shinkan-jinkendo/backend/routers/training_planning.py

"""
Training Planning – Trainingseinheiten, strukturierter Ablauf (Sektionen + Übungen/Notizen)
und wiederverwendbare Trainingsvorlagen (Sektions-Gliederung).

Governance (Vorlagen-rechte über Vereine/„offiziell“) kann später nachgezogen werden.
"""
from typing import Any, Dict, List, Optional

from fastapi import APIRouter, Depends, HTTPException, Query

from db import get_db, get_cursor, r2d
from auth import require_auth

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


def _has_planning_role(role: Optional[str]) -> bool:
    """Kann Trainingseinheiten/Vorlagen anlegen (bis Governance: auch einfacher Account)."""
    return role in ("admin", "superadmin", "trainer", "user")


def _optional_positive_int(val, field_name: str) -> Optional[int]:
    if val is None or val == "":
        return None
    try:
        i = int(val)
    except (TypeError, ValueError):
        raise HTTPException(status_code=400, detail=f"Ungültige {field_name}")
    if i < 1:
        raise HTTPException(status_code=400, detail=f"Ungültige {field_name}")
    return i


def _validate_variant_for_exercise(cur, exercise_id: Optional[int], variant_id: Optional[int]):
    if not variant_id:
        return
    if not exercise_id:
        raise HTTPException(
            status_code=400, detail="exercise_variant_id nur zusammen mit exercise_id erlaubt"
        )
    cur.execute(
        "SELECT 1 FROM exercise_variants WHERE id = %s AND exercise_id = %s",
        (variant_id, exercise_id),
    )
    if not cur.fetchone():
        raise HTTPException(status_code=400, detail="Variante passt nicht zur gewählten Übung")


def _can_access_group_for_create(cur, group_id: int, profile_id: int, role: str) -> None:
    cur.execute(
        "SELECT trainer_id, co_trainer_ids FROM training_groups WHERE id = %s",
        (group_id,),
    )
    group = cur.fetchone()
    if not group:
        raise HTTPException(status_code=404, detail="Trainingsgruppe nicht gefunden")
    co_trainers = group["co_trainer_ids"] or []
    if not _has_planning_role(role):
        raise HTTPException(status_code=403, detail="Nur Trainer dürfen Trainingseinheiten erstellen")
    if role not in ["admin", "superadmin"]:
        if group["trainer_id"] != profile_id and profile_id not in co_trainers:
            raise HTTPException(
                status_code=403, detail="Nur der zuständige Trainer darf für diese Gruppe planen"
            )


def _training_unit_guard_row(cur, unit_id: int) -> Dict[str, Any]:
    cur.execute(
        """
        SELECT tu.id, tu.created_by, tu.group_id, tu.plan_template_id,
            tg.trainer_id, tg.co_trainer_ids
        FROM training_units tu
        LEFT JOIN training_groups tg ON tu.group_id = tg.id
        WHERE tu.id = %s
        """,
        (unit_id,),
    )
    row = cur.fetchone()
    if not row:
        raise HTTPException(status_code=404, detail="Trainingseinheit nicht gefunden")
    return r2d(row)


def _assert_training_unit_permission(
    cur, unit_row: Dict[str, Any], profile_id: int, role: str
) -> None:
    co_trainers = unit_row["co_trainer_ids"] or []
    if role not in ["admin", "superadmin"]:
        if (
            unit_row["created_by"] != profile_id
            and unit_row["trainer_id"] != profile_id
            and profile_id not in co_trainers
        ):
            raise HTTPException(status_code=403, detail="Keine Berechtigung")


def _assert_delete_training_unit(role: str, created_by: int, profile_id: int) -> None:
    if role not in ["admin", "superadmin"] and created_by != profile_id:
        raise HTTPException(status_code=403, detail="Keine Berechtigung")


