more conflict-resistant comment storage

Until now, comments were stored in filenames with an incrementing
counter. As a result, conflicts are easy; two people commenting on a
post around the same time would create the same filename. Then they'd
run into conflicts when merging.

Now comment filenames include a random slug.

A secondary consideration is filtering out comments from the file-picker
screen. It's only intended for top-level posts. I had a hacky way to do
this. My ideal approach would be a directory per post, but Lua+LÖVE
doesn't have a portable way to create directories.

Now you now have to manually create a single directory called
`comments/` in the directory of articles before using pothi.love.

0119-load_metadata

@@ -2,6 +2,8 @@ load_metadata = function(filename)
 	local mfile = metadata_file(filename)
 	local mpath = save_dir_path(mfile)
 	if not love.filesystem.getInfo(mpath) then
+		-- comments will always have metadata,
+		-- so we only get here for top-level posts with no parent
 		return {replies={}}
 	end
 	return json.decode(love.filesystem.read(mpath))

0120-initialize_item

@@ -1,7 +1,13 @@
 initialize_item = function(id, depth)
+	local path
+	if depth == 0 then
+		path = full_path(id)
+	else
+		path = comment_path(id)
+	end
 	local result = {
 		type='text',
-		id=id, filename=full_path(id),
+		id=id, filename=path,
 		width=Width, depth=depth,
 		metadata=load_metadata(id),
 		border=Border_color,

0129-initialize_file_picker

@@ -1,7 +1,7 @@
 initialize_file_picker = function()
 	Files = love.filesystem.getDirectoryItems('data')
 	for i=#Files,1,-1 do
-		if (not Files[i]:match('%.md$')) or Files[i]:match('%-%d+.md$') then
+		if not Files[i]:match('%.md$') then
 			table.remove(Files, i)
 		end
 	end
@@ -16,4 +16,4 @@ initialize_file_picker = function()
 			border={r=0.4, g=0.4, b=0.7}
 		})
 	end
-end
+end

0139-new_comment

@@ -1,14 +1,14 @@
 new_comment = function(parent_id, depth)
-	local id = next_comment_id(parent_id)
+	local id = new_comment_id(parent_id)
 	print('creating', id)
 	local comment = {
 		type='text',
 		id=id,
-		filename=full_path(id),
+		filename=comment_path(id),
 		data={{data=''}},
 		width=Width,
 		depth=depth+1,
-		metadata={replies={}},
+		metadata={parent=parent_id, replies={}},
 		border=Border_color,
 	}
 	save_metadata(comment)
@@ -20,4 +20,4 @@ new_comment = function(parent_id, depth)
 	table.insert(item_stuff.data,
 		reply_button(comment.id, depth+1))
 	return result, id
-end
+end

0144-new_comment_id

@@ -0,0 +1,12 @@
+new_comment_id = function(id)
+	local corename = id:gsub('%.md$', '')
+	-- there'll be a collision on avarage every #Random_string_chars^(n/2) = 1296 comments
+	local n = 4
+	local result = ('%s-%s.md'):format(corename, random_string(4))
+	if file_exists(comment_path(result)) then
+		-- retry
+		-- This will infinite loop every #Random_string_chars^n = 1.6M, but it'll start taking a long time by halfway as long.
+		return new_comment_id(id)
+	end
+	return result
+end

0144-next_comment_id

@@ -1,5 +0,0 @@
-next_comment_id = function(id)
-	local num_replies = #load_metadata(id).replies
-	local corename = id:gsub('%.md$', '')
-	return ('%s-%d.md'):format(corename, num_replies)
-end

0145-save_metadata

@@ -1,6 +1,11 @@
 save_metadata = function(node)
 	--print('saving metadata for', node.id)
 	local mfile = metadata_file(node.id)
-	local mpath = save_dir_path(mfile)
+	local mpath
+	if node.metadata.parent then
+		mpath = save_dir_path('comments/'..mfile)
+	else
+		mpath = save_dir_path(mfile)
+	end
 	love.filesystem.write(mpath, json.encode(node.metadata))
-end
+end

0149-Random_string_chars

@@ -0,0 +1 @@
+Random_string_chars = 'abcdefghijklmnopqrstuvwxyz0123456789'

0150-random_string

@@ -0,0 +1,10 @@
+random_string = function(n)
+	-- generate a random string of length n
+	local result = {}
+	local nchars = #Random_string_chars
+	for i=1,n do
+		local idx = math.random(1, nchars)
+		table.insert(result, Random_string_chars:sub(idx, idx))
+	end
+	return table.concat(result)
+end

0151-comment_path

@@ -0,0 +1,3 @@
+comment_path = function(id)
+	return full_path('comments/'..id)
+end