from fastapi import APIRouter, Depends
from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.database import get_session
from app.models.encounter import Encounter
from app.models.game import Game
from app.models.nuzlocke_run import NuzlockeRun
from app.models.pokemon import Pokemon
from app.schemas.stats import (
    DeathCause,
    GameRunCount,
    PokemonRanking,
    StatsResponse,
    TypeCount,
)

router = APIRouter()


@router.get("", response_model=StatsResponse)
async def get_stats(session: AsyncSession = Depends(get_session)):
    # --- Run overview ---
    run_counts = await session.execute(
        select(
            func.count().label("total"),
            func.count().filter(NuzlockeRun.status == "active").label("active"),
            func.count().filter(NuzlockeRun.status == "completed").label("completed"),
            func.count().filter(NuzlockeRun.status == "failed").label("failed"),
        ).select_from(NuzlockeRun)
    )
    row = run_counts.one()
    total_runs = row.total
    active_runs = row.active
    completed_runs = row.completed
    failed_runs = row.failed

    finished = completed_runs + failed_runs
    win_rate = round(completed_runs / finished, 4) if finished > 0 else None

    # Average duration for finished runs
    avg_dur = await session.execute(
        select(
            func.avg(
                func.extract("epoch", NuzlockeRun.completed_at)
                - func.extract("epoch", NuzlockeRun.started_at)
            )
        )
        .select_from(NuzlockeRun)
        .where(NuzlockeRun.completed_at.is_not(None))
    )
    avg_seconds = avg_dur.scalar()
    avg_duration_days = round(avg_seconds / 86400, 1) if avg_seconds else None

    # --- Runs by game ---
    runs_by_game_q = await session.execute(
        select(
            Game.id,
            Game.name,
            Game.color,
            func.count().label("count"),
        )
        .join(NuzlockeRun, NuzlockeRun.game_id == Game.id)
        .group_by(Game.id, Game.name, Game.color)
        .order_by(func.count().desc())
    )
    runs_by_game = [
        GameRunCount(game_id=r.id, game_name=r.name, game_color=r.color, count=r.count)
        for r in runs_by_game_q.all()
    ]

    # --- Encounter stats ---
    enc_counts = await session.execute(
        select(
            func.count().label("total"),
            func.count().filter(Encounter.status == "caught").label("caught"),
            func.count().filter(Encounter.status == "fainted").label("fainted"),
            func.count().filter(Encounter.status == "missed").label("missed"),
        ).select_from(Encounter)
    )
    enc = enc_counts.one()
    total_encounters = enc.total
    caught_count = enc.caught
    fainted_count = enc.fainted
    missed_count = enc.missed

    catch_rate = round(caught_count / total_encounters, 4) if total_encounters > 0 else None
    avg_encounters_per_run = round(total_encounters / total_runs, 1) if total_runs > 0 else None

    # --- Top caught pokemon (top 10) ---
    top_caught_q = await session.execute(
        select(
            Pokemon.id,
            Pokemon.name,
            Pokemon.sprite_url,
            func.count().label("count"),
        )
        .join(Encounter, Encounter.pokemon_id == Pokemon.id)
        .where(Encounter.status == "caught")
        .group_by(Pokemon.id, Pokemon.name, Pokemon.sprite_url)
        .order_by(func.count().desc())
        .limit(10)
    )
    top_caught_pokemon = [
        PokemonRanking(pokemon_id=r.id, name=r.name, sprite_url=r.sprite_url, count=r.count)
        for r in top_caught_q.all()
    ]

    # --- Top encountered pokemon (top 10) ---
    top_enc_q = await session.execute(
        select(
            Pokemon.id,
            Pokemon.name,
            Pokemon.sprite_url,
            func.count().label("count"),
        )
        .join(Encounter, Encounter.pokemon_id == Pokemon.id)
        .group_by(Pokemon.id, Pokemon.name, Pokemon.sprite_url)
        .order_by(func.count().desc())
        .limit(10)
    )
    top_encountered_pokemon = [
        PokemonRanking(pokemon_id=r.id, name=r.name, sprite_url=r.sprite_url, count=r.count)
        for r in top_enc_q.all()
    ]

    # --- Deaths ---
    total_deaths_q = await session.execute(
        select(func.count())
        .select_from(Encounter)
        .where(Encounter.status == "caught", Encounter.faint_level.is_not(None))
    )
    total_deaths = total_deaths_q.scalar() or 0

    mortality_rate = round(total_deaths / caught_count, 4) if caught_count > 0 else None

    # Top death causes
    death_causes_q = await session.execute(
        select(
            Encounter.death_cause,
            func.count().label("count"),
        )
        .where(
            Encounter.death_cause.is_not(None),
            Encounter.death_cause != "",
        )
        .group_by(Encounter.death_cause)
        .order_by(func.count().desc())
        .limit(5)
    )
    top_death_causes = [
        DeathCause(cause=r.death_cause, count=r.count)
        for r in death_causes_q.all()
    ]

    # Average levels
    avg_levels = await session.execute(
        select(
            func.avg(Encounter.catch_level).label("avg_catch"),
            func.avg(Encounter.faint_level).label("avg_faint"),
        )
        .select_from(Encounter)
        .where(Encounter.status == "caught")
    )
    levels = avg_levels.one()
    avg_catch_level = round(float(levels.avg_catch), 1) if levels.avg_catch else None
    avg_faint_level = round(float(levels.avg_faint), 1) if levels.avg_faint else None

    # --- Type distribution ---
    # Pokemon types is a PostgreSQL ARRAY, unnest it
    type_q = await session.execute(
        select(
            func.unnest(Pokemon.types).label("type_name"),
            func.count().label("count"),
        )
        .join(Encounter, Encounter.pokemon_id == Pokemon.id)
        .where(Encounter.status == "caught")
        .group_by("type_name")
        .order_by(func.count().desc())
    )
    type_distribution = [
        TypeCount(type=r.type_name, count=r.count)
        for r in type_q.all()
    ]

    return StatsResponse(
        total_runs=total_runs,
        active_runs=active_runs,
        completed_runs=completed_runs,
        failed_runs=failed_runs,
        win_rate=win_rate,
        avg_duration_days=avg_duration_days,
        runs_by_game=runs_by_game,
        total_encounters=total_encounters,
        caught_count=caught_count,
        fainted_count=fainted_count,
        missed_count=missed_count,
        catch_rate=catch_rate,
        avg_encounters_per_run=avg_encounters_per_run,
        top_caught_pokemon=top_caught_pokemon,
        top_encountered_pokemon=top_encountered_pokemon,
        total_deaths=total_deaths,
        mortality_rate=mortality_rate,
        top_death_causes=top_death_causes,
        avg_catch_level=avg_catch_level,
        avg_faint_level=avg_faint_level,
        type_distribution=type_distribution,
    )