# app/api/v1/admin/inventory.py
"""
Admin inventory management endpoints.

Provides inventory management capabilities for administrators:
- View inventory across all vendors
- View vendor-specific inventory
- Set/adjust inventory on behalf of vendors
- Low stock alerts and reporting

Admin Context: Uses admin JWT authentication.
Vendor selection is passed as a request parameter.
"""

import logging

from fastapi import APIRouter, Depends, File, Form, Query, UploadFile
from pydantic import BaseModel
from sqlalchemy.orm import Session

from app.api.deps import get_current_admin_api
from app.core.database import get_db
from app.services.inventory_import_service import inventory_import_service
from app.services.inventory_service import inventory_service
from app.services.inventory_transaction_service import inventory_transaction_service
from models.database.user import User
from app.modules.inventory.schemas import (
    AdminInventoryAdjust,
    AdminInventoryCreate,
    AdminInventoryListResponse,
    AdminInventoryLocationsResponse,
    AdminInventoryStats,
    AdminInventoryTransactionItem,
    AdminInventoryTransactionListResponse,
    AdminLowStockItem,
    AdminTransactionStatsResponse,
    AdminVendorsWithInventoryResponse,
    InventoryAdjust,
    InventoryCreate,
    InventoryMessageResponse,
    InventoryResponse,
    InventoryUpdate,
    ProductInventorySummary,
)

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


# ============================================================================
# List & Statistics Endpoints
# ============================================================================


@router.get("", response_model=AdminInventoryListResponse)
def get_all_inventory(
    skip: int = Query(0, ge=0),
    limit: int = Query(50, ge=1, le=500),
    vendor_id: int | None = Query(None, description="Filter by vendor"),
    location: str | None = Query(None, description="Filter by location"),
    low_stock: int | None = Query(None, ge=0, description="Filter items below threshold"),
    search: str | None = Query(None, description="Search by product title or SKU"),
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """
    Get inventory across all vendors with filtering.

    Allows admins to view and filter inventory across the platform.
    """
    return inventory_service.get_all_inventory_admin(
        db=db,
        skip=skip,
        limit=limit,
        vendor_id=vendor_id,
        location=location,
        low_stock=low_stock,
        search=search,
    )


@router.get("/stats", response_model=AdminInventoryStats)
def get_inventory_stats(
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """Get platform-wide inventory statistics."""
    return inventory_service.get_inventory_stats_admin(db)


@router.get("/low-stock", response_model=list[AdminLowStockItem])
def get_low_stock_items(
    threshold: int = Query(10, ge=0, description="Stock threshold"),
    vendor_id: int | None = Query(None, description="Filter by vendor"),
    limit: int = Query(50, ge=1, le=200),
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """Get items with low stock levels."""
    return inventory_service.get_low_stock_items_admin(
        db=db,
        threshold=threshold,
        vendor_id=vendor_id,
        limit=limit,
    )


@router.get("/vendors", response_model=AdminVendorsWithInventoryResponse)
def get_vendors_with_inventory(
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """Get list of vendors that have inventory entries."""
    return inventory_service.get_vendors_with_inventory_admin(db)


@router.get("/locations", response_model=AdminInventoryLocationsResponse)
def get_inventory_locations(
    vendor_id: int | None = Query(None, description="Filter by vendor"),
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """Get list of unique inventory locations."""
    return inventory_service.get_inventory_locations_admin(db, vendor_id)


# ============================================================================
# Vendor-Specific Endpoints
# ============================================================================


@router.get("/vendors/{vendor_id}", response_model=AdminInventoryListResponse)
def get_vendor_inventory(
    vendor_id: int,
    skip: int = Query(0, ge=0),
    limit: int = Query(50, ge=1, le=500),
    location: str | None = Query(None, description="Filter by location"),
    low_stock: int | None = Query(None, ge=0, description="Filter items below threshold"),
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """Get inventory for a specific vendor."""
    return inventory_service.get_vendor_inventory_admin(
        db=db,
        vendor_id=vendor_id,
        skip=skip,
        limit=limit,
        location=location,
        low_stock=low_stock,
    )


