PUT /invoices/{invoice_id}/status - Update invoice status
- GET /invoices/{invoice_id}/pdf - Download invoice PDF
- POST /invoices/{invoice_id}/pdf - Generate/regenerate invoice PDF
- GET /invoices/settings - Get invoice settings
- POST /invoices/settings - Create invoice settings
- PUT /invoices/settings - Update invoice settings
- GET /invoices/stats - Get invoice statistics
"""

import logging
from pathlib import Path

from fastapi import APIRouter, Depends, Query
from fastapi.responses import FileResponse
from sqlalchemy.orm import Session

from app.api.deps import get_current_vendor_api
from app.core.database import get_db
from app.exceptions.invoice import (
    InvoiceNotFoundException,
    InvoicePDFGenerationException,
    InvoicePDFNotFoundException,
    InvoiceSettingsNotFoundException,
)
from app.services.invoice_service import invoice_service
from models.database.user import User
from models.schema.invoice import (
    InvoiceCreate,
    InvoiceListPaginatedResponse,
    InvoiceListResponse,
    InvoicePDFGeneratedResponse,
    InvoiceResponse,
    InvoiceStatsResponse,
    InvoiceStatusUpdate,
    VendorInvoiceSettingsCreate,
    VendorInvoiceSettingsResponse,
    VendorInvoiceSettingsUpdate,
)

router = APIRouter(prefix="/invoices")
logger = logging.getLogger(__name__)


# ============================================================================
# Invoice Settings
# ============================================================================


@router.get("/settings", response_model=VendorInvoiceSettingsResponse | None)
def get_invoice_settings(
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Get vendor invoice settings.

    Returns null if settings not yet configured.
    """
    settings = invoice_service.get_settings(db, current_user.token_vendor_id)
    if settings:
        return VendorInvoiceSettingsResponse.model_validate(settings)
    return None


@router.post("/settings", response_model=VendorInvoiceSettingsResponse, status_code=201)
def create_invoice_settings(
    data: VendorInvoiceSettingsCreate,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Create vendor invoice settings.

    Required before creating invoices. Sets company details,
    VAT number, invoice numbering preferences, and payment info.
    """
    settings = invoice_service.create_settings(
        db=db,
        vendor_id=current_user.token_vendor_id,
        data=data,
    )
    return VendorInvoiceSettingsResponse.model_validate(settings)


@router.put("/settings", response_model=VendorInvoiceSettingsResponse)
def update_invoice_settings(
    data: VendorInvoiceSettingsUpdate,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Update vendor invoice settings.
    """
    settings = invoice_service.update_settings(
        db=db,
        vendor_id=current_user.token_vendor_id,
        data=data,
    )
    return VendorInvoiceSettingsResponse.model_validate(settings)


# ============================================================================
# Invoice Statistics
# ============================================================================


@router.get("/stats", response_model=InvoiceStatsResponse)
def get_invoice_stats(
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Get invoice statistics for the vendor.

    Returns:
    - total_invoices: Total number of invoices
    - total_revenue: Total revenue from issued/paid invoices (EUR)
    - draft_count: Number of draft invoices
    - paid_count: Number of paid invoices
    """
    stats = invoice_service.get_invoice_stats(db, current_user.token_vendor_id)
    return InvoiceStatsResponse(
        total_invoices=stats.get("total_invoices", 0),
        total_revenue_cents=stats.get("total_revenue_cents", 0),
        draft_count=stats.get("draft_count", 0),
        issued_count=stats.get("issued_count", 0),
        paid_count=stats.get("paid_count", 0),
        cancelled_count=stats.get("cancelled_count", 0),
    )


# ============================================================================
# Invoice CRUD
# ============================================================================


@router.get("", response_model=InvoiceListPaginatedResponse)
def list_invoices(
    page: int = Query(1, ge=1, description="Page number"),
    per_page: int = Query(20, ge=1, le=100, description="Items per page"),
    status: str | None = Query(None, description="Filter by status"),
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    List vendor invoices with pagination.

