From 012c5fe97eccf5e00feedb6b3e228a819fde7edb Mon Sep 17 00:00:00 2001
From: AThePeanut4 <49614525+AThePeanut4@users.noreply.github.com>
Date: Fri, 23 Jun 2023 02:32:21 +0200
Subject: [PATCH 1/3] fix: store paths in g:BufferlinePositions

---
 lua/bufferline/commands.lua |  7 ++++---
 lua/bufferline/state.lua    | 13 ++++++++-----
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/lua/bufferline/commands.lua b/lua/bufferline/commands.lua
index 7bea9f95..e105307a 100644
--- a/lua/bufferline/commands.lua
+++ b/lua/bufferline/commands.lua
@@ -13,13 +13,14 @@ local pick = lazy.require("bufferline.pick") ---@module "bufferline.pick"
 
 local M = {}
 
-local positions_key = constants.positions_key
-
 local fmt = string.format
 local api = vim.api
 
 ---@param ids number[]
-local function save_positions(ids) vim.g[positions_key] = table.concat(ids, ",") end
+local function save_positions(ids)
+  local paths = vim.tbl_map(function(id) return vim.api.nvim_buf_get_name(id) end, ids)
+  vim.g[constants.positions_key] = vim.json.encode(paths)
+end
 
 --- @param elements bufferline.TabElement[]
 --- @return number[]
diff --git a/lua/bufferline/state.lua b/lua/bufferline/state.lua
index 90f23dbf..0ee284ca 100644
--- a/lua/bufferline/state.lua
+++ b/lua/bufferline/state.lua
@@ -23,11 +23,14 @@ local state = {
 
 function M.restore_positions()
   local str = vim.g[constants.positions_key]
-  if not str then return str end
-  -- these are converted to strings when stored
-  -- so have to be converted back before usage
-  local ids = vim.split(str, ",")
-  if ids and #ids > 0 then state.custom_sort = vim.tbl_map(tonumber, ids) end
+  local ok, paths = pcall(vim.json.decode, str)
+  if not ok or type(paths) ~= "table" or #paths == 0 then return end
+  local ids = vim.tbl_map(function(path)
+    local escaped = vim.fn.fnameescape(path)
+    return vim.fn.bufnr("^" .. escaped .. "$" --[[@as integer]])
+  end, paths)
+  ids = vim.tbl_filter(function(id) return id ~= -1 end, ids)
+  state.custom_sort = ids
 end
 
 ---@param list bufferline.Component[]

From 84ad560697b6435e334711d805616c2fc804f736 Mon Sep 17 00:00:00 2001
From: AThePeanut4 <49614525+AThePeanut4@users.noreply.github.com>
Date: Tue, 27 Jun 2023 16:46:21 +0200
Subject: [PATCH 2/3] refactor: move restore_positions, save_positions and
 get_ids into utils

---
 lua/bufferline.lua            |  2 +-
 lua/bufferline/commands.lua   | 21 ++++-----------------
 lua/bufferline/state.lua      | 13 -------------
 lua/bufferline/types.lua      |  2 +-
 lua/bufferline/utils/init.lua | 24 ++++++++++++++++++++++++
 5 files changed, 30 insertions(+), 32 deletions(-)

diff --git a/lua/bufferline.lua b/lua/bufferline.lua
index 7bc28950..6e68aa9b 100644
--- a/lua/bufferline.lua
+++ b/lua/bufferline.lua
@@ -116,7 +116,7 @@ local function setup_autocommands(conf)
     api.nvim_create_autocmd("SessionLoadPost", {
       pattern = "*",
       group = BUFFERLINE_GROUP,
-      callback = function() state.restore_positions() end,
+      callback = function() state.custom_sort = utils.restore_positions() end,
     })
   end
   if not options.always_show_bufferline then
diff --git a/lua/bufferline/commands.lua b/lua/bufferline/commands.lua
index e105307a..8b8c1283 100644
--- a/lua/bufferline/commands.lua
+++ b/lua/bufferline/commands.lua
@@ -8,7 +8,6 @@ local utils = lazy.require("bufferline.utils") ---@module "bufferline.utils"
 local config = lazy.require("bufferline.config") ---@module "bufferline.config"
 local groups = lazy.require("bufferline.groups") ---@module "bufferline.groups"
 local sorters = lazy.require("bufferline.sorters") ---@module "bufferline.sorters"
-local constants = lazy.require("bufferline.constants") ---@module "bufferline.constants"
 local pick = lazy.require("bufferline.pick") ---@module "bufferline.pick"
 
