From b25fe21151adde382d3b87532fd9fe8b19f3cff8 Mon Sep 17 00:00:00 2001
From: Kassio Borges <kassioborgesm@gmail.com>
Date: Mon, 30 Nov 2020 00:29:42 +0000
Subject: [PATCH] Use the minimum available ID

Fixes #309
---
 CHANGELOG.md         |  3 +++
 autoload/neoterm.vim | 16 ++++++++++++++++
 doc/neoterm.txt      |  4 ++--
 plugin/neoterm.vim   | 14 +++-----------
 vmtest/neoterm.vim   | 23 +++++++++++++++++++++++
 5 files changed, 47 insertions(+), 13 deletions(-)
 create mode 100644 vmtest/neoterm.vim

diff --git a/CHANGELOG.md b/CHANGELOG.md
index eee9d51..ad61296 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,6 @@
+### 30/11/2020
+  - Change the next id calculation to use the minimum available value.
+    ([\#309](https://github.com/kassio/neoterm/issues/309))
 ### 05/11/2020
   - Better exception handling when toggling neoterm and it's the last open
     window.
diff --git a/autoload/neoterm.vim b/autoload/neoterm.vim
index 765f28b..c3a758f 100644
--- a/autoload/neoterm.vim
+++ b/autoload/neoterm.vim
@@ -319,3 +319,19 @@ function! s:resize_instance(instance) abort
     exec printf('%s resize %s', a:instance.mod, size)
   endif
 endfunction
+
+" Calculates the next neoterm's ID.
+" Returns the minimum next available id, an id not related
+" to an neoterm instance.
+function! neoterm#next_id(instances, last_id)
+  let l:instance_ids = map(keys(a:instances), {_, v -> str2nr(v) })
+
+  for i in range(1, max(l:instance_ids) + 1)
+    if index(l:instance_ids, i) < 0
+      let l:last_id = i
+      return l:last_id
+    end
+  endfor
+
+  return a:last_id + 1
+endfunction
diff --git a/doc/neoterm.txt b/doc/neoterm.txt
index 0492da1..077a7fc 100644
--- a/doc/neoterm.txt
+++ b/doc/neoterm.txt
@@ -39,8 +39,8 @@ Commands lacking a prefix will always be executed in the last active neoterm.
 
 1.4 ID calculation                                      *neoterm-id-calculation*
 
-The ID is a sequential number starting from 1. To avoid big ID numbers, the ID
-is reseted to 1 when there is no instance of a neoterm windows open.
+The ID is a numeric value. It's calculates the minimum available value,
+starting from 1.
 
 1.4 Last Active                                            *neoterm-last-active*
 
diff --git a/plugin/neoterm.vim b/plugin/neoterm.vim
index 812e1de..1b86c13 100644
--- a/plugin/neoterm.vim
+++ b/plugin/neoterm.vim
@@ -12,18 +12,10 @@ let g:neoterm = {
       \ 'managed': []
       \ }
 
-" Calculates the next neoterm's ID.
-" The ID is a sequential number starting from 1.
-" To avoid big ID numbers, the ID is reseted to 1
-" when there is no instance of a neoterm windows open
 function! g:neoterm.next_id()
-  if len(keys(l:self.instances)) == 0
-    let l:self.last_id = 1
-    return l:self.last_id
-  else
-    let l:self.last_id += 1
-    return l:self.last_id
-  end
+  let l:self.last_id = neoterm#next_id(l:self.instances, l:self.last_id)
+
+  return l:self.last_id
 endfunction
 
 function! g:neoterm.has_any()
diff --git a/vmtest/neoterm.vim b/vmtest/neoterm.vim
new file mode 100644
index 0000000..394a7be
--- /dev/null
+++ b/vmtest/neoterm.vim
@@ -0,0 +1,23 @@
+call vmtest#plugin('neoterm')
+let g:vmtests.neoterm.neoterm = { '_name': 'g:neoterm tests' }
+
+function! g:vmtests.neoterm.neoterm.test_when_theres_no_instances()
+  call assert_equal(
+        \ 1,
+        \ neoterm#next_id({}, 0)
+        \ )
+endfunction
+
+function! g:vmtests.neoterm.neoterm.test_when_theres_sequential_instances()
+  call assert_equal(
+        \ 4,
+        \ neoterm#next_id({'1': v:null, '2': v:null, '3': v:null}, 3)
+        \ )
+endfunction
+
+function! g:vmtests.neoterm.neoterm.test_when_instances_are_not_sequential()
+  call assert_equal(
+        \ 2,
+        \ neoterm#next_id({'1': v:null, '3': v:null}, 3)
+        \ )
+endfunction