import json
from collections import defaultdict
from datetime import datetime, timedelta
from typing import Any, Dict, List, Optional

from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel
from sqlmodel import Session, select

from app.ai.kettlebell import kettlebell_module, kettlebell_refine_module
from app.api import deps
from app.models.kettlebell import KettlebellSession, KettlebellSetLog

router = APIRouter()


class KettlebellGenerateRequest(BaseModel):
    focus: str
    duration_minutes: int
    available_weights: list[float]


class DraftExercise(BaseModel):
    order: int
    name: str
    description: str
    sets: int
    reps: int
    duration_seconds: int
    weight_kg: float
    rest_seconds: int
    coaching_tip: str


class DraftSession(BaseModel):
    title: str
    focus: str
    total_duration_min: int
    difficulty: str
    exercises: list[DraftExercise]
    notes: str


class RefineRequest(BaseModel):
    draft: DraftSession
    feedback: str
    focus: str
    duration_minutes: int
    available_weights: list[float]


class SaveDraftRequest(BaseModel):
    draft: DraftSession


class LogSetRequest(BaseModel):
    exercise_order: int
    set_number: int
    actual_reps: int
    actual_weight_kg: float
    actual_duration_seconds: int
    perceived_effort: int


class CompleteSessionRequest(BaseModel):
    notes: Optional[str] = None


class ExerciseProgression(BaseModel):
    date: str
    max_weight: float
    avg_rpe: float
    total_volume: float


class PersonalRecord(BaseModel):
    exercise_name: str
    max_weight: float
    date: str


class WeeklyVolume(BaseModel):
    week: str
    sessions: int
    total_volume: float


class AnalyticsResponse(BaseModel):
    weekly_sessions: List[WeeklyVolume]
    exercise_progressions: Dict[str, List[ExerciseProgression]]
    personal_records: List[PersonalRecord]
    avg_rpe_trend: List[Dict]


@router.get("/analytics", response_model=AnalyticsResponse)
def get_analytics(
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Get aggregated analytics across all completed sessions."""
    completed_sessions = session.exec(
        select(KettlebellSession)
        .where(KettlebellSession.user_id == current_user.id)
        .where(KettlebellSession.status == "completed")
        .order_by(KettlebellSession.completed_at)
    ).all()

    if not completed_sessions:
        return AnalyticsResponse(
            weekly_sessions=[],
            exercise_progressions={},
            personal_records=[],
            avg_rpe_trend=[],
        )

    session_ids = [s.id for s in completed_sessions]
    all_sets = session.exec(select(KettlebellSetLog).where(KettlebellSetLog.session_id.in_(session_ids))).all()

    # Map session_id -> session
    session_map = {s.id: s for s in completed_sessions}
    # Map session_id -> exercise_order -> exercise_name
    exercise_name_map: Dict[int, Dict[int, str]] = {}
    for s in completed_sessions:
        exercises = s.exercises.get("exercises", []) if s.exercises else []
        exercise_name_map[s.id] = {ex["order"]: ex["name"] for ex in exercises if "order" in ex and "name" in ex}

    # Weekly sessions + volume
    weeks: Dict[str, Dict] = defaultdict(lambda: {"sessions": set(), "volume": 0.0})
    for set_log in all_sets:
        s = session_map.get(set_log.session_id)
        if not s or not s.completed_at:
            continue
        week_start = s.completed_at - timedelta(days=s.completed_at.weekday())
        week_key = week_start.strftime("%Y-%m-%d")
        weeks[week_key]["sessions"].add(set_log.session_id)
        volume = set_log.actual_reps * set_log.actual_weight_kg
        weeks[week_key]["volume"] += volume

    weekly_sessions = [
        WeeklyVolume(week=k, sessions=len(v["sessions"]), total_volume=round(v["volume"], 1))
        for k, v in sorted(weeks.items())
    ]

