input_handlers.py

from __future__ import annotations

import os
import time

from typing import Callable, Optional, Tuple, TYPE_CHECKING, Union

import tcod
from tcod import libtcodpy

import actions
from actions import (
    Action,
    BumpAction,
    MovementRepeatedAction,
    PickupAction,
    TargetMovementAction,
    WaitAction,
)
import color
import exceptions

if TYPE_CHECKING:
    from engine import Engine
    from entity import Item


MOVE_KEYS = {
    # Arrow keys.
    tcod.event.KeySym.UP: (0, -1),
    tcod.event.KeySym.DOWN: (0, 1),
    tcod.event.KeySym.LEFT: (-1, 0),
    tcod.event.KeySym.RIGHT: (1, 0),
    tcod.event.KeySym.HOME: (-1, -1),
    tcod.event.KeySym.END: (-1, 1),
    tcod.event.KeySym.PAGEUP: (1, -1),
    tcod.event.KeySym.PAGEDOWN: (1, 1),
    # Numpad keys.
    tcod.event.KeySym.KP_1: (-1, 1),
    tcod.event.KeySym.KP_2: (0, 1),
    tcod.event.KeySym.KP_3: (1, 1),
    tcod.event.KeySym.KP_4: (-1, 0),
    tcod.event.KeySym.KP_6: (1, 0),
    tcod.event.KeySym.KP_7: (-1, -1),
    tcod.event.KeySym.KP_8: (0, -1),
    tcod.event.KeySym.KP_9: (1, -1),
    # Vi keys.
    tcod.event.KeySym.h: (-1, 0),
    tcod.event.KeySym.j: (0, 1),
    tcod.event.KeySym.k: (0, -1),
    tcod.event.KeySym.l: (1, 0),
    tcod.event.KeySym.y: (-1, -1),
    tcod.event.KeySym.u: (1, -1),
    tcod.event.KeySym.b: (-1, 1),
    tcod.event.KeySym.n: (1, 1),
}

WAIT_KEYS = {
    tcod.event.KeySym.PERIOD,
    tcod.event.KeySym.KP_5,
    tcod.event.KeySym.CLEAR,
}

CONFIRM_KEYS = {
    tcod.event.KeySym.RETURN,
    tcod.event.KeySym.KP_ENTER,
}

MIN_FRAME_INTERVAL = 0.01

# TODO: theoretically newer notation is preferred:
#        Action | "BaseEventHandler"
# See:
#   https://docs.python.org/3/library/stdtypes.html#union-type

ActionOrHandler = Union[Action, "BaseEventHandler"]
"""An event handler return value which can trigger an action or switch active handlers.

If a handler is returned then it will become the active handler for future events.
If an action is returned it will be attempted and if it's valid then
MainGameEventHandler will become the active handler.
"""


class BaseEventHandler(tcod.event.EventDispatch[ActionOrHandler]):
    def handle_events(self, event: tcod.event.Event) -> BaseEventHandler:
        """Handle an event and return the next active event handler."""
        state = self.dispatch(event)
        if isinstance(state, BaseEventHandler):
            return state
        assert not isinstance(state, Action), f"{self!r} can not handle actions."
        return self

    def on_render(self, console: tcod.Console) -> None:
        raise NotImplementedError()

    def ev_quit(self, event: tcod.event.Quit) -> Optional[Action]:
        raise SystemExit()

class PopupMessage(BaseEventHandler):
    """Display a popup text window."""

    def __init__(self, parent_handler: BaseEventHandler, text: str):
        self.parent = parent_handler
        self.text = text

    def on_render(self, console: tcod.Console) -> None:
        """Render the parent and dim the result, then print the message on top."""
        self.parent.on_render(console)
        console.rgb["fg"] //= 8
        console.rgb["bg"] //= 8

        console.print(
            console.width // 2,
            console.height // 2,
            self.text,
            fg=color.white,
            bg=color.black,
            alignment=libtcodpy.CENTER,
        )

