From 00eebc9859be03fb974449c785398e706cf6a14c Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Wed, 30 Jun 2021 22:20:40 +0200
Subject: [PATCH] composer: cycle through auto-completions

Closes: https://todo.sr.ht/~emersion/gamja/42
---
 components/app.js      | 14 +++-----
 components/composer.js | 79 +++++++++++++++++++++++++++++-------------
 2 files changed, 58 insertions(+), 35 deletions(-)

diff --git a/components/app.js b/components/app.js
index 78e7550..b27a671 100644
--- a/components/app.js
+++ b/components/app.js
@@ -1007,13 +1007,10 @@ export default class App extends Component {
 	autocomplete(prefix) {
 		function fromList(l, prefix) {
 			prefix = prefix.toLowerCase();
-			let repl = null;
+			let repl = [];
 			for (let item of l) {
 				if (item.toLowerCase().startsWith(prefix)) {
-					if (repl) {
-						return null;
-					}
-					repl = item;
+					repl.push(item);
 				}
 			}
 			return repl;
@@ -1021,15 +1018,12 @@ export default class App extends Component {
 
 		if (prefix.startsWith("/")) {
 			let repl = fromList(Object.keys(commands), prefix.slice(1));
-			if (repl) {
-				repl = "/" + repl;
-			}
-			return repl;
+			return repl.map(cmd => "/" + cmd);
 		}
 
 		let buf = this.state.buffers.get(this.state.activeBuffer);
 		if (!buf || !buf.members) {
-			return null;
+			return [];
 		}
 		return fromList(buf.members.keys(), prefix);
 	}
diff --git a/components/composer.js b/components/composer.js
index cd62797..d33720a 100644
--- a/components/composer.js
+++ b/components/composer.js
@@ -5,6 +5,7 @@ export default class Composer extends Component {
 		text: "",
 	};
 	textInput = createRef();
+	lastAutocomplete = null;
 
 	constructor(props) {
 		super(props);
@@ -42,48 +43,76 @@ export default class Composer extends Component {
 
 		event.preventDefault();
 
-		let carretIndex = input.selectionStart;
+		let carretPos = input.selectionStart;
 		let text = this.state.text;
-		let wordStart;
-		for (wordStart = carretIndex - 1; wordStart >= 0; wordStart--) {
-			if (text[wordStart] === " ") {
-				break;
+		let autocomplete;
+		if (this.lastAutocomplete && this.lastAutocomplete.text === text && this.lastAutocomplete.carretPos === carretPos) {
+			autocomplete = this.lastAutocomplete;
+		} else {
+			this.lastAutocomplete = null;
+
+			let wordStart;
+			for (wordStart = carretPos - 1; wordStart >= 0; wordStart--) {
+				if (text[wordStart] === " ") {
+					break;
+				}
 			}
-		}
-		wordStart++;
+			wordStart++;
 
-		let wordEnd;
-		for (wordEnd = carretIndex; wordEnd < text.length; wordEnd++) {
-			if (text[wordEnd] === " ") {
-				break;
+			let wordEnd;
+			for (wordEnd = carretPos; wordEnd < text.length; wordEnd++) {
+				if (text[wordEnd] === " ") {
+					break;
+				}
 			}
+
+			let word = text.slice(wordStart, wordEnd);
+			if (!word) {
+				return;
+			}
+
+			let replacements = this.props.autocomplete(word);
+			if (replacements.length === 0) {
+				return;
+			}
+
+			autocomplete = {
+				text,
+				carretPos: input.selectionStart,
+				prefix: text.slice(0, wordStart),
+				suffix: text.slice(wordEnd),
+				replacements,
+				replIndex: -1,
+			};
 		}
 
-		let word = text.slice(wordStart, wordEnd);
-		if (!word) {
-			return;
+		let n = autocomplete.replacements.length;
+		if (event.shiftKey) {
+			autocomplete.replIndex--;
+		} else {
+			autocomplete.replIndex++;
 		}
+		autocomplete.replIndex = (autocomplete.replIndex + n) % n;
 
-		let repl = this.props.autocomplete(word);
-		if (!repl) {
-			return;
-		}
-
-		if (wordStart === 0 && wordEnd === text.length) {
-			if (word.startsWith("/")) {
+		let repl = autocomplete.replacements[autocomplete.replIndex];
+		if (!autocomplete.prefix && !autocomplete.suffix) {
+			if (repl.startsWith("/")) {
 				repl += " ";
 			} else {
 				repl += ": ";
 			}
 		}
 
-		text = text.slice(0, wordStart) + repl + text.slice(wordEnd);
+		autocomplete.text = autocomplete.prefix + repl + autocomplete.suffix;
+		autocomplete.carretPos = autocomplete.prefix.length + repl.length;
 
-		input.value = text;
-		input.selectionStart = wordStart + repl.length;
+		input.value = autocomplete.text;
+		input.selectionStart = autocomplete.carretPos;
 		input.selectionEnd = input.selectionStart;
 
-		this.setState({ text });
+		this.lastAutocomplete = autocomplete;
+
+		this.setState({ text: autocomplete.text });
 	}
 
 	handleWindowKeyDown(event) {