    # Exercise progressions + PRs
    exercise_data: Dict[str, List[Dict]] = defaultdict(list)
    for set_log in all_sets:
        s = session_map.get(set_log.session_id)
        if not s or not s.completed_at:
            continue
        ex_name = exercise_name_map.get(set_log.session_id, {}).get(set_log.exercise_order)
        if not ex_name:
            continue
        exercise_data[ex_name].append(
            {
                "date": s.completed_at.strftime("%Y-%m-%d"),
                "weight": set_log.actual_weight_kg,
                "rpe": set_log.perceived_effort,
                "volume": set_log.actual_reps * set_log.actual_weight_kg,
            }
        )

    exercise_progressions: Dict[str, List[ExerciseProgression]] = {}
    personal_records: List[PersonalRecord] = []

    for ex_name, sets in exercise_data.items():
        by_date: Dict[str, Dict] = defaultdict(lambda: {"weights": [], "rpes": [], "volume": 0.0})
        for s in sets:
            by_date[s["date"]]["weights"].append(s["weight"])
            by_date[s["date"]]["rpes"].append(s["rpe"])
            by_date[s["date"]]["volume"] += s["volume"]

        progressions = [
            ExerciseProgression(
                date=d,
                max_weight=max(v["weights"]),
                avg_rpe=round(sum(v["rpes"]) / len(v["rpes"]), 1),
                total_volume=round(v["volume"], 1),
            )
            for d, v in sorted(by_date.items())
        ]
        exercise_progressions[ex_name] = progressions

        all_weights = [s["weight"] for s in sets]
        max_w = max(all_weights)
        pr_date = next(s["date"] for s in sorted(sets, key=lambda x: x["date"]) if s["weight"] == max_w)
        personal_records.append(PersonalRecord(exercise_name=ex_name, max_weight=max_w, date=pr_date))

    personal_records.sort(key=lambda x: x.max_weight, reverse=True)

    # Avg RPE trend by session
    avg_rpe_trend = []
    sets_by_session: Dict[int, List] = defaultdict(list)
    for set_log in all_sets:
        sets_by_session[set_log.session_id].append(set_log.perceived_effort)

    for s in completed_sessions:
        rpes = sets_by_session.get(s.id, [])
        if rpes and s.completed_at:
            avg_rpe_trend.append(
                {
                    "date": s.completed_at.strftime("%Y-%m-%d"),
                    "avg_rpe": round(sum(rpes) / len(rpes), 1),
                    "session_title": s.title,
                }
            )

    return AnalyticsResponse(
        weekly_sessions=weekly_sessions,
        exercise_progressions=exercise_progressions,
        personal_records=personal_records,
        avg_rpe_trend=avg_rpe_trend,
    )


@router.post("/generate-draft", response_model=DraftSession)
def generate_draft(
    *,
    current_user: deps.CurrentUser,
    request: KettlebellGenerateRequest,
) -> Any:
    """Generate a draft kettlebell session (not saved to DB) for review."""
    try:
        user_profile = (
            f"Age: {current_user.age or 'unknown'}, "
            f"Gender: {current_user.gender or 'unknown'}, "
            f"Weight: {current_user.weight or 'unknown'} kg, "
            f"Height: {current_user.height or 'unknown'} cm"
        )
        available_weights_kg = ", ".join(str(w) for w in sorted(request.available_weights))
        generated = kettlebell_module(
            user_profile=user_profile,
            available_weights_kg=available_weights_kg,
            focus=request.focus,
            duration_minutes=request.duration_minutes,
        )
        s = generated.session
        return DraftSession(
            title=s.title,
            focus=s.focus,
            total_duration_min=s.total_duration_min,
            difficulty=s.difficulty,
            exercises=[DraftExercise(**ex.model_dump()) for ex in s.exercises],
            notes=s.notes,
        )
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