@router.get("/products/{product_id}", response_model=ProductInventorySummary)
def get_product_inventory(
    product_id: int,
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """Get inventory summary for a specific product across all locations."""
    return inventory_service.get_product_inventory_admin(db, product_id)


# ============================================================================
# Inventory Modification Endpoints
# ============================================================================


@router.post("/set", response_model=InventoryResponse)
def set_inventory(
    inventory_data: AdminInventoryCreate,
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """
    Set exact inventory quantity for a product at a location.

    Admin version - requires explicit vendor_id in request body.
    """
    # Verify vendor exists
    inventory_service.verify_vendor_exists(db, inventory_data.vendor_id)

    # Convert to standard schema for service
    service_data = InventoryCreate(
        product_id=inventory_data.product_id,
        location=inventory_data.location,
        quantity=inventory_data.quantity,
    )

    result = inventory_service.set_inventory(
        db=db,
        vendor_id=inventory_data.vendor_id,
        inventory_data=service_data,
    )

    logger.info(
        f"Admin {current_admin.email} set inventory for product {inventory_data.product_id} "
        f"at {inventory_data.location}: {inventory_data.quantity} units"
    )

    db.commit()
    return result


@router.post("/adjust", response_model=InventoryResponse)
def adjust_inventory(
    adjustment: AdminInventoryAdjust,
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """
    Adjust inventory by adding or removing quantity.

    Positive quantity = add stock, negative = remove stock.
    Admin version - requires explicit vendor_id in request body.
    """
    # Verify vendor exists
    inventory_service.verify_vendor_exists(db, adjustment.vendor_id)

    # Convert to standard schema for service
    service_data = InventoryAdjust(
        product_id=adjustment.product_id,
        location=adjustment.location,
        quantity=adjustment.quantity,
    )

    result = inventory_service.adjust_inventory(
        db=db,
        vendor_id=adjustment.vendor_id,
        inventory_data=service_data,
    )

    sign = "+" if adjustment.quantity >= 0 else ""
    logger.info(
        f"Admin {current_admin.email} adjusted inventory for product {adjustment.product_id} "
        f"at {adjustment.location}: {sign}{adjustment.quantity} units"
        f"{f' (reason: {adjustment.reason})' if adjustment.reason else ''}"
    )

    db.commit()
    return result


@router.put("/{inventory_id}", response_model=InventoryResponse)
def update_inventory(
    inventory_id: int,
    inventory_update: InventoryUpdate,
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """Update inventory entry fields."""
    # Get inventory to find vendor_id
    inventory = inventory_service.get_inventory_by_id_admin(db, inventory_id)

    result = inventory_service.update_inventory(
        db=db,
        vendor_id=inventory.vendor_id,
        inventory_id=inventory_id,
        inventory_update=inventory_update,
    )

    logger.info(f"Admin {current_admin.email} updated inventory {inventory_id}")

    db.commit()
    return result


@router.delete("/{inventory_id}", response_model=InventoryMessageResponse)
def delete_inventory(
    inventory_id: int,
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """Delete inventory entry."""
    # Get inventory to find vendor_id and log details
    inventory = inventory_service.get_inventory_by_id_admin(db, inventory_id)
    vendor_id = inventory.vendor_id
    product_id = inventory.product_id
    location = inventory.location

    inventory_service.delete_inventory(
        db=db,
        vendor_id=vendor_id,
        inventory_id=inventory_id,
    )

    logger.info(
        f"Admin {current_admin.email} deleted inventory {inventory_id} "
        f"(product {product_id} at {location})"
    )

    db.commit()
    return InventoryMessageResponse(message="Inventory deleted successfully")


# ============================================================================
# Import Endpoints
# ============================================================================


class UnmatchedGtin(BaseModel):
    """GTIN that couldn't be matched to a product."""

