//! Test harness: the thin adapter the course tests call. It translates each
//! call into engine operations and holds no rules of its own.

use crate::content;
use crate::engine::{self, run_sequence, summon, Action, CardLibrary, Event, World};

pub use crate::engine::{AssembleError, CardDef, Half, Zone};

pub type Id = u32;
pub type Player = u8;

#[derive(Debug, Default, Clone)]
pub struct GameOpts {
    pub decks: Option<[Vec<String>; 2]>,
}

/// The events the tests read from `log()` (see course/harness.md).
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum GameEvent {
    Summoned { id: Id },
    Damaged { target: Id, amount: i32 },
    Triggered { source: Id, trigger: String },
    Destroyed { id: Id },
    DeathPhase { round: u32 },
    Drew { player: Player, id: Id },
    Fatigue { player: Player },
    ArmorGained { player: Player, amount: i32 },
    StatsChanged { id: Id, attack: i32, health: i32 },
    SpellCast { card: String },
}

impl GameEvent {
    /// The course's view of an engine event; `None` for engine events the course log
    /// doesn't show.
    fn from_engine(event: &Event) -> Option<GameEvent> {
        Some(match event.clone() {
            Event::Summoned { id } => GameEvent::Summoned { id },
            Event::Damaged { target, amount } => GameEvent::Damaged { target, amount },
            Event::Triggered { source, on } => GameEvent::Triggered {
                source,
                trigger: on.label().to_string(),
            },
            Event::Drew { player, id } => GameEvent::Drew { player, id },
            Event::Fatigue { player } => GameEvent::Fatigue { player },
            Event::ArmorGained { player, amount } => GameEvent::ArmorGained { player, amount },
            Event::StatsChanged { id, attack, health } => {
                GameEvent::StatsChanged { id, attack, health }
            }
            Event::SpellCast { card } => GameEvent::SpellCast { card },
            Event::Destroyed { id, .. } => GameEvent::Destroyed { id },
            Event::DeathPhase { round } => GameEvent::DeathPhase { round },
            // A played minion's `Summoned` already shows it entering the board.
            Event::Played { .. } => return None,
        })
    }
}

pub struct Game {
    world: World,
}

pub fn new_game(opts: GameOpts) -> Game {
    let mut world = World::new(CardLibrary::new(content::cards()));
    if let Some(decks) = opts.decks {
        for (player, deck) in decks.iter().enumerate() {
            for card in deck {
                world.create(card, player as Player, Zone::Deck);
            }
        }
    }
    Game { world }
}

impl Game {
    /// Put `card` at the right end of `player`'s board.
    pub fn summon(&mut self, card: &str, player: Player) -> Id {
        summon(&mut self.world, card, player, None)
    }
    pub fn add_to_hand(&mut self, card: &str, player: Player) -> Id {
        self.world.create(card, player, Zone::Hand)
    }
    pub fn add_to_deck(&mut self, card: &str, player: Player) -> Id {
        self.world.create(card, player, Zone::Deck)
    }
    /// Play a card from hand, as one Sequence: it enters the right end of the board, then
    /// its Battlecry resolves. (The Module 1 Expansion Drop; required from Module 4.)
    pub fn play(&mut self, hand_id: Id) {
        run_sequence(&mut self.world, Action::Play { id: hand_id });
    }
    pub fn zone_of(&self, id: Id) -> Zone {
        self.world.zone_of(id)
    }
    /// Board ids, left to right.
    pub fn board(&self, player: Player) -> Vec<Id> {
        self.world.zone(player, Zone::Board).to_vec()
    }
    pub fn hand(&self, player: Player) -> Vec<Id> {
        self.world.zone(player, Zone::Hand).to_vec()
    }
    pub fn order_of_play(&self, id: Id) -> u32 {
        self.world
            .order_of_play(id)
            .unwrap_or_else(|| panic!("entity {id} has not entered play"))
    }
    pub fn name_of(&self, id: Id) -> String {
        self.world.card_name(id).to_string()
    }

    // ---- Module 2 ----

    pub fn hero(&self, player: Player) -> Id {
        self.world.hero(player)
    }
    /// Deal damage to one character, as one Sequence.
    pub fn deal_damage(&mut self, target: Id, amount: i32) {
        let targets = vec![target];
        run_sequence(&mut self.world, Action::Damage { targets, amount });
    }
    pub fn cast(&mut self, card: &str, player: Player, target: Option<Id>) {
        let card = card.to_string();
        run_sequence(
            &mut self.world,
            Action::Cast {
                card,
                player,
                target,
            },
        );
    }
    pub fn health(&self, id: Id) -> i32 {
        self.world.health(id)
    }
    pub fn attack(&self, id: Id) -> i32 {
        self.world.attack(id)
    }
    pub fn armor(&self, player: Player) -> i32 {
        self.world.armor(player)
    }
    pub fn log(&self) -> Vec<GameEvent> {
        self.world
            .log()
            .iter()
            .filter_map(GameEvent::from_engine)
            .collect()
    }
    pub fn clear_log(&mut self) {
        self.world.clear_log();
    }

    // ---- Module 3 ----

    /// Mark `target` pending destroy, as one Sequence. It leaves play in the death step.
    pub fn destroy(&mut self, target: Id) {
        let targets = vec![target];
        run_sequence(&mut self.world, Action::Destroy { targets });
    }

    // ---- Module 5 ----

    /// Add card definitions to this game, replacing any with the same name.
    pub fn register_cards(&mut self, defs: Vec<CardDef>) {
        for def in defs {
            self.world.register(def);
        }
    }

    /// Register `base` with `half` of its text replaced by the same half of `donor`,
    /// and return the new card's name, `"<base> (Assembled)"`.
    pub fn assemble(
        &mut self,
        base: &str,
        donor: &str,
        half: Half,
    ) -> Result<String, AssembleError> {
        let base = &self.world.card(base).def;
        let donor = &self.world.card(donor).def;
        let def = engine::assemble(base, donor, half)?;
        Ok(engine::register_assembled(&mut self.world, def))
    }

    pub fn cost(&self, id: Id) -> i32 {
        self.world.cost(id)
    }

    /// Who makes choices (Assemble's base, donor and half): called with the kind of
    /// choice (`"base"`, `"donor"`, `"half"`) and the options; returns one of them.
    pub fn set_chooser(&mut self, chooser: impl FnMut(&str, &[String]) -> String + 'static) {
        self.world.set_chooser(Box::new(chooser));
    }
}