@router.post("/refine", response_model=DraftSession)
def refine_draft(
    *,
    current_user: deps.CurrentUser,
    request: RefineRequest,
) -> Any:
    """Refine a draft session based on user feedback."""
    try:
        user_profile = (
            f"Age: {current_user.age or 'unknown'}, "
            f"Gender: {current_user.gender or 'unknown'}, "
            f"Weight: {current_user.weight or 'unknown'} kg, "
            f"Height: {current_user.height or 'unknown'} cm"
        )
        available_weights_kg = ", ".join(str(w) for w in sorted(request.available_weights))
        current_session_json = json.dumps(request.draft.model_dump(), indent=2)
        generated = kettlebell_refine_module(
            current_session=current_session_json,
            user_feedback=request.feedback,
            user_profile=user_profile,
            available_weights_kg=available_weights_kg,
            focus=request.focus,
            duration_minutes=request.duration_minutes,
        )
        s = generated.session
        return DraftSession(
            title=s.title,
            focus=s.focus,
            total_duration_min=s.total_duration_min,
            difficulty=s.difficulty,
            exercises=[DraftExercise(**ex.model_dump()) for ex in s.exercises],
            notes=s.notes,
        )
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


@router.post("/save-draft", response_model=KettlebellSession)
def save_draft(
    *,
    current_user: deps.CurrentUser,
    request: SaveDraftRequest,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Save a finalized draft as a new session."""
    draft = request.draft
    kb_session = KettlebellSession(
        user_id=current_user.id,
        title=draft.title,
        focus=draft.focus,
        exercises={"exercises": [ex.model_dump() for ex in draft.exercises]},
        total_duration_min=draft.total_duration_min,
        difficulty=draft.difficulty,
        notes=draft.notes,
        status="generated",
    )
    session.add(kb_session)
    session.commit()
    session.refresh(kb_session)
    return kb_session


@router.post("/generate", response_model=KettlebellSession)
def generate_session(
    *,
    current_user: deps.CurrentUser,
    request: KettlebellGenerateRequest,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Generate a new kettlebell session using AI."""
    try:
        user_profile = (
            f"Age: {current_user.age or 'unknown'}, "
            f"Gender: {current_user.gender or 'unknown'}, "
            f"Weight: {current_user.weight or 'unknown'} kg, "
            f"Height: {current_user.height or 'unknown'} cm"
        )
        available_weights_kg = ", ".join(str(w) for w in sorted(request.available_weights))

        generated = kettlebell_module(
            user_profile=user_profile,
            available_weights_kg=available_weights_kg,
            focus=request.focus,
            duration_minutes=request.duration_minutes,
        )

        s = generated.session
        kb_session = KettlebellSession(
            user_id=current_user.id,
            title=s.title,
            focus=s.focus,
            exercises={"exercises": [ex.model_dump() for ex in s.exercises]},
            total_duration_min=s.total_duration_min,
            difficulty=s.difficulty,
            notes=s.notes,
            status="generated",
        )
        session.add(kb_session)
        session.commit()
        session.refresh(kb_session)
        return kb_session
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))


@router.get("/", response_model=List[KettlebellSession])
def list_sessions(
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Get all kettlebell sessions for the current user."""
    statement = (
        select(KettlebellSession)
        .where(KettlebellSession.user_id == current_user.id)
        .order_by(KettlebellSession.created_at.desc())
    )
    return session.exec(statement).all()


@router.get("/{session_id}", response_model=KettlebellSession)
def get_session(
    session_id: int,
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Get a single kettlebell session."""
    kb_session = session.get(KettlebellSession, session_id)
    if not kb_session:
        raise HTTPException(status_code=404, detail="Session not found")
    if kb_session.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not authorized")
    return kb_session


@router.patch("/{session_id}/start", response_model=KettlebellSession)
def start_session(
    session_id: int,
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Mark a session as in progress."""
    kb_session = session.get(KettlebellSession, session_id)
    if not kb_session:
        raise HTTPException(status_code=404, detail="Session not found")
    if kb_session.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not authorized")
    kb_session.status = "in_progress"
    kb_session.started_at = datetime.utcnow()
    session.add(kb_session)
    session.commit()
    session.refresh(kb_session)
    return kb_session


