outline.nvim/lua/symbols-outline/preview.lua

local so = require 'symbols-outline'
local config = require 'symbols-outline.config'

local M = {}

local state = {
  preview_buf = nil,
  preview_win = nil,
  hover_buf = nil,
  hover_win = nil,
}

local function is_current_win_outline()
  local curwin = vim.api.nvim_get_current_win()
  return curwin == so.view.winnr
end

local function has_code_win()
  local isWinValid = vim.api.nvim_win_is_valid(so.state.code_win)
  if not isWinValid then
    return false
  end
  local bufnr = vim.api.nvim_win_get_buf(so.state.code_win)
  local isBufValid = vim.api.nvim_buf_is_valid(bufnr)
  return isBufValid
end

local function get_offset()
  local outline_winnr = so.view.winnr
  local width = 53
  local height = 0

  if config.has_numbers() then
    width = width + 4
  end

  if config.options.position == 'right' then
    width = 0 - width
  else
    width = vim.api.nvim_win_get_width(outline_winnr) + 1
  end
  return { height, width }
end

local function get_height()
  local uis = vim.api.nvim_list_uis()
  return math.ceil(uis[1].height / 3)
end

local function get_hovered_node()
  local hovered_line = vim.api.nvim_win_get_cursor(so.view.winnr)[1]
  local node = so.state.outline_items[hovered_line]
  return node
end

local function update_preview(code_buf)
  code_buf = code_buf or vim.api.nvim_win_get_buf(so.state.code_win)

  local node = get_hovered_node()
  if not node then
    return
  end
  local lines = vim.api.nvim_buf_get_lines(code_buf, 0, -1, false)

  if state.preview_buf ~= nil then
    vim.api.nvim_buf_set_lines(state.preview_buf, 0, -1, 0, lines)
    vim.api.nvim_win_set_cursor(
      state.preview_win,
      { node.line + 1, node.character }
    )
  end
end

local function setup_preview_buf()
  local code_buf = vim.api.nvim_win_get_buf(so.state.code_win)
  local ft = vim.api.nvim_buf_get_option(code_buf, 'filetype')

  local function treesitter_attach()
    local ts_highlight = require 'nvim-treesitter.highlight'

    ts_highlight.attach(state.preview_buf, ft)
  end

  -- user might not have tree sitter installed
  pcall(treesitter_attach)

  vim.api.nvim_buf_set_option(state.preview_buf, 'syntax', ft)
  vim.api.nvim_buf_set_option(state.preview_buf, 'bufhidden', 'delete')
  vim.api.nvim_win_set_option(state.preview_win, 'cursorline', true)
  update_preview(code_buf)
end

local function get_hover_params(node, winnr)
  local bufnr = vim.api.nvim_win_get_buf(winnr)
  local uri = vim.uri_from_bufnr(bufnr)

  return {
    textDocument = { uri = uri },
    position = { line = node.line, character = node.character },
    bufnr = bufnr,
  }
end

local function update_hover()
  if not has_code_win() then
    return
  end

  local node = get_hovered_node()
  if not node then
    return
  end

  local provider = _G._symbols_outline_current_provider
  local params = get_hover_params(node, so.state.code_win)

  provider.hover_info(params.bufnr, params, function(err, result)
    if err then
      print(vim.inspect(err))
    end
    local markdown_lines = {}
    if result ~= nil then
      markdown_lines = vim.lsp.util.convert_input_to_markdown_lines(
        result.contents
      )
    end
    markdown_lines = vim.lsp.util.trim_empty_lines(markdown_lines)
    if vim.tbl_isempty(markdown_lines) then
      markdown_lines = { '###No info available!' }
    end

    markdown_lines = vim.lsp.util.stylize_markdown(
      state.hover_buf,
      markdown_lines,
      {}
    )

    if state.hover_buf ~= nil then
      vim.api.nvim_buf_set_lines(state.hover_buf, 0, -1, 0, markdown_lines)
    end
  end)
end

local function setup_hover_buf()
  if not has_code_win() then
    return
  end
  local code_buf = vim.api.nvim_win_get_buf(so.state.code_win)
  local ft = vim.api.nvim_buf_get_option(code_buf, 'filetype')
  vim.api.nvim_buf_set_option(state.hover_buf, 'syntax', ft)
  vim.api.nvim_buf_set_option(state.hover_buf, 'bufhidden', 'delete')
  vim.api.nvim_win_set_option(state.hover_win, 'wrap', true)
  vim.api.nvim_win_set_option(state.hover_win, 'cursorline', false)
  update_hover()
end

local function set_bg_hl()
  local winhi = 'Normal:' .. config.options.preview_bg_highlight
  vim.api.nvim_win_set_option(state.preview_win, 'winhighlight', winhi)
  vim.api.nvim_win_set_option(state.hover_win, 'winhighlight', winhi)
  local winblend = config.options.winblend
  vim.api.nvim_win_set_option(state.preview_win, 'winblend', winblend)
  vim.api.nvim_win_set_option(state.hover_win, 'winblend', winblend)
end

local function show_preview()
  if state.preview_win == nil and state.preview_buf == nil then
    state.preview_buf = vim.api.nvim_create_buf(false, true)
    vim.api.nvim_buf_attach(state.preview_buf, false, {
      on_detach = function()
        state.preview_buf = nil
        state.preview_win = nil
      end,
    })
    local offsets = get_offset()
    state.preview_win = vim.api.nvim_open_win(state.preview_buf, false, {
      relative = 'win',
      width = 50,
      height = get_height(),
      bufpos = { 0, 0 },
      row = offsets[1],
      col = offsets[2],
      border = config.options.border,
    })
    setup_preview_buf()
  else
    update_preview()
  end
end

local function show_hover()
  if state.hover_win == nil and state.hover_buf == nil then
    state.hover_buf = vim.api.nvim_create_buf(false, true)
    vim.api.nvim_buf_attach(state.hover_buf, false, {
      on_detach = function()
        state.hover_buf = nil
        state.hover_win = nil
      end,
    })
    local offsets = get_offset()
    local height = get_height()
    state.hover_win = vim.api.nvim_open_win(state.hover_buf, false, {
      relative = 'win',
      width = 50,
      height = height,
      bufpos = { 0, 0 },
      row = offsets[1] + height + 2,
      col = offsets[2],
      border = config.options.border,
    })
    setup_hover_buf()
  else
    update_hover()
  end
end

function M.show()
  if not is_current_win_outline() or #vim.api.nvim_list_wins() < 2 then
    return
  end

  show_preview()
  show_hover()
  set_bg_hl()
end

function M.close()
  if has_code_win() then
    if
      state.preview_win ~= nil and vim.api.nvim_win_is_valid(state.preview_win)
    then
      vim.api.nvim_win_close(state.preview_win, true)
    end
    if
      state.hover_win ~= nil and vim.api.nvim_win_is_valid(state.hover_win)
    then
      vim.api.nvim_win_close(state.hover_win, true)
    end
  end
end

function M.toggle()
  if state.preview_win ~= nil then
    M.close()
  else
    M.show()
  end
end

return M