def _fetch_sections(cur, unit_id: int) -> List[Dict[str, Any]]:
    cur.execute(
        """
        SELECT id, training_unit_id, order_index, title, guidance_notes, source_template_section_id
        FROM training_unit_sections
        WHERE training_unit_id = %s
        ORDER BY order_index
        """,
        (unit_id,),
    )
    secs = []
    for sec_row in cur.fetchall():
        sec = r2d(sec_row)
        cur.execute(
            """
            SELECT tusi.*,
                e.title AS exercise_title,
                e.summary AS exercise_summary,
                (
                    SELECT fa.name FROM exercise_focus_areas efa
                    JOIN focus_areas fa ON fa.id = efa.focus_area_id
                    WHERE efa.exercise_id = e.id
                    ORDER BY efa.is_primary DESC NULLS LAST, fa.name ASC
                    LIMIT 1
                ) AS exercise_focus_area,
                ev.variant_name AS exercise_variant_name
            FROM training_unit_section_items tusi
            LEFT JOIN exercises e ON tusi.exercise_id = e.id
            LEFT JOIN exercise_variants ev ON tusi.exercise_variant_id = ev.id
            WHERE tusi.section_id = %s
            ORDER BY tusi.order_index
            """,
            (sec["id"],),
        )
        sec["items"] = [r2d(r) for r in cur.fetchall()]
        secs.append(sec)
    return secs


def _flatten_exercises_from_sections(unit: Dict[str, Any]) -> None:
    flat: List[Dict[str, Any]] = []
    for sec in sorted(unit.get("sections", []), key=lambda s: s.get("order_index", 0)):
        for item in sorted(sec.get("items", []), key=lambda i: i.get("order_index", 0)):
            if item.get("item_type") == "exercise":
                flat.append(item)
    unit["exercises"] = flat


def _hydrate_training_unit_payload(cur, unit: Dict[str, Any]) -> Dict[str, Any]:
    uid = unit["id"]
    unit["sections"] = _fetch_sections(cur, uid)
    _flatten_exercises_from_sections(unit)
    return unit


def _insert_section_items(cur, section_id: int, items_in: Optional[List[Any]], start_order: int = 0):
    if items_in is None:
        items_in = []
    for i, raw in enumerate(items_in):
        itype = raw.get("item_type")
        if not itype:
            itype = "exercise" if raw.get("exercise_id") else "note"
        order_ix = raw.get("order_index")
        if order_ix is None:
            order_ix = start_order + i
        if itype == "note":
            body = raw.get("note_body")
            if body is None:
                body = ""
            cur.execute(
                """
                INSERT INTO training_unit_section_items (
                    section_id, order_index, item_type,
                    exercise_id, exercise_variant_id,
                    planned_duration_min, actual_duration_min,
                    notes, modifications, note_body
                ) VALUES (%s, %s, 'note',
                    NULL, NULL, NULL, NULL, NULL, NULL, %s
                )
                """,
                (section_id, order_ix, body),
            )
            continue

        eid = raw.get("exercise_id")
        if not eid:
            continue
        eid = int(eid)
        vid = _optional_positive_int(raw.get("exercise_variant_id"), "exercise_variant_id")
        _validate_variant_for_exercise(cur, eid, vid)
        cur.execute(
            """
            INSERT INTO training_unit_section_items (
                section_id, order_index, item_type,
                exercise_id, exercise_variant_id,
                planned_duration_min, actual_duration_min,
                notes, modifications, note_body
            ) VALUES (%s, %s, 'exercise',
                %s, %s, %s, %s, %s, %s, NULL
            )
            """,
            (
                section_id,
                order_ix,
                eid,
                vid,
                raw.get("planned_duration_min"),
                raw.get("actual_duration_min"),
                raw.get("notes"),
                raw.get("modifications"),
            ),
        )


