From d16557c3e67c78b14881c1da872eebaf861deb50 Mon Sep 17 00:00:00 2001
From: danymat <d.danymat@gmail.com>
Date: Fri, 7 Jan 2022 19:44:41 +0100
Subject: [PATCH] feat: Allow users to jump previous (#13)

---
 README.md                       | 34 ++++++++++++++++------------
 lua/neogen.lua                  | 11 ++++++++--
 lua/neogen/utilities/cursor.lua | 39 ++++++++++++++++++++++++++++-----
 3 files changed, 63 insertions(+), 21 deletions(-)

diff --git a/README.md b/README.md
index 5748b50..40833d7 100644
--- a/README.md
+++ b/README.md
@@ -114,20 +114,26 @@ cmp.setup {
 
     -- You must set mapping if you want.
     mapping = {
-        ["<tab>"] = cmp.mapping(function(fallback)
-            if vim.fn.pumvisible() == 1 then
-                vim.fn.feedkeys(t("<C-n>"), "n")
-            elseif neogen.jumpable() then
-                vim.fn.feedkeys(t("<cmd>lua require('neogen').jump_next()<CR>"), "")
-            elseif check_back_space() then
-                vim.fn.feedkeys(t("<tab>"), "n")
-            else
-                fallback()
-            end
-        end, {
-            "i",
-            "s",
-        }),
+		["<tab>"] = cmp.mapping(function(fallback)
+			if neogen.jumpable() then
+				vim.fn.feedkeys(t("<cmd>lua require('neogen').jump_next()<CR>"), "")
+			else
+				fallback()
+			end
+		end, {
+			"i",
+			"s",
+		}),
+		["<S-tab>"] = cmp.mapping(function(fallback)
+			if neogen.jumpable(-1) then
+				vim.fn.feedkeys(t("<cmd>lua require('neogen').jump_prev()<CR>"), "")
+			else
+				fallback()
+			end
+		end, {
+			"i",
+			"s",
+		}),
     },
     ...
 }
diff --git a/lua/neogen.lua b/lua/neogen.lua
index 949a92f..6a8eca5 100644
--- a/lua/neogen.lua
+++ b/lua/neogen.lua
@@ -88,6 +88,7 @@ neogen.generate = function(opts)
                 vim.fn.append(to_place, content)
 
                 -- Place cursor after annotations and start editing
+                -- First and last extmarks are needed to know the range of inserted content
                 if neogen.configuration.input_after_comment == true then
                     -- Creates extmark for the beggining of the content
                     neogen.utilities.cursor.create(to_place + 1, start_column)
@@ -113,10 +114,16 @@ function neogen.jump_next()
     neogen.utilities.cursor.jump()
 end
 
-function neogen.jumpable()
-    return neogen.utilities.cursor.jumpable()
+function neogen.jump_prev()
+    neogen.utilities.cursor.jump_prev()
 end
 
+function neogen.jumpable(reverse)
+    return neogen.utilities.cursor.jumpable(reverse)
+end
+
+
+
 function neogen.generate_command()
     vim.api.nvim_command('command! -range -bar Neogen lua require("neogen").generate()')
 end
diff --git a/lua/neogen/utilities/cursor.lua b/lua/neogen/utilities/cursor.lua
index 5d6bc63..d72673f 100644
--- a/lua/neogen/utilities/cursor.lua
+++ b/lua/neogen/utilities/cursor.lua
@@ -1,12 +1,14 @@
 neogen.utilities.cursor = {}
 
 local neogen_ns = vim.api.nvim_create_namespace("neogen")
+local current_position = 1
 
 --- Wrapper around set_extmark with 1-based numbering for `line` and `col`, and returns the id of the created extmark
 --- @param line string
 --- @param col string
 --- @return number
 neogen.utilities.cursor.create = function(line, col)
+    current_position = 1
     return vim.api.nvim_buf_set_extmark(0, neogen_ns, line - 1, col - 1, {})
 end
 
@@ -15,13 +17,13 @@ end
 --- First jumpable extmark is the one after the extmarks responsible of start/end of annotation
 neogen.utilities.cursor.go_next_extmark = function()
     local extm_list = vim.api.nvim_buf_get_extmarks(0, neogen_ns, 0, -1, {})
+    local position = current_position + 1
+
     if #extm_list ~= 2 then
-        local pos = { extm_list[2][2] + 1, extm_list[2][3] }
+        local pos = { extm_list[position][2] + 1, extm_list[position][3] }
 
         vim.api.nvim_win_set_cursor(0, pos)
-        if #extm_list ~= 0 then
-            vim.api.nvim_buf_del_extmark(0, neogen_ns, extm_list[1][1])
-        end
+        current_position = current_position + 1
         return true
     else
         return false
@@ -45,6 +47,20 @@ neogen.utilities.cursor.jump = function(opts)
     end
 end
 
+neogen.utilities.cursor.jump_prev = function()
+    local marks = vim.api.nvim_buf_get_extmarks(0, neogen_ns, 0, -1, {})
+
+    if #marks == 2 then
+        return false
+    end
+
+    local position = current_position - 1
+    local pos = { marks[position][2] + 1, marks[position][3] }
+    vim.api.nvim_win_set_cursor(0, pos)
+    current_position = current_position - 1
+    return true
+end
+
 --- Delete all active extmarks
 neogen.utilities.cursor.del_extmarks = function()
     local extmarks = vim.api.nvim_buf_get_extmarks(0, neogen_ns, 0, -1, {})
@@ -55,7 +71,7 @@ end
 
 --- Checks if there are still possible jump positions to perform
 --- Verifies if the cursor is in the last annotated part
-neogen.utilities.cursor.jumpable = function()
+neogen.utilities.cursor.jumpable = function(reverse)
     local extm_list = vim.api.nvim_buf_get_extmarks(0, neogen_ns, 0, -1, {})
     if #extm_list == 0 then
         return false
@@ -64,6 +80,19 @@ neogen.utilities.cursor.jumpable = function()
     if cursor[1] > extm_list[#extm_list][2] or cursor[1] < extm_list[1][2] then
         return false
     end
+
+    -- We arrive at the end, we can't jump anymore
+    if current_position == #extm_list then
+        return false
+    end
+
+    if reverse == -1 then
+        -- Check first boundaries
+        if current_position == 1 then
+            return false
+        end
+    end
+
     if #extm_list > 2 then
         return true
     else