"""
Exercises Router - v2.0 (Clean-Room Rebuild)

Komplett neu gebaut nach EXERCISES_API_SPEC.md v1.2
KEIN Legacy-Code aus v1 - nur M:N Relations, keine JSONB-Felder für Kataloge
"""
import json
import logging
from typing import Optional

from fastapi import APIRouter, HTTPException, Depends, Query
from pydantic import BaseModel, Field

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

logger = logging.getLogger(__name__)

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


# ============================================================================
# Pydantic Models
# ============================================================================

class ExerciseCreate(BaseModel):
    # Basis-Felder
    title: str = Field(..., min_length=3, max_length=300)
    summary: Optional[str] = None
    goal: str = Field(..., min_length=10, max_length=5000)
    execution: str = Field(..., min_length=10, max_length=10000)
    preparation: Optional[str] = None
    trainer_notes: Optional[str] = None

    # Dauer & Gruppengröße
    duration_min: Optional[int] = None
    duration_max: Optional[int] = None
    group_size_min: Optional[int] = None
    group_size_max: Optional[int] = None

    # Equipment (Liste von Strings)
    equipment: list[str] = []

    # M:N Relations (Liste von {id: int, is_primary: bool})
    focus_areas_multi: list[dict] = []
    training_styles_multi: list[dict] = []
    target_groups_multi: list[dict] = []
    age_groups: list[str] = []  # ["Kinder", "Teenager"] aus Katalog

    # Skills (Liste von {skill_id: int, is_primary: bool, intensity: str, required_level: str, target_level: str})
    skills: list[dict] = []

    # Sichtbarkeit & Status
    visibility: str = "private"
    status: str = "draft"
    club_id: Optional[int] = None


class ExerciseUpdate(BaseModel):
    # Alle Felder optional für Partial Update
    title: Optional[str] = Field(None, min_length=3, max_length=300)
    summary: Optional[str] = None
    goal: Optional[str] = Field(None, min_length=10, max_length=5000)
    execution: Optional[str] = Field(None, min_length=10, max_length=10000)
    preparation: Optional[str] = None
    trainer_notes: Optional[str] = None
    duration_min: Optional[int] = None
    duration_max: Optional[int] = None
    group_size_min: Optional[int] = None
    group_size_max: Optional[int] = None
    equipment: Optional[list[str]] = None
    focus_areas_multi: Optional[list[dict]] = None
    training_styles_multi: Optional[list[dict]] = None
    target_groups_multi: Optional[list[dict]] = None
    age_groups: Optional[list[str]] = None
    skills: Optional[list[dict]] = None
    visibility: Optional[str] = None
    status: Optional[str] = None
    club_id: Optional[int] = None


# ============================================================================
# Helper Functions
# ============================================================================

def enrich_exercise_detail(exercise_id: int, cur) -> dict:
    """
    Lädt alle M:N Relations für eine Übung und gibt ein vollständiges
    Exercise-Objekt zurück (wie in API-Spec GET /exercises/{id}).
    """
    # Basis-Exercise
    cur.execute(
        """SELECT e.*, p.name as creator_name, c.name as club_name
           FROM exercises e
           LEFT JOIN profiles p ON e.created_by = p.id
           LEFT JOIN clubs c ON e.club_id = c.id
           WHERE e.id = %s""",
        (exercise_id,)
    )
    row = cur.fetchone()
    if not row:
        return None

    exercise = r2d(row)

    # Equipment JSONB → List
    if exercise.get("equipment"):
        exercise["equipment"] = exercise["equipment"] if isinstance(exercise["equipment"], list) else []
    else:
        exercise["equipment"] = []

    # Focus Areas (M:N)
    cur.execute(
        """SELECT efa.id, efa.focus_area_id, fa.name, fa.abbreviation, fa.color, fa.icon, efa.is_primary
           FROM exercise_focus_areas efa
           JOIN focus_areas fa ON efa.focus_area_id = fa.id
           WHERE efa.exercise_id = %s
           ORDER BY efa.is_primary DESC, fa.name""",
        (exercise_id,)
    )
    exercise["focus_areas"] = [r2d(r) for r in cur.fetchall()]

    # Training Styles (M:N)
    cur.execute(
        """SELECT ets.id, ets.style_direction_id as training_style_id, sd.name, sd.abbreviation, ets.is_primary
           FROM exercise_style_directions ets
           JOIN style_directions sd ON ets.style_direction_id = sd.id
           WHERE ets.exercise_id = %s
           ORDER BY ets.is_primary DESC, sd.name""",
        (exercise_id,)
    )
    exercise["training_styles"] = [r2d(r) for r in cur.fetchall()]