@router.post("/{session_id}/sets", response_model=KettlebellSetLog)
def log_set(
    session_id: int,
    request: LogSetRequest,
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Log a completed set."""
    kb_session = session.get(KettlebellSession, session_id)
    if not kb_session:
        raise HTTPException(status_code=404, detail="Session not found")
    if kb_session.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not authorized")
    set_log = KettlebellSetLog(
        session_id=session_id,
        exercise_order=request.exercise_order,
        set_number=request.set_number,
        actual_reps=request.actual_reps,
        actual_weight_kg=request.actual_weight_kg,
        actual_duration_seconds=request.actual_duration_seconds,
        perceived_effort=request.perceived_effort,
    )
    session.add(set_log)
    session.commit()
    session.refresh(set_log)
    return set_log


@router.get("/{session_id}/sets", response_model=List[KettlebellSetLog])
def get_sets(
    session_id: int,
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Get all logged sets for a session."""
    kb_session = session.get(KettlebellSession, session_id)
    if not kb_session:
        raise HTTPException(status_code=404, detail="Session not found")
    if kb_session.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not authorized")
    statement = select(KettlebellSetLog).where(KettlebellSetLog.session_id == session_id)
    return session.exec(statement).all()


@router.post("/{session_id}/retry", response_model=KettlebellSession)
def retry_session(
    session_id: int,
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Clone an abandoned session as a fresh generated session."""
    kb_session = session.get(KettlebellSession, session_id)
    if not kb_session:
        raise HTTPException(status_code=404, detail="Session not found")
    if kb_session.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not authorized")
    new_session = KettlebellSession(
        user_id=current_user.id,
        title=kb_session.title,
        focus=kb_session.focus,
        exercises=kb_session.exercises,
        total_duration_min=kb_session.total_duration_min,
        difficulty=kb_session.difficulty,
        notes="",
        status="generated",
    )
    session.add(new_session)
    session.commit()
    session.refresh(new_session)
    return new_session


@router.patch("/{session_id}/abandon", response_model=KettlebellSession)
def abandon_session(
    session_id: int,
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Mark a session as abandoned."""
    kb_session = session.get(KettlebellSession, session_id)
    if not kb_session:
        raise HTTPException(status_code=404, detail="Session not found")
    if kb_session.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not authorized")
    kb_session.status = "abandoned"
    session.add(kb_session)
    session.commit()
    session.refresh(kb_session)
    return kb_session


@router.delete("/{session_id}", status_code=204)
def delete_session(
    session_id: int,
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> None:
    """Delete a session and all its set logs."""
    kb_session = session.get(KettlebellSession, session_id)
    if not kb_session:
        raise HTTPException(status_code=404, detail="Session not found")
    if kb_session.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not authorized")
    statement = select(KettlebellSetLog).where(KettlebellSetLog.session_id == session_id)
    for log in session.exec(statement).all():
        session.delete(log)
    session.flush()
    session.delete(kb_session)
    session.commit()


@router.patch("/{session_id}/complete", response_model=KettlebellSession)
def complete_session(
    session_id: int,
    request: CompleteSessionRequest,
    current_user: deps.CurrentUser,
    session: Session = Depends(deps.get_session),
) -> Any:
    """Mark a session as completed."""
    kb_session = session.get(KettlebellSession, session_id)
    if not kb_session:
        raise HTTPException(status_code=404, detail="Session not found")
    if kb_session.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not authorized")
    kb_session.status = "completed"
    kb_session.completed_at = datetime.utcnow()
    if request.notes is not None:
        kb_session.notes = request.notes
    session.add(kb_session)
    session.commit()
    session.refresh(kb_session)
    return kb_session