    gtin: str
    quantity: int
    product_name: str


class InventoryImportResponse(BaseModel):
    """Response from inventory import."""

    success: bool
    total_rows: int
    entries_created: int
    entries_updated: int
    quantity_imported: int
    unmatched_gtins: list[UnmatchedGtin]
    errors: list[str]


@router.post("/import", response_model=InventoryImportResponse)
async def import_inventory(
    file: UploadFile = File(..., description="TSV/CSV file with BIN, EAN, PRODUCT, QUANTITY columns"),
    vendor_id: int = Form(..., description="Vendor ID"),
    warehouse: str = Form("strassen", description="Warehouse name"),
    clear_existing: bool = Form(False, description="Clear existing inventory before import"),
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """
    Import inventory from a TSV/CSV file.

    File format (TSV recommended):
    - Required columns: BIN, EAN
    - Optional columns: PRODUCT (for display), QUANTITY (defaults to 1 per row)

    If QUANTITY column is present, each row represents the quantity specified.
    If QUANTITY is absent, each row counts as 1 unit (rows with same EAN+BIN are summed).

    Products are matched by GTIN/EAN. Unmatched GTINs are reported in the response.
    """
    # Verify vendor exists
    inventory_service.verify_vendor_exists(db, vendor_id)

    # Read file content
    content = await file.read()
    try:
        content_str = content.decode("utf-8")
    except UnicodeDecodeError:
        content_str = content.decode("latin-1")

    # Detect delimiter
    first_line = content_str.split("\n")[0] if content_str else ""
    delimiter = "\t" if "\t" in first_line else ","

    # Run import
    result = inventory_import_service.import_from_text(
        db=db,
        content=content_str,
        vendor_id=vendor_id,
        warehouse=warehouse,
        delimiter=delimiter,
        clear_existing=clear_existing,
    )

    if result.success:
        db.commit()
        logger.info(
            f"Admin {current_admin.email} imported inventory: "
            f"{result.entries_created} created, {result.entries_updated} updated, "
            f"{result.quantity_imported} total units"
        )
    else:
        db.rollback()
        logger.error(f"Inventory import failed: {result.errors}")

    return InventoryImportResponse(
        success=result.success,
        total_rows=result.total_rows,
        entries_created=result.entries_created,
        entries_updated=result.entries_updated,
        quantity_imported=result.quantity_imported,
        unmatched_gtins=[UnmatchedGtin(**g) for g in result.unmatched_gtins],
        errors=result.errors,
    )


# ============================================================================
# Transaction History Endpoints
# ============================================================================


@router.get("/transactions", response_model=AdminInventoryTransactionListResponse)
def get_all_transactions(
    skip: int = Query(0, ge=0),
    limit: int = Query(50, ge=1, le=200),
    vendor_id: int | None = Query(None, description="Filter by vendor"),
    product_id: int | None = Query(None, description="Filter by product"),
    transaction_type: str | None = Query(None, description="Filter by type"),
    order_id: int | None = Query(None, description="Filter by order"),
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """
    Get inventory transaction history across all vendors.

    Returns a paginated list of all stock movements with vendor and product details.
    """
    transactions, total = inventory_transaction_service.get_all_transactions_admin(
        db=db,
        skip=skip,
        limit=limit,
        vendor_id=vendor_id,
        product_id=product_id,
        transaction_type=transaction_type,
        order_id=order_id,
    )

    return AdminInventoryTransactionListResponse(
        transactions=[AdminInventoryTransactionItem(**tx) for tx in transactions],
        total=total,
        skip=skip,
        limit=limit,
    )


@router.get("/transactions/stats", response_model=AdminTransactionStatsResponse)
def get_transaction_stats(
    db: Session = Depends(get_db),
    current_admin: User = Depends(get_current_admin_api),
):
    """Get transaction statistics for the platform."""
    stats = inventory_transaction_service.get_transaction_stats_admin(db)
    return AdminTransactionStatsResponse(**stats)