*mini.starter* Start screen
*MiniStarter*

MIT License Copyright (c) 2021 Evgeni Chasnovski

==============================================================================

Displayed items are fully customizable both in terms of what they do and
how they look (with reasonable defaults). Item selection can be done using
prefix query with instant visual feedback.

Key design ideas:
- All available actions are defined inside items. Each item should have the
  following info:
    - <action> - function or string for |vim.cmd| which is executed when
      item is chosen. Empty string result in placeholder "inactive" item.
    - <name> - string which will be displayed and used for choosing.
    - <section> - string representing to which section item belongs.
  There are pre-configured whole sections in |MiniStarter.sections|.

- Configure what items are displayed by supplying an array which can be
  normalized to an array of items. Read about how supplied items are
  normalized in |MiniStarter.refresh|.

- Modify the final look by supplying content hooks: functions which take
  buffer content (see |MiniStarter.get_content()|) and identifier as input
  while returning buffer content as output. There are pre-configured
  content hook generators in |MiniStarter.gen_hook|.

- Choosing an item can be done in two ways:
    - Type prefix query to filter item by matching its name (ignoring
      case). Displayed information is updated after every typed character.
      For every item its unique prefix is highlighted.
    - Use Up/Down arrows and hit Enter.

- Allow multiple simultaneously open Starter buffers.

What is doesn't do:
- It doesn't support fuzzy query for items. And probably will never do.

# Setup ~

This module needs a setup with `require('mini.starter').setup({})`
(replace `{}` with your `config` table). It will create global Lua table
`MiniStarter` which you can use for scripting or manually (with
`:lua MiniStarter.*`).

See |MiniStarter.config| for `config` structure and default values. For
some configuration examples (including one similar to 'vim-startify' and
'dashboard-nvim'), see |MiniStarter-example-config|.

You can override runtime config settings locally to buffer inside
`vim.b.ministarter_config` which should have same structure as
`MiniStarter.config`. See |mini.nvim-buffer-local-config| for more details.
Note: `vim.b.ministarter_config` is copied to Starter buffer from current
buffer allowing full customization.

To stop module from showing non-error feedback, set `config.silent = true`.

# Highlight groups ~

* `MiniStarterCurrent` - current item.
* `MiniStarterFooter` - footer units.
* `MiniStarterHeader` - header units.
* `MiniStarterInactive` - inactive item.
* `MiniStarterItem` - item name.
* `MiniStarterItemBullet` - units from |MiniStarter.gen_hook.adding_bullet|.
* `MiniStarterItemPrefix` - unique query for item.
* `MiniStarterSection` - section units.
* `MiniStarterQuery` - current query in active items.

To change any highlight group, modify it directly with |:highlight|.

# Disabling ~

To disable core functionality, set `vim.g.ministarter_disable` (globally) or
`vim.b.ministarter_disable` (for a buffer) to `true`. Considering high number
of different scenarios and customization intentions, writing exact rules
for disabling module's functionality is left to user. See
|mini.nvim-disabling-recipes| for common recipes.

------------------------------------------------------------------------------
                                                    *MiniStarter-example-config*
Example configurations

Configuration similar to 'mhinz/vim-startify': >lua

  local starter = require('mini.starter')
  starter.setup({
    evaluate_single = true,
    items = {
      starter.sections.builtin_actions(),
      starter.sections.recent_files(10, false),
      starter.sections.recent_files(10, true),
      -- Use this if you set up 'mini.sessions'
      starter.sections.sessions(5, true)
    },
    content_hooks = {
      starter.gen_hook.adding_bullet(),
      starter.gen_hook.indexing('all', { 'Builtin actions' }),
      starter.gen_hook.padding(3, 2),
    },
  })
<
Configuration similar to 'glepnir/dashboard-nvim': >lua

  local starter = require('mini.starter')
  starter.setup({
    items = {
      starter.sections.telescope(),
    },
    content_hooks = {
      starter.gen_hook.adding_bullet(),
      starter.gen_hook.aligning('center', 'center'),
    },
  })
<
Elaborated configuration showing capabilities of custom items,
header/footer, and content hooks: >lua

