client/src/ui.js

function UI(async, buttons, screen, session) {
	var lineWidth = 36;
	var textSpeeds = {
		slow: 100,
		medium: 50,
		fast: 20
	};
	var textDelay = textSpeeds[session.getOptions().textSpeed];

	return {
		animation: animation,
		ask: ask,
		cinematic: cinematic,
		frame: frame,
		menu: menu,
		text: text
	};

	function animation(frames) {
		var frameCounter = 0;
		var scheduled;
		var step = function() {
			if(frameCounter < frames.length) {
				scheduled = null;
				frames[frameCounter].action();
				if(frames[frameCounter].delay != undefined) {
					scheduled = setTimeout(step, frames[frameCounter].delay);
				}
				frameCounter++
			}
		};
		return {
			run: step,
			pause: function() { if(scheduled != undefined) { clearTimeout(scheduled); } }
		};
	}

	function cinematic(frames, controls) {
		var remote = animation(frames);
		var mapping = {};
		var escaper = function(f) {
			return function() {
				buttons.pop();
				remote.pause();
				f();
			};
		}
		for(var key in controls) {
			mapping[key] = escaper(controls[key]);
		}
		return function(f) {
			buttons.push(mapping);
			remote.run();
			f();
		};
	}

	function close(elem) {
		buttons.pop();
		screen.clear(elem);
	}

	function frame(id) {
		screen.clear();
		screen.frame(id);
	}

	function menu(config) {
		var cursor = 0;
		var m = screen.menu(config.name + 'Menu', config.entries);
		var sync = function() { screen.select(cursor); };
		var mapping = {
			Up: function() {
				cursor = (config.entries.length + cursor - 1) % config.entries.length;
				sync();
			},
			Down: function() {
				cursor = (cursor + 1) % config.entries.length;
				sync();
			},
			A: function() {
				var entry = config.entries[cursor];
				if(entry.action != undefined) {
					entry.action(m);
				} else if(entry.quit != undefined) {
					close(m);
					entry.quit();
				}
			}
		};
		if(config.cancel != undefined) {
			mapping['B'] = function() { close(m); config.cancel(); }
		}
		buttons.push(mapping);
	}

	function ask(config) {
		var menuConfig = {entries: [], name: config.name};
		var apply = function(f, val) { return function() { return f(val); }; };
		return function(f) {
			for(var i = 0; i < config.entries.length; i++) {
				var entry;
				if(config.entries[i].label != undefined) {
					entry = {label: config.entries[i].label, quit: apply(f, config.entries[i].value)};
				} else {
					entry = {label: '___', action: promptValue(config.entries[i].size, f)};
				}
				menuConfig.entries.push(entry);
			}
			menu(menuConfig);
		};
	}

	function promptValue(size, f) {
		return function(m) {
			var input = screen.input(size);
			input.focus();
			buttons.push({});
			input.addEventListener('keydown', function(event) {
				switch(event.key) {
					case 'Escape': close(input); break;
					case 'Enter':
						var value = input.value;
						close(input);
						close(m);
						return f(value);
				}
			});
		};
	}

	function textScreen(message) {
		var characters = message.split('');
		var frames = [];
		var ready = false;
		var append = function(c) { return function() { screen.appendText(c); }; };
		for(var i = 0; i < characters.length; i++) {
			frames.push({action: append(characters[i]), delay: textDelay});
		}
		frames.push({action: function() { ready = true; screen.markAsRead(); }, delay: null});
		var remote = animation(frames);
		return function(f) {
			buttons.push({
				'A': function() {
					if(ready) {
						f();
					} else {
						remote.pause();
						screen.text(message);
						ready = true;
					}
				}
			});
			screen.text('');
			remote.run();
		};
	}

	function text(message) {
		var words = message.split(' ');
		var i = 0;
		var line = '';
		var screen = null;
		var screens = [];
		var width = 0;
		while (i < words.length) {
			if(width == 0) {
				line = words[i];
				width += line.length;
				i++;
			} else {
				if(width + words[i].length + 1 <= lineWidth) {
					line += ' ' + words[i];
					width += 1 + words[i].length;
					i++;
				} else {
					if(screen === null) {
						screen = line;
					} else {
						screens.push(screen + ' ' + line);
						screen = null;
					}
					line = '';
					width = 0;
				}
			}
		}
		screens.push(screen === null ? line : screen + ' ' + line);
		return async.sequence.apply(null,
			screens.map(function(s) { return textScreen(s); })
		);
	}
}