from __future__ import annotations

import uuid
from collections import defaultdict
from datetime import date, datetime, timedelta
from pathlib import Path

from flask import (
    Blueprint,
    current_app,
    flash,
    g,
    jsonify,
    redirect,
    render_template,
    request,
    url_for,
)
from werkzeug.utils import secure_filename

from .auth import login_required
from .constants import (
    AVAILABILITY_LABELS,
    CATEGORIES,
    ITEM_KIND_LABELS,
    ITEM_KIND_SINGULAR_LABELS,
)
from .db import get_db


main_bp = Blueprint("main", __name__)

ALLOWED_IMAGE_EXTENSIONS = {"png", "jpg", "jpeg", "gif", "webp"}
ACTIVE_STATE_OPTIONS = [
    ("", "Alle aktiven"),
    ("home", "Zuhause"),
    ("idea", "Merkliste"),
]
KIND_FILTER_OPTIONS = [
    ("", "Alles"),
    ("food", "Lebensmittel"),
    ("meal", "Mahlzeitenideen"),
]


def get_dayparts() -> list:
    return get_db().execute("SELECT * FROM dayparts ORDER BY sort_order").fetchall()


def get_daypart_by_id(daypart_id: int):
    return get_db().execute(
        "SELECT * FROM dayparts WHERE id = ?",
        (daypart_id,),
    ).fetchone()


def parse_week_start(raw: str | None) -> date:
    if raw:
        try:
            parsed = datetime.strptime(raw, "%Y-%m-%d").date()
            return parsed - timedelta(days=parsed.weekday())
        except ValueError:
            pass
    today = date.today()
    return today - timedelta(days=today.weekday())


def parse_plan_date(raw: str | None, fallback: date | None = None) -> date:
    if raw:
        try:
            return datetime.strptime(raw, "%Y-%m-%d").date()
        except ValueError:
            pass
    return fallback or date.today()


def allowed_file(filename: str) -> bool:
    return "." in filename and filename.rsplit(".", 1)[1].lower() in ALLOWED_IMAGE_EXTENSIONS


def save_photo(upload, current_filename: str | None = None) -> str | None:
    if not upload or not upload.filename:
        return current_filename

    if not allowed_file(upload.filename):
        raise ValueError("Bitte ein Bild als PNG, JPG, GIF oder WEBP hochladen.")

    original_name = secure_filename(upload.filename)
    extension = original_name.rsplit(".", 1)[1].lower()
    filename = f"{uuid.uuid4().hex}.{extension}"
    destination = Path(current_app.config["UPLOAD_FOLDER"]) / filename
    upload.save(destination)

    if current_filename:
        old_path = Path(current_app.config["UPLOAD_FOLDER"]) / current_filename
        if old_path.exists():
            old_path.unlink()

    return filename


def get_item(item_id: int):
    item = get_db().execute(
        """
        SELECT *
        FROM items
        WHERE id = ?
        """,
        (item_id,),
    ).fetchone()
    if item is None:
        raise ValueError("Der Eintrag wurde nicht gefunden.")
    return item


def get_item_daypart_ids(item_id: int) -> list[int]:
    rows = get_db().execute(
        "SELECT daypart_id FROM item_dayparts WHERE item_id = ?",
        (item_id,),
    ).fetchall()
    return [row["daypart_id"] for row in rows]


def get_meal_component_ids(meal_id: int) -> list[int]:
    rows = get_db().execute(
        "SELECT food_item_id FROM meal_components WHERE meal_item_id = ?",
        (meal_id,),
    ).fetchall()
    return [row["food_item_id"] for row in rows]


def attach_dayparts(items: list) -> list[dict]:
    if not items:
        return []

    database = get_db()
    item_ids = [item["id"] for item in items]
    placeholders = ",".join("?" for _ in item_ids)
    rows = database.execute(
        f"""
        SELECT item_dayparts.item_id, dayparts.id, dayparts.slug, dayparts.name
        FROM item_dayparts
        JOIN dayparts ON dayparts.id = item_dayparts.daypart_id
        WHERE item_dayparts.item_id IN ({placeholders})
        ORDER BY dayparts.sort_order
        """,
        item_ids,
    ).fetchall()
    grouped = defaultdict(list)
    for row in rows:
        grouped[row["item_id"]].append(
            {
                "id": row["id"],
                "slug": row["slug"],
                "name": row["name"],
            }
        )

