local M = {}

local luasnip = require("luasnip")
local types = require("luasnip.util.types")

function M.visual_isn(pos)
  local d = luasnip.dynamic_node
  local i = luasnip.insert_node
  local isn = luasnip.indent_snippet_node
  local sn = luasnip.snippet_node

  return isn(pos, d(1, function(_, parent)
    local res, env = {}, parent.snippet.env
    for _, ele in ipairs(env.LS_SELECT_DEDENT or {}) do
      table.insert(res, ele)
    end
    return sn(nil, i(1, res))
  end), "$PARENT_INDENT\t")
end

function M.choice_index(choice_node)
  for i, c in ipairs(choice_node.choices) do
    if c == choice_node.active_choice then
      return i
    end
  end
  return 1
end

function M.setup()
  luasnip.config.setup {
    region_check_events = "InsertEnter",
    delete_check_events = "InsertLeave",
    store_selection_keys = "<tab>",
    enable_autosnippets = true,
    ext_opts = {
      [types.snippet] = {
        active = {
          virt_text = { { "●", "DiagnosticWarn" } },
        },
      },
      [types.insertNode] = {
        passive = {
          hl_group = "DiagnosticVirtualTextWarn",
        },
      },
      [types.choiceNode] = {
        active = {
          hl_group = "DiagnosticVirtualTextHint",
          virt_text = { { "⧨", "DiagnosticHint" } },
        },
      },
    },
  }

  -- Track where we are expanding the snippet.
  luasnip.env_namespace("INFO", {
    init = function(info) return { POS = info.pos } end,
  })

  vim.keymap.set({ "i", "s" }, "<c-e>", function()
    if luasnip.choice_active() then
      return "<Plug>luasnip-next-choice"
    else
      return "<c-e>"
    end
  end, { silent = true, expr = true, remap = true })

  vim.keymap.set({ "i", "s" }, "<c-y>", function()
    if luasnip.choice_active() then
      return "<Plug>luasnip-prev-choice"
    else
      return "<c-y>"
    end
  end, { silent = true, expr = true, remap = true })

  -- Allow aborting the active snippet at any point in time.
  vim.keymap.set({ "n", "i", "s" }, "<c-l>", "<cmd>LuaSnipUnlinkCurrent<cr>")

  -- Allow toggling autoexpansion on and off. This is more or less the intended
  -- approach: https://github.com/L3MON4D3/LuaSnip/issues/832#issuecomment-1474993417
  luasnip.expand_auto_on = true

  local expand_auto = luasnip.expand_auto
  local toggle_expand_auto = function()
    if luasnip.expand_auto_on then
      luasnip.expand_auto = function() end
    else
      luasnip.expand_auto = expand_auto
    end
    luasnip.expand_auto_on = not luasnip.expand_auto_on
  end

  toggle_expand_auto()
  vim.keymap.set({ "n", "i", "s" }, "", toggle_expand_auto)
end

return M