url_query_parse.lua

---@param input string
---@return table<string>
local function parse_raw(input)
  local res = {}

  local is_key = true
  local is_value = false

  local key_t = {}
  local value_t = {}

  local function set_kv()
    if #key_t == 0 then
      return
    end
    local key = ngx.unescape_uri(table.concat(key_t, ''))
    local value = ngx.unescape_uri(table.concat(value_t, ''))
    res[#res + 1] = key
    res[#res + 1] = value
    key_t = {}
    value_t = {}
  end

  for i = 1, #input do
    local char = input:sub(i, i)

    if char == '=' and is_key then
      is_key = false
      is_value = true
      goto continue
    end

    if char == '&' then
      is_key = true
      is_value = false
      set_kv()
      goto continue
    end

    if is_key then
      key_t[#key_t + 1] = char
      goto continue
    end

    if is_value then
      value_t[#value_t + 1] = char
      goto continue
    end

    ::continue::
  end

  set_kv()

  return res
end

---@param raw table<string>
---@return string
local function stringify(raw)
  local pairs = {}
  for i = 1, #raw, 2 do
    local key = raw[i]
    local value = raw[i + 1]
    table.insert(pairs, ngx.escape_uri(key) .. '=' .. ngx.escape_uri(value))
  end
  return table.concat(pairs, '&')
end

describe('#only URLSearchParams', function()
  it('should parse', function()
    local res = parse_raw('')
    assert.equal(0, #res)
    assert.equal('', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('&&&&&&&&&')
    assert.equal(0, #res)
    assert.equal('', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('&&&&&a&&&&')
    assert.equal(2, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('a=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('a')
    assert.equal(2, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('a=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('a==')
    assert.equal(2, #res)
    assert.equal('a', res[1])
    assert.equal('=', res[2])
    assert.equal('a=%3D', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('a&')
    assert.equal(2, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('a=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('a=&')
    assert.equal(2, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('a=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('&a')
    assert.equal(2, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('a=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('&a=')
    assert.equal(2, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('a=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('a&b')
    assert.equal(4, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('b', res[3])
    assert.equal('', res[4])
    assert.equal('a=&b=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('a=&b')
    assert.equal(4, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('b', res[3])
    assert.equal('', res[4])
    assert.equal('a=&b=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('a&b=')
    assert.equal(4, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('b', res[3])
    assert.equal('', res[4])
    assert.equal('a=&b=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('a=&b=')
    assert.equal(4, #res)
    assert.equal('a', res[1])
    assert.equal('', res[2])
    assert.equal('b', res[3])
    assert.equal('', res[4])
    assert.equal('a=&b=', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('a=1&b=2&a=3')
    assert.equal(6, #res)
    assert.equal('a', res[1])
    assert.equal('1', res[2])
    assert.equal('b', res[3])
    assert.equal('2', res[4])
    assert.equal('a', res[5])
    assert.equal('3', res[6])
    assert.equal('a=1&b=2&a=3', stringify(res))
  end)

  it('should parse', function()
    local res = parse_raw('url=/foo?a=b&b=$path')
    assert.equal(4, #res)
    assert.equal('url', res[1])
    assert.equal('/foo?a=b', res[2])
    assert.equal('b', res[3])
    assert.equal('$path', res[4])
    assert.equal('url=%2Ffoo%3Fa%3Db&b=%24path', stringify(res))
  end)

  it('should parse', function()
    ngx.update_time()
    local start = ngx.now()
    for _ = 1, 1000 do
      parse_raw(
        'userId=1234567890&userStatus=active&userRole=administrator&location=unitedStates&category=subcategory1|subcategory2|subcategory3&timestamp=164124841&token=abcd1234efgh5678ijkl9012mnopqrst&sortOrder=desc&pageSize=50&pageNumber=1&fields=name,email,phone,address')
    end
    ngx.update_time()
    local ms = (ngx.now() - start) * 1000
    assert(ms < 100)
  end)
end)