    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[BaseEventHandler]:
        """Any key returns to the parent handler."""
        return self.parent

class EventHandler(BaseEventHandler):
    def __init__(self, engine: Engine):
        self.engine = engine

    def handle_events(self, event: tcod.event.Event) -> BaseEventHandler:
        """Handle events for input handlers with an engine."""
        action_or_state = self.dispatch(event)
        if isinstance(action_or_state, BaseEventHandler):
            return action_or_state
        if self.handle_action(action_or_state):
            # A valid action was performed.
            if not self.engine.player.is_alive:
                # The player was killed sometime during or after the action.
                return GameOverEventHandler(self.engine)
            elif self.engine.player.level.requires_level_up:
                self.engine.message_log.add_message("You leveled up!", stack=False)
                return LevelUpEventHandler(self.engine)
            return MainGameEventHandler(self.engine)  # Return to the main handler.
        return self

    def handle_action(self, action: Optional[Action]) -> bool:
        """Handle actions returned from event methods.
        Returns True if the action will advance a turn.
        """
        if action is None:
            return False

        while True:
            try:
                should_repeat = action.perform()
            except exceptions.Impossible as exc:
                self.engine.message_log.add_message(exc.args[0], color.impossible)
                return False  # Skip enemy turn on exceptions.

            self.engine.end_turn()
            if not should_repeat:
                break

            time.sleep(MIN_FRAME_INTERVAL)

        return True

    def ev_mousemotion(self, event: tcod.event.MouseMotion) -> None:
        if self.engine.game_map.in_bounds(event.tile.x, event.tile.y):
            self.engine.mouse_location = event.tile.x, event.tile.y

    def ev_quit(self, event: tcod.event.Quit) -> Optional[Action]:
        raise SystemExit()

    def on_render(self, console: tcod.Console) -> None:
        self.engine.render(console)


class AskUserEventHandler(EventHandler):
    """Handles user input for actions which require special input."""

    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[ActionOrHandler]:
        """By default, any key exits this input handler."""
        if event.sym in {  # Ignore modifier keys.
            tcod.event.KeySym.LSHIFT,
            tcod.event.KeySym.RSHIFT,
            tcod.event.KeySym.LCTRL,
            tcod.event.KeySym.RCTRL,
            tcod.event.KeySym.LALT,
            tcod.event.KeySym.RALT,
        }:
            return None
        return self.on_exit()

    def ev_mousebuttondown(
        self, event: tcod.event.MouseButtonDown
    ) -> Optional[ActionOrHandler]:
        """By default, any mouse click exits this input handler."""
        return self.on_exit()

    def on_exit(self) -> Optional[ActionOrHandler]:
        """Called when the user is trying to exit or cancel an action.
        By default, this returns to the main event handler.
        """
        return MainGameEventHandler(self.engine)

class CharacterScreenEventHandler(AskUserEventHandler):
    TITLE = "Character Information"

    def on_render(self, console: tcod.Console) -> None:
        super().on_render(console)

        if self.engine.player.x <= 30:
            x = 40
        else:
            x = 0

        y = 0

        width = len(self.TITLE) + 4

        console.draw_frame(
            x=x,
            y=y,
            width=width,
            height=7,
            title=self.TITLE,
            clear=True,
            fg=(255, 255, 255),
            bg=(0, 0, 0),
        )

        console.print(
            x=x + 1, y=y + 1, string=f"Level: {self.engine.player.level.current_level}"
        )
        console.print(
            x=x + 1, y=y + 2, string=f"XP: {self.engine.player.level.current_xp}"
        )
        console.print(
            x=x + 1,
            y=y + 3,
            string=f"XP for next Level: {self.engine.player.level.experience_to_next_level}",
        )

        console.print(
            x=x + 1, y=y + 4, string=f"Attack: {self.engine.player.fighter.power}"
        )
        console.print(
            x=x + 1, y=y + 5, string=f"Defense: {self.engine.player.fighter.defense}"
        )

class LevelUpEventHandler(AskUserEventHandler):
    TITLE = "Level Up"

    def on_render(self, console: tcod.Console) -> None:
        super().on_render(console)

        if self.engine.player.x <= 30:
            x = 40
        else:
            x = 0

        console.draw_frame(
            x=x,
            y=0,
            width=35,
            height=8,
            title=self.TITLE,
            clear=True,
            fg=(255, 255, 255),
            bg=(0, 0, 0),
        )

        console.print(x=x + 1, y=1, string="Congratulations! You level up!")
        console.print(x=x + 1, y=2, string="Select an attribute to increase.")

        console.print(
            x=x + 1,
            y=4,
            string=f"a) CON: +5-10 HP (@{self.engine.player.fighter.max_hp})",
        )
        console.print(
            x=x + 1,
            y=5,
            string=f"b) STR: +1 attack (@{self.engine.player.fighter.power})",
        )
        console.print(
            x=x + 1,
            y=6,
            string=f"c) AGI: +1 defense (@{self.engine.player.fighter.defense})",
        )

