"""CSV-Import: Templates verwalten, Datei-Vorschau, verbuchen, rückgängig machen."""

import json

from fastapi import APIRouter, Depends, File, Form, HTTPException, UploadFile, status
from sqlalchemy.orm import Session

from ..database import get_db
from ..deps import get_current_user, get_owned
from ..models import Account, AmountMode, ImportBatch, ImportStatus, ImportTemplate, User
from ..schemas import (
    ImportBatchOut,
    ImportCommitIn,
    ImportTemplateCreate,
    ImportTemplateOut,
    ImportTemplateUpdate,
)
from ..services import csv_import

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


def _to_out(tpl: ImportTemplate) -> ImportTemplateOut:
    return ImportTemplateOut(
        id=tpl.id, name=tpl.name, delimiter=tpl.delimiter, decimal_sep=tpl.decimal_sep,
        date_format=tpl.date_format, encoding=tpl.encoding, has_header=tpl.has_header,
        skip_rows=tpl.skip_rows, amount_mode=tpl.amount_mode,
        column_map=json.loads(tpl.column_map or "{}"),
        filter_column=tpl.filter_column, filter_value=tpl.filter_value,
    )


# --- Templates -------------------------------------------------------------


@router.get("/presets")
def list_presets(_: User = Depends(get_current_user)) -> list[dict]:
    """Vorgefertigte Bank-Vorlagen (füllen die Format-/Spalten-Einstellungen)."""
    return csv_import.PRESETS


@router.get("/templates", response_model=list[ImportTemplateOut])
def list_templates(db: Session = Depends(get_db), user: User = Depends(get_current_user)):
    rows = db.query(ImportTemplate).filter(ImportTemplate.owner_id == user.id).order_by(ImportTemplate.name).all()
    return [_to_out(t) for t in rows]


@router.post("/templates", response_model=ImportTemplateOut, status_code=status.HTTP_201_CREATED)
def create_template(payload: ImportTemplateCreate, db: Session = Depends(get_db), user: User = Depends(get_current_user)):
    tpl = ImportTemplate(
        owner_id=user.id, name=payload.name.strip(), delimiter=payload.delimiter,
        decimal_sep=payload.decimal_sep, date_format=payload.date_format, encoding=payload.encoding,
        has_header=payload.has_header, skip_rows=payload.skip_rows, amount_mode=payload.amount_mode,
        column_map=json.dumps(payload.column_map),
        filter_column=payload.filter_column, filter_value=payload.filter_value,
    )
    db.add(tpl)
    db.commit()
    db.refresh(tpl)
    return _to_out(tpl)


@router.patch("/templates/{template_id}", response_model=ImportTemplateOut)
def update_template(template_id: int, payload: ImportTemplateUpdate, db: Session = Depends(get_db), user: User = Depends(get_current_user)):
    tpl = get_owned(db, ImportTemplate, template_id, user)
    data = payload.model_dump(exclude_unset=True)
    if "column_map" in data and data["column_map"] is not None:
        tpl.column_map = json.dumps(data.pop("column_map"))
    for key, value in data.items():
        if value is not None:
            setattr(tpl, key, value)
    db.commit()
    db.refresh(tpl)
    return _to_out(tpl)


@router.delete("/templates/{template_id}", status_code=status.HTTP_204_NO_CONTENT)
def delete_template(template_id: int, db: Session = Depends(get_db), user: User = Depends(get_current_user)):
    tpl = get_owned(db, ImportTemplate, template_id, user)
    db.delete(tpl)
    db.commit()


# --- Datei-Vorschau --------------------------------------------------------


def _transient(user_id: int, **fields) -> ImportTemplate:
    return ImportTemplate(owner_id=user_id, name="_transient", **fields)


@router.post("/raw")
async def raw_preview(
    file: UploadFile = File(...),
    delimiter: str = Form(";"),
    encoding: str = Form("utf-8"),
    has_header: bool = Form(True),
    skip_rows: int = Form(0),
    _: User = Depends(get_current_user),
) -> dict:
    data = await file.read()
    tpl = _transient(0, delimiter=delimiter, encoding=encoding, has_header=has_header, skip_rows=skip_rows)
    return csv_import.preview_raw(data, tpl)


@router.post("/preview")
async def preview(
    file: UploadFile = File(...),
    account_id: int = Form(...),
    delimiter: str = Form(";"),
    decimal_sep: str = Form(","),
    date_format: str = Form("%d.%m.%Y"),
    encoding: str = Form("utf-8"),
    has_header: bool = Form(True),
    skip_rows: int = Form(0),
    amount_mode: str = Form("signed"),
    column_map: str = Form("{}"),
    filter_column: int | None = Form(None),
    filter_value: str | None = Form(None),
    db: Session = Depends(get_db),
    user: User = Depends(get_current_user),
) -> dict:
    account = get_owned(db, Account, account_id, user)
    data = await file.read()
    tpl = _transient(
        user.id, delimiter=delimiter, decimal_sep=decimal_sep, date_format=date_format,
        encoding=encoding, has_header=has_header, skip_rows=skip_rows,
        amount_mode=AmountMode(amount_mode), column_map=column_map,
        filter_column=filter_column, filter_value=filter_value,
    )
    rows = csv_import.build_preview(db, user, account, tpl, data)
    return {
        "rows": rows,
        "filename": file.filename or "",
        # Abgleich gegen die Saldo-Spalte der Datei (falls zugeordnet).
        "reconciliation": csv_import.reconcile(rows),
    }


# --- Verbuchen / Undo ------------------------------------------------------


@router.post("/commit", response_model=ImportBatchOut)
def commit(payload: ImportCommitIn, db: Session = Depends(get_db), user: User = Depends(get_current_user)):
    account = get_owned(db, Account, payload.account_id, user)
    return csv_import.commit_import(db, user, account, payload.template_id, payload.filename, payload.rows)


@router.get("/batches", response_model=list[ImportBatchOut])
def list_batches(db: Session = Depends(get_db), user: User = Depends(get_current_user)):
    return (
        db.query(ImportBatch)
        .filter(ImportBatch.owner_id == user.id)
        .order_by(ImportBatch.created_at.desc(), ImportBatch.id.desc())
        .all()
    )


@router.delete("/batches/{batch_id}")
def undo(batch_id: int, db: Session = Depends(get_db), user: User = Depends(get_current_user)) -> dict:
    batch = get_owned(db, ImportBatch, batch_id, user)
    deleted = csv_import.undo_batch(db, user, batch)
    return {"deleted": deleted}


@router.delete("/batches/{batch_id}/record", status_code=status.HTTP_204_NO_CONTENT)
def remove_batch_record(
    batch_id: int, db: Session = Depends(get_db), user: User = Depends(get_current_user)
):
    """Entfernt einen rückgängig gemachten Eintrag aus dem Verlauf.

    Nur für bereits zurückgenommene Importe: Solange ein Import steht, ist der
    Eintrag die einzige Möglichkeit, seine Buchungen wieder loszuwerden."""
    batch = get_owned(db, ImportBatch, batch_id, user)
    if batch.status != ImportStatus.undone:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Nur rückgängig gemachte Importe lassen sich aus dem Verlauf entfernen.",
        )
    db.delete(batch)
    db.commit()