  local my_items = {
    { name = 'Echo random number', action = 'lua print(math.random())', section = 'Section 1' },
    function()
      return {
        { name = 'Item #1 from function', action = [[echo 'Item #1']], section = 'From function' },
        { name = 'Placeholder (always inactive) item', action = '', section = 'From function' },
        function()
          return {
            name = 'Item #1 from double function',
            action = [[echo 'Double function']],
            section = 'From double function',
          }
        end,
      }
    end,
    { name = [[Another item in 'Section 1']], action = 'lua print(math.random() + 10)', section = 'Section 1' },
  }

  local footer_n_seconds = (function()
    local timer = vim.loop.new_timer()
    local n_seconds = 0
    timer:start(0, 1000, vim.schedule_wrap(function()
      if vim.bo.filetype ~= 'ministarter' then
        timer:stop()
        return
      end
      n_seconds = n_seconds + 1
      MiniStarter.refresh()
    end))

    return function()
      return 'Number of seconds since opening: ' .. n_seconds
    end
  end)()

  local hook_top_pad_10 = function(content)
    -- Pad from top
    for _ = 1, 10 do
      -- Insert at start a line with single content unit
      table.insert(content, 1, { { type = 'empty', string = '' } })
    end
    return content
  end

  local starter = require('mini.starter')
  starter.setup({
    items = my_items,
    footer = footer_n_seconds,
    content_hooks = { hook_top_pad_10 },
  })
<
------------------------------------------------------------------------------
                                                         *MiniStarter-lifecycle*
# Lifecycle of Starter buffer ~

- Open with |MiniStarter.open()|. It includes creating buffer with
  appropriate options, mappings, behavior; call to |MiniStarter.refresh()|;
  issue `MiniStarterOpened` |User| event.
- Wait for user to choose an item. This is done using following logic:
    - Typing any character from `MiniStarter.config.query_updaters` leads
      to updating query. Read more in |MiniStarter.add_to_query|.
    - <BS> deletes latest character from query.
    - <Down>/<Up>, <C-n>/<C-p>, <M-j>/<M-k> move current item.
    - <CR> executes action of current item.
    - <C-c> closes Starter buffer.
- Evaluate current item when appropriate (after `<CR>` or when there is a
  single item and `MiniStarter.config.evaluate_single` is `true`). This
  executes item's `action`.

------------------------------------------------------------------------------
                                                           *MiniStarter.setup()*
                         `MiniStarter.setup`({config})
Module setup

Parameters ~
{config} `(table|nil)` Module config table. See |MiniStarter.config|.

Usage ~
>lua
  require('mini.starter').setup() -- use default config
  -- OR
  require('mini.starter').setup({}) -- replace {} with your config table
<
------------------------------------------------------------------------------
                                                            *MiniStarter.config*
                              `MiniStarter.config`
Module config

Default values:
>lua
  MiniStarter.config = {
    -- Whether to open Starter buffer on VimEnter. Not opened if Neovim was
    -- started with intent to show something else.
    autoopen = true,

    -- Whether to evaluate action of single active item
    evaluate_single = false,

    -- Items to be displayed. Should be an array with the following elements:
    -- - Item: table with <action>, <name>, and <section> keys.
    -- - Function: should return one of these three categories.
    -- - Array: elements of these three types (i.e. item, array, function).
    -- If `nil` (default), default items will be used (see |mini.starter|).
    items = nil,

    -- Header to be displayed before items. Converted to single string via
    -- `tostring` (use `\n` to display several lines). If function, it is
    -- evaluated first. If `nil` (default), polite greeting will be used.
    header = nil,

    -- Footer to be displayed after items. Converted to single string via
    -- `tostring` (use `\n` to display several lines). If function, it is
    -- evaluated first. If `nil` (default), default usage help will be shown.
    footer = nil,

    -- Array  of functions to be applied consecutively to initial content.
    -- Each function should take and return content for Starter buffer (see
    -- |mini.starter| and |MiniStarter.get_content()| for more details).
    content_hooks = nil,

    -- Characters to update query. Each character will have special buffer
    -- mapping overriding your global ones. Be careful to not add `:` as it
    -- allows you to go into command mode.
    query_updaters = 'abcdefghijklmnopqrstuvwxyz0123456789_-.',

    -- Whether to disable showing non-error feedback
    silent = false,
  }
<
------------------------------------------------------------------------------
                                                            *MiniStarter.open()*
                          `MiniStarter.open`({buf_id})
Open Starter buffer

- Create buffer if necessary and move into it.
- Set buffer options. Note that settings are done with |noautocmd| to
  achieve a massive speedup.
- Set buffer mappings. Besides basic mappings (described inside "Lifecycle
  of Starter buffer" of |mini.starter|), map every character from
  `MiniStarter.config.query_updaters` to add itself to query with
  |MiniStarter.add_to_query|.
- Populate buffer with |MiniStarter.refresh|.
- Issue custom `MiniStarterOpened` event to allow acting upon opening
  Starter buffer. Use it with
  `autocmd User MiniStarterOpened <your command>`.

