From d2f76201dd6143067e70a30ebddc3b84837748d7 Mon Sep 17 00:00:00 2001
From: Trey Hunner <trey@treyhunner.com>
Date: Sat, 23 Apr 2022 20:51:19 -0700
Subject: [PATCH] Add buffer for pasted stdin and inactive stdin

---
 browser-ui/wasm-terminal.js | 86 +++++++++++++++++++++++++++++++------
 1 file changed, 72 insertions(+), 14 deletions(-)

diff --git a/browser-ui/wasm-terminal.js b/browser-ui/wasm-terminal.js
index 220988c..c6a5cbf 100644
--- a/browser-ui/wasm-terminal.js
+++ b/browser-ui/wasm-terminal.js
@@ -1,7 +1,40 @@
+class BufferQueue {
+
+  constructor(xterm) {
+    this.buffer = [];
+  }
+
+  isEmpty() {
+    return this.buffer.length == 0;
+  }
+
+  lastLineIsIncomplete() {
+    return !this.isEmpty() && !this.buffer[this.buffer.length-1].endsWith("\n");
+  }
+
+  hasLineReady() {
+    return !this.isEmpty() && this.buffer[0].endsWith("\n");
+  }
+
+  addData(data) {
+    let lines = data.split(/(?<=\n)/g);
+    if (this.lastLineIsIncomplete()) {
+      this.buffer[this.buffer.length-1] += lines.shift();
+    }
+    for (let line of lines) {
+      this.buffer.push(line);
+    }
+  }
+
+  nextLine() {
+    return this.buffer.shift();
+  }
+}
 
 export class WasmTerminal {
 
   constructor() {
+    this.inputBuffer = new BufferQueue();
     this.input = ''
     this.resolveInput = null
     this.activeInput = false
@@ -25,41 +58,58 @@ export class WasmTerminal {
     this.xterm.open(container);
   }
 
-  handleReadComplete(lastChar) {
-    this.resolveInput(this.input + lastChar)
-    this.activeInput = false
-  }
-
   handleTermData = (data) => {
-    if (!this.activeInput) {
-      return
-    }
     const ord = data.charCodeAt(0);
-    let ofs;
 
+    data = data.replace(/\r\n|\r|\n/g, "\n")
+    if (data.length > 1 && data.includes("\n")) {
+      // Handle pasted data
+      let alreadyWritten = 0;
+      if (this.input != '') {
+        // If line already had data on it, merge pasted data with it
+        this.inputBuffer.addData(this.input);
+        alreadyWritten = this.input.length;
+        this.input = '';
+      }
+      this.inputBuffer.addData(data);
+      if (this.activeInput) {
+        let line = this.inputBuffer.nextLine();
+        this.writeLine(line.slice(alreadyWritten));
+        this.resolveInput(line);
+        this.activeInput = false;
+      }
+    } else if (!this.activeInput) {
+      this.inputBuffer.addData(data);
     // TODO: Handle ANSI escape sequences
-    if (ord === 0x1b) {
+    } else if (ord === 0x1b) {
     // Handle special characters
     } else if (ord < 32 || ord === 0x7f) {
       switch (data) {
         case "\r": // ENTER
         case "\x0a": // CTRL+J
         case "\x0d": // CTRL+M
-          this.xterm.write('\r\n');
-          this.handleReadComplete('\n');
+          this.resolveInput(this.input + this.writeLine('\n'));
+          this.input = '';
+          this.activeInput = false;
           break;
         case "\x7F": // BACKSPACE
         case "\x08": // CTRL+H
         case "\x04": // CTRL+D
           this.handleCursorErase(true);
           break;
-        
+
       }
     } else {
       this.handleCursorInsert(data);
     }
   }
 
+  writeLine(line) {
+    this.xterm.write(line.slice(0, -1))
+    this.xterm.write('\r\n');
+    return line;
+  }
+
   handleCursorInsert(data) {
     this.input += data;
     this.xterm.write(data)
@@ -79,9 +129,17 @@ export class WasmTerminal {
     this.activeInput = true
     // Hack to allow stdout/stderr to finish before we figure out where input starts
     setTimeout(() => {this.inputStartCursor = this.xterm.buffer.active.cursorX}, 1)
+    if (this.inputBuffer.hasLineReady()) {
+        return new Promise((resolve, reject) => {
+          resolve(this.writeLine(this.inputBuffer.nextLine()));
+          this.activeInput = false;
+        })
+    } else if (this.inputBuffer.lastLineIsIncomplete()) {
+      // Hack to ensure cursor input start doesn't end up after user input
+      setTimeout(() => {this.handleCursorInsert(this.inputBuffer.nextLine())}, 1);
+    }
     return new Promise((resolve, reject) => {
       this.resolveInput = (value) => {
-        this.input = ''
         resolve(value)
       }
     })