local config = require("persisted.config")

local M = {}

local e = vim.fn.fnameescape

local function setup_commands()
  vim.cmd([[
    command! SessionStart :lua require("persisted").start()
    command! SessionStop :lua require("persisted").stop()
    command! SessionSave :lua require("persisted").save()
    command! SessionLoad :lua require("persisted").load()
    command! SessionLoadLast :lua require("persisted").load({ last = true })
    command! SessionDelete :lua require("persisted").delete()
    command! SessionToggle :lua require("persisted").toggle()
  ]])
end

function M.get_current()
  local pattern = "/"
  if vim.fn.has("win32") == 1 then
    pattern = "[\\:]"
  end
  local name = vim.fn.getcwd():gsub(pattern, "%%")
  return config.options.dir .. name .. get_branch() .. ".vim"
end

function get_branch()
  local git_enabled = (vim.fn.isdirectory(vim.fn.getcwd() .. "/.git") == 1)

  if config.options.use_git_branch and git_enabled then
    local branch = vim.api.nvim_exec([[!git rev-parse --abbrev-ref HEAD 2>/dev/null]], true)

    -- The branch command returns two lines. We only need the second one
    local lines = {}
    for s in branch:gmatch("[^\r\n]+") do
      table.insert(lines, "_" .. s)
    end
    return lines[2]:gsub("/", "%%")
  end

  return ""
end

function M.get_last()
  local sessions = M.list()
  table.sort(sessions, function(a, b)
    return vim.loop.fs_stat(a).mtime.sec > vim.loop.fs_stat(b).mtime.sec
  end)
  return sessions[1]
end

function M.setup(opts)
  config.setup(opts)
  setup_commands()
  if config.options.autosave then
    M.start()
  end
end

function M.start()
  vim.cmd([[
    augroup Persisted
      autocmd!
      autocmd VimLeavePre * lua require("persisted").save()
    augroup end
  ]])
  vim.g.persisting = true
end

function M.stop()
  vim.cmd([[
    autocmd! Persisted
    augroup! Persisted
  ]])
  vim.g.persisting = false
end

function M.save()
  config.options.before_save()

  local tmp = vim.o.sessionoptions
  vim.o.sessionoptions = table.concat(config.options.options, ",")
  vim.cmd("mks! " .. e(M.get_current()))
  vim.o.sessionoptions = tmp
  vim.g.persisting = true

  config.options.after_save()
end

function M.delete()
  local session = M.get_current()
  if session and vim.loop.fs_stat(session) ~= 0 then
    M.stop()
    vim.fn.system("rm " .. e(session))
  end
end

function M.load(opt)
  opt = opt or {}
  local session = opt.last and M.get_last() or M.get_current()
  if session and vim.fn.filereadable(session) ~= 0 then
    vim.cmd("source " .. e(session))
    vim.g.persisting = true
  end
end

function M.list()
  return vim.fn.glob(config.options.dir .. "*.vim", true, true)
end

function M.toggle()
  if vim.g.persisting == nil then
    return M.load()
  end
  if vim.g.persisting then
    return M.stop()
  end
  return M.start()
end

return M