feat: Fix markdown provider icon kind

Closes #2

lua/outline/providers/init.lua

@@ -3,6 +3,11 @@ local M = {}
 local providers = {
   'outline/providers/nvim-lsp',
   'outline/providers/coc',
+  -- NOTE: There is in fact a markdown LSP that can provide symbols. However
+  -- on buffer open the LSP may not be attached immediately. Before the LSP is
+  -- ready if the user opens the outline, our own markdown provider will be
+  -- used. After refreshing/reopening, the provider will then switch to the LSP
+  -- (if the user has a markdown LSP).
   'outline/providers/markdown',
 }
 

lua/outline/providers/markdown.lua

@@ -1,10 +1,13 @@
-local md_parser = require 'outline.markdown'
+-- Our own markdown provider is used because legacy symbols-outline considered
+-- the case where markdown does not have an LSP. However, it does, so as of now
+-- this module is kept for use when user opens symbols outline before the
+-- markdown LSP is ready. Please also see comment in providers/init.lua
 
 local M = {}
 
--- probably change this
+---@return boolean ft_is_markdown
 function M.should_use_provider(bufnr)
-  return string.match(vim.api.nvim_buf_get_option(bufnr, 'ft'), 'markdown')
+  return vim.api.nvim_buf_get_option(bufnr, 'ft') == 'markdown'
 end
 
 function M.hover_info(_, _, on_info)
@@ -16,10 +19,96 @@ function M.hover_info(_, _, on_info)
   })
 end
 
+-- Parses markdown files and returns a table of SymbolInformation[] which is
+-- used by the plugin to show the outline.
+---@return table
+function M.handle_markdown()
+  local lines = vim.api.nvim_buf_get_lines(0, 0, -1, false)
+  local level_symbols = { { children = {} } }
+  local max_level = 1
+  local is_inside_code_block = false
+
+  for line, value in ipairs(lines) do
+    if string.find(value, '^```') then
+      is_inside_code_block = not is_inside_code_block
+    end
+    if is_inside_code_block then
+      goto nextline
+    end
+
+    local next_value = lines[line+1]
+    local is_emtpy_line = #value:gsub("^%s*(.-)%s*$", "%1") == 0
+
+    local header, title = string.match(value, '^(#+)%s+(.+)$')
+    if not header and next_value and not is_emtpy_line then
+      if string.match(next_value, '^=+%s*$') then
+        header = '#'
+        title = value
+      elseif string.match(next_value, '^-+%s*$') then
+        header = '##'
+        title = value
+      end
+    end
+    if not header or not title then
+      goto nextline
+    end
+    -- TODO: This is not needed and it works?
+    -- if #header > 6 then
+    --   goto nextline
+    -- end
+
+    local depth = #header + 1
+
+    local parent
+    for i = depth - 1, 1, -1 do
+      if level_symbols[i] ~= nil then
+        parent = level_symbols[i].children
+        break
+      end
+    end
+
+    for i = depth, max_level do
+      if level_symbols[i] ~= nil then
+        level_symbols[i].selectionRange['end'].line = line - 1
+        level_symbols[i].range['end'].line = line - 1
+        level_symbols[i] = nil
+      end
+    end
+    max_level = depth
+
+    local entry = {
+      kind = 15,
+      name = title,
+      selectionRange = {
+        start = { character = 1, line = line - 1 },
+        ['end'] = { character = 1, line = line - 1 },
+      },
+      range = {
+        start = { character = 1, line = line - 1 },
+        ['end'] = { character = 1, line = line - 1 },
+      },
+      children = {},
+    }
+
+    parent[#parent + 1] = entry
+    level_symbols[depth] = entry
+    ::nextline::
+  end
+
+  for i = 2, max_level do
+    if level_symbols[i] ~= nil then
+      level_symbols[i].selectionRange['end'].line = #lines
+      level_symbols[i].range['end'].line = #lines
+    end
+  end
+
+  return level_symbols[1].children
+end
+
 ---@param on_symbols function
 ---@param opts table
 function M.request_symbols(on_symbols, opts)
-  on_symbols(md_parser.handle_markdown(), opts)
+  on_symbols(M.handle_markdown(), opts)
 end
 
 return M