    enriched = []
    for item in items:
        entry = dict(item)
        entry["dayparts_meta"] = grouped.get(item["id"], [])
        entry["dayparts"] = [daypart["name"] for daypart in entry["dayparts_meta"]]
        entry["primary_daypart_id"] = entry["dayparts_meta"][0]["id"] if entry["dayparts_meta"] else None
        enriched.append(entry)
    return enriched


def attach_components(items: list[dict]) -> list[dict]:
    meal_ids = [item["id"] for item in items if item["kind"] == "meal"]
    if not meal_ids:
        for item in items:
            item["components"] = []
        return items

    placeholders = ",".join("?" for _ in meal_ids)
    rows = get_db().execute(
        f"""
        SELECT meal_components.meal_item_id, items.name
        FROM meal_components
        JOIN items ON items.id = meal_components.food_item_id
        WHERE meal_components.meal_item_id IN ({placeholders})
        ORDER BY LOWER(items.name)
        """,
        meal_ids,
    ).fetchall()
    grouped = defaultdict(list)
    for row in rows:
        grouped[row["meal_item_id"]].append(row["name"])

    for item in items:
        item["components"] = grouped.get(item["id"], [])
    return items


def fetch_items(
    kind: str | None = None,
    availability: str | None = None,
    include_archived: bool = False,
    query: str | None = None,
    daypart_id: int | None = None,
):
    database = get_db()
    conditions = []
    params = []

    if kind:
        conditions.append("items.kind = ?")
        params.append(kind)
    if availability:
        conditions.append("items.availability_state = ?")
        params.append(availability)
    elif not include_archived:
        conditions.append("items.availability_state != 'archived'")
    if query:
        conditions.append("LOWER(items.name) LIKE ?")
        params.append(f"%{query.lower()}%")
    if daypart_id:
        conditions.append(
            """
            EXISTS (
                SELECT 1
                FROM item_dayparts
                WHERE item_dayparts.item_id = items.id
                  AND item_dayparts.daypart_id = ?
            )
            """
        )
        params.append(daypart_id)

    where_clause = f"WHERE {' AND '.join(conditions)}" if conditions else ""
    rows = database.execute(
        f"""
        SELECT items.*,
               EXISTS(
                   SELECT 1
                   FROM shopping_entries
                   WHERE shopping_entries.item_id = items.id AND shopping_entries.is_checked = 0
               ) AS is_on_shopping_list
        FROM items
        {where_clause}
        ORDER BY
            CASE items.availability_state WHEN 'home' THEN 0 WHEN 'idea' THEN 1 ELSE 2 END,
            LOWER(items.name)
        """,
        params,
    ).fetchall()
    return attach_components(attach_dayparts(rows))


def fetch_food_options():
    return fetch_items(kind="food", include_archived=True)


def group_items_by_availability(items: list[dict]) -> list[dict]:
    grouped = defaultdict(list)
    for item in items:
        grouped[item["availability_state"]].append(item)

    ordered_states = ["home", "idea", "archived"]
    result = []
    for state in ordered_states:
        entries = grouped.get(state, [])
        if entries:
            result.append(
                {
                    "state": state,
                    "title": AVAILABILITY_LABELS[state],
                    "items": entries,
                }
            )
    return result


def extract_item_form_data() -> dict:
    return {
        "name": request.form.get("name", "").strip(),
        "category": request.form.get("category", "").strip(),
        "note": request.form.get("note", "").strip(),
        "daypart_ids": [int(value) for value in request.form.getlist("daypart_ids")],
        "component_ids": [int(value) for value in request.form.getlist("component_ids")],
        "quick_food_name": request.form.get("quick_food_name", "").strip(),
        "quick_food_category": request.form.get("quick_food_category", "").strip(),
        "quick_food_note": request.form.get("quick_food_note", "").strip(),
    }


def create_quick_food_from_form(form_data: dict) -> int:
    database = get_db()
    # Inline item creation keeps the meal-idea flow intact instead of forcing a detour.
    cursor = database.execute(
        """
        INSERT INTO items (kind, name, category, note, created_by, updated_by)
        VALUES ('food', ?, ?, ?, ?, ?)
        """,
        (
            form_data["quick_food_name"],
            form_data["quick_food_category"],
            form_data["quick_food_note"],
            g.user["id"],
            g.user["id"],
        ),
    )
    food_id = cursor.lastrowid
    sync_item_dayparts(food_id, form_data["daypart_ids"])
    database.commit()
    return food_id


def add_to_shopping_list(item_id: int, user_id: int) -> bool:
    database = get_db()
    existing = database.execute(
        """
        SELECT id FROM shopping_entries
        WHERE item_id = ? AND is_checked = 0
        """,
        (item_id,),
    ).fetchone()
    if existing:
        return False

