From a7957b2bdc5c3ce86092544448b4eb6ebcbb645e Mon Sep 17 00:00:00 2001
From: Senghan Bright <senghan.bright@deltaprojects.com>
Date: Wed, 7 Oct 2020 22:01:47 +0200
Subject: [PATCH] feat: Manpages finder (output of apropos) (#134)

First edition. Sometimes weird things can happen with the previewer, but I think I got it 99% working.

* feat: Manpages finder (output of apropos)

* fixup: Add previewer and fix comments

Co-authored-by: TJ DeVries <devries.timothyj@gmail.com>
---
 lua/telescope/builtin.lua    | 39 ++++++++++++++++++++++++++++++++
 lua/telescope/make_entry.lua | 18 ++++++++++++---
 lua/telescope/previewers.lua | 43 ++++++++++++++++++++++++++++++++++--
 3 files changed, 95 insertions(+), 5 deletions(-)

diff --git a/lua/telescope/builtin.lua b/lua/telescope/builtin.lua
index fc63f1f..de56da7 100644
--- a/lua/telescope/builtin.lua
+++ b/lua/telescope/builtin.lua
@@ -737,4 +737,43 @@ builtin.current_buffer_fuzzy_find = function(opts)
   }):find()
 end
 
+builtin.man_pages = function(opts)
+  opts = opts or {}
+
+  local cmd = opts.man_cmd or "apropos --sections=1 ''"
+
+  local f = assert(io.popen(cmd, 'r'))
+  local pages = assert(f:read('*a'))
+  f:close()
+
+  local lines = {}
+  for s in pages:gmatch("[^\r\n]+") do
+    table.insert(lines, s)
+  end
+
+  pickers.new(opts, {
+    prompt    = 'Man',
+    finder    = finders.new_table {
+      results = lines,
+      entry_maker = make_entry.gen_from_apropos(opts),
+    },
+    previewer = previewers.man.new(opts),
+    sorter = sorters.get_generic_fuzzy_sorter(),
+    attach_mappings = function(prompt_bufnr, map)
+      local view_manpage = function()
+        local selection = actions.get_selected_entry(prompt_bufnr)
+
+        actions.close(prompt_bufnr)
+        print(vim.inspect(selection.value))
+        vim.cmd("Man " .. selection.value)
+      end
+
+      map('i', '<CR>', view_manpage)
+      map('n', '<CR>', view_manpage)
+
+      return true
+    end
+  }):find()
+end
+
 return builtin
diff --git a/lua/telescope/make_entry.lua b/lua/telescope/make_entry.lua
index 276f149..891d4af 100644
--- a/lua/telescope/make_entry.lua
+++ b/lua/telescope/make_entry.lua
@@ -403,15 +403,27 @@ function make_entry.gen_from_packages(opts)
   return function(module_name)
     local entry = {
       valid = module_name ~= "",
-      entry_type = make_entry.types.GENERIC,
-
       value = module_name,
       ordinal = module_name,
-      }
+    }
     entry.display = make_display(module_name)
 
     return entry
   end
 end
 
+function make_entry.gen_from_apropos(opts)
+  opts = opts or {}
+
+  return function(line)
+    local cmd, _, desc = line:match("^(.*)%s+%((.*)%)%s+%-%s(.*)$")
+
+    return {
+      value = cmd,
+      ordinal = cmd,
+      display = string.format("%-30s : %s", cmd, desc)
+    }
+  end
+end
+
 return make_entry
diff --git a/lua/telescope/previewers.lua b/lua/telescope/previewers.lua
index 100a59c..7187549 100644
--- a/lua/telescope/previewers.lua
+++ b/lua/telescope/previewers.lua
@@ -2,6 +2,7 @@ local context_manager = require('plenary.context_manager')
 
 local from_entry = require('telescope.from_entry')
 local log = require('telescope.log')
+local debounce = require('telescope.debounce')
 local utils = require('telescope.utils')
 
 local flatten = vim.tbl_flatten
@@ -62,9 +63,9 @@ local with_preview_window = function(status, bufnr, callable)
     vim.api.nvim_buf_call(bufnr, callable)
   else
     return context_manager.with(function()
-      vim.cmd(string.format("noautocmd call win_gotoid(%s)", status.preview_win))
+      vim.cmd(string.format("noautocmd call nvim_set_current_win(%s)", status.preview_win))
       coroutine.yield()
-      vim.cmd(string.format("noautocmd call win_gotoid(%s)", status.prompt_win))
+      vim.cmd(string.format("noautocmd call nvim_set_current_win(%s)", status.prompt_win))
     end, callable)
   end
 end
@@ -495,6 +496,44 @@ previewers.nvim_file = defaulter(function(_)
   }
 end)
 
+previewers.man = defaulter(function(_)
+  return previewers.new {
+    preview_fn = debounce.throttle_leading(function(_, entry, status)
+      local cmd = entry.value
+
+      local st = {}
+      st.prompt_win = status.prompt_win
+      st.preview_win = status.preview_win
+
+      with_preview_window(st, nil, function()
+        if not vim.api.nvim_win_is_valid(st.preview_win) then
+          return
+        end
+
+        local man_value = vim.fn['man#goto_tag'](cmd, '', '')
+        if #man_value == 0 then
+          print("No value for:", cmd)
+          return
+        end
+
+        local filename = man_value[1].filename
+        if vim.api.nvim_buf_get_name(0) == filename then
+          return
+        end
+
+        local bufnr = vim.api.nvim_create_buf(false, true)
+        vim.api.nvim_win_set_buf(st.preview_win, bufnr)
+        vim.api.nvim_command('view ' .. filename)
+
+        vim.api.nvim_buf_set_option(bufnr, 'buftype', 'nofile')
+        vim.api.nvim_buf_set_option(bufnr, 'bufhidden', 'hide')
+        vim.api.nvim_buf_set_option(bufnr, 'swapfile', false)
+        vim.api.nvim_buf_set_option(bufnr, 'buflisted', false)
+      end)
+    end, 5)
+  }
+end)
+
 previewers.Previewer = Previewer
 
 return previewers