Note: to fully use it in autocommand, use |autocmd-nested|. Example: >lua

  local starter_open = function() MiniStarter.open() end
  local au_opts = { nested = true, callback = starter_open }
  vim.api.nvim_create_autocmd('TabNewEntered', au_opts)
<
Parameters ~
{buf_id} `(number|nil)` Identifier of existing valid buffer (see |bufnr()|) to
  open inside. Default: create a new one.

------------------------------------------------------------------------------
                                                         *MiniStarter.refresh()*
                        `MiniStarter.refresh`({buf_id})
Refresh Starter buffer

- Normalize `MiniStarter.config.items`:
    - Flatten: recursively (in depth-first fashion) parse its elements. If
      function is found, execute it and continue with parsing its output
      (this allows deferring item collection up until it is actually
      needed).  If proper item is found (table with fields `action`,
      `name`, `section`), add it to output.
    - Sort: order first by section and then by item id (both in order of
      appearance).
- Normalize `MiniStarter.config.header` and `MiniStarter.config.footer` to
  be multiple lines by splitting at `\n`. If function - evaluate it first.
- Make initial buffer content (see |MiniStarter.get_content()| for a
  description of what a buffer content is). It consist from content lines
  with single content unit:
    - First lines contain strings of normalized header.
    - Body is for normalized items. Section names have own lines preceded
      by empty line.
    - Last lines contain separate strings of normalized footer.
- Sequentially apply hooks from `MiniStarter.config.content_hooks` to
  content. All hooks are applied with `(content, buf_id)` signature. Output
  of one hook serves as first argument to the next.
- Gather final items from content with |MiniStarter.content_to_items|.
- Convert content to buffer lines with |MiniStarter.content_to_lines| and
  add them to buffer.
- Add highlighting of content units.
- Position cursor.
- Make current query. This results into some items being marked as
  "inactive" and updating highlighting of current query on "active" items.

Note: this function is executed on every |VimResized| to allow more
responsive behavior.

Parameters ~
{buf_id} `(number|nil)` Buffer identifier of a valid Starter buffer.
  Default: current buffer.

------------------------------------------------------------------------------
                                                           *MiniStarter.close()*
                         `MiniStarter.close`({buf_id})
Close Starter buffer

Parameters ~
{buf_id} `(number|nil)` Buffer identifier of a valid Starter buffer.
  Default: current buffer.

------------------------------------------------------------------------------
                                                          *MiniStarter.sections*
                             `MiniStarter.sections`
Table of pre-configured sections

------------------------------------------------------------------------------
                                        *MiniStarter.sections.builtin_actions()*
                    `MiniStarter.sections.builtin_actions`()
Section with builtin actions

Return ~
`(table)` Array of items.

------------------------------------------------------------------------------
                                               *MiniStarter.sections.sessions()*
                 `MiniStarter.sections.sessions`({n}, {recent})
Section with |MiniSessions| sessions

Sessions are taken from |MiniSessions.detected|. Notes:
- If it shows "'mini.sessions' is not set up", it means that you didn't
  call `require('mini.sessions').setup()`.
- If it shows "There are no detected sessions in 'mini.sessions'", it means
  that there are no sessions at the current sessions directory. Either
  create session or supply different directory where session files are
  stored (see |MiniSessions.setup|).
- Local session (if detected) is always displayed first.

Parameters ~
{n} `(number|nil)` Number of returned items. Default: 5.
{recent} `(boolean|nil)` Whether to use recent sessions (instead of
  alphabetically by name). Default: true.

Return ~
`(function)` Function which returns array of items.

------------------------------------------------------------------------------
                                           *MiniStarter.sections.recent_files()*
      `MiniStarter.sections.recent_files`({n}, {current_dir}, {show_path})
Section with most recently used files

Files are taken from |vim.v.oldfiles|.