def _replace_unit_sections(cur, unit_id: int, sections_in: List[Any]):
    cur.execute("DELETE FROM training_unit_sections WHERE training_unit_id = %s", (unit_id,))
    for si, sec in enumerate(sections_in):
        title = (sec.get("title") or "").strip() or "Abschnitt"
        order_ix = sec.get("order_index")
        if order_ix is None:
            order_ix = si
        src_tsec = _optional_positive_int(sec.get("source_template_section_id"), "source_template_section_id")
        cur.execute(
            """
            INSERT INTO training_unit_sections (
                training_unit_id, order_index, title, guidance_notes, source_template_section_id
            ) VALUES (%s, %s, %s, %s, %s)
            RETURNING id
            """,
            (
                unit_id,
                order_ix,
                title,
                sec.get("guidance_notes"),
                src_tsec,
            ),
        )
        sid = cur.fetchone()["id"]
        _insert_section_items(cur, sid, sec.get("items"))


def _insert_sections_from_legacy_exercises(cur, unit_id: int, exercises_in: List[Any]):
    if not exercises_in:
        return
    cur.execute(
        """
        INSERT INTO training_unit_sections (training_unit_id, order_index, title, guidance_notes)
        VALUES (%s, 0, %s, NULL)
        RETURNING id
        """,
        (unit_id, "Übungen"),
    )
    sid = cur.fetchone()["id"]
    slot = 0
    filtered: List[Dict[str, Any]] = []
    for ex in exercises_in:
        eid = ex.get("exercise_id")
        if not eid:
            continue
        eid = int(eid)
        vid = _optional_positive_int(ex.get("exercise_variant_id"), "exercise_variant_id")
        _validate_variant_for_exercise(cur, eid, vid)
        filtered.append(
            {
                "item_type": "exercise",
                "order_index": slot,
                "exercise_id": eid,
                "exercise_variant_id": vid,
                "planned_duration_min": ex.get("planned_duration_min"),
                "actual_duration_min": ex.get("actual_duration_min"),
                "notes": ex.get("notes"),
                "modifications": ex.get("modifications"),
            }
        )
        slot += 1
    _insert_section_items(cur, sid, filtered, start_order=0)


def _instantiate_from_template(cur, unit_id: int, template_id: int):
    cur.execute(
        """
        SELECT id, title, guidance_text
        FROM training_plan_template_sections
        WHERE template_id = %s
        ORDER BY order_index
        """,
        (template_id,),
    )
    rows = cur.fetchall()
    for row in rows:
        r = r2d(row)
        cur.execute(
            """
            INSERT INTO training_unit_sections (
                training_unit_id, order_index, title, guidance_notes, source_template_section_id
            ) VALUES (%s, (
                SELECT COALESCE(MAX(order_index), -1) + 1 FROM training_unit_sections u2
                WHERE u2.training_unit_id = %s
            ), %s, %s, %s)
            """,
            (unit_id, unit_id, r["title"], r["guidance_text"], r["id"]),
        )

    # Fallback: keine Sektionen in Vorlage → ein leerer Block
    if not rows:
        cur.execute(
            """
            INSERT INTO training_unit_sections (training_unit_id, order_index, title, guidance_notes)
            SELECT %s, 0, %s, NULL
            WHERE NOT EXISTS (SELECT 1 FROM training_unit_sections WHERE training_unit_id = %s)
            """,
            (unit_id, "Hauptteil", unit_id),
        )


def _template_access(cur, tid: int, profile_id: int, role: str) -> Dict[str, Any]:
    cur.execute(
        """
        SELECT *
        FROM training_plan_templates
        WHERE id = %s
        """,
        (tid,),
    )
    r = cur.fetchone()
    if not r:
        raise HTTPException(status_code=404, detail="Trainingsvorlage nicht gefunden")
    row = r2d(r)
    if role in ["admin", "superadmin"]:
        return row
    if row["created_by"] != profile_id:
        raise HTTPException(status_code=403, detail="Keine Berechtigung für diese Vorlage")
    return row