    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[ActionOrHandler]:
        player = self.engine.player
        key = event.sym
        index = key - tcod.event.KeySym.a

        if 0 <= index <= 2:
            if index == 0:
                player.level.increase_max_hp()
            elif index == 1:
                player.level.increase_power()
            else:
                player.level.increase_defense()
        else:
            self.engine.message_log.add_message("Invalid entry.", color.invalid)

            return None

        return super().ev_keydown(event)

    def ev_mousebuttondown(
        self, event: tcod.event.MouseButtonDown
    ) -> Optional[ActionOrHandler]:
        """
        Don't allow the player to click to exit the menu, like normal.
        """
        return None

class InventoryEventHandler(AskUserEventHandler):
    """This handler lets the user select an item.
    What happens then depends on the subclass.
    """

    TITLE = "<missing title>"

    def on_render(self, console: tcod.Console) -> None:
        """Render an inventory menu, which displays the items in the inventory, and the letter to select them.
        Will move to a different position based on where the player is located, so the player can always see where
        they are.
        """
        super().on_render(console)
        number_of_items_in_inventory = len(self.engine.player.inventory.items)

        height = number_of_items_in_inventory + 2

        if height <= 3:
            height = 3

        if self.engine.player.x <= 30:
            x = 40
        else:
            x = 0

        y = 0

        width = len(self.TITLE) + 4

        console.draw_frame(
            x=x,
            y=y,
            width=width,
            height=height,
            title=self.TITLE,
            clear=True,
            fg=(255, 255, 255),
            bg=(0, 0, 0),
        )

        if number_of_items_in_inventory > 0:
            for i, item in enumerate(self.engine.player.inventory.items):
                item_key = chr(ord("a") + i)
                is_equipped = self.engine.player.equipment.item_is_equipped(item)
                item_string = f"({item_key}) {item.name}"

                if is_equipped:
                    item_string = f"{item_string} (E)"

                console.print(x + 1, y + i + 1, item_string)
        else:
            console.print(x + 1, y + 1, "(Empty)")

    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[ActionOrHandler]:
        player = self.engine.player
        key = event.sym
        index = key - tcod.event.KeySym.a

        if 0 <= index <= 26:
            try:
                selected_item = player.inventory.items[index]
            except IndexError:
                self.engine.message_log.add_message("Invalid entry.", color.invalid)
                return None
            return self.on_item_selected(selected_item)
        return super().ev_keydown(event)

    def on_item_selected(self, item: Item) -> Optional[ActionOrHandler]:
        """Called when the user selects a valid item."""
        raise NotImplementedError()


class InventoryActivateHandler(InventoryEventHandler):
    """Handle using an inventory item."""

    TITLE = "Select an item to use"

    def on_item_selected(self, item: Item) -> Optional[ActionOrHandler]:
        if item.consumable:
            # Return the action for the selected item.
            return item.consumable.get_action(self.engine.player)
        elif item.equippable:
            return actions.EquipAction(self.engine.player, item)
        else:
            return None

class InventoryDropHandler(InventoryEventHandler):
    """Handle dropping an inventory item."""

    TITLE = "Select an item to drop"

    def on_item_selected(self, item: Item) -> Optional[ActionOrHandler]:
        """Drop this item."""
        return actions.DropItem(self.engine.player, item)


class SelectIndexHandler(AskUserEventHandler):
    """Handles asking the user for an index on the map."""

    def __init__(self, engine: Engine):
        """Sets the cursor to the player when this handler is constructed."""
        super().__init__(engine)
        player = self.engine.player
        engine.mouse_location = player.x, player.y

    def on_render(self, console: tcod.Console) -> None:
        """Highlight the tile under the cursor."""
        super().on_render(console)
        x, y = self.engine.mouse_location
        console.tiles_rgb["bg"][x, y] = color.white
        console.tiles_rgb["fg"][x, y] = color.black