    database.execute(
        """
        INSERT INTO shopping_entries (item_id, added_by)
        VALUES (?, ?)
        """,
        (item_id, user_id),
    )
    database.commit()
    return True


def ensure_planned_item_is_shopped(item_id: int, user_id: int) -> bool:
    item = get_item(item_id)
    if item["availability_state"] == "home":
        return False
    # Planning something that is not at home should create a gentle follow-up on the shopping list.
    return add_to_shopping_list(item_id, user_id)


def sync_item_dayparts(item_id: int, daypart_ids: list[int]) -> None:
    database = get_db()
    database.execute("DELETE FROM item_dayparts WHERE item_id = ?", (item_id,))
    for daypart_id in daypart_ids:
        database.execute(
            "INSERT INTO item_dayparts (item_id, daypart_id) VALUES (?, ?)",
            (item_id, daypart_id),
        )


def sync_meal_components(meal_id: int, food_ids: list[int]) -> None:
    database = get_db()
    database.execute("DELETE FROM meal_components WHERE meal_item_id = ?", (meal_id,))
    for food_id in food_ids:
        database.execute(
            """
            INSERT INTO meal_components (meal_item_id, food_item_id)
            VALUES (?, ?)
            """,
            (meal_id, food_id),
        )


def fetch_shopping_entries():
    return get_db().execute(
        """
        SELECT shopping_entries.*,
               items.name AS item_name,
               items.kind AS item_kind,
               items.photo_filename,
               items.availability_state,
               users.display_name,
               users.username
        FROM shopping_entries
        JOIN items ON items.id = shopping_entries.item_id
        LEFT JOIN users ON users.id = shopping_entries.added_by
        WHERE shopping_entries.is_checked = 0
        ORDER BY shopping_entries.added_at DESC
        """
    ).fetchall()


def fetch_plan_entries_for_range(start_date: date, end_date: date):
    rows = get_db().execute(
        """
        SELECT plan_entries.*,
               items.name AS item_name,
               items.kind AS item_kind,
               items.photo_filename,
               items.availability_state,
               dayparts.name AS daypart_name,
               dayparts.slug AS daypart_slug,
               dayparts.sort_order
        FROM plan_entries
        JOIN items ON items.id = plan_entries.item_id
        JOIN dayparts ON dayparts.id = plan_entries.daypart_id
        WHERE plan_date BETWEEN ? AND ?
        ORDER BY plan_date, dayparts.sort_order, items.name
        """,
        (start_date.isoformat(), end_date.isoformat()),
    ).fetchall()
    grouped = defaultdict(list)
    for row in rows:
        grouped[(row["plan_date"], row["daypart_id"])].append(dict(row))
    return grouped


def fetch_day_plan_entries(selected_date: date):
    return fetch_plan_entries_for_range(selected_date, selected_date)


def fetch_week_cards(week_start: date):
    days = [week_start + timedelta(days=index) for index in range(7)]
    dayparts = get_dayparts()
    grouped_entries = fetch_plan_entries_for_range(week_start, week_start + timedelta(days=6))
    cards = []
    for current_day in days:
        filled_dayparts = []
        planned_count = 0
        preview_items = []
        slots = []
        for daypart in dayparts:
            slot_entries = grouped_entries.get((current_day.isoformat(), daypart["id"]), [])
            slots.append(
                {
                    "daypart": dict(daypart),
                    "entries": slot_entries,
                }
            )
            if slot_entries:
                filled_dayparts.append(
                    {
                        "id": daypart["id"],
                        "name": daypart["name"],
                        "count": len(slot_entries),
                    }
                )
                planned_count += len(slot_entries)
                preview_items.extend(entry["item_name"] for entry in slot_entries[:2])
        cards.append(
            {
                "date": current_day,
                "filled_dayparts": filled_dayparts,
                "planned_count": planned_count,
                "preview_items": preview_items[:4],
                "slots": slots,
            }
        )
    return cards


def dedupe_items(items: list[dict], limit: int = 6) -> list[dict]:
    seen_ids = set()
    result = []
    for item in items:
        if item["id"] in seen_ids:
            continue
        seen_ids.add(item["id"])
        result.append(item)
        if len(result) >= limit:
            break
    return result