Parameters ~
{n} `(number|nil)` Number of returned items. Default: 5.
{current_dir} `(boolean|nil)` Whether to return files only from current working
  directory and its subdirectories. Default: `false`.
{show_path} `(boolean|function|nil)` Whether to append file name with its path.
  If callable, will be called with full path and should return string to be
  directly appended to file name. Default: `true`.

Return ~
`(function)` Function which returns array of items.

------------------------------------------------------------------------------
                                                   *MiniStarter.sections.pick()*
                         `MiniStarter.sections.pick`()
Section with 'mini.pick' pickers

Notes:
- All actions require |mini.pick| module of 'mini.nvim'.
- "Command history", "Explorer", and "Visited paths" items
  require |mini.extra| module of 'mini.nvim'.
- "Visited paths" items requires |mini.visits| module of 'mini.nvim'.

Return ~
`(function)` Function which returns array of items.

------------------------------------------------------------------------------
                                              *MiniStarter.sections.telescope()*
                       `MiniStarter.sections.telescope`()
Section with basic Telescope pickers relevant to start screen

Notes:
- All actions require 'nvim-telescope/telescope.nvim' plugin.
- "Browser" item requires 'nvim-telescope/telescope-file-browser.nvim'.

Return ~
`(function)` Function which returns array of items.

------------------------------------------------------------------------------
                                                          *MiniStarter.gen_hook*
                             `MiniStarter.gen_hook`
Table with pre-configured content hook generators

Each element is a function which returns content hook. So to use them
inside |MiniStarter.setup|, call them.

------------------------------------------------------------------------------
                                                *MiniStarter.gen_hook.padding()*
                 `MiniStarter.gen_hook.padding`({left}, {top})
Hook generator for padding

Output is a content hook which adds constant padding from left and top.
This allows tweaking the screen position of buffer content.

Parameters ~
{left} `(number|nil)` Number of empty spaces to add to start of each content
  line. Default: 0.
{top} `(number|nil)` Number of empty lines to add to start of content.
  Default: 0.

Return ~
`(function)` Content hook.

------------------------------------------------------------------------------
                                          *MiniStarter.gen_hook.adding_bullet()*
         `MiniStarter.gen_hook.adding_bullet`({bullet}, {place_cursor})
Hook generator for adding bullet to items

Output is a content hook which adds supplied string to be displayed to the
left of item.

Parameters ~
{bullet} `(string|nil)` String to be placed to the left of item name.
  Default: "░ ".
{place_cursor} `(boolean|nil)` Whether to place cursor on the first character
  of bullet when corresponding item becomes current. Default: true.

Return ~
`(function)` Content hook.

------------------------------------------------------------------------------
                                               *MiniStarter.gen_hook.indexing()*
        `MiniStarter.gen_hook.indexing`({grouping}, {exclude_sections})
Hook generator for indexing items

Output is a content hook which adds unique index to the start of item's
name. It results into shortening queries required to choose an item (at
expense of clarity).

Parameters ~
{grouping} `(string|nil)` One of "all" (number indexing across all sections) or
  "section" (letter-number indexing within each section). Default: "all".
{exclude_sections} `(table|nil)` Array of section names (values of `section`
  element of item) for which index won't be added. Default: `{}`.

Return ~
`(function)` Content hook.

------------------------------------------------------------------------------
                                               *MiniStarter.gen_hook.aligning()*
           `MiniStarter.gen_hook.aligning`({horizontal}, {vertical})
Hook generator for aligning content

Output is a content hook which independently aligns content horizontally
and vertically. Window width and height are taken from first window in current
tabpage displaying the Starter buffer.

Basically, this computes left and top pads for |MiniStarter.gen_hook.padding|
such that output lines would appear aligned in certain way.

Parameters ~
{horizontal} `(string|nil)` One of "left", "center", "right". Default: "left".
{vertical} `(string|nil)` One of "top", "center", "bottom". Default: "top".

Return ~
`(function)` Content hook.

------------------------------------------------------------------------------
                                                     *MiniStarter.get_content()*
                      `MiniStarter.get_content`({buf_id})
Get content of Starter buffer

Generally, buffer content is a table in the form of "2d array" (or rather
"2d list" because number of elements can differ):
- Each element represents content line: an array with content units to be
  displayed in one buffer line.
- Each content unit is a table with at least the following elements:
    - "type" - string with type of content. Something like "item",
      "section", "header", "footer", "empty", etc.
    - "string" - which string should be displayed. May be an empty string.
    - "hl" - which highlighting should be applied to content string. May be
      `nil` for no highlighting.