    # Target Groups (M:N)
    cur.execute(
        """SELECT etg.id, etg.target_group_id, tg.name, tg.description, etg.is_primary
           FROM exercise_target_groups etg
           JOIN target_groups tg ON etg.target_group_id = tg.id
           WHERE etg.exercise_id = %s
           ORDER BY etg.is_primary DESC, tg.name""",
        (exercise_id,)
    )
    exercise["target_groups"] = [r2d(r) for r in cur.fetchall()]

    # Age Groups (M:N) - direkt als VARCHAR gespeichert
    cur.execute(
        """SELECT age_group
           FROM exercise_age_groups
           WHERE exercise_id = %s
           ORDER BY age_group""",
        (exercise_id,)
    )
    exercise["age_groups"] = [r["age_group"] for r in cur.fetchall()]

    # Skills (M:N) mit Levels und Intensity
    cur.execute(
        """SELECT es.id, es.skill_id, s.name as skill_name, s.category as skill_category,
                  es.is_primary, es.intensity, es.required_level, es.target_level, es.ai_suggested
           FROM exercise_skills es
           JOIN skills s ON es.skill_id = s.id
           WHERE es.exercise_id = %s
           ORDER BY es.is_primary DESC, s.name""",
        (exercise_id,)
    )
    exercise["skills"] = [r2d(r) for r in cur.fetchall()]

    # Variants (1:N) - mit Progression
    cur.execute(
        """SELECT id, variant_name, description, execution_changes,
                  duration_min, duration_max, equipment_changes, difficulty_adjustment,
                  progression_level, sequence_order, prerequisite_variant_id
           FROM exercise_variants
           WHERE exercise_id = %s
           ORDER BY progression_level, sequence_order""",
        (exercise_id,)
    )
    exercise["variants"] = [r2d(r) for r in cur.fetchall()]

    # Media (1:N)
    cur.execute(
        """SELECT id, media_type, file_path, file_size, mime_type, original_filename,
                  embed_url, embed_platform, title, description, sort_order, is_primary, context
           FROM exercise_media
           WHERE exercise_id = %s
           ORDER BY sort_order, id""",
        (exercise_id,)
    )
    exercise["media"] = [r2d(r) for r in cur.fetchall()]

    return exercise


def assign_exercise_relations(cur, conn, exercise_id: int, data: dict):
    """
    Weist M:N Relations für eine Übung zu.
    Löscht alte Zuordnungen und legt neue an (REPLACE-Logik).
    """
    # Focus Areas
    if "focus_areas_multi" in data:
        cur.execute("DELETE FROM exercise_focus_areas WHERE exercise_id = %s", (exercise_id,))
        for fa in data["focus_areas_multi"]:
            cur.execute(
                """INSERT INTO exercise_focus_areas (exercise_id, focus_area_id, is_primary)
                   VALUES (%s, %s, %s)""",
                (exercise_id, fa["focus_area_id"], fa.get("is_primary", False))
            )

    # Training Styles
    if "training_styles_multi" in data:
        cur.execute("DELETE FROM exercise_style_directions WHERE exercise_id = %s", (exercise_id,))
        for ts in data["training_styles_multi"]:
            cur.execute(
                """INSERT INTO exercise_style_directions (exercise_id, style_direction_id, is_primary)
                   VALUES (%s, %s, %s)""",
                (exercise_id, ts["training_style_id"], ts.get("is_primary", False))
            )

    # Target Groups
    if "target_groups_multi" in data:
        cur.execute("DELETE FROM exercise_target_groups WHERE exercise_id = %s", (exercise_id,))
        for tg in data["target_groups_multi"]:
            cur.execute(
                """INSERT INTO exercise_target_groups (exercise_id, target_group_id, is_primary)
                   VALUES (%s, %s, %s)""",
                (exercise_id, tg["target_group_id"], tg.get("is_primary", False))
            )

    # Age Groups (direkt als VARCHAR, CHECK constraint validiert)
    if "age_groups" in data:
        cur.execute("DELETE FROM exercise_age_groups WHERE exercise_id = %s", (exercise_id,))
        for age_group_name in data["age_groups"]:
            try:
                cur.execute(
                    "INSERT INTO exercise_age_groups (exercise_id, age_group) VALUES (%s, %s)",
                    (exercise_id, age_group_name)
                )
            except Exception as e:
                logger.warning("Age Group '%s' ungültig: %s", age_group_name, e)

