"""
Export Router — Generates downloadable files from extracted field data.

POST /api/export
  - Accepts JSON body with fields and desired format
  - Generates the file using the export engine
  - Returns the file as a streaming download
"""
from fastapi import APIRouter, HTTPException
from fastapi.responses import Response

from models.schemas import ExportRequest, ExtractedField
from services.export_engine import generate_export


router = APIRouter(prefix="/api", tags=["export"])


@router.post("/export")
async def export_file(request: ExportRequest):
    """
    Generate and download an export file.

    Body:
      - fields: List of { name, value, field_type, confidence } objects
      - format: "csv" | "xlsx" | "docx" | "pdf"
      - filename: Optional base filename (default: "export")
    """
    if not request.fields:
        raise HTTPException(status_code=400, detail="No fields provided for export.")

    try:
        file_bytes, content_type, extension = generate_export(
            fields=request.fields,
            format=request.format.value,
            filename=request.filename or "export",
        )

        safe_filename = (request.filename or "puffnparse_export") + extension

        return Response(
            content=file_bytes,
            media_type=content_type,
            headers={
                "Content-Disposition": f'attachment; filename="{safe_filename}"',
                "Access-Control-Expose-Headers": "Content-Disposition",
            },
        )

    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Export error: {str(e)}")