See |MiniStarter.content_to_lines| for converting content to buffer lines
and |MiniStarter.content_to_items| - to list of parsed items.

Notes:
- Content units with type "item" also have `item` element with all
  information about an item it represents. Those elements are used directly
  to create an array of items used for query.

Parameters ~
{buf_id} `(number|nil)` Buffer identifier of a valid Starter buffer.
  Default: current buffer.

------------------------------------------------------------------------------
                                                  *MiniStarter.content_coords()*
              `MiniStarter.content_coords`({content}, {predicate})
Helper to iterate through content

Basically, this traverses content "2d array" (in depth-first fashion; top
to bottom, left to right) and returns "coordinates" of units for which
`predicate` is true-ish.

Parameters ~
{content} `(table|nil)` Content "2d array". Default: content of current buffer.
{predicate} `(function|string|nil)` Predictate to filter units. If it is:
   - Function, then it is evaluated with unit as input.
   - String, then it checks unit to have this type (allows easy getting of
     units with some type).
   - `nil`, all units are kept.

Return ~
`(table)` Array of resulting units' coordinates. Each coordinate is a
  table with <line> and <unit> keys. To retrieve actual unit from coordinate
  `c`, use `content[c.line][c.unit]`.

------------------------------------------------------------------------------
                                                *MiniStarter.content_to_lines()*
                   `MiniStarter.content_to_lines`({content})
Convert content to buffer lines

One buffer line is made by concatenating `string` element of units within
same content line.

Parameters ~
{content} `(table|nil)` Content "2d array". Default: content of current buffer.

Return ~
`(table)` Array of strings for each buffer line.

------------------------------------------------------------------------------
                                                *MiniStarter.content_to_items()*
                   `MiniStarter.content_to_items`({content})
Convert content to items

Parse content (in depth-first fashion) and retrieve each item from `item`
element of content units with type "item". This also:
- Computes some helper information about how item will be actually
  displayed (after |MiniStarter.content_to_lines|) and minimum number of
  prefix characters needed for a particular item to be queried single.
- Modifies item's `name` element taking it from corresponding `string`
  element of content unit. This allows modifying item's `name` at the stage
  of content hooks (like, for example, in |MiniStarter.gen_hook.indexing|).

Parameters ~
{content} `(table|nil)` Content "2d array". Default: content of current buffer.

Return ~
`(table)` Array of items.

------------------------------------------------------------------------------
                                               *MiniStarter.eval_current_item()*
                   `MiniStarter.eval_current_item`({buf_id})
Evaluate current item

Note that it resets current query before evaluation, as it is rarely needed
any more.

Parameters ~
{buf_id} `(number|nil)` Buffer identifier of a valid Starter buffer.
  Default: current buffer.

------------------------------------------------------------------------------
                                             *MiniStarter.update_current_item()*
            `MiniStarter.update_current_item`({direction}, {buf_id})
Update current item

This makes next (with respect to `direction`) active item to be current.

Parameters ~
{direction} `(string)` One of "next" or "previous".
{buf_id} `(number|nil)` Buffer identifier of a valid Starter buffer.
  Default: current buffer.

------------------------------------------------------------------------------
                                                    *MiniStarter.add_to_query()*
                  `MiniStarter.add_to_query`({char}, {buf_id})
Add character to current query

- Update current query by appending `char` to its end (only if it results
  into at least one active item) or delete latest character if `char` is `nil`.
- Recompute status of items: "active" if its name starts with new query,
  "inactive" otherwise.
- Update highlighting: whole strings for "inactive" items, current query
  for "active" items.

Parameters ~
{char} `(string|nil)` Single character to be added to query. If `nil`, deletes
  latest character from query.
{buf_id} `(number|nil)` Buffer identifier of a valid Starter buffer.
  Default: current buffer.

------------------------------------------------------------------------------
                                                       *MiniStarter.set_query()*
                   `MiniStarter.set_query`({query}, {buf_id})
Set current query

Parameters ~
{query} `(string|nil)` Query to be set (only if it results into at least one
  active item). Default: `nil` for setting query to empty string, which
  essentially resets query.
{buf_id} `(number|nil)` Buffer identifier of a valid Starter buffer.
  Default: current buffer.


 vim:tw=78:ts=8:noet:ft=help:norl: