usg/src/Game.zig

const std = @import("std");
const SDL = @import("sdl2");

const Grid = @import("Grid.zig");
const Piece = @import("Piece.zig");
const Bag = @import("Bag.zig");
const Timer = @import("Timer.zig");

const renderer = @import("renderer.zig");
const movement = @import("movement.zig");

const Self = @This();

const Action = struct {
    activate: bool = false,
    holding: bool = false,
    code: u8,
    callback: fn (*Self) void,
    pub const Offset = enum(usize) {
        right = 0,
        left = 1,
        down = 2,
        hard = 3,
        swap = 4,
        rot_r = 5,
        rot_l = 6,
    };
};

grid: Grid,
grid_cell_size: i32,
grid_pos_x: i32,
grid_pos_y: i32,

bag: Bag,

held: ?Piece.Type,
piece: Piece,
shadow: Piece,

renderer: *SDL.SDL_Renderer,

action_list: [7]Action = .{
    .{ .code = SDL.SDL_SCANCODE_D, .callback = actionRight }, // Right
    .{ .code = SDL.SDL_SCANCODE_A, .callback = actionLeft }, // Left
    .{ .code = SDL.SDL_SCANCODE_S, .callback = actionDown }, // Down
    .{ .code = SDL.SDL_SCANCODE_W, .callback = actionHard }, // Instant Drop
    .{ .code = SDL.SDL_SCANCODE_SPACE, .callback = actionSwap }, // Swap Piece
    .{ .code = SDL.SDL_SCANCODE_RIGHT, .callback = actionRotR }, // Rotate
    .{ .code = SDL.SDL_SCANCODE_LEFT, .callback = actionRotL }, // Rotate
},

timer_down: Timer,

pub fn init(_renderer: *SDL.SDL_Renderer) Self {
    var ret = Self{
        .grid = Grid.init(),
        .grid_cell_size = undefined,
        .grid_pos_x = undefined,
        .grid_pos_y = undefined,

        .bag = Bag.init(),
        .piece = undefined,
        .shadow = undefined,
        .held = null,
        .renderer = _renderer,

        .timer_down = Timer.init(33),
    };

    // Calculate positions
    {
        var aux_w: i32 = undefined;
        var aux_h: i32 = undefined;

        _ = SDL.SDL_GetRendererOutputSize(_renderer, &aux_w, &aux_h);

        ret.grid_cell_size = @divFloor(@minimum(aux_w, aux_h), 32);

        ret.grid_pos_x = @divFloor(aux_w, 2) - (ret.grid_cell_size * @divFloor(Grid.ncolumns, 2));
        ret.grid_pos_y = @divFloor(aux_h, 2) - (ret.grid_cell_size * @divFloor(Grid.nrows + Grid.buffer, 2));

        ret.piece = ret.bag.pop();
    }

    return ret;
}
pub fn tick(self: *Self) void {

    // TIMERS
    if (self.piece.timer_dropped.finished()) {
        self.piece.timer_dropped.stop();
        self.piece.dropped = true;
    }

    if (self.action_list[@enumToInt(Action.Offset.down)].holding) {
        if (!self.timer_down.started) {
            self.timer_down.start();
        } else if (self.timer_down.finished()) {
            self.timer_down.stop();
            self.action_list[@enumToInt(Action.Offset.down)].holding = false;
        }
    } else {
        self.timer_down.stop();
    }

    // DROP

    if (self.piece.dropped) {
        self.grid = movement.drop(self.grid, self.piece);
        // New Piece
        self.piece = self.bag.pop();
    }

    // KEY EVENTS
    var key_state = SDL.SDL_GetKeyboardState(null);

    for (self.action_list) |*action| {
        if (key_state[action.*.code] == 1 and !action.*.holding) {
            action.*.holding = true;
            action.*.activate = true;
        }
        if (key_state[action.*.code] == 0) {
            action.*.holding = false;
        }

        // Action
        if (action.*.activate) {
            action.*.activate = false;
            @call(.{}, action.*.callback, .{self});
        }
    }

    // Update Shadow
    {
        self.shadow = movement.shadow(self.grid, self.piece);
        self.shadow.color.a /= 4;
    }

    self.grid.clearLines();

    renderer.render(self.*);
}

// ACTION CALLBACKS

fn actionDown(self: *Self) void {
    self.piece = movement.moveDown(self.grid, self.piece);
}

fn actionRight(self: *Self) void {
    self.piece = movement.moveRight(self.grid, self.piece);
}

fn actionLeft(self: *Self) void {
    self.piece = movement.moveLeft(self.grid, self.piece);
}
fn actionHard(self: *Self) void {
    self.piece = movement.hardDrop(self.grid, self.piece);
}
fn actionSwap(self: *Self) void {
    if (self.held) |held_piece| {
        if (!self.piece.swapped) {
            self.held = self.piece.piece_type;
            self.piece = Piece.init(held_piece);
            self.piece.swapped = true;
        }
    } else {
        self.held = self.piece.piece_type;
        self.piece = self.bag.pop();
        self.piece.swapped = true;
    }
}
fn actionRotR(self: *Self) void {
    self.piece = movement.rotateRight(self.grid, self.piece);
}
fn actionRotL(self: *Self) void {
    self.piece = movement.rotateLeft(self.grid, self.piece);
}