def fetch_recent_plan_items(daypart_id: int, limit: int = 6):
    rows = get_db().execute(
        """
        SELECT DISTINCT items.id, items.name, items.kind, items.photo_filename, items.availability_state
        FROM plan_entries
        JOIN items ON items.id = plan_entries.item_id
        WHERE plan_entries.daypart_id = ?
        ORDER BY plan_entries.created_at DESC
        LIMIT ?
        """,
        (daypart_id, limit * 3),
    ).fetchall()
    return attach_components(attach_dayparts(rows))


def fetch_plan_candidates(daypart_id: int, query: str | None = None):
    params = [daypart_id]
    conditions = ["items.availability_state != 'archived'"]
    if query:
        conditions.append("LOWER(items.name) LIKE ?")
        params.append(f"%{query.lower()}%")

    where_clause = f"WHERE {' AND '.join(conditions)}"
    rows = get_db().execute(
        f"""
        SELECT items.*,
               EXISTS(
                   SELECT 1
                   FROM item_dayparts
                   WHERE item_dayparts.item_id = items.id AND item_dayparts.daypart_id = ?
               ) AS matches_daypart
        FROM items
        {where_clause}
        ORDER BY
            CASE items.availability_state WHEN 'home' THEN 0 WHEN 'idea' THEN 1 ELSE 2 END,
            matches_daypart DESC,
            LOWER(items.name)
        """,
        params,
    ).fetchall()
    return attach_components(attach_dayparts(rows))


def build_home_sections(items: list[dict], dayparts: list, selected_daypart_id: int | None):
    sections = []
    if selected_daypart_id:
        selected_daypart = next((daypart for daypart in dayparts if daypart["id"] == selected_daypart_id), None)
        matching_items = [item for item in items if any(dp["id"] == selected_daypart_id for dp in item["dayparts_meta"])]
        sections.append(
            {
                "title": selected_daypart["name"] if selected_daypart else "Ausgewählte Tageszeit",
                "items": matching_items,
                "slug": selected_daypart["slug"] if selected_daypart else "selected",
            }
        )
        return sections

    for daypart in dayparts:
        matching_items = [item for item in items if any(dp["id"] == daypart["id"] for dp in item["dayparts_meta"])]
        sections.append(
            {
                "title": daypart["name"],
                "items": matching_items,
                "slug": daypart["slug"],
            }
        )

    anytime_items = [item for item in items if not item["dayparts_meta"]]
    if anytime_items:
        sections.append(
            {
                "title": "Ohne feste Tageszeit",
                "items": anytime_items,
                "slug": "anytime",
            }
        )
    return sections


def build_day_planner_sections(selected_date: date, selected_item_id: int | None, selected_daypart_id: int | None):
    dayparts = get_dayparts()
    day_entries = fetch_day_plan_entries(selected_date)
    sections = []

    for daypart in dayparts:
        candidates = fetch_plan_candidates(daypart["id"])
        home_candidates = [item for item in candidates if item["availability_state"] == "home"]
        matching_candidates = [
            item for item in candidates
            if any(meta["id"] == daypart["id"] for meta in item["dayparts_meta"])
        ]
        recent_candidates = fetch_recent_plan_items(daypart["id"])
        quick_items = dedupe_items(home_candidates + recent_candidates + matching_candidates, limit=6)
        sections.append(
            {
                "daypart": daypart,
                "entries": day_entries.get((selected_date.isoformat(), daypart["id"]), []),
                "candidates": candidates,
                "quick_items": quick_items,
                "selected_item_id": selected_item_id if selected_daypart_id == daypart["id"] else None,
                "is_open": selected_daypart_id == daypart["id"],
                "summary_items": [entry["item_name"] for entry in day_entries.get((selected_date.isoformat(), daypart["id"]), [])][:2],
            }
        )
    return sections


@main_bp.get("/")
@login_required
def dashboard():
    database = get_db()
    today = date.today()
    home_count = database.execute(
        "SELECT COUNT(*) AS count FROM items WHERE availability_state = 'home'"
    ).fetchone()["count"]
    shopping_count = database.execute(
        "SELECT COUNT(*) AS count FROM shopping_entries WHERE is_checked = 0"
    ).fetchone()["count"]
    archive_count = database.execute(
        "SELECT COUNT(*) AS count FROM items WHERE availability_state = 'archived'"
    ).fetchone()["count"]
    today_entries = database.execute(
        """
        SELECT plan_entries.id,
               items.name AS item_name,
               items.kind AS item_kind,
               items.availability_state,
               dayparts.name AS daypart_name
        FROM plan_entries
        JOIN items ON items.id = plan_entries.item_id
        JOIN dayparts ON dayparts.id = plan_entries.daypart_id
        WHERE plan_entries.plan_date = ?
        ORDER BY dayparts.sort_order, items.name
        """,
        (today.isoformat(),),
    ).fetchall()
    week_cards = fetch_week_cards(today - timedelta(days=today.weekday()))
    home_items = fetch_items(availability="home")
    return render_template(
        "dashboard.html",
        home_count=home_count,
        shopping_count=shopping_count,
        archive_count=archive_count,
        today_entries=today_entries,
        home_items=home_items[:8],
        today=today,
        week_cards=week_cards[:3],
    )


