From 8a8daa0ea1b288011f2118155b5620ec3cfc4ec6 Mon Sep 17 00:00:00 2001
From: "T. H. Wright" <github@redemption.studio>
Date: Fri, 19 May 2023 15:04:30 -0400
Subject: [PATCH] Add @tag support (#247)

Co-authored-by: T. H. Wright <thwright@redemption.studio>
---
 README.md                         |  5 ++--
 doc/telekasten.txt                |  2 +-
 lua/telekasten/utils/taglinks.lua |  3 ++
 lua/telekasten/utils/tags.lua     | 47 +++++++++++++++++++++----------
 4 files changed, 39 insertions(+), 18 deletions(-)

diff --git a/README.md b/README.md
index 57d95a1..4e52f48 100644
--- a/README.md
+++ b/README.md
@@ -362,8 +362,9 @@ See the documentation for more details regarding the different types of links
 Telekasten supports the following tag notations:
 
 1. `#tag`
-2. `:tag:`
-3. `yaml-bare`: bare tags in a tag collection in the yaml metadata:
+2. `@tag`
+3. `:tag:`
+4. `yaml-bare`: bare tags in a tag collection in the yaml metadata:
 
 
 See the documentation for more details regarding the tag syntax (`:h
diff --git a/doc/telekasten.txt b/doc/telekasten.txt
index 1b136a6..c956221 100644
--- a/doc/telekasten.txt
+++ b/doc/telekasten.txt
@@ -114,7 +114,7 @@ telekasten.setup({opts})
       -- Make syntax available to markdown buffers and telescope previewers
       install_syntax = true,
 
-      -- Tag notation: '#tag', ':tag:', 'yaml-bare'
+      -- Tag notation: '#tag', '@tag', ':tag:', 'yaml-bare'
       tag_notation = "#tag",
 
       -- When linking to a note in subdir/, create a [[subdir/title]] link
diff --git a/lua/telekasten/utils/taglinks.lua b/lua/telekasten/utils/taglinks.lua
index 28ea5e6..54aed5c 100644
--- a/lua/telekasten/utils/taglinks.lua
+++ b/lua/telekasten/utils/taglinks.lua
@@ -52,6 +52,9 @@ M.is_tag_or_link_at = function(line, col, opts)
             if char == "#" then
                 seen_hashtag = true
             end
+            if char == "@" then
+                seen_hashtag = true
+            end
             -- Tags should have a space before #, if not we are likely in a link
             if char == " " and seen_hashtag and opts.tag_notation == "#tag" then
                 if not cannot_be_tag then
diff --git a/lua/telekasten/utils/tags.lua b/lua/telekasten/utils/tags.lua
index 6abcf44..faf39e8 100644
--- a/lua/telekasten/utils/tags.lua
+++ b/lua/telekasten/utils/tags.lua
@@ -5,6 +5,9 @@ local hashtag_re = "(^|\\s|'|\")#[a-zA-ZÀ-ÿ]+[a-zA-ZÀ-ÿ0-9/\\-_]*"
 -- PCRE hashtag allows to remove the hex color codes from hastags
 local hashtag_re_pcre =
     "(^|\\s|'|\")((?!(#[a-fA-F0-9]{3})(\\W|$)|(#[a-fA-F0-9]{6})(\\W|$))#[a-zA-ZÀ-ÿ]+[a-zA-ZÀ-ÿ0-9/\\-_]*)"
+local atsign_re = "(^|\\s|'|\")@[a-zA-ZÀ-ÿ]+[a-zA-ZÀ-ÿ0-9/\\-_]*"
+local atsign_re_pcre =
+    "(^|\\s|'|\")((?!(@[a-fA-F0-9]{3})(\\W|$)|(@[a-fA-F0-9]{6})(\\W|$))@[a-zA-ZÀ-ÿ]+[a-zA-ZÀ-ÿ0-9/\\-_]*)"
 local colon_re = "(^|\\s):[a-zA-ZÀ-ÿ]+[a-zA-ZÀ-ÿ0-9/\\-_]*:"
 local yaml_re =
     "(^|\\s)tags:\\s*\\[\\s*([a-zA-ZÀ-ÿ]+[a-zA-ZÀ-ÿ0-9/\\-_]*(,\\s*)*)*\\s*]"
@@ -23,11 +26,11 @@ local function command_find_all_tags(opts)
 
     local re = hashtag_re
 
-    if opts.tag_notation == ":tag:" then
+    if opts.tag_notation == "@tag" then
+        re = atsign_re
+    elseif opts.tag_notation == ":tag:" then
         re = colon_re
-    end
-
-    if opts.tag_notation == "yaml-bare" then
+    elseif opts.tag_notation == "yaml-bare" then
         re = yaml_re
     end
 
@@ -41,18 +44,32 @@ local function command_find_all_tags(opts)
     }
 
     -- PCRE engine allows to remove hex color codes from #hastags
-    if opts.rg_pcre and (re == hashtag_re) then
-        re = hashtag_re_pcre
+    if opts.rg_pcre then
+        if re == hashtag_re then
+            re = hashtag_re_pcre
 
-        rg_args = {
-            "--vimgrep",
-            "--pcre2",
-            globArg,
-            "-o",
-            re,
-            "--",
-            opts.cwd,
-        }
+            rg_args = {
+                "--vimgrep",
+                "--pcre2",
+                globArg,
+                "-o",
+                re,
+                "--",
+                opts.cwd,
+            }
+        elseif re == atsign_re then
+            re = atsign_re_pcre
+
+            rg_args = {
+                "--vimgrep",
+                "--pcre2",
+                globArg,
+                "-o",
+                re,
+                "--",
+                opts.cwd,
+            }
+        end
     end
 
     return "rg", rg_args