"""Import/export routes — CSV/JSON/XLSX import, preview, validate, background jobs, CSV/XLSX export."""

from __future__ import annotations

import io
import json
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
from app.services.import_export_helpers import (
    parse_file,
    write_xlsx,
)

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

# Row threshold for background job processing
_BACKGROUND_THRESHOLD = 1000


@router.post("/import")
async def import_csv(
    file: UploadFile = File(...),
    entity_type: str = Form(...),
    field_mapping: str = Form(None),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("import_export:write")),
):
    """Import companies or contacts from CSV/JSON/XLSX file.

    entity_type: 'companies' or 'contacts'.
    field_mapping: Optional JSON string of source_column -> target_field mapping.
    For files > 1000 rows, the import runs as a background ARQ job.
    """
    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", errors="replace")

    # Parse mapping if provided
    mapping = None
    if field_mapping:
        try:
            mapping = json.loads(field_mapping)
        except json.JSONDecodeError:
            raise HTTPException(status_code=400, detail="Invalid field_mapping JSON") from None

    # Check row count for background processing
    try:
        rows = parse_file(file.filename or "upload.csv", content)
    except Exception as exc:
        raise HTTPException(status_code=400, detail=f"Failed to parse file: {exc}") from exc

    if len(rows) > _BACKGROUND_THRESHOLD:
        # Enqueue as background job
        from app.services.import_export_jobs import create_import_job

        try:
            job_id = await create_import_job(
                entity_type=entity_type,
                csv_content=csv_content,
                tenant_id=tenant_id,
                user_id=user_id,
                field_mapping=mapping,
            )
            return {
                "status": "pending",
                "job_id": job_id,
                "message": f"Import enqueued as background job ({len(rows)} rows)",
                "total": len(rows),
            }
        except Exception as exc:
            raise HTTPException(status_code=500, detail=f"Failed to enqueue import job: {exc}") from exc

    # Synchronous import for smaller files
    result = await import_export_service.import_csv(
        db,
        tenant_id,
        user_id,
        csv_content,
        entity_type=entity_type,
        dry_run=False,
        field_mapping=mapping,
    )
    return result


@router.post("/import/preview")
async def import_csv_preview(
    file: UploadFile = File(...),
    entity_type: str = Form(...),
    current_user: dict = Depends(require_permission("import_export:read")),
):
    """Preview CSV import (dry-run — no DB changes).

    Returns first 10 rows, detected columns, and mapping suggestion.
    """
    content = await file.read()

    try:
        result = import_export_service.preview_import(
            filename=file.filename or "upload.csv",
            content=content,
            entity_type=entity_type,
        )
    except Exception as exc:
        raise HTTPException(status_code=400, detail=f"Failed to parse file: {exc}") from exc

    return result


@router.post("/import/validate")
async def import_validate(
    file: UploadFile = File(...),
    entity_type: str = Form(...),
    field_mapping: str = Form(None),
    current_user: dict = Depends(require_permission("import_export:read")),
):
    """Validate all rows against mapping and return error report without importing."""
    content = await file.read()

    mapping = None
    if field_mapping:
        try:
            mapping = json.loads(field_mapping)
        except json.JSONDecodeError:
            raise HTTPException(status_code=400, detail="Invalid field_mapping JSON") from None

    try:
        result = import_export_service.validate_import(
            filename=file.filename or "upload.csv",
            content=content,
            entity_type=entity_type,
            field_mapping=mapping,
        )
    except Exception as exc:
        raise HTTPException(status_code=400, detail=f"Failed to validate file: {exc}") from exc

    return result


@router.get("/import/status/{job_id}")
async def import_job_status(
    job_id: str,
    current_user: dict = Depends(require_permission("import_export:read")),
):
    """Get status of a background import job."""
    from app.services.import_export_jobs import get_import_job_status

    status = await get_import_job_status(job_id)
    if status is None:
        raise HTTPException(status_code=404, detail=f"Job {job_id} not found")
    return status


@router.post("/import/contacts")
async def import_contacts_route(
    file: UploadFile = File(...),
    field_mapping: str = Form(None),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("import_export:write")),
):
    """Import contacts from CSV/JSON/XLSX file.

