From f23876f07babaa56753d0adb4fc1c5f79abf5434 Mon Sep 17 00:00:00 2001
From: "sashakoshka@tebibyte.media" <sashakoshka@tebibyte.media>
Date: Thu, 9 Jan 2025 21:41:43 -0500
Subject: [PATCH] flow: Add text reflow plugin

---
 flow/go.lua    | 168 +++++++++++++++++++++++++++++++++++++++++++++++++
 flow/repo.json |   5 ++
 2 files changed, 173 insertions(+)
 create mode 100644 flow/go.lua
 create mode 100644 flow/repo.json

diff --git a/flow/go.lua b/flow/go.lua
new file mode 100644
index 0000000..862cbf1
--- /dev/null
+++ b/flow/go.lua
@@ -0,0 +1,168 @@
+VERSION = "0.1.0"
+PLUGIN_NAME = "flow"
+
+local micro  = import("micro")
+local config = import("micro/config")
+local util   = import("micro/util")
+local buffer = import("micro/buffer")
+
+function init()
+	config.MakeCommand(PLUGIN_NAME,               flowIndent,  config.NoComplete)
+	config.MakeCommand(PLUGIN_NAME .. ".left",    flowLeft,    config.NoComplete)
+	config.MakeCommand(PLUGIN_NAME .. ".right",   flowRight,   config.NoComplete)
+	config.MakeCommand(PLUGIN_NAME .. ".center",  flowCenter,  config.NoComplete)
+	-- config.MakeCommand(PLUGIN_NAME .. ".justify", flowJustify, config.NoComplete)
+end
+
+function flowIndent(bufferPane)
+	return flow(bufferPane, "indent")
+end
+
+function flowLeft(bufferPane)
+	return flow(bufferPane, "left")
+end
+
+function flowRight(bufferPane)
+	return flow(bufferPane, "right")
+end
+
+function flowCenter(bufferPane)
+	return flow(bufferPane, "center")
+end
+
+function flowJustify(bufferPane)
+	return flow(bufferPane, "justify")
+end
+
+function flow(bufferPane, align)
+	local cursor = bufferPane.Buf:GetActiveCursor()
+	if not (cursor and cursor:HasSelection()) then return end
+
+	-- TODO: if there is no selection, operate on the start and end of
+	-- the currently selected paragraph, which is demarcated by double line
+	-- breaks/beginning/end of file
+
+	local sstart, send = nil, nil
+        if cursor.CurSelection[1]:GreaterThan(-cursor.CurSelection[2]) then
+            sstart, send = cursor.CurSelection[2], cursor.CurSelection[1]
+        else
+            sstart, send = cursor.CurSelection[1], cursor.CurSelection[2]
+        end
+        sstart = buffer.Loc(sstart.X, sstart.Y)
+        send   = buffer.Loc(send.X, send.Y)
+        
+	local selection = util.String(cursor:GetSelection())
+	selection = reflow(selection, align, colorColumn())
+	bufferPane.Buf:Replace(sstart, send, selection)
+end
+
+function reflow(text, alignment, columns)
+	-- get indentation information
+	local firstLineIndent, middleLineIndent, inputLines = splitIndentation(text)
+	firstLineIndent  = firstLineIndent  or ""
+	middleLineIndent = middleLineIndent or ""
+	
+	-- tokenize
+	local tokens = { }
+	for _, line in ipairs(inputLines) do
+		tokens = append(tokens, tokenize(line))
+	end
+
+	-- format tokens
+	local result = ""
+	local line   = ""
+	local currentColumns = columns - measure(firstLineIndent)
+	function addLine()
+		local first = false
+		if result == "" then
+			first = true
+		else
+			result = result .. "\n"
+		end
+		if alignment == "indent" then
+			if first then
+				line = firstLineIndent .. line
+			else
+				line = middleLineIndent .. line
+			end
+		else
+			line = align(line, alignment, columns)
+		end
+		result = result .. line
+		currentColumns = columns - measure(middleLineIndent)
+	end
+	for _, token in ipairs(tokens) do
+		local forecast = #line + 1 + #token
+		if forecast > currentColumns then
+			addLine()
+			line = ""
+		end
+		if line ~= "" then line = line .. " " end
+		line = line .. token
+	end
+	addLine()
+	
+	return result
+end
+
+-- assumes the text begins directly at the start of the file or directly after
+-- a line break. returns the indentation for the first line, lines in the
+-- middle, and the last line.
+function splitIndentation(text)
+	local indents = { }
+	local lines   = { }
+	for line in text:gmatch("([^\n]*)\n?") do
+		local indent = line:match("^[ \t/#*-]+") or ""
+		table.insert(indents, indent)
+		table.insert(lines, line:sub(#indent + 1))
+	end
+	if #indents < 1 then
+		return "", "", "", lines
+	end
+	local firstLineIndent  = indents[1] or ""
+	local middleLineIndent = indents[2] or ""
+	return firstLineIndent, middleLineIndent, lines
+end
+
+function align(line, alignment, columns)
+	local gap = columns - #line
+	if alignment == "right" then
+		return string.rep(" ", gap) .. line
+	elseif alignment == "center" then
+		return string.rep(" ", math.floor(gap / 2)) .. line
+	else
+		return line
+	end
+end
+
+function tokenize(text)
+	local tokens = { }
+	for token in text:gmatch("%S+") do
+		table.insert(tokens, token)
+	end
+	return tokens
+end
+
+function measure(text)
+	if not text then return 0 end
+	local width = 0
+	for index = 1, #text do
+		if text:sub(index, index) == "\t" then
+			width = math.ceil((width + 1) / 8) * 8
+		else
+			width = width + 1
+		end
+	end
+	return width
+end
+
+function append(dest, src)
+	for index = 1, #src do
+		dest[#dest + 1] = src[index]
+	end
+	return dest
+end
+
+function colorColumn()
+	return config.GetGlobalOption("colorcolumn")
+end
diff --git a/flow/repo.json b/flow/repo.json
new file mode 100644
index 0000000..e367562
--- /dev/null
+++ b/flow/repo.json
@@ -0,0 +1,5 @@
+[{
+	"Name": "case",
+	"Description": "Change the case of the selection",
+	"License": "GPLv3",
+}]