---@class chunk: table
---@field [1] string text to be displayed
---@field [2] string neovim highlight group to use

---@class page
---@field name string name of the ui page
---@field kb string keybind of the page
---@field content chunk[]|chunk[][] all the chunks
---@field hlns number highlight namespace
---@field pre_draw function things to do prior to drawing to the buffer
---@field post_draw function things to do post drawing to the buffer
local page = {}

--- create a new page
---@param name string the name of the page
---@param kb string keybind to change to the page
---@return page page
function page:new(name, kb)
  local o = {}
  self.__index = self
  setmetatable(o, self)

  o.hlns = vim.api.nvim_create_namespace("DepUi")
  o.name = name
  o.kb = kb
  o.content = {}

  return o
end

--- add a new line to the page
---@param line chunk|chunk[] new line
function page:new_line(line)
  table.insert(self.content, line)
end

--- draw the page to the given buffer
---@param bufnr number buffer number
function page:draw(bufnr)
  -- try to run pre_draw steps
  if self.pre_draw then
    self.pre_draw()
  end

  -- ready all information for rendering
  for i, chunk in ipairs(self.content) do
    local linenr = i - 1
    local text = ""
    local hls = {}

    if type(chunk[1]) == "table" then
      local j = 0
      for _, ch in ipairs(chunk) do
        text = text..ch[1]
        table.insert(hls, { ch[2], j, j + #ch[1] })
        j = j + #ch[1]
      end
    elseif type(chunk[1]) == "string" then
      text = chunk[1]
      table.insert(hls, { chunk[2], 0, #text })
    end

    -- draw the text to the buffer
    vim.api.nvim_buf_set_lines(bufnr, linenr, -1, false, { text })

    -- highlight the buffer
    for _, hl in ipairs(hls) do
      vim.api.nvim_buf_set_extmark(bufnr, self.hlns, linenr, hl[2], {
        hl_mode = "replace",
        hl_group = hl[1],
        end_col = hl[3],
        end_row = linenr
      })
    end

  end

  -- try to run post_draw steps
  if self.post_draw then
    self.post_draw()
  end
end

return page