local Utils = require("avante.utils")

---@class AvanteTokenizer
---@field from_pretrained fun(model: string): nil
---@field encode fun(string): integer[]
local tokenizers = nil

local M = {}

---@param model "gpt-4o" | string
---@param warning? boolean
M.setup = function(model, warning)
  warning = warning or true
  vim.defer_fn(function()
    local ok, core = pcall(require, "avante_tokenizers")
    if not ok then return end

    ---@cast core AvanteTokenizer
    if tokenizers == nil then tokenizers = core end

    core.from_pretrained(model)
  end, 1000)

  if warning then
    local HF_TOKEN = os.getenv("HF_TOKEN")
    if HF_TOKEN == nil and model ~= "gpt-4o" then
      Utils.warn(
        "Please set HF_TOKEN environment variable to use HuggingFace tokenizer if " .. model .. " is gated",
        { once = true }
      )
    end
  end
end

M.available = function() return tokenizers ~= nil end

---@param prompt string
M.encode = function(prompt)
  if not tokenizers then return nil end
  if not prompt or prompt == "" then return nil end
  if type(prompt) ~= "string" then error("Prompt is not type string", 2) end

  return tokenizers.encode(prompt)
end

---@param prompt string
M.count = function(prompt)
  if not tokenizers then return math.ceil(#prompt * 0.5) end

  local tokens = M.encode(prompt)
  if not tokens then return 0 end
  return #tokens
end

return M