"""Import/export routes — CSV import, dry-run preview, CSV/XLSX export."""

from __future__ import annotations

import io
import uuid

from fastapi import (
    APIRouter,
    Depends,
    File,
    Form,
    HTTPException,
    Query,
    UploadFile,
)
from sqlalchemy.ext.asyncio import AsyncSession
from starlette.responses import StreamingResponse

from app.core.db import get_db
from app.deps import require_permission
from app.services import import_export_service

router = APIRouter(prefix="/api/v1", tags=["import_export"])


@router.post("/import")
async def import_csv(
    file: UploadFile = File(...),
    entity_type: str = Form("companies"),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("import_export:write")),
):
    """Import companies or contacts from CSV file.
    entity_type: 'companies' or 'contacts'.
    """
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])


    content = await file.read()
    csv_content = content.decode("utf-8")

    result = await import_export_service.import_csv(
        db,
        tenant_id,
        user_id,
        csv_content,
        entity_type=entity_type,
        dry_run=False,
    )
    return result


@router.post("/import/preview")
async def import_csv_preview(
    file: UploadFile = File(...),
    entity_type: str = Form("companies"),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("import_export:read")),
):
    """Preview CSV import (dry-run — no DB changes)."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])


    content = await file.read()
    csv_content = content.decode("utf-8")

    result = await import_export_service.import_csv(
        db,
        tenant_id,
        user_id,
        csv_content,
        entity_type=entity_type,
        dry_run=True,
    )
    return result


@router.get("/export")
async def export_data(
    entity_type: str = Query("contacts", pattern="^(contacts|companies)$"),
    format: str = Query("csv", pattern="^(csv|xlsx)$"),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("import_export:read")),
):
    """Export contacts or companies as CSV or XLSX file download.

    Query params:
      - entity_type: 'contacts' or 'companies' (default: contacts)
      - format: 'csv' or 'xlsx' (default: csv)
    """
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    is_system_admin = current_user.get("is_system_admin", False)

    # Determine filename based on entity_type
    filename = f"{entity_type}_export.csv"

    # Fetch CSV data from the appropriate service function
    if entity_type == "contacts":
        csv_data = await import_export_service.export_contacts_csv(
            db, tenant_id, user_id=user_id, is_system_admin=is_system_admin
        )
    elif entity_type == "companies":
        csv_data = await import_export_service.export_companies_csv(
            db, tenant_id, user_id=user_id, is_system_admin=is_system_admin
        )
    else:
        raise HTTPException(status_code=400, detail=f"Unsupported entity_type: {entity_type}")

    # XLSX format handling
    if format == "xlsx":
        try:
            import openpyxl

            wb = openpyxl.Workbook()
            ws = wb.active
            ws.title = entity_type.capitalize()

            # Parse the CSV string and populate the worksheet
            import csv as _csv

            reader = _csv.reader(io.StringIO(csv_data))
            for row in reader:
                ws.append(row)

            xlsx_buffer = io.BytesIO()
            wb.save(xlsx_buffer)
            xlsx_buffer.seek(0)

            xlsx_filename = f"{entity_type}_export.xlsx"
            return StreamingResponse(
                xlsx_buffer,
                media_type="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
                headers={"Content-Disposition": f'attachment; filename="{xlsx_filename}"'},
            )
        except ImportError:
            # openpyxl not available — fall back to CSV with a warning header
            media_type = "text/csv"
            headers = {
                "Content-Disposition": f'attachment; filename="{filename}"',
                "X-Export-Warning": "openpyxl not installed, falling back to CSV format",
            }
            return StreamingResponse(
                iter([csv_data.encode("utf-8")]),
                media_type=media_type,
                headers=headers,
            )

    # Default: CSV format
    return StreamingResponse(
        iter([csv_data.encode("utf-8")]),
        media_type="text/csv",
        headers={"Content-Disposition": f'attachment; filename="{filename}"'},
    )