@main_bp.route("/items/<kind>")
@login_required
def item_list(kind: str):
    if kind not in ITEM_KIND_LABELS:
        return redirect(url_for("main.dashboard"))

    query = request.args.get("q", "").strip()
    state = request.args.get("state", "").strip()
    raw_daypart_id = request.args.get("daypart_id", "").strip()
    daypart_id = int(raw_daypart_id) if raw_daypart_id.isdigit() else None

    items = fetch_items(
        kind=kind,
        availability=state or None,
        query=query or None,
        daypart_id=daypart_id,
    )
    return render_template(
        "items/list.html",
        kind=kind,
        items=items,
        availability_labels=AVAILABILITY_LABELS,
        query=query,
        selected_state=state,
        selected_daypart_id=daypart_id,
        dayparts=get_dayparts(),
        state_options=ACTIVE_STATE_OPTIONS,
        today=date.today(),
    )


@main_bp.route("/items/<kind>/new", methods=("GET", "POST"))
@login_required
def item_create(kind: str):
    if kind not in ITEM_KIND_LABELS:
        return redirect(url_for("main.dashboard"))

    database = get_db()
    dayparts = get_dayparts()
    foods = fetch_food_options()
    food_groups = group_items_by_availability(foods)
    form_data = {
        "name": "",
        "category": "",
        "note": "",
        "daypart_ids": [],
        "component_ids": [],
        "quick_food_name": "",
        "quick_food_category": "",
        "quick_food_note": "",
    }

    if request.method == "POST":
        form_action = request.form.get("form_action", "save_item")
        form_data.update(extract_item_form_data())
        name = form_data["name"]
        category = form_data["category"]
        note = form_data["note"]
        daypart_ids = form_data["daypart_ids"]
        component_ids = form_data["component_ids"]

        if kind == "meal" and form_action == "quick_add_food":
            if not form_data["quick_food_name"]:
                flash("Bitte einen Namen für das neue Lebensmittel eintragen.", "error")
            else:
                new_food_id = create_quick_food_from_form(form_data)
                if new_food_id not in form_data["component_ids"]:
                    form_data["component_ids"].append(new_food_id)
                form_data["component_ids"] = sorted(form_data["component_ids"])
                form_data["quick_food_name"] = ""
                form_data["quick_food_category"] = ""
                form_data["quick_food_note"] = ""
                foods = fetch_food_options()
                food_groups = group_items_by_availability(foods)
                flash("Das neue Lebensmittel wurde angelegt und direkt zur Mahlzeitenidee hinzugefügt.", "success")
                return render_template(
                    "items/form.html",
                    kind=kind,
                    item=None,
                    dayparts=dayparts,
                    foods=foods,
                    food_groups=food_groups,
                    categories=CATEGORIES,
                    form_data=form_data,
                )

        error = None
        if not name:
            error = "Bitte einen Namen eintragen."

        photo_filename = None
        if error is None:
            try:
                photo_filename = save_photo(request.files.get("photo"))
            except ValueError as exc:
                error = str(exc)

        if error is None:
            cursor = database.execute(
                """
                INSERT INTO items (kind, name, category, note, photo_filename, created_by, updated_by)
                VALUES (?, ?, ?, ?, ?, ?, ?)
                """,
                (kind, name, category, note, photo_filename, g.user["id"], g.user["id"]),
            )
            item_id = cursor.lastrowid
            sync_item_dayparts(item_id, daypart_ids)
            if kind == "meal":
                sync_meal_components(item_id, component_ids)
            database.commit()
            flash(f"{ITEM_KIND_SINGULAR_LABELS[kind]} wurde angelegt.", "success")
            return redirect(url_for("main.item_list", kind=kind))

        flash(error, "error")

    return render_template(
        "items/form.html",
        kind=kind,
        item=None,
        dayparts=dayparts,
        foods=foods,
        food_groups=food_groups,
        categories=CATEGORIES,
        form_data=form_data,
    )