# ── Vorlagen ────────────────────────────────────────────────────────────


@router.get("/training-plan-templates")
def list_training_plan_templates(session=Depends(require_auth)):
    profile_id = session["profile_id"]
    role = session.get("role")
    with get_db() as conn:
        cur = get_cursor(conn)
        if role in ["admin", "superadmin"]:
            cur.execute(
                """
                SELECT t.*,
                    (SELECT COUNT(*) FROM training_plan_template_sections s WHERE s.template_id = t.id)
                    AS sections_count
                FROM training_plan_templates t
                ORDER BY t.updated_at DESC NULLS LAST, t.name
                """
            )
        else:
            cur.execute(
                """
                SELECT t.*,
                    (SELECT COUNT(*) FROM training_plan_template_sections s WHERE s.template_id = t.id)
                    AS sections_count
                FROM training_plan_templates t
                WHERE t.created_by = %s
                ORDER BY t.updated_at DESC NULLS LAST, t.name
                """,
                (profile_id,),
            )
        return [r2d(r) for r in cur.fetchall()]


@router.get("/training-plan-templates/{template_id}")
def get_training_plan_template(template_id: int, session=Depends(require_auth)):
    profile_id = session["profile_id"]
    role = session.get("role")
    with get_db() as conn:
        cur = get_cursor(conn)
        row = _template_access(cur, template_id, profile_id, role)
        cur.execute(
            """
            SELECT *
            FROM training_plan_template_sections
            WHERE template_id = %s
            ORDER BY order_index
            """,
            (template_id,),
        )
        row["sections"] = [r2d(r) for r in cur.fetchall()]
        return row


@router.post("/training-plan-templates")
def create_training_plan_template(data: dict, session=Depends(require_auth)):
    profile_id = session["profile_id"]
    role = session.get("role")
    if not _has_planning_role(role):
        raise HTTPException(status_code=403, detail="Nur Trainer dürfen Vorlagen anlegen")
    name = (data.get("name") or "").strip()
    if not name:
        raise HTTPException(status_code=400, detail="name ist Pflicht")
    club_id = data.get("club_id")
    sections_in = data.get("sections") or []

    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute(
            """
            INSERT INTO training_plan_templates (club_id, created_by, name, description)
            VALUES (%s, %s, %s, %s)
            RETURNING id
            """,
            (club_id, profile_id, name, data.get("description")),
        )
        tid = cur.fetchone()["id"]
        for si, sec in enumerate(sections_in):
            title = (sec.get("title") or "").strip() or f"Abschnitt {si + 1}"
            order_ix = sec.get("order_index")
            if order_ix is None:
                order_ix = si
            cur.execute(
                """
                INSERT INTO training_plan_template_sections (template_id, order_index, title, guidance_text)
                VALUES (%s, %s, %s, %s)
                """,
                (tid, order_ix, title, sec.get("guidance_text")),
            )
        conn.commit()
    return get_training_plan_template(tid, session)


@router.put("/training-plan-templates/{template_id}")
def update_training_plan_template(template_id: int, data: dict, session=Depends(require_auth)):
    profile_id = session["profile_id"]
    role = session.get("role")
    with get_db() as conn:
        cur = get_cursor(conn)
        _template_access(cur, template_id, profile_id, role)
        fields = []
        params: List[Any] = []
        if "name" in data:
            name = data.get("name")
            name = name.strip() if isinstance(name, str) else ""
            if not name:
                raise HTTPException(status_code=400, detail="name ist Pflicht")
            fields.append("name = %s")
            params.append(name)
        if "description" in data:
            fields.append("description = %s")
            params.append(data.get("description"))
        if "club_id" in data:
            fields.append("club_id = %s")
            params.append(data.get("club_id"))
        fields.append("updated_at = NOW()")
        params.append(template_id)
        cur.execute(
            f"""
            UPDATE training_plan_templates SET {", ".join(fields)}
            WHERE id = %s
            """,
            tuple(params),
        )
        if "sections" in data:
            cur.execute(
                "DELETE FROM training_plan_template_sections WHERE template_id = %s", (template_id,)
            )
            sections_in = data["sections"] or []
            for si, sec in enumerate(sections_in):
                title = (sec.get("title") or "").strip() or f"Abschnitt {si + 1}"
                order_ix = sec.get("order_index")
                if order_ix is None:
                    order_ix = si
                cur.execute(
                    """
                    INSERT INTO training_plan_template_sections (template_id, order_index, title, guidance_text)
                    VALUES (%s, %s, %s, %s)
                    """,
                    (template_id, order_ix, title, sec.get("guidance_text")),
                )
        conn.commit()
    return get_training_plan_template(template_id, session)


