import csv
import io

from fastapi import APIRouter, Request, Depends
from fastapi.responses import RedirectResponse, StreamingResponse
from web.templates_env import templates
from sqlalchemy.orm import Session

from web.auth import get_current_user
from web.database import get_db
from web.evotor_api import refresh_catalog_cache
from web.models import User, EvotorConnection, SyncConfig, SyncFilter, CachedStore, CachedGroup, CachedProduct

router = APIRouter(prefix="/catalog")


def _get_or_create_sync_config(db: Session, user_id: int) -> SyncConfig:
    config = db.query(SyncConfig).filter(SyncConfig.user_id == user_id).first()
    if not config:
        config = SyncConfig(user_id=user_id, is_enabled=False)
        db.add(config)
        db.commit()
        db.refresh(config)
    return config


def _filter_map(config: SyncConfig) -> dict:
    """Returns {entity_id: filter_mode} for quick lookup."""
    return {f.entity_id: f.filter_mode for f in config.filters}


def _filter_label(mode: str | None) -> str:
    if mode == "include":
        return "include"
    if mode == "exclude":
        return "exclude"
    return "none"


@router.get("")
async def catalog_stores(
    request: Request,
    db: Session = Depends(get_db),
    user: User | None = Depends(get_current_user),
):
    if not user:
        return RedirectResponse("/login", 303)

    evotor = db.query(EvotorConnection).filter(EvotorConnection.user_id == user.id).first()
    if not evotor:
        return templates.TemplateResponse("catalog_stores.html", {
            "request": request, "user": user,
            "evotor": None, "stores": [], "filter_map": {}, "fetched_at": None,
        })

    stores = db.query(CachedStore).filter(CachedStore.user_id == user.id).order_by(CachedStore.name).all()

    # Auto-refresh if cache is empty
    if not stores:
        await refresh_catalog_cache(user.id, evotor.access_token, db)
        stores = db.query(CachedStore).filter(CachedStore.user_id == user.id).order_by(CachedStore.name).all()

    config = _get_or_create_sync_config(db, user.id)
    fmap = _filter_map(config)
    fetched_at = stores[0].fetched_at if stores else None

    return templates.TemplateResponse("catalog_stores.html", {
        "request": request,
        "user": user,
        "evotor": evotor,
        "stores": stores,
        "filter_map": fmap,
        "fetched_at": fetched_at,
    })


@router.get("/groups")
def catalog_groups(
    request: Request,
    store_id: str,
    db: Session = Depends(get_db),
    user: User | None = Depends(get_current_user),
):
    if not user:
        return RedirectResponse("/login", 303)

    store = db.query(CachedStore).filter(
        CachedStore.user_id == user.id,
        CachedStore.evotor_id == store_id,
    ).first()
    if not store:
        return RedirectResponse("/catalog", 303)

    groups = db.query(CachedGroup).filter(
        CachedGroup.user_id == user.id,
        CachedGroup.store_evotor_id == store_id,
    ).order_by(CachedGroup.name).all()

    # Count products per group
    product_counts = {}
    for g in groups:
        product_counts[g.evotor_id] = db.query(CachedProduct).filter(
            CachedProduct.user_id == user.id,
            CachedProduct.group_evotor_id == g.evotor_id,
        ).count()

    config = _get_or_create_sync_config(db, user.id)
    fmap = _filter_map(config)

    return templates.TemplateResponse("catalog_groups.html", {
        "request": request,
        "user": user,
        "store": store,
        "groups": groups,
        "product_counts": product_counts,
        "filter_map": fmap,
    })


@router.get("/products")
def catalog_products(
    request: Request,
    store_id: str,
    group_id: str | None = None,
    db: Session = Depends(get_db),
    user: User | None = Depends(get_current_user),
):
    if not user:
        return RedirectResponse("/login", 303)

    store = db.query(CachedStore).filter(
        CachedStore.user_id == user.id,
        CachedStore.evotor_id == store_id,
    ).first()
    if not store:
        return RedirectResponse("/catalog", 303)

    group = None
    query = db.query(CachedProduct).filter(
        CachedProduct.user_id == user.id,
        CachedProduct.store_evotor_id == store_id,
    )
    if group_id:
        group = db.query(CachedGroup).filter(
            CachedGroup.user_id == user.id,
            CachedGroup.evotor_id == group_id,
        ).first()
        query = query.filter(CachedProduct.group_evotor_id == group_id)

    products = query.order_by(CachedProduct.name).all()

    config = _get_or_create_sync_config(db, user.id)
    fmap = _filter_map(config)

    return templates.TemplateResponse("catalog_products.html", {
        "request": request,
        "user": user,
        "store": store,
        "group": group,
        "products": products,
        "filter_map": fmap,
    })


