-- ============================================================================
-- UFO: Modern folding with LSP/treesitter support
-- ============================================================================
-- Better code folding using LSP or treesitter. Shows fold preview on hover.
-- zR to open all folds, zM to close all. Includes statuscol for fold icons
-- in the gutter. Has OptionSet autocmd to track folding option changes.
-- ============================================================================
return {
  "kevinhwang91/nvim-ufo",
  dependencies = {
    "kevinhwang91/promise-async",
    "nvim-treesitter/nvim-treesitter",
    {
      "luukvbaal/statuscol.nvim",
      config = function()
        local builtin = require("statuscol.builtin")
        require("statuscol").setup({
          relculright = true,
          segments = {
            { text = { builtin.foldfunc }, click = "v:lua.ScFa" },
            { text = { "%s" }, click = "v:lua.ScSa" },
            { text = { builtin.lnumfunc, " " }, click = "v:lua.ScLa" },
          },
        })
      end,
    },
  },
  event = { "BufReadPost", "BufNewFile" },
  init = function()
    vim.o.foldcolumn = "1"
    vim.o.foldlevel = 99
    vim.o.foldlevelstart = 99
    vim.o.foldenable = true
    -- Use valid Unicode characters for foldopen and foldclose
    vim.o.fillchars = [[eob: ,fold: ,foldopen:▾,foldsep: ,foldclose:▸]]
    vim.o.foldmethod = "manual"
    vim.o.foldexpr = ""
  end,
  opts = {
    open_fold_hl_timeout = 150,
    close_fold_kinds_for_ft = {
      default = { 'imports', 'comment' },
      c = { 'comment', 'region' },
    },
    preview = {
      win_config = {
        border = { "", "─", "", "", "", "─", "", "" },
        winhighlight = "Normal:Folded",
        winblend = 0,
      },
      mappings = {
        scrollU = "<C-u>",
        scrollD = "<C-d>",
        jumpTop = "[",
        jumpBot = "]",
      },
    },
    provider_selector = function(bufnr, filetype, buftype)
      return { "treesitter", "indent" }
    end,
    fold_virt_text_handler = function(virtText, lnum, endLnum, width, truncate)
      local newVirtText = {}
      local suffix = (" 󰁂 %d "):format(endLnum - lnum)
      local sufWidth = vim.fn.strdisplaywidth(suffix)
      local targetWidth = width - sufWidth
      local curWidth = 0
      for _, chunk in ipairs(virtText) do
        local chunkText = chunk[1]
        local chunkWidth = vim.fn.strdisplaywidth(chunkText)
        if targetWidth > curWidth + chunkWidth then
          table.insert(newVirtText, chunk)
        else
          chunkText = truncate(chunkText, targetWidth - curWidth)
          local hlGroup = chunk[2]
          table.insert(newVirtText, { chunkText, hlGroup })
          chunkWidth = vim.fn.strdisplaywidth(chunkText)
          if curWidth + chunkWidth < targetWidth then
            suffix = suffix .. (" "):rep(targetWidth - curWidth - chunkWidth)
          end
          break
        end
        curWidth = curWidth + chunkWidth
      end
      table.insert(newVirtText, { suffix, "MoreMsg" })
      return newVirtText
    end,
  },
  config = function(_, opts)
    local ufo = require("ufo")
    ufo.setup(opts)
    -- Keymaps are in keymaps/ufo.lua
    vim.api.nvim_create_autocmd("FileType", {
      pattern = { "lua", "python", "javascript", "typescript", "c", "cpp", "rust", "go" },
      callback = function()
        ufo.setFoldVirtTextHandler(nil, function(virtText, lnum, endLnum, width, truncate)
          local newVirtText = {}
          local suffix = (" 󰁂 %d "):format(endLnum - lnum)
          local sufWidth = vim.fn.strdisplaywidth(suffix)
          local targetWidth = width - sufWidth
          local curWidth = 0
          for _, chunk in ipairs(virtText) do
            local chunkText = chunk[1]
            local chunkWidth = vim.fn.strdisplaywidth(chunkText)
            if targetWidth > curWidth + chunkWidth then
              table.insert(newVirtText, chunk)
            else
              chunkText = truncate(chunkText, targetWidth - curWidth)
              local hlGroup = chunk[2]
              table.insert(newVirtText, { chunkText, hlGroup })
              chunkWidth = vim.fn.strdisplaywidth(chunkText)
              if curWidth + chunkWidth < targetWidth then
                suffix = suffix .. (" "):rep(targetWidth - curWidth - chunkWidth)
              end
              break
            end
            curWidth = curWidth + chunkWidth
          end
          table.insert(newVirtText, { suffix, "MoreMsg" })
          return newVirtText
        end)
      end,
    })
  end,
}