    # Skills
    if "skills" in data:
        cur.execute("DELETE FROM exercise_skills WHERE exercise_id = %s", (exercise_id,))
        for skill in data["skills"]:
            cur.execute(
                """INSERT INTO exercise_skills
                   (exercise_id, skill_id, is_primary, intensity, required_level, target_level, ai_suggested)
                   VALUES (%s, %s, %s, %s, %s, %s, %s)""",
                (
                    exercise_id,
                    skill["skill_id"],
                    skill.get("is_primary", False),
                    skill.get("intensity"),
                    skill.get("required_level"),
                    skill.get("target_level"),
                    skill.get("ai_suggested", False),
                )
            )

    conn.commit()


# ============================================================================
# Endpoints
# ============================================================================

@router.get("/exercises")
def list_exercises(
    focus_area: Optional[int] = Query(default=None),
    visibility: Optional[str] = Query(default=None),
    status: Optional[str] = Query(default=None),
    skill_id: Optional[int] = Query(default=None),
    search: Optional[str] = Query(default=None),
    limit: int = Query(default=50, ge=1, le=100),
    offset: int = Query(default=0, ge=0),
    session: dict = Depends(require_auth),
):
    """
    Liste aller Übungen mit Filtern.
    Lightweight Response (ohne M:N Details, nur IDs und Namen).
    """
    profile_id = session["profile_id"]

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

        # WHERE-Bedingungen
        where = ["1=1"]
        params = []

        # Visibility Filter (private nur für Owner)
        where.append("(e.visibility = 'official' OR e.visibility = 'club' OR e.created_by = %s)")
        params.append(profile_id)

        if visibility:
            where.append("e.visibility = %s")
            params.append(visibility)

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

        # Focus Area Filter (M:N Join)
        if focus_area:
            where.append("EXISTS (SELECT 1 FROM exercise_focus_areas efa WHERE efa.exercise_id = e.id AND efa.focus_area_id = %s)")
            params.append(focus_area)

        # Skill Filter (M:N Join)
        if skill_id:
            where.append("EXISTS (SELECT 1 FROM exercise_skills es WHERE es.exercise_id = e.id AND es.skill_id = %s)")
            params.append(skill_id)

        # Volltext-Suche (tsvector)
        if search:
            where.append("e.search_vector @@ plainto_tsquery('german', %s)")
            params.append(search)

        # Query
        query = f"""
            SELECT e.id, e.title, e.summary, e.visibility, e.status,
                   e.created_by, p.name as creator_name,
                   e.club_id, c.name as club_name,
                   e.created_at, e.updated_at
            FROM exercises e
            LEFT JOIN profiles p ON e.created_by = p.id
            LEFT JOIN clubs c ON e.club_id = c.id
            WHERE {' AND '.join(where)}
            ORDER BY e.updated_at DESC
            LIMIT %s OFFSET %s
        """
        params.extend([limit, offset])

        cur.execute(query, params)
        rows = cur.fetchall()

    return [r2d(r) for r in rows]


@router.get("/exercises/{exercise_id}")
def get_exercise(
    exercise_id: int,
    session: dict = Depends(require_auth),
):
    """
    Exercise Detail mit allen M:N Relations (vollständig enriched).
    """
    profile_id = session["profile_id"]

    with get_db() as conn:
        cur = get_cursor(conn)
        exercise = enrich_exercise_detail(exercise_id, cur)

    if not exercise:
        raise HTTPException(status_code=404, detail="Übung nicht gefunden")

    # Permission Check (private nur für Owner)
    if exercise["visibility"] == "private" and exercise["created_by"] != profile_id:
        raise HTTPException(status_code=403, detail="Keine Berechtigung für diese Übung")

    return exercise


@router.post("/exercises", status_code=201)
def create_exercise(
    body: ExerciseCreate,
    session: dict = Depends(require_auth),
):
    """
    Erstellt eine neue Übung mit allen M:N Relations.
    """
    profile_id = session["profile_id"]

    # Validierung
    if body.status not in ("draft", "in_review", "approved", "archived"):
        raise HTTPException(status_code=400, detail="Ungültiger Status")
    if body.visibility not in ("private", "club", "official"):
        raise HTTPException(status_code=400, detail="Ungültige Visibility")