@main_bp.route("/items/<int:item_id>/edit", methods=("GET", "POST"))
@login_required
def item_edit(item_id: int):
    database = get_db()
    item = get_item(item_id)
    kind = item["kind"]
    dayparts = get_dayparts()
    foods = fetch_food_options()
    food_groups = group_items_by_availability(foods)
    form_data = {
        "name": item["name"],
        "category": item["category"] or "",
        "note": item["note"] or "",
        "daypart_ids": get_item_daypart_ids(item_id),
        "component_ids": get_meal_component_ids(item_id) if kind == "meal" else [],
        "quick_food_name": "",
        "quick_food_category": "",
        "quick_food_note": "",
    }

    if request.method == "POST":
        form_action = request.form.get("form_action", "save_item")
        form_data.update(extract_item_form_data())
        name = form_data["name"]
        category = form_data["category"]
        note = form_data["note"]
        daypart_ids = form_data["daypart_ids"]
        component_ids = form_data["component_ids"]

        if kind == "meal" and form_action == "quick_add_food":
            if not form_data["quick_food_name"]:
                flash("Bitte einen Namen für das neue Lebensmittel eintragen.", "error")
            else:
                new_food_id = create_quick_food_from_form(form_data)
                if new_food_id not in form_data["component_ids"]:
                    form_data["component_ids"].append(new_food_id)
                form_data["component_ids"] = sorted(form_data["component_ids"])
                form_data["quick_food_name"] = ""
                form_data["quick_food_category"] = ""
                form_data["quick_food_note"] = ""
                foods = fetch_food_options()
                food_groups = group_items_by_availability(foods)
                flash("Das neue Lebensmittel wurde angelegt und direkt zur Mahlzeitenidee hinzugefügt.", "success")
                return render_template(
                    "items/form.html",
                    kind=kind,
                    item=item,
                    dayparts=dayparts,
                    foods=foods,
                    food_groups=food_groups,
                    categories=CATEGORIES,
                    form_data=form_data,
                )

        error = None
        if not name:
            error = "Bitte einen Namen eintragen."

        photo_filename = item["photo_filename"]
        if error is None:
            try:
                photo_filename = save_photo(request.files.get("photo"), current_filename=item["photo_filename"])
            except ValueError as exc:
                error = str(exc)

        if error is None:
            database.execute(
                """
                UPDATE items
                SET name = ?, category = ?, note = ?, photo_filename = ?, updated_by = ?, updated_at = CURRENT_TIMESTAMP
                WHERE id = ?
                """,
                (name, category, note, photo_filename, g.user["id"], item_id),
            )
            sync_item_dayparts(item_id, daypart_ids)
            if kind == "meal":
                sync_meal_components(item_id, component_ids)
            database.commit()
            flash("Der Eintrag wurde aktualisiert.", "success")
            return redirect(url_for("main.item_list", kind=kind))

        flash(error, "error")

    return render_template(
        "items/form.html",
        kind=kind,
        item=item,
        dayparts=dayparts,
        foods=foods,
        food_groups=food_groups,
        categories=CATEGORIES,
        form_data=form_data,
    )


@main_bp.post("/items/<int:item_id>/shopping")
@login_required
def item_add_to_shopping(item_id: int):
    item = get_item(item_id)
    added = add_to_shopping_list(item_id, g.user["id"])
    if added:
        flash(f"{item['name']} steht jetzt auf der Einkaufsliste.", "success")
    else:
        flash(f"{item['name']} ist bereits auf der Einkaufsliste.", "info")
    return redirect(request.referrer or url_for("main.shopping_list"))


@main_bp.post("/items/<int:item_id>/set-home")
@login_required
def item_set_home(item_id: int):
    item = get_item(item_id)
    database = get_db()
    database.execute(
        """
        UPDATE items
        SET availability_state = 'home', updated_by = ?, updated_at = CURRENT_TIMESTAMP
        WHERE id = ?
        """,
        (g.user["id"], item_id),
    )
    database.commit()
    flash(f"{item['name']} ist jetzt unter Zuhause sichtbar.", "success")
    return redirect(request.referrer or url_for("main.home_view"))


@main_bp.post("/items/<int:item_id>/archive")
@login_required
def item_archive(item_id: int):
    item = get_item(item_id)
    database = get_db()
    database.execute(
        """
        UPDATE items
        SET availability_state = 'archived', updated_by = ?, updated_at = CURRENT_TIMESTAMP
        WHERE id = ?
        """,
        (g.user["id"], item_id),
    )
    database.commit()
    flash(f"{item['name']} liegt jetzt im Archiv und bleibt später leicht wiederfindbar.", "info")
    return redirect(request.referrer or url_for("main.archive_view"))