@router.delete("/training-plan-templates/{template_id}")
def delete_training_plan_template(template_id: int, session=Depends(require_auth)):
    profile_id = session["profile_id"]
    role = session.get("role")
    with get_db() as conn:
        cur = get_cursor(conn)
        _template_access(cur, template_id, profile_id, role)
        cur.execute("DELETE FROM training_plan_templates WHERE id = %s", (template_id,))
        conn.commit()
    return {"ok": True}


# ── Einheiten ─────────────────────────────────────────────────────────────


@router.get("/training-units")
def list_training_units(
    group_id: Optional[int] = Query(default=None),
    start_date: Optional[str] = Query(default=None),
    end_date: Optional[str] = Query(default=None),
    status: Optional[str] = Query(default=None),
    session=Depends(require_auth),
):
    profile_id = session["profile_id"]
    role = session.get("role")

    with get_db() as conn:
        cur = get_cursor(conn)

        query = """
            SELECT tu.*,
                tg.name as group_name,
                tg.weekday as group_weekday,
                c.name as club_name,
                p.name as trainer_name
            FROM training_units tu
            LEFT JOIN training_groups tg ON tu.group_id = tg.id
            LEFT JOIN clubs c ON tg.club_id = c.id
            LEFT JOIN profiles p ON tu.created_by = p.id
        """

        where = []
        params = []

        if role not in ["admin", "superadmin"]:
            where.append("(tu.created_by = %s OR tg.trainer_id = %s)")
            params.extend([profile_id, profile_id])

        if group_id:
            where.append("tu.group_id = %s")
            params.append(group_id)

        if start_date:
            where.append("tu.planned_date >= %s")
            params.append(start_date)

        if end_date:
            where.append("tu.planned_date <= %s")
            params.append(end_date)

        if status:
            where.append("tu.status = %s")
            params.append(status)

        if where:
            query += " WHERE " + " AND ".join(where)

        query += " ORDER BY tu.planned_date DESC, tu.planned_time_start DESC"

        cur.execute(query, params)
        rows = cur.fetchall()
        return [r2d(r) for r in rows]


@router.get("/training-units/{unit_id}")
def get_training_unit(unit_id: int, session=Depends(require_auth)):
    profile_id = session["profile_id"]
    role = session.get("role")

    with get_db() as conn:
        cur = get_cursor(conn)

        cur.execute(
            """
            SELECT tu.*,
                tg.name as group_name,
                tg.weekday as group_weekday,
                tg.time_start as group_time_start,
                tg.time_end as group_time_end,
                tg.location as group_location,
                c.name as club_name,
                p.name as trainer_name
            FROM training_units tu
            LEFT JOIN training_groups tg ON tu.group_id = tg.id
            LEFT JOIN clubs c ON tg.club_id = c.id
            LEFT JOIN profiles p ON tu.created_by = p.id
            WHERE tu.id = %s
            """,
            (unit_id,),
        )

        unit = cur.fetchone()
        if not unit:
            raise HTTPException(status_code=404, detail="Trainingseinheit nicht gefunden")

        unit = r2d(unit)

        cur.execute("SELECT trainer_id FROM training_groups WHERE id = %s", (unit["group_id"],))
        group = cur.fetchone()

        if role not in ["admin", "superadmin"]:
            if unit["created_by"] != profile_id and (not group or group["trainer_id"] != profile_id):
                raise HTTPException(status_code=403, detail="Keine Berechtigung")