    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[ActionOrHandler]:
        """Check for key movement or confirmation keys."""
        key = event.sym
        if key in MOVE_KEYS:
            modifier = 1  # Holding modifier keys will speed up key movement.
            if event.mod & (tcod.event.KMOD_LSHIFT | tcod.event.KMOD_RSHIFT):
                modifier *= 5
            if event.mod & (tcod.event.KMOD_LCTRL | tcod.event.KMOD_RCTRL):
                modifier *= 10
            if event.mod & (tcod.event.KMOD_LALT | tcod.event.KMOD_RALT):
                modifier *= 20

            x, y = self.engine.mouse_location
            dx, dy = MOVE_KEYS[key]
            x += dx * modifier
            y += dy * modifier
            # Clamp the cursor index to the map size.
            x = max(0, min(x, self.engine.game_map.width - 1))
            y = max(0, min(y, self.engine.game_map.height - 1))
            self.engine.mouse_location = x, y
            return None
        elif key in CONFIRM_KEYS:
            return self.on_index_selected(*self.engine.mouse_location)
        return super().ev_keydown(event)

    def ev_mousebuttondown(
        self, event: tcod.event.MouseButtonDown
    ) -> Optional[ActionOrHandler]:
        """Left click confirms a selection."""
        if self.engine.game_map.in_bounds(*event.tile):
            if event.button == 1:
                return self.on_index_selected(*event.tile)
        return super().ev_mousebuttondown(event)

    def on_index_selected(self, x: int, y: int) -> Optional[ActionOrHandler]:
        """Called when an index is selected."""
        raise NotImplementedError()


class LookHandler(SelectIndexHandler):
    """Lets the player look around using the keyboard."""

    def on_index_selected(self, x: int, y: int) -> MainGameEventHandler:
        """Return to main handler."""
        return MainGameEventHandler(self.engine)

class WalkChoiceHandler(SelectIndexHandler):
    def on_index_selected(self, x: int, y: int):
        return TargetMovementAction(self.engine.player, x, y)


class SingleRangedAttackHandler(SelectIndexHandler):
    """Handles targeting a single enemy. Only the enemy selected will be affected."""

    def __init__(
        self, engine: Engine, callback: Callable[[Tuple[int, int]], Optional[Action]]
    ):
        super().__init__(engine)

        self.callback = callback

    def on_index_selected(self, x: int, y: int) -> Optional[Action]:
        return self.callback((x, y))


class AreaRangedAttackHandler(SelectIndexHandler):
    """Handles targeting an area within a given radius. Any entity within the area will be affected."""

    def __init__(
        self,
        engine: Engine,
        radius: int,
        callback: Callable[[Tuple[int, int]], Optional[Action]],
    ):
        super().__init__(engine)

        self.radius = radius
        self.callback = callback

    def on_render(self, console: tcod.Console) -> None:
        """Highlight the tile under the cursor."""
        super().on_render(console)

        x, y = self.engine.mouse_location

        # Draw a rectangle around the targeted area, so the player can see the affected tiles.
        console.draw_frame(
            x=x - self.radius - 1,
            y=y - self.radius - 1,
            width=self.radius ** 2,
            height=self.radius ** 2,
            fg=color.red,
            clear=False,
        )

    def on_index_selected(self, x: int, y: int) -> Optional[Action]:
        return self.callback((x, y))


class MainGameEventHandler(EventHandler):
    def __init__(self, engine: Engine):
        super().__init__(engine)

    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[ActionOrHandler]:
        action: Optional[Action] = None

        key = event.sym
        modifier = event.mod

        player = self.engine.player

        if key == tcod.event.KeySym.PERIOD and modifier & (
            tcod.event.KMOD_LSHIFT | tcod.event.KMOD_RSHIFT
        ):
            return actions.TakeStairsAction(player)

        if key in MOVE_KEYS:
            dx, dy = MOVE_KEYS[key]
            if modifier & (tcod.event.KMOD_LSHIFT | tcod.event.KMOD_RSHIFT):
                action = MovementRepeatedAction(player, dx, dy)
            else:
                action = BumpAction(player, dx, dy)
        elif key in WAIT_KEYS:
            action = WaitAction(player)
        elif key == tcod.event.KeySym.ESCAPE:
            raise SystemExit()
        elif key == tcod.event.KeySym.v:
            return HistoryViewer(self.engine)
        elif key == tcod.event.KeySym.s:
            return ViewKeybinds(self.engine)
        elif key == tcod.event.KeySym.g:
            action = PickupAction(player)
        elif key == tcod.event.KeySym.i:
            return InventoryActivateHandler(self.engine)
        elif key == tcod.event.KeySym.d:
            return InventoryDropHandler(self.engine)
        elif key == tcod.event.KeySym.c:
            return CharacterScreenEventHandler(self.engine)
        elif key == tcod.event.KeySym.SLASH:
            return LookHandler(self.engine)
        elif key == tcod.event.KeySym.w:
            return WalkChoiceHandler(self.engine)
        # No valid key was pressed
        return action

