"""
Admin export endpoints for inventory snapshot and audit trail exports.
Supports CSV and Excel formats.
"""

from datetime import datetime
from fastapi import APIRouter, Depends, HTTPException, Query
from fastapi.responses import StreamingResponse
from sqlalchemy.orm import Session

from backend.database import get_db
from backend.auth import get_current_admin
from backend.models import Item, AuditLog
from backend.services.export_service import (
    InventorySnapshotExporter,
    AuditTrailExporter,
    get_export_filename,
)

router = APIRouter(prefix="/admin", tags=["admin-exports"])


def validate_export_format(format_str: str) -> str:
    """Validate and normalize export format."""
    format_lower = format_str.lower() if format_str else "csv"
    if format_lower not in ("csv", "xlsx"):
        raise HTTPException(
            status_code=400, detail="Invalid format. Use 'csv' or 'xlsx'."
        )
    return format_lower


@router.post("/inventory-snapshot")
async def export_inventory_snapshot(
    format: str = Query("csv", description="Export format: csv or xlsx"),
    db: Session = Depends(get_db),
    admin_user=Depends(get_current_admin),
):
    """
    Export inventory snapshot in CSV or Excel format.

    Requires admin authorization.
    Returns file download with timestamp in filename.
    """
    format_type = validate_export_format(format)
    timestamp = datetime.now().strftime("%Y-%m-%d")

    # Fetch all items
    items = db.query(Item).all()

    # Generate export
    if format_type == "csv":
        content = InventorySnapshotExporter.to_csv(items, timestamp)
        media_type = "text/csv; charset=utf-8"
    else:
        content = InventorySnapshotExporter.to_excel(items, timestamp)
        media_type = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"

    filename = get_export_filename("inventory_snapshot", format_type, timestamp)

    # Log export action
    from backend.models import AuditLog
    audit_entry = AuditLog(
        user_id=admin_user.sub,
        action="EXPORT_INVENTORY_SNAPSHOT",
        details=f"Exported in {format_type} format",
    )
    db.add(audit_entry)
    db.commit()

    # Return file response
    if format_type == "csv":
        return StreamingResponse(
            io.BytesIO(content.encode("utf-8")),
            media_type=media_type,
            headers={"Content-Disposition": f"attachment; filename={filename}"}
        )
    else:
        return StreamingResponse(
            io.BytesIO(content),
            media_type=media_type,
            headers={"Content-Disposition": f"attachment; filename={filename}"}
        )


@router.post("/audit-trail")
async def export_audit_trail(
    format: str = Query("csv", description="Export format: csv or xlsx"),
    db: Session = Depends(get_db),
    admin_user=Depends(get_current_admin),
):
    """
    Export audit trail in CSV or Excel format.

    Requires admin authorization.
    Returns file download with timestamp in filename.
    """
    format_type = validate_export_format(format)
    timestamp = datetime.now().strftime("%Y-%m-%d")

    # Fetch all audit logs
    logs = db.query(AuditLog).all()

    # Generate export
    if format_type == "csv":
        content = AuditTrailExporter.to_csv(logs, timestamp)
        media_type = "text/csv; charset=utf-8"
    else:
        content = AuditTrailExporter.to_excel(logs, timestamp)
        media_type = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"

    filename = get_export_filename("audit_trail", format_type, timestamp)

    # Log export action
    audit_entry = AuditLog(
        user_id=admin_user.sub,
        action="EXPORT_AUDIT_TRAIL",
        details=f"Exported in {format_type} format",
    )
    db.add(audit_entry)
    db.commit()

    # Return file response
    if format_type == "csv":
        return StreamingResponse(
            io.BytesIO(content.encode("utf-8")),
            media_type=media_type,
            headers={"Content-Disposition": f"attachment; filename={filename}"}
        )
    else:
        return StreamingResponse(
            io.BytesIO(content),
            media_type=media_type,
            headers={"Content-Disposition": f"attachment; filename={filename}"}
        )


@router.get("/reports/export")
async def export_db(
    format: str = Query("csv", description="Export format: csv or xlsx"),
    type: str = Query("inventory", description="Export type: inventory, audit, or combined"),
    db: Session = Depends(get_db),
    admin_user=Depends(get_current_admin),
):
    """
    Combined export endpoint for frontend.
    Supports inventory snapshot and audit trail exports.

    Parameters:
    - format: 'csv' or 'xlsx'
    - type: 'inventory', 'audit', or 'combined'

    Requires admin authorization.
    """
    import io

    format_type = validate_export_format(format)
    timestamp = datetime.now().strftime("%Y-%m-%d")

    if type not in ("inventory", "audit", "combined"):
        raise HTTPException(
            status_code=400,
            detail="Invalid type. Use 'inventory', 'audit', or 'combined'."
        )

    # Determine what to export
    export_inventory = type in ("inventory", "combined")
    export_audit = type in ("audit", "combined")

    # For combined or single exports
    if export_inventory and not export_audit:
        # Inventory only
        items = db.query(Item).all()
        if format_type == "csv":
            content = InventorySnapshotExporter.to_csv(items, timestamp)
            media_type = "text/csv; charset=utf-8"
        else:
            content = InventorySnapshotExporter.to_excel(items, timestamp)
            media_type = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
        filename = get_export_filename("inventory_snapshot", format_type, timestamp)

    elif export_audit and not export_inventory:
        # Audit only
        logs = db.query(AuditLog).all()
        if format_type == "csv":
            content = AuditTrailExporter.to_csv(logs, timestamp)
            media_type = "text/csv; charset=utf-8"
        else:
            content = AuditTrailExporter.to_excel(logs, timestamp)
            media_type = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
        filename = get_export_filename("audit_trail", format_type, timestamp)

    else:
        # Combined - inventory + audit trail
        items = db.query(Item).all()
        logs = db.query(AuditLog).all()

        if format_type == "csv":
            inv_content = InventorySnapshotExporter.to_csv(items, timestamp)
            audit_content = AuditTrailExporter.to_csv(logs, timestamp)
            # Combine with separator
            content = f"{inv_content}\n\n--- AUDIT TRAIL ---\n\n{audit_content}"
            media_type = "text/csv; charset=utf-8"
        else:
            # For Excel, we'd need to create multi-sheet workbook (openpyxl)
            # For now, just export inventory
            content = InventorySnapshotExporter.to_excel(items, timestamp)
            media_type = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"

        filename = get_export_filename("inventory_and_audit", format_type, timestamp)

    # Log export action
    audit_entry = AuditLog(
        user_id=admin_user.sub,
        action="EXPORT_DB",
        details=f"Exported {type} in {format_type} format",
    )
    db.add(audit_entry)
    db.commit()

    # Return file response
    if format_type == "csv":
        return StreamingResponse(
            io.BytesIO(content.encode("utf-8")),
            media_type=media_type,
            headers={"Content-Disposition": f"attachment; filename={filename}"}
        )
    else:
        return StreamingResponse(
            io.BytesIO(content),
            media_type=media_type,
            headers={"Content-Disposition": f"attachment; filename={filename}"}
        )