        _hydrate_training_unit_payload(cur, unit)
        return unit


@router.post("/training-units")
def create_training_unit(data: dict, session=Depends(require_auth)):
    profile_id = session["profile_id"]
    role = session.get("role")

    group_id = data.get("group_id")
    planned_date = data.get("planned_date")

    if not group_id or not planned_date:
        raise HTTPException(status_code=400, detail="group_id und planned_date sind Pflichtfelder")

    plan_template_id = _optional_positive_int(data.get("plan_template_id"), "plan_template_id")

    with get_db() as conn:
        cur = get_cursor(conn)

        _can_access_group_for_create(cur, group_id, profile_id, role)

        tpl_id_safe = None
        if plan_template_id:
            _template_access(cur, plan_template_id, profile_id, role)
            tpl_id_safe = plan_template_id

        cur.execute(
            """
            INSERT INTO training_units (
                group_id, planned_date, planned_time_start, planned_time_end,
                planned_focus, status, notes, trainer_notes, created_by,
                plan_template_id
            ) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s)
            RETURNING id
            """,
            (
                group_id,
                planned_date,
                data.get("planned_time_start"),
                data.get("planned_time_end"),
                data.get("planned_focus"),
                data.get("status", "planned"),
                data.get("notes"),
                data.get("trainer_notes"),
                profile_id,
                tpl_id_safe,
            ),
        )

        unit_id = cur.fetchone()["id"]

        sections_in = data.get("sections")
        exercises_in = data.get("exercises")

        if sections_in is not None:
            _replace_unit_sections(cur, unit_id, sections_in)
        elif tpl_id_safe:
            _instantiate_from_template(cur, unit_id, tpl_id_safe)
        elif exercises_in is not None:
            _insert_sections_from_legacy_exercises(cur, unit_id, exercises_in)

        conn.commit()

    return get_training_unit(unit_id, session)


@router.put("/training-units/{unit_id}")
def update_training_unit(unit_id: int, data: dict, session=Depends(require_auth)):
    profile_id = session["profile_id"]
    role = session.get("role")

    with get_db() as conn:
        cur = get_cursor(conn)

        unit_row = _training_unit_guard_row(cur, unit_id)
        _assert_training_unit_permission(cur, unit_row, profile_id, role)

        tpl_upd = data.get("plan_template_id") if "plan_template_id" in data else None
        tpl_id_val = None
        if tpl_upd not in (None, ""):
            tid = _optional_positive_int(tpl_upd, "plan_template_id")
            if tid:
                _template_access(cur, tid, profile_id, role)
                tpl_id_val = tid

        trainer_notes_val = None
        if "trainer_notes" not in data:
            cur.execute(
                "SELECT trainer_notes FROM training_units WHERE id = %s",
                (unit_id,),
            )
            row_tn = cur.fetchone()
            trainer_notes_val = row_tn["trainer_notes"] if row_tn else None
        else:
            trainer_notes_val = data.get("trainer_notes")

        cur.execute(
            """
            UPDATE training_units SET
                planned_date = COALESCE(%s, planned_date),
                planned_time_start = %s,
                planned_time_end = %s,
                planned_focus = %s,
                actual_date = %s,
                actual_time_start = %s,
                actual_time_end = %s,
                attendance_count = %s,
                status = %s,
                notes = %s,
                trainer_notes = %s,
                plan_template_id = COALESCE(%s, plan_template_id),
                updated_at = NOW()
            WHERE id = %s
            """,
            (
                data.get("planned_date"),
                data.get("planned_time_start"),
                data.get("planned_time_end"),
                data.get("planned_focus"),
                data.get("actual_date"),
                data.get("actual_time_start"),
                data.get("actual_time_end"),
                data.get("attendance_count"),
                data.get("status"),
                data.get("notes"),
                trainer_notes_val,
                tpl_id_val,
                unit_id,
            ),
        )