@main_bp.post("/items/<int:item_id>/restore")
@login_required
def item_restore(item_id: int):
    item = get_item(item_id)
    database = get_db()
    database.execute(
        """
        UPDATE items
        SET availability_state = 'idea', updated_by = ?, updated_at = CURRENT_TIMESTAMP
        WHERE id = ?
        """,
        (g.user["id"], item_id),
    )
    database.commit()
    flash(f"{item['name']} ist wieder in der aktiven Liste.", "success")
    return redirect(request.referrer or url_for("main.archive_view"))


@main_bp.route("/shopping", methods=("GET", "POST"))
@login_required
def shopping_list():
    database = get_db()

    if request.method == "POST":
        selected_item_id = request.form.get("item_id", "").strip()
        if not selected_item_id:
            flash("Bitte zuerst etwas auswählen.", "error")
        else:
            item = get_item(int(selected_item_id))
            added = add_to_shopping_list(item["id"], g.user["id"])
            if added:
                flash(f"{item['name']} wurde auf die Einkaufsliste gesetzt.", "success")
            else:
                flash(f"{item['name']} ist bereits auf der Einkaufsliste.", "info")
        return redirect(url_for("main.shopping_list"))

    entries = fetch_shopping_entries()
    addable_items = database.execute(
        """
        SELECT items.id, items.name, items.kind, items.availability_state
        FROM items
        WHERE items.availability_state != 'archived'
          AND NOT EXISTS (
              SELECT 1 FROM shopping_entries
              WHERE shopping_entries.item_id = items.id AND shopping_entries.is_checked = 0
          )
        ORDER BY CASE items.availability_state WHEN 'home' THEN 0 ELSE 1 END, LOWER(items.name)
        """
    ).fetchall()
    return render_template("shopping/list.html", entries=entries, addable_items=addable_items)


@main_bp.post("/shopping/<int:entry_id>/check")
@login_required
def shopping_check(entry_id: int):
    database = get_db()
    entry = database.execute(
        "SELECT * FROM shopping_entries WHERE id = ?",
        (entry_id,),
    ).fetchone()
    if entry is None:
        flash("Der Einkaufseintrag wurde nicht gefunden.", "error")
        return redirect(url_for("main.shopping_list"))

    item = get_item(entry["item_id"])
    database.execute(
        """
        UPDATE shopping_entries
        SET is_checked = 1, checked_at = CURRENT_TIMESTAMP, checked_by = ?
        WHERE id = ?
        """,
        (g.user["id"], entry_id),
    )
    database.execute(
        """
        UPDATE items
        SET availability_state = 'home', updated_by = ?, updated_at = CURRENT_TIMESTAMP
        WHERE id = ?
        """,
        (g.user["id"], item["id"]),
    )
    database.commit()
    flash(f"{item['name']} ist jetzt als Zuhause vorhanden markiert.", "success")
    return redirect(url_for("main.shopping_list"))


@main_bp.post("/shopping/<int:entry_id>/remove")
@login_required
def shopping_remove(entry_id: int):
    database = get_db()
    database.execute("DELETE FROM shopping_entries WHERE id = ?", (entry_id,))
    database.commit()
    flash("Der Eintrag wurde von der Einkaufsliste entfernt.", "info")
    return redirect(url_for("main.shopping_list"))


@main_bp.get("/home")
@login_required
def home_view():
    query = request.args.get("q", "").strip()
    raw_daypart_id = request.args.get("daypart_id", "").strip()
    daypart_id = int(raw_daypart_id) if raw_daypart_id.isdigit() else None
    dayparts = get_dayparts()
    items = fetch_items(
        availability="home",
        query=query or None,
        daypart_id=daypart_id,
    )
    sections = build_home_sections(items, dayparts, daypart_id)
    return render_template(
        "home/list.html",
        sections=sections,
        query=query,
        dayparts=dayparts,
        selected_daypart_id=daypart_id,
        today=date.today(),
    )


@main_bp.get("/archive")
@login_required
def archive_view():
    query = request.args.get("q", "").strip()
    selected_kind = request.args.get("kind", "").strip()
    kind = selected_kind if selected_kind in ITEM_KIND_LABELS else None
    items = fetch_items(
        kind=kind,
        availability="archived",
        include_archived=True,
        query=query or None,
    )
    return render_template(
        "archive/list.html",
        items=items,
        query=query,
        selected_kind=selected_kind,
        kind_options=KIND_FILTER_OPTIONS,
    )