@router.post("/filter")
async def catalog_filter(
    request: Request,
    db: Session = Depends(get_db),
    user: User | None = Depends(get_current_user),
):
    if not user:
        return RedirectResponse("/login", 303)

    form = await request.form()
    entity_type = form.get("entity_type")
    entity_id = form.get("entity_id")
    entity_name = form.get("entity_name")
    filter_mode = form.get("filter_mode")  # "include", "exclude", "none"
    parent_entity_id = form.get("parent_entity_id") or None
    redirect_to = form.get("redirect_to", "/catalog")

    config = _get_or_create_sync_config(db, user.id)

    existing = db.query(SyncFilter).filter(
        SyncFilter.sync_config_id == config.id,
        SyncFilter.entity_type == entity_type,
        SyncFilter.entity_id == entity_id,
    ).first()

    if filter_mode == "none":
        if existing:
            db.delete(existing)
    elif existing:
        existing.filter_mode = filter_mode
        existing.entity_name = entity_name
    else:
        db.add(SyncFilter(
            sync_config_id=config.id,
            entity_type=entity_type,
            entity_id=entity_id,
            entity_name=entity_name,
            filter_mode=filter_mode,
            parent_entity_id=parent_entity_id,
        ))
    db.commit()

    return RedirectResponse(redirect_to, 303)


@router.post("/refresh")
async def catalog_refresh(
    request: Request,
    db: Session = Depends(get_db),
    user: User | None = Depends(get_current_user),
):
    if not user:
        return RedirectResponse("/login", 303)

    evotor = db.query(EvotorConnection).filter(EvotorConnection.user_id == user.id).first()
    if evotor:
        await refresh_catalog_cache(user.id, evotor.access_token, db)

    return RedirectResponse("/catalog", 303)


@router.get("/export")
def catalog_export(
    request: Request,
    type: str,
    store_id: str | None = None,
    group_id: str | None = None,
    db: Session = Depends(get_db),
    user: User | None = Depends(get_current_user),
):
    if not user:
        return RedirectResponse("/login", 303)

    config = _get_or_create_sync_config(db, user.id)
    fmap = _filter_map(config)

    def filter_label(eid):
        m = fmap.get(eid)
        if m == "include":
            return "Включено"
        if m == "exclude":
            return "Исключено"
        return "Нет правила"

    output = io.StringIO()
    output.write("\ufeff")  # UTF-8 BOM for Excel
    writer = csv.writer(output)

    from datetime import date
    today = date.today().strftime("%Y%m%d")

    if type == "stores":
        writer.writerow(["Название", "Адрес", "ID", "Фильтр"])
        stores = db.query(CachedStore).filter(CachedStore.user_id == user.id).order_by(CachedStore.name).all()
        for s in stores:
            writer.writerow([s.name, s.address or "", s.evotor_id, filter_label(s.evotor_id)])
        filename = f"stores_{today}.csv"

    elif type == "groups":
        writer.writerow(["Магазин", "Название", "ID", "Фильтр"])
        q = db.query(CachedGroup, CachedStore).join(
            CachedStore,
            (CachedStore.evotor_id == CachedGroup.store_evotor_id) & (CachedStore.user_id == user.id)
        ).filter(CachedGroup.user_id == user.id)
        if store_id:
            q = q.filter(CachedGroup.store_evotor_id == store_id)
        for g, s in q.order_by(CachedGroup.name).all():
            writer.writerow([s.name, g.name, g.evotor_id, filter_label(g.evotor_id)])
        filename = f"groups_{today}.csv"

    else:  # products
        writer.writerow(["Магазин", "Группа", "Название", "Артикул", "Цена", "Количество", "Ед. измерения", "В продаже", "ID", "Фильтр"])
        q = db.query(CachedProduct, CachedStore, CachedGroup).join(
            CachedStore,
            (CachedStore.evotor_id == CachedProduct.store_evotor_id) & (CachedStore.user_id == user.id)
        ).outerjoin(
            CachedGroup,
            (CachedGroup.evotor_id == CachedProduct.group_evotor_id) & (CachedGroup.user_id == user.id)
        ).filter(CachedProduct.user_id == user.id)
        if store_id:
            q = q.filter(CachedProduct.store_evotor_id == store_id)
        if group_id:
            q = q.filter(CachedProduct.group_evotor_id == group_id)
        for p, s, g in q.order_by(CachedProduct.name).all():
            writer.writerow([
                s.name,
                g.name if g else "",
                p.name,
                p.article_number or "",
                p.price or "",
                p.quantity or "",
                p.measure_name or "",
                "Да" if p.allow_to_sell else ("Нет" if p.allow_to_sell is not None else ""),
                p.evotor_id,
                filter_label(p.evotor_id),
            ])
        filename = f"products_{today}.csv"

    output.seek(0)
    return StreamingResponse(
        iter([output.getvalue()]),
        media_type="text/csv; charset=utf-8",
        headers={"Content-Disposition": f"attachment; filename={filename}"},
    )