From 2fffb11a69c235953e3fb11c3dec850bcc256d7f Mon Sep 17 00:00:00 2001
From: prod2 <prod2@norlang.art>
Date: Thu, 29 Dec 2022 18:50:57 +0100
Subject: [PATCH] work on multiline, horizontal scroll

---
 editor.nim               |  4 ++-
 example.nim              |  5 ++++
 renderer.nim             | 54 ++++++++++++++++++++++++++++++++++------
 terminalUtils/buffer.nim | 34 ++++++++++++++++++++-----
 textBuffer.nim           |  9 ++++++-
 5 files changed, 91 insertions(+), 15 deletions(-)

diff --git a/editor.nim b/editor.nim
index c32a625..85ac8d3 100644
--- a/editor.nim
+++ b/editor.nim
@@ -49,8 +49,10 @@ proc read*(ed: EditorState): (EditorResult, string) =
   ed.history.add(ed.textBuffer)
   ed.historyIndex = ed.history.high()
 
+  var scroll: Scroll = new(Scroll)
+
   while true:
-    render(ed.textBuffer, ed.termBuffer, ed.prompt)
+    render(ed.textBuffer, ed.termBuffer, ed.prompt, scroll)
     let (getKeyResult, key) = getKey()
     case getKeyResult:
     of gkChar:
diff --git a/example.nim b/example.nim
index 797fdff..5fe04b8 100644
--- a/example.nim
+++ b/example.nim
@@ -1,4 +1,5 @@
 import editor
+import terminal
 
 let e = newEditor(">>> ")
 
@@ -6,5 +7,9 @@ while true:
   let (res, text) = e.read()
   if res in {erCtrlC, erCtrlD} or text == "quit":
     break
+  elif text == "clear":
+    eraseScreen()
+    setCursorPos(0, 0)
+    continue
   if text.len() > 0:
     echo text
\ No newline at end of file
diff --git a/renderer.nim b/renderer.nim
index db495c4..09372bc 100644
--- a/renderer.nim
+++ b/renderer.nim
@@ -2,26 +2,66 @@
 # when render() is called, rewrites the terminal buffer completely as a function of
 # of the text buffer
 
+import strutils
+
 import textBuffer
 import terminalUtils/buffer
 import terminalUtils/terminalGetInfo
 
-proc render*(textBuffer: TextBuffer, termBuffer: Buffer, prompt: string) =
+type Scroll* = ref object
+  x, y: int
+
+proc render*(textBuffer: TextBuffer, termBuffer: Buffer, prompt: string, scroll: Scroll) =
   # we are free to "redraw" everything everytime
   # since termBuffer double buffers
 
   # resizing the buffer if needed
   let lineCount = textBuffer.getLineCount()
   let termWidth = termGetWidth()
-  let termHeight = termGetHeight() # TODO
+  let termHeight = termGetHeight()
 
   let (bufWidth, bufHeight) = termBuffer.getSize()
-  
 
-  termBuffer.clearLine()
-  termBuffer.write(prompt)
-  termBuffer.write(textBuffer.getLine())
+  if bufWidth != termWidth or bufHeight != min(lineCount, termHeight):
+    termBuffer.resize(termWidth, min(lineCount, termHeight))
+
+  termBuffer.clear()
+
   let (x, y) = textBuffer.getCursorPos()
-  termBuffer.setCursorPos(x + prompt.len(), y)
+
+  let lines = textBuffer.lines()
+  let promptLen = prompt.len()
+  let maxTextLen = termWidth - promptLen
+  if maxTextLen < 1:
+    termBuffer.redraw()
+    return # nothing will fit anyways
+
+  for i in 0..lines.high():
+    let line = lines[i]
+    if i == 0:
+      termBuffer.write(prompt)
+    else:
+      termBuffer.write(" ".repeat(promptLen))
+
+    let lineLen = line.len()
+    if lineLen < maxTextLen - 1:
+      scroll.x = 0
+      termBuffer.write(line)
+    else:
+      const scrollOffset = 2
+      # horizontal scroll
+      # right scroll
+      if x - scroll.x >= maxTextLen - scrollOffset:
+        scroll.x = x - maxTextLen + scrollOffset
+      # left scroll
+      if x - scroll.x < 0:
+        scroll.x = x
+      # left scroll
+      # keep what's in range
+      let fromPos = scroll.x
+      let toPos = min(scroll.x+maxTextLen-2, line.high())
+      termBuffer.write(line[fromPos..toPos])
+    termBuffer.newLine()
+  termBuffer.setCursorPos(x + promptLen - scroll.x, y - scroll.y)
   termBuffer.redraw()
 