 local M = {}
@@ -16,18 +15,6 @@ local M = {}
 local fmt = string.format
 local api = vim.api
 
----@param ids number[]
-local function save_positions(ids)
-  local paths = vim.tbl_map(function(id) return vim.api.nvim_buf_get_name(id) end, ids)
-  vim.g[constants.positions_key] = vim.json.encode(paths)
-end
-
---- @param elements bufferline.TabElement[]
---- @return number[]
-local function get_ids(elements)
-  return vim.tbl_map(function(item) return item.id end, elements)
-end
-
 --- open the current element
 ---@param id number
 local function open_element(id)
@@ -171,9 +158,9 @@ function M.move_to(to_index, from_index)
     local destination_buf = state.components[next_index]
     state.components[next_index] = item
     state.components[index] = destination_buf
-    state.custom_sort = get_ids(state.components)
+    state.custom_sort = utils.get_ids(state.components)
     local opts = config.options
-    if opts.persist_buffer_sort then save_positions(state.custom_sort) end
+    if opts.persist_buffer_sort then utils.save_positions(state.custom_sort) end
     ui.refresh()
   end
 end
@@ -270,9 +257,9 @@ end
 function M.sort_by(sort_by)
   if next(state.components) == nil then return utils.notify("Unable to find elements to sort, sorry", "warn") end
   sorters.sort(state.components, { sort_by = sort_by })
-  state.custom_sort = get_ids(state.components)
+  state.custom_sort = utils.get_ids(state.components)
   local opts = config.options
-  if opts.persist_buffer_sort then save_positions(state.custom_sort) end
+  if opts.persist_buffer_sort then utils.save_positions(state.custom_sort) end
   ui.refresh()
 end
 
diff --git a/lua/bufferline/state.lua b/lua/bufferline/state.lua
index 0ee284ca..c45f91a2 100644
--- a/lua/bufferline/state.lua
+++ b/lua/bufferline/state.lua
@@ -1,7 +1,6 @@
 local M = {}
 
 local lazy = require("bufferline.lazy")
-local constants = lazy.require("bufferline.constants") ---@module "bufferline.constants"
 local utils = lazy.require("bufferline.utils") ---@module "bufferline.utils"
 
 -----------------------------------------------------------------------------//
@@ -21,18 +20,6 @@ local state = {
   right_offset_size = 0,
 }
 
-function M.restore_positions()
-  local str = vim.g[constants.positions_key]
-  local ok, paths = pcall(vim.json.decode, str)
-  if not ok or type(paths) ~= "table" or #paths == 0 then return end
-  local ids = vim.tbl_map(function(path)
-    local escaped = vim.fn.fnameescape(path)
-    return vim.fn.bufnr("^" .. escaped .. "$" --[[@as integer]])
-  end, paths)
-  ids = vim.tbl_filter(function(id) return id ~= -1 end, ids)
-  state.custom_sort = ids
-end
-
 ---@param list bufferline.Component[]
 ---@return bufferline.Component[]
 local function filter_invisible(list)
diff --git a/lua/bufferline/types.lua b/lua/bufferline/types.lua
index f7aeb4eb..0dba6e76 100644
--- a/lua/bufferline/types.lua
+++ b/lua/bufferline/types.lua
@@ -216,7 +216,7 @@
 ---@field is_picking boolean
 ---@field visible_components bufferline.Component[]
 ---@field __components bufferline.Component[]
----@field custom_sort number[]
+---@field custom_sort number[]?
 ---@field left_offset_size number
 ---@field right_offset_size number
 
diff --git a/lua/bufferline/utils/init.lua b/lua/bufferline/utils/init.lua
index 4c06c08c..726ba7f2 100644
--- a/lua/bufferline/utils/init.lua
+++ b/lua/bufferline/utils/init.lua
@@ -154,6 +154,30 @@ function M.notify(msg, level, opts)
   vim.schedule(function() vim.notify(msg, level, nopts) end)
 end
 
