local Meta = require "cave.meta"
local Util = require "cave.util"
local Context = require "cave.context"
local ClassLogger = require "cave.log.class_logger"

local validate = Meta.validate
local Optional = Meta.Optional

---@class cave.Env
---@field vars table<string, string>
---@field on_update_cbs function[]
local Env = Meta.derive "Env"
Env.log = ClassLogger.new(Env)

---@param context cave.Context?
---@return cave.Env
function Env:new(context)
  local env = setmetatable({}, Env)
  env.vars = {}
  local dir, name, uuid
  if context then
    dir, name, uuid = tostring(context.dir), context.name, context.uuid
  else
    dir, name, uuid = nil, nil, nil
  end
  vim.fn.setenv("NVIM_PROJECT_DIR", dir)
  vim.fn.setenv("NVIM_PROJECT_NAME", name)
  vim.fn.setenv("NVIM_PROJECT_UUID", uuid)
  for _, entry in ipairs(vim.fn.systemlist { "nvim_env" }) do
    local split_idx = entry:find "="
    assert(split_idx ~= nil)
    env.vars[entry:sub(1, split_idx - 1)] = entry:sub(split_idx + 1, -1)
  end
  return env
end

---@param context cave.Context?
function Env:update(context)
  validate { context = { context, Optional(Context) } }
  local log = Env.log:call("%s", context)

  local new_env = Env:new(context)
  local env_var_diff = Util.tbl_diff(self.vars, new_env.vars)

  for name, value in pairs(env_var_diff.added) do
    vim.fn.setenv(name, value)
  end
  for name, values in pairs(env_var_diff.modified) do
    vim.fn.setenv(name, values.new)
  end
  for name, _ in pairs(env_var_diff.removed) do
    vim.fn.setenv(name, nil)
  end

  self.vars = new_env.vars

  -- vim.g.python3_host_prog = get_python3_host_prog()

  log:ok("environment variables changed:\n%s", vim.inspect(env_var_diff))
end

return Env