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

        # Equipment als JSONB
        equipment_json = json.dumps(body.equipment) if body.equipment else None

        # INSERT
        cur.execute(
            """INSERT INTO exercises
               (title, summary, goal, execution, preparation, trainer_notes,
                duration_min, duration_max, group_size_min, group_size_max,
                equipment, visibility, status, created_by, club_id)
               VALUES (%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s)
               RETURNING id""",
            (
                body.title, body.summary, body.goal, body.execution,
                body.preparation, body.trainer_notes,
                body.duration_min, body.duration_max,
                body.group_size_min, body.group_size_max,
                equipment_json,
                body.visibility, body.status, profile_id, body.club_id,
            )
        )
        row = cur.fetchone()
        exercise_id = row['id'] if isinstance(row, dict) else row[0]
        conn.commit()

        # M:N Relations zuweisen
        data = body.dict()
        assign_exercise_relations(cur, conn, exercise_id, data)

        # Vollständiges Objekt zurückgeben
        exercise = enrich_exercise_detail(exercise_id, cur)

    return exercise


@router.put("/exercises/{exercise_id}")
def update_exercise(
    exercise_id: int,
    body: ExerciseUpdate,
    session: dict = Depends(require_auth),
):
    """
    Aktualisiert eine Übung (Partial Update).
    Nur Owner darf editieren.
    """
    profile_id = session["profile_id"]

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

        # Existiert die Übung?
        cur.execute("SELECT created_by FROM exercises WHERE id = %s", (exercise_id,))
        row = cur.fetchone()
        if not row:
            raise HTTPException(status_code=404, detail="Übung nicht gefunden")

        # Permission Check
        if row[0] != profile_id:
            raise HTTPException(status_code=403, detail="Nur der Ersteller darf editieren")

        # UPDATE (nur gesetzte Felder)
        fields = []
        params = []

        data = body.dict(exclude_unset=True)

        # Basis-Felder
        for field in ["title", "summary", "goal", "execution", "preparation", "trainer_notes",
                      "duration_min", "duration_max", "group_size_min", "group_size_max",
                      "visibility", "status", "club_id"]:
            if field in data and data[field] is not None:
                fields.append(f"{field} = %s")
                params.append(data[field])

        # Equipment (JSONB)
        if "equipment" in data:
            fields.append("equipment = %s")
            params.append(json.dumps(data["equipment"]) if data["equipment"] else None)

        # UPDATE ausführen (wenn Basis-Felder geändert wurden)
        if fields:
            fields.append("updated_at = NOW()")
            params.append(exercise_id)
            query = f"UPDATE exercises SET {', '.join(fields)} WHERE id = %s"
            cur.execute(query, params)
            conn.commit()

        # M:N Relations aktualisieren (wenn angegeben)
        assign_exercise_relations(cur, conn, exercise_id, data)

        # Vollständiges Objekt zurückgeben
        exercise = enrich_exercise_detail(exercise_id, cur)

    return exercise


@router.delete("/exercises/{exercise_id}")
def delete_exercise(
    exercise_id: int,
    session: dict = Depends(require_auth),
):
    """
    Löscht eine Übung.
    Nur Owner oder Admin darf löschen.
    """
    profile_id = session["profile_id"]
    role = session.get("role")

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

        # Existiert die Übung?
        cur.execute("SELECT created_by FROM exercises WHERE id = %s", (exercise_id,))
        row = cur.fetchone()
        if not row:
            raise HTTPException(status_code=404, detail="Übung nicht gefunden")

        # Permission Check
        if row[0] != profile_id and role not in ("admin", "superadmin"):
            raise HTTPException(status_code=403, detail="Nur Ersteller oder Admin darf löschen")

        # Prüfen ob Übung in Trainingseinheiten verwendet wird
        cur.execute(
            "SELECT COUNT(*) FROM exercise_block_items WHERE exercise_id = %s",
            (exercise_id,)
        )
        count = cur.fetchone()[0]
        if count > 0:
            raise HTTPException(
                status_code=409,
                detail=f"Übung wird in {count} Block-Item(s) verwendet und kann nicht gelöscht werden"
            )

        # DELETE (Cascade löscht M:N Zuordnungen automatisch)
        cur.execute("DELETE FROM exercises WHERE id = %s", (exercise_id,))
        conn.commit()

    return {"ok": True}