        content_handled = False
        if data.get("reset_from_template"):
            tid = tpl_id_val or unit_row.get("plan_template_id")
            if not tid:
                raise HTTPException(
                    status_code=400,
                    detail="reset_from_template erfordert plan_template_id auf der Einheit oder im Request",
                )
            _template_access(cur, tid, profile_id, role)
            cur.execute("DELETE FROM training_unit_sections WHERE training_unit_id = %s", (unit_id,))
            cur.execute(
                "UPDATE training_units SET plan_template_id = %s WHERE id = %s", (tid, unit_id)
            )
            _instantiate_from_template(cur, unit_id, tid)
            content_handled = True

        if not content_handled and "sections" in data:
            _replace_unit_sections(cur, unit_id, data["sections"] or [])
        elif not content_handled and "exercises" in data:
            cur.execute("DELETE FROM training_unit_sections WHERE training_unit_id = %s", (unit_id,))
            _insert_sections_from_legacy_exercises(cur, unit_id, data["exercises"] or [])

        conn.commit()

    return get_training_unit(unit_id, session)


@router.delete("/training-units/{unit_id}")
def delete_training_unit(unit_id: int, session=Depends(require_auth)):
    profile_id = session["profile_id"]
    role = session.get("role")

    with get_db() as conn:
        cur = get_cursor(conn)

        cur.execute(
            "SELECT created_by FROM training_units WHERE id = %s",
            (unit_id,),
        )

        unit = cur.fetchone()

        if not unit:
            raise HTTPException(status_code=404, detail="Trainingseinheit nicht gefunden")

        _assert_delete_training_unit(role, unit["created_by"], profile_id)

        cur.execute("DELETE FROM training_units WHERE id = %s", (unit_id,))
        conn.commit()

    return {"ok": True}


@router.post("/training-units/quick-create")
def quick_create_training_unit(data: dict, session=Depends(require_auth)):
    profile_id = session["profile_id"]

    group_id = data.get("group_id")
    planned_date = data.get("planned_date")
    plan_template_id = _optional_positive_int(data.get("plan_template_id"), "plan_template_id")

    if not group_id or not planned_date:
        raise HTTPException(status_code=400, detail="group_id und planned_date sind Pflichtfelder")

    with get_db() as conn:
        cur = get_cursor(conn)

        cur.execute(
            """
            SELECT weekday, time_start, time_end, trainer_id, co_trainer_ids
            FROM training_groups
            WHERE id = %s
            """,
            (group_id,),
        )

        group = cur.fetchone()

        if not group:
            raise HTTPException(status_code=404, detail="Trainingsgruppe nicht gefunden")

        role = session.get("role")
        co_trainers = group["co_trainer_ids"] or []

        if not _has_planning_role(role):
            raise HTTPException(status_code=403, detail="Nur Trainer dürfen Trainingseinheiten erstellen")

        if role not in ["admin", "superadmin"]:
            if group["trainer_id"] != profile_id and profile_id not in co_trainers:
                raise HTTPException(status_code=403, detail="Keine Berechtigung für diese Gruppe")

        tpl_id_safe = None
        if plan_template_id:
            _template_access(cur, plan_template_id, profile_id, role)
            tpl_id_safe = plan_template_id

        cur.execute(
            """
            INSERT INTO training_units (
                group_id, planned_date,
                planned_time_start, planned_time_end,
                status, created_by, plan_template_id
            ) VALUES (%s, %s, %s, %s, %s, %s, %s)
            RETURNING id
            """,
            (
                group_id,
                planned_date,
                group["time_start"],
                group["time_end"],
                "planned",
                profile_id,
                tpl_id_safe,
            ),
        )

        unit_id = cur.fetchone()["id"]

        if tpl_id_safe:
            _instantiate_from_template(cur, unit_id, tpl_id_safe)

        conn.commit()

    return get_training_unit(unit_id, session)