+---@return number[]?
+function M.restore_positions()
+  local str = vim.g[constants.positions_key]
+  local ok, paths = pcall(vim.json.decode, str)
+  if not ok or type(paths) ~= "table" or #paths == 0 then return nil end
+  local ids = vim.tbl_map(function(path)
+    local escaped = vim.fn.fnameescape(path)
+    return vim.fn.bufnr("^" .. escaped .. "$" --[[@as integer]])
+  end, paths)
+  return vim.tbl_filter(function(id) return id ~= -1 end, ids)
+end
+
+---@param ids number[]
+function M.save_positions(ids)
+  local paths = vim.tbl_map(function(id) return vim.api.nvim_buf_get_name(id) end, ids)
+  vim.g[constants.positions_key] = vim.json.encode(paths)
+end
+
+--- @param elements bufferline.TabElement[]
+--- @return number[]
+function M.get_ids(elements)
+  return vim.tbl_map(function(item) return item.id end, elements)
+end
+
 ---Get an icon for a filetype using either nvim-web-devicons or vim-devicons
 ---if using the lua plugin this also returns the icon's highlights
 ---@param opts bufferline.IconFetcherOpts

From 7cde1a16f94e67efd2a262ce04f13a363fa24eb3 Mon Sep 17 00:00:00 2001
From: AThePeanut4 <49614525+AThePeanut4@users.noreply.github.com>
Date: Tue, 27 Jun 2023 18:44:18 +0200
Subject: [PATCH 3/3] test: add save/restore tests

---
 tests/utils_spec.lua | 47 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/tests/utils_spec.lua b/tests/utils_spec.lua
index ccdf8a48..39923825 100644
--- a/tests/utils_spec.lua
+++ b/tests/utils_spec.lua
@@ -18,4 +18,51 @@ describe("Utils tests", function()
     local truncated = utils.truncate_name("filename.md.md", 13)
     assert.is_equal(truncated, "filename.md" .. constants.ELLIPSIS)
   end)
+
+  it("should save/restore positions correctly", function()
+    -- remove existing buffers
+    vim.cmd("silent %bwipeout!")
+
+    local names = { "c.txt", "a.txt", "d.txt", "e.txt", "b.txt" }
+    local bufs = {}
+    for _, name in ipairs(names) do
+      vim.cmd.edit(name)
+      bufs[name] = api.nvim_get_current_buf()
+    end
+
+    local ids = {
+      bufs["a.txt"],
+      bufs["b.txt"],
+      bufs["c.txt"],
+      bufs["d.txt"],
+      bufs["e.txt"],
+    }
+
+    utils.save_positions(ids)
+
+    assert.same(utils.restore_positions(), ids)
+
+    -- restore_positions should not return invalid bufids
+
+    vim.cmd("bwipeout! " .. bufs["c.txt"])
+
+    ids = {
+      bufs["a.txt"],
+      bufs["b.txt"],
+      bufs["d.txt"],
+      bufs["e.txt"],
+    }
+    assert.same(utils.restore_positions(), ids)
+
+    vim.g[constants.positions_key] = '["INVALID_PATH"]'
+    assert.same(utils.restore_positions(), {})
+
+    -- empty or invalid JSON should return nil
+
+    vim.g[constants.positions_key] = "[]"
+    assert.is_equal(utils.restore_positions(), nil)
+
+    vim.g[constants.positions_key] = ""
+    assert.is_equal(utils.restore_positions(), nil)
+  end)
 end)