from dataclasses import dataclass, field
from random import Random

from budget import Card
from primitives import Effect

STARTING_HP = 20
MAX_ENERGY = 5
HALF_HP = STARTING_HP // 2


@dataclass
class PlayerState:
    name: str
    deck: list[Card]
    hand: list[Card] = field(default_factory=list)
    discard: list[Card] = field(default_factory=list)
    hp: int = STARTING_HP
    energy: int = 0
    block: int = 0
    ward: int = 0
    shield_charge: int = 0
    fatigue: int = 1
    vulnerable: int = 0
    vulnerable_turns: int = 0
    weak: int = 0
    weak_turns: int = 0
    cards_played_this_turn: int = 0


@dataclass
class PendingEffect:
    primitive_id: str
    owner: str
    target: str
    amount: int
    delay: int = 0
    duration: int = 0


@dataclass
class DuelState:
    player: PlayerState
    enemy: PlayerState
    pending: list[PendingEffect] = field(default_factory=list)
    round_number: int = 0
    forced_second: str | None = None


# Create a player state from an ordered deck.
def create_player(name: str, deck: list[Card] | tuple[Card, ...]) -> PlayerState:
    return PlayerState(name=name, deck=list(deck))


# Return the opposing player state.
def opponent(state: DuelState, actor: PlayerState) -> PlayerState:
    return state.enemy if actor is state.player else state.player


# Draw cards, applying escalating fatigue on deck-out.
def draw_cards(player: PlayerState, count: int) -> None:
    for _ in range(count):
        if player.deck:
            player.hand.append(player.deck.pop(0))
        else:
            player.hp -= player.fatigue
            player.fatigue += 1


# Start a paired round with energy refill and one draw each.
def start_round(state: DuelState, rng: Random | None = None) -> tuple[str, str]:
    state.round_number += 1
    for player in (state.player, state.enemy):
        begin_turn(player, state.round_number)
        draw_cards(player, 1)
    advance_pending(state)
    return round_order(state, rng or Random())


# Prepare one player for the current round.
def begin_turn(player: PlayerState, round_number: int) -> None:
    player.energy = min(MAX_ENERGY, round_number)
    player.block = 0
    player.cards_played_this_turn = 0
    tick_statuses(player)


# Tick one-turn status durations.
def tick_statuses(player: PlayerState) -> None:
    if player.vulnerable_turns > 0:
        player.vulnerable_turns -= 1
        if player.vulnerable_turns == 0:
            player.vulnerable = 0
    if player.weak_turns > 0:
        player.weak_turns -= 1
        if player.weak_turns == 0:
            player.weak = 0


# Choose action order for the current paired round.
def round_order(state: DuelState, rng: Random) -> tuple[str, str]:
    if state.forced_second == state.player.name:
        state.forced_second = None
        return (state.enemy.name, state.player.name)
    if state.forced_second == state.enemy.name:
        state.forced_second = None
        return (state.player.name, state.enemy.name)
    names = (state.player.name, state.enemy.name)
    return names if rng.randint(0, 1) == 0 else (names[1], names[0])


# Play a card from hand by index.
def play_card_from_hand(state: DuelState, actor: PlayerState, hand_index: int) -> Card:
    card = actor.hand.pop(hand_index)
    play_card(state, actor, card)
    actor.discard.append(card)
    return card


# Resolve a card if the actor can pay its energy cost.
def play_card(state: DuelState, actor: PlayerState, card: Card) -> None:
    if card.cost > actor.energy:
        raise ValueError("not enough energy")
    actor.energy -= card.cost
    actor.cards_played_this_turn += 1
    target = opponent(state, actor)
    for effect in card.effects:
        apply_effect(state, actor, target, effect)


# Apply one deterministic effect.
def apply_effect(state: DuelState, actor: PlayerState, target: PlayerState, effect: Effect) -> None:
    match effect.primitive_id:
        case "deal":
            deal_damage(actor, target, effect.amount)
        case "burn":
            state.pending.append(PendingEffect("burn", actor.name, target.name, effect.amount, delay=1, duration=effect.duration))
        case "bomb":
            state.pending.append(PendingEffect("bomb", actor.name, target.name, effect.amount, delay=effect.delay))
        case "block":
            actor.block += effect.amount
        case "ward":
            actor.ward += effect.amount
        case "weak":
            target.weak += effect.amount
            target.weak_turns = max(target.weak_turns, effect.duration)
        case "draw":
            draw_cards(actor, effect.amount)
        case "energy":
            actor.energy += effect.amount
        case "initiative":
            state.forced_second = target.name
        case "multi_hit":
            for _ in range(effect.hits):
                deal_damage(actor, target, effect.amount)
        case "vulnerable":
            target.vulnerable += effect.amount
            target.vulnerable_turns = max(target.vulnerable_turns, effect.duration)
        case "conditional":
            damage = conditional_damage(target, effect.amount)
            if damage > 0:
                deal_damage(actor, target, damage)
        case "scaling":
            deal_damage(actor, target, scaling_damage(actor, effect))


# Deal damage through weak, vulnerable, ward, and block.
def deal_damage(actor: PlayerState, target: PlayerState, amount: int) -> int:
    damage = max(0, amount - actor.weak)
    if damage == 0:
        return 0
    damage += target.vulnerable
    if target.ward > 0:
        if damage >= target.ward:
            target.ward = 0
        return 0
    blocked = min(target.block, damage)
    target.shield_charge += blocked // 2
    target.block -= blocked
    target.hp -= damage - blocked
    return damage - blocked


# Return scaling damage and spend shield charge when used.
def scaling_damage(actor: PlayerState, effect: Effect) -> int:
    if effect.condition == "shield_charge":
        damage = effect.amount + actor.shield_charge
        actor.shield_charge = 0
        return damage
    return effect.amount + actor.cards_played_this_turn


# Return missing-HP-scaled conditional damage.
def conditional_damage(target: PlayerState, amount: int) -> int:
    missing_hp = max(0, STARTING_HP - target.hp)
    return amount * missing_hp // STARTING_HP


# Advance all deferred effects by one schedule tick.
def advance_pending(state: DuelState) -> None:
    remaining: list[PendingEffect] = []
    for effect in state.pending:
        if effect.delay > 0:
            effect.delay -= 1
            remaining.append(effect)
        elif effect.primitive_id == "burn":
            deal_damage(named_player(state, effect.owner), named_player(state, effect.target), effect.amount)
            effect.duration -= 1
            if effect.duration > 0:
                remaining.append(effect)
        elif effect.primitive_id == "bomb":
            deal_damage(named_player(state, effect.owner), named_player(state, effect.target), effect.amount)
    state.pending = remaining


# Return a player by name.
def named_player(state: DuelState, name: str) -> PlayerState:
    if state.player.name == name:
        return state.player
    if state.enemy.name == name:
        return state.enemy
    raise KeyError(name)


# Return whether either side has won.
def winner(state: DuelState) -> str | None:
    player_dead = state.player.hp <= 0
    enemy_dead = state.enemy.hp <= 0
    if player_dead and enemy_dead:
        return "draw"
    if enemy_dead:
        return state.player.name
    if player_dead:
        return state.enemy.name
    return None