diff --git a/terminalUtils/buffer.nim b/terminalUtils/buffer.nim
index 8a1c6e7..27a5679 100644
--- a/terminalUtils/buffer.nim
+++ b/terminalUtils/buffer.nim
@@ -104,6 +104,9 @@ proc write*(buf: Buffer, text: string) =
   let runes = text.toRunes()
   buf.write(runes)
 
+proc newLine*(buf: Buffer) =
+  buf.bufferY += 1
+  buf.bufferX = 0
 
 proc redraw*(buf: Buffer, force: bool = false) =
   var toPrint = ""
@@ -144,17 +147,36 @@ proc redraw*(buf: Buffer, force: bool = false) =
 func getSize*(buf: Buffer): (int, int) =
   (buf.width, buf.height)
 
-proc resize*(buf: Buffer, newX, newY: int) =
+proc resize*(buf: Buffer, newWidth, newHeight: int) =
   # shrinking X
-  if newX < buf.width:
+  if newWidth < buf.width:
     # dropping cells outside the screen
     var i = 0
-    
+    buf.buffered.keepItIf(i mod buf.width < newWidth)
+    i = 0
+    buf.displayed.keepItIf(i mod buf.width < newWidth)
+  # increasing X
+  elif newWidth > buf.width:
+    let extra = newWidth - buf.width
+    let extraCells = Cell(text: Rune(0)).repeat(extra)
+    for i in 0..buf.height-1:
+      let pos = i * newWidth + buf.width
+      buf.buffered.insert(extraCells, pos)
+      buf.displayed.insert(extraCells, pos)
 
-  
+  # shrinking Y
+  if newHeight < buf.height:
+    buf.buffered.setLen(newHeight * newWidth)
+    buf.displayed.setLen(newHeight * newWidth)
+  # increasing Y
+  elif newHeight > buf.height:
+    let extra = newHeight - buf.height
+    let extraCells = Cell(text: Rune(0)).repeat(extra * newWidth)
+    buf.buffered &= extraCells
+    buf.displayed &= extraCells
 
-  buf.width = newX
-  buf.height = newY
+  buf.width = newWidth
+  buf.height = newHeight
 
 func getPosition*(buf: Buffer): (int, int) =
   (buf.positionX, buf.positionY)
diff --git a/textBuffer.nim b/textBuffer.nim
index 8194fcf..93f328d 100644
--- a/textBuffer.nim
+++ b/textBuffer.nim
@@ -67,6 +67,10 @@ proc moveCursor*(buf: TextBuffer, dx, dy: int) =
       buf.cursorY = 0
     elif buf.cursorY > buf.content.high():
       buf.cursorY = buf.content.high()
+    
+    if buf.cursorX > buf.cline().len():
+      buf.cursorX = buf.cline().len()
+
 
 proc getCursorPos*(buf: TextBuffer): (int, int) =
   (buf.cursorX, buf.cursorY)
@@ -98,4 +102,7 @@ proc newLine*(buf: TextBuffer) =
   buf.cursorX = 0
 
 proc getLineCount*(buf: TextBuffer): int =
-  buf.content.len()
\ No newline at end of file
+  buf.content.len()
+
+proc lines*(buf: TextBuffer): seq[seq[Rune]] =
+  buf.content
\ No newline at end of file