@main_bp.get("/planner")
@login_required
def planner():
    week_start = parse_week_start(request.args.get("week"))
    return render_template(
        "planner/week.html",
        week_start=week_start,
        week_end=week_start + timedelta(days=6),
        prev_week=week_start - timedelta(days=7),
        next_week=week_start + timedelta(days=7),
        week_cards=fetch_week_cards(week_start),
        today=date.today(),
    )


@main_bp.route("/planner/day", methods=("GET", "POST"))
@login_required
def planner_day():
    selected_date = parse_plan_date(request.values.get("date"))

    if request.method == "POST":
        item_id_raw = request.form.get("item_id", "").strip()
        daypart_id_raw = request.form.get("daypart_id", "").strip()
        note = request.form.get("note", "").strip()
        selected_date = parse_plan_date(request.form.get("plan_date"))

        error = None
        if not item_id_raw:
            error = "Bitte etwas für den Tagesplan auswählen."
        elif not daypart_id_raw:
            error = "Bitte eine Tageszeit auswählen."

        if error is None:
            item_id = int(item_id_raw)
            daypart_id = int(daypart_id_raw)
            get_db().execute(
                """
                INSERT INTO plan_entries (plan_date, daypart_id, item_id, note, created_by)
                VALUES (?, ?, ?, ?, ?)
                """,
                (selected_date.isoformat(), daypart_id, item_id, note, g.user["id"]),
            )
            get_db().commit()
            if ensure_planned_item_is_shopped(item_id, g.user["id"]):
                flash("Der Eintrag ist noch nicht zuhause und wurde zusätzlich auf die Einkaufsliste gesetzt.", "info")
            flash("Der Eintrag wurde in den Tagesplan gelegt.", "success")
            return redirect(
                f"{url_for('main.planner_day', date=selected_date.isoformat(), daypart_id=daypart_id)}#daypart-{daypart_id}"
            )

        flash(error, "error")

    selected_item_raw = request.args.get("item_id", "").strip()
    selected_daypart_raw = request.args.get("daypart_id", "").strip()
    selected_item_id = int(selected_item_raw) if selected_item_raw.isdigit() else None
    selected_daypart_id = int(selected_daypart_raw) if selected_daypart_raw.isdigit() else None
    sections = build_day_planner_sections(selected_date, selected_item_id, selected_daypart_id)
    return render_template(
        "planner/day.html",
        selected_date=selected_date,
        previous_day=selected_date - timedelta(days=1),
        next_day=selected_date + timedelta(days=1),
        sections=sections,
        today=date.today(),
    )


@main_bp.post("/planner/<int:entry_id>/remove")
@login_required
def planner_remove(entry_id: int):
    selected_date = request.args.get("date", "")
    get_db().execute("DELETE FROM plan_entries WHERE id = ?", (entry_id,))
    get_db().commit()
    flash("Der Planeintrag wurde entfernt.", "info")
    if selected_date:
        return redirect(url_for("main.planner_day", date=selected_date))
    return redirect(url_for("main.planner"))


@main_bp.post("/planner/<int:entry_id>/move")
@login_required
def planner_move(entry_id: int):
    target_date = parse_plan_date(request.form.get("target_date"))
    target_daypart_raw = request.form.get("target_daypart_id", "").strip()

    if not target_daypart_raw.isdigit():
        return jsonify({"ok": False, "error": "Ungültige Tageszeit"}), 400

    database = get_db()
    entry = database.execute(
        "SELECT * FROM plan_entries WHERE id = ?",
        (entry_id,),
    ).fetchone()
    if entry is None:
        return jsonify({"ok": False, "error": "Eintrag nicht gefunden"}), 404

    target_daypart_id = int(target_daypart_raw)
    database.execute(
        """
        UPDATE plan_entries
        SET plan_date = ?, daypart_id = ?
        WHERE id = ?
        """,
        (target_date.isoformat(), target_daypart_id, entry_id),
    )
    database.commit()

    # Reuse the same shopping safeguard as the day planner after drag-and-drop moves.
    was_added_to_shopping = ensure_planned_item_is_shopped(entry["item_id"], g.user["id"])
    if was_added_to_shopping:
        flash("Der verschobene Eintrag ist noch nicht zuhause und wurde auf die Einkaufsliste gesetzt.", "info")
    return jsonify(
        {
            "ok": True,
            "added_to_shopping": was_added_to_shopping,
            "redirect_url": url_for("main.planner", week=parse_week_start(target_date.isoformat()).isoformat()),
        }
    )