    Supports filtering by status: draft, issued, paid, cancelled
    """
    invoices, total = invoice_service.list_invoices(
        db=db,
        vendor_id=current_user.token_vendor_id,
        status=status,
        page=page,
        per_page=per_page,
    )

    # Build response with buyer name from snapshot
    items = []
    for inv in invoices:
        buyer_name = inv.buyer_details.get("name") if inv.buyer_details else None
        items.append(
            InvoiceListResponse(
                id=inv.id,
                invoice_number=inv.invoice_number,
                invoice_date=inv.invoice_date,
                status=inv.status,
                currency=inv.currency,
                total_cents=inv.total_cents,
                order_id=inv.order_id,
                buyer_name=buyer_name,
            )
        )

    pages = (total + per_page - 1) // per_page if total > 0 else 1

    return InvoiceListPaginatedResponse(
        items=items,
        total=total,
        page=page,
        per_page=per_page,
        pages=pages,
    )


@router.get("/{invoice_id}", response_model=InvoiceResponse)
def get_invoice(
    invoice_id: int,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Get invoice details by ID.
    """
    invoice = invoice_service.get_invoice_or_raise(
        db=db,
        vendor_id=current_user.token_vendor_id,
        invoice_id=invoice_id,
    )
    return InvoiceResponse.model_validate(invoice)


@router.post("", response_model=InvoiceResponse, status_code=201)
def create_invoice(
    data: InvoiceCreate,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Create an invoice from an order.

    Automatically:
    - Captures seller/buyer details snapshots
    - Calculates VAT based on buyer country and OSS settings
    - Generates invoice number
    """
    invoice = invoice_service.create_invoice_from_order(
        db=db,
        vendor_id=current_user.token_vendor_id,
        order_id=data.order_id,
        notes=data.notes,
    )
    return InvoiceResponse.model_validate(invoice)


@router.put("/{invoice_id}/status", response_model=InvoiceResponse)
def update_invoice_status(
    invoice_id: int,
    data: InvoiceStatusUpdate,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Update invoice status.

    Valid statuses:
    - draft: Invoice created but not yet sent
    - issued: Invoice sent to customer
    - paid: Payment received
    - cancelled: Invoice cancelled

    Note: Cancelled invoices cannot be modified.
    """
    invoice = invoice_service.update_status(
        db=db,
        vendor_id=current_user.token_vendor_id,
        invoice_id=invoice_id,
        new_status=data.status,
    )
    return InvoiceResponse.model_validate(invoice)


# ============================================================================
# PDF Generation
# ============================================================================


@router.post("/{invoice_id}/pdf", response_model=InvoicePDFGeneratedResponse)
def generate_invoice_pdf(
    invoice_id: int,
    regenerate: bool = Query(False, description="Force regenerate if exists"),
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Generate PDF for an invoice.

    Set regenerate=true to force regeneration if PDF already exists.
    Returns the path to the generated PDF.
    """
    pdf_path = invoice_service.generate_pdf(
        db=db,
        vendor_id=current_user.token_vendor_id,
        invoice_id=invoice_id,
        force_regenerate=regenerate,
    )
    return InvoicePDFGeneratedResponse(pdf_path=pdf_path)


@router.get("/{invoice_id}/pdf")
def download_invoice_pdf(
    invoice_id: int,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Download invoice PDF.

    Returns the PDF file for download.
    Generates PDF if not already generated.
    """
    # Check if PDF exists, generate if not
    pdf_path = invoice_service.get_pdf_path(
        db=db,
        vendor_id=current_user.token_vendor_id,
        invoice_id=invoice_id,
    )

    if not pdf_path:
        # Generate PDF
        pdf_path = invoice_service.generate_pdf(
            db=db,
            vendor_id=current_user.token_vendor_id,
            invoice_id=invoice_id,
        )

    # Verify file exists
    if not Path(pdf_path).exists():
        raise InvoicePDFNotFoundException(invoice_id)

    # Get invoice for filename
    invoice = invoice_service.get_invoice_or_raise(
        db=db,
        vendor_id=current_user.token_vendor_id,
        invoice_id=invoice_id,
    )

    filename = f"invoice-{invoice.invoice_number}.pdf"

    return FileResponse(
        path=pdf_path,
        media_type="application/pdf",
        filename=filename,
        headers={
            "Content-Disposition": f'attachment; filename="{filename}"'
        },
    )