    def ev_textinput(self, event: tcod.event.TextInput):
        match event:
            # We cannot trigger the following on ev_keydown as the subsequent TextInput will pollute text field.
            case tcod.event.TextInput(text=text):
                if text == "q":
                    return DebugHandler(self.engine)

        return None


class GameOverEventHandler(EventHandler):
    def on_quit(self) -> None:
        """Handle exiting out of a finished game."""
        if os.path.exists("savegame.sav"):
            os.remove("savegame.sav")  # Deletes the active save file.
        raise exceptions.QuitWithoutSaving()  # Avoid saving a finished game.

    def ev_quit(self, event: tcod.event.Quit) -> None:
        self.on_quit()

    def ev_keydown(self, event: tcod.event.KeyDown) -> None:
        if event.sym == tcod.event.KeySym.ESCAPE:
            self.on_quit()


CURSOR_Y_KEYS = {
    tcod.event.KeySym.UP: -1,
    tcod.event.KeySym.DOWN: 1,
    tcod.event.KeySym.PAGEUP: -10,
    tcod.event.KeySym.PAGEDOWN: 10,
}


class HistoryViewer(EventHandler):
    """Print the history on a larger window which can be navigated."""

    def __init__(self, engine: Engine):
        super().__init__(engine)
        self.log_length = len(engine.message_log.messages)
        self.cursor = self.log_length - 1

    def on_render(self, console: tcod.Console) -> None:
        super().on_render(console)  # Draw the main state as the background.

        log_console = tcod.Console(console.width - 6, console.height - 6)

        # Draw a frame with a custom banner title.
        log_console.draw_frame(0, 0, log_console.width, log_console.height)
        log_console.print_box(
            0, 0, log_console.width, 1, "┤Message history├", alignment=tcod.CENTER
        )

        # Render the message log using the cursor parameter.
        self.engine.message_log.render_messages(
            log_console,
            1,
            1,
            log_console.width - 2,
            log_console.height - 2,
            self.engine.message_log.messages[: self.cursor + 1],
        )
        log_console.blit(console, 3, 3)

    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[MainGameEventHandler]:
        # Fancy conditional movement to make it feel right.
        if event.sym in CURSOR_Y_KEYS:
            adjust = CURSOR_Y_KEYS[event.sym]
            if adjust < 0 and self.cursor == 0:
                # Only move from the top to the bottom when you're on the edge.
                self.cursor = self.log_length - 1
            elif adjust > 0 and self.cursor == self.log_length - 1:
                # Same with bottom to top movement.
                self.cursor = 0
            else:
                # Otherwise move while staying clamped to the bounds of the history log.
                self.cursor = max(0, min(self.cursor + adjust, self.log_length - 1))
        elif event.sym == tcod.event.KeySym.HOME:
            self.cursor = 0  # Move directly to the top message.
        elif event.sym == tcod.event.KeySym.END:
            self.cursor = self.log_length - 1  # Move directly to the last message.
        else:  # Any other key moves back to the main game state.
            return MainGameEventHandler(self.engine)
        return None

class ViewKeybinds(AskUserEventHandler):
    """Print the history on a larger window which can be navigated."""
    TITLE = "KEYBOARD SHORTCUTS"
    TEXT = [
        "v: View History",
        "s: view keybinds",
        "g: Pick up item on the ground",
        "i: view and use inventory items",
        "d: drop items in inventory",
        "c: view character stats",
        "SHIFT + period: Enter next dungeon",
        "Press V to view!",
    ]
    def on_render(self, console: tcod.Console) -> None:
        super().on_render(console)

        if self.engine.player.x <= 30:
            x = 40
        else:
            x = 0

        y = 0

        width = 38

        console.draw_frame(
            x=x,
            y=y,
            width=width,
            height=len(self.TEXT)+2,
            title=self.TITLE,
            clear=True,
            fg=(255, 255, 255),
            bg=(0, 0, 0),
        )

        for i, line in enumerate(self.TEXT):
            console.print(x=x + 1, y=y + 1 + i, string=line)


# Import at end, to avoid circular dependency.
from debug import DebugHandler