--
-- https://gist.github.com/numToStr/1ab83dd2e919de9235f9f774ef8076da
--
local cmd = vim.api.nvim_command

local function autocmd(this, event, spec)
    local is_table = type(spec) == 'table'
    local pattern = is_table and spec[1] or '*'
    local action = is_table and spec[2] or spec
    if type(action) == 'function' then
        action = this.set(action)
    end
    local e = type(event) == 'table' and table.concat(event, ',') or event
    cmd('autocmd ' .. e .. ' ' .. pattern .. ' ' .. action)
end

local S = {
    __au = {},
}

local X = setmetatable({}, {
    __index = S,
    __newindex = autocmd,
    __call = autocmd,
})

function S.exec(id)
    S.__au[id]()
end

function S.set(fn)
    local id = string.format('%p', fn)
    S.__au[id] = fn
    return string.format('lua require("au").exec("%s")', id)
end

function S.group(grp, cmds)
    cmd('augroup ' .. grp)
    cmd('autocmd!')
    if type(cmds) == 'function' then
        cmds(X)
    else
        for _, au in ipairs(cmds) do
            autocmd(S, au[1], { au[2], au[3] })
        end
    end
    cmd('augroup END')
end

return X