    For files > 1000 rows, runs as background ARQ job.
    """
    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", errors="replace")

    mapping = None
    if field_mapping:
        try:
            mapping = json.loads(field_mapping)
        except json.JSONDecodeError:
            raise HTTPException(status_code=400, detail="Invalid field_mapping JSON") from None

    # Check row count for background processing
    try:
        rows = parse_file(file.filename or "upload.csv", content)
    except Exception as exc:
        raise HTTPException(status_code=400, detail=f"Failed to parse file: {exc}") from exc

    if len(rows) > _BACKGROUND_THRESHOLD:
        from app.services.import_export_jobs import create_import_job

        try:
            job_id = await create_import_job(
                entity_type="contacts",
                csv_content=csv_content,
                tenant_id=tenant_id,
                user_id=user_id,
                field_mapping=mapping,
            )
            return {
                "status": "pending",
                "job_id": job_id,
                "message": f"Import enqueued as background job ({len(rows)} rows)",
                "total": len(rows),
            }
        except Exception as exc:
            raise HTTPException(status_code=500, detail=f"Failed to enqueue import job: {exc}") from exc

    result = await import_export_service.import_contacts(
        db,
        tenant_id,
        user_id,
        csv_content,
        dry_run=False,
        field_mapping=mapping,
    )
    return result


@router.post("/import/companies")
async def import_companies_route(
    file: UploadFile = File(...),
    field_mapping: str = Form(None),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(require_permission("import_export:write")),
):
    """Import companies from CSV/JSON/XLSX file.

    For files > 1000 rows, runs as background ARQ job.
    """
    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", errors="replace")

    mapping = None
    if field_mapping:
        try:
            mapping = json.loads(field_mapping)
        except json.JSONDecodeError:
            raise HTTPException(status_code=400, detail="Invalid field_mapping JSON") from None

    # Check row count for background processing
    try:
        rows = parse_file(file.filename or "upload.csv", content)
    except Exception as exc:
        raise HTTPException(status_code=400, detail=f"Failed to parse file: {exc}") from exc

    if len(rows) > _BACKGROUND_THRESHOLD:
        from app.services.import_export_jobs import create_import_job

        try:
            job_id = await create_import_job(
                entity_type="companies",
                csv_content=csv_content,
                tenant_id=tenant_id,
                user_id=user_id,
                field_mapping=mapping,
            )
            return {
                "status": "pending",
                "job_id": job_id,
                "message": f"Import enqueued as background job ({len(rows)} rows)",
                "total": len(rows),
            }
        except Exception as exc:
            raise HTTPException(status_code=500, detail=f"Failed to enqueue import job: {exc}") from exc

    result = await import_export_service.import_companies(
        db,
        tenant_id,
        user_id,
        csv_content,
        dry_run=False,
        field_mapping=mapping,
    )
    return result


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

    Query params:
      - entity_type: 'contacts' or 'companies' (default: contacts)
      - format: 'csv', 'xlsx', or 'json' (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)

    # Fetch 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}")

    # Parse CSV data back to rows for format conversion
    import csv as _csv

    reader = _csv.reader(io.StringIO(csv_data))
    all_rows = list(reader)
    if not all_rows:
        raise HTTPException(status_code=404, detail="No data to export")
    headers = all_rows[0]
    data_rows = [dict(zip(headers, row, strict=False)) for row in all_rows[1:]]

    if format == "xlsx":
        try:
            xlsx_bytes = write_xlsx(data_rows, headers)
            xlsx_filename = f"{entity_type}_export.xlsx"
            return StreamingResponse(
                io.BytesIO(xlsx_bytes),
                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="{entity_type}_export.csv"',
                "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,
            )

    if format == "json":
        from app.services.import_export_helpers import write_json

        json_bytes = write_json(data_rows)
        json_filename = f"{entity_type}_export.json"
        return StreamingResponse(
            io.BytesIO(json_bytes),
            media_type="application/json",
            headers={"Content-Disposition": f'attachment; filename="{json_filename}"'},
        )

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