/*
 * This file is part of laurelin_client
 * Copyright (C) 2023 Jonni Liljamo <jonni@liljamo.com>
 *
 * Licensed under GPL-3.0-only.
 * See LICENSE for licensing information.
 */

use std::collections::HashMap;

use fastrand::Rng;

use crate::{api::game::{Action, Command, Game}, game_status::SupplyPile};

use super::{GameStatus, PlayerState, PlayerStatus, Card};

/// funny unsafe wrapper
fn get_invoker_target<'a, K, V>(
    players: &'a mut HashMap<K, V>,
    invoker: &K,
    target: &K
) -> (&'a mut V, &'a mut V)
where
    K: Eq + std::hash::Hash,
{
    unsafe {
        // NOTE: soo... I don't really know the consequences of possibly
        // having two mutable references to the same value, but I guess
        // I'll find out!
        // in many instances where people wanted multiple mutable references
        // to Vec or HashMap values, they only gave one in wrappers like this,
        // if the wanted values were the same.
        // e.g. returning (V, None), if the keys were the same.

        let invoker_ref = players.get_mut(invoker).unwrap() as *mut _;
        let target_ref = players.get_mut(target).unwrap() as *mut _;
        (&mut *invoker_ref, &mut *target_ref)
    }
}

pub fn parse(game: &Game) -> Result<GameStatus, ()> {
    let mut game_status = GameStatus {
        actions: game.actions.as_ref().unwrap().to_vec(),
        supply_piles: vec![],
        players: HashMap::new()
    };

    game_status.players.insert(game.host_id.clone(), PlayerStatus {
        state: PlayerState::Idle,
        currency: 0,
        vp: 2,
        hand: vec![],
        deck: vec![],
        discard: vec![]
    });

    game_status.players.insert(game.guest_id.clone(), PlayerStatus {
        state: PlayerState::Idle,
        currency: 0,
        vp: 2,
        hand: vec![],
        deck: vec![],
        discard: vec![]
    });

    // TODO: a system for reparsing if needed, e.g. after something
    // modifies the actions Vector.
    for action in &game_status.actions {
        // invoker: the one who invoked the action
        // target: the one who the action affects, may also be the invoker, e.g. draw
        let (invoker, target) = get_invoker_target(&mut game_status.players, &action.invoker, &action.target);

        match &action.command {
            Command::InitSupplyPile { card, amount } => {
                let pile = SupplyPile {
                    card: card.clone(),
                    amount: *amount,
                };

                game_status.supply_piles.push(pile);
            }
            Command::TakeFromPile { index, for_cost } => {
                // index should be within range
                assert!(*index <= game_status.supply_piles.len());
                let pile = &mut game_status.supply_piles.get_mut(*index)
                    .unwrap_or_else(|| unreachable!());

                // pile should not be empty
                assert!(pile.amount > 0);
                pile.amount = pile.amount - 1;

                // player should have enough
                assert!(*for_cost <= target.currency);
                target.currency = target.currency - for_cost;

                target.discard.push(pile.card.clone());
            }
            Command::Draw { amount } => {
                for _ in 0..*amount {
                    if target.deck.is_empty() {
                        shuffle_discard_to_deck(target, action.seed.parse::<u64>().unwrap());
                    }

                    target.hand.push(target.deck.pop()
                                     .unwrap_or_else(|| unreachable!()));
                }
            }
            Command::Discard { index } => {
                // index should be within range
                assert!(*index <= target.hand.len());
                target.discard.push(target.hand.remove(*index));
            }
            Command::EndTurn {  } => {
                // NOTE: target will be the next player

                // set player to idle
                invoker.state = PlayerState::Idle;

                // set the target to action phase
                target.state = PlayerState::ActionPhase;

                // clear currency
                invoker.currency = 0;

                // other?
            }
            Command::ChangePlayerState { state } => {
                target.state = *state;
            }
            _ => todo!(),
        }
    }

    Ok(game_status)
}

fn shuffle_discard_to_deck(target: &mut PlayerStatus, seed: u64) {
    let cards = target.discard.to_vec();
    target.discard.clear();

    target.deck = cards;

    let rng = Rng::with_seed(seed);
    rng.shuffle(&mut target.deck);
}