local hlib = {}
local fmt = string.format
local g_version = "1.1"
local g_status_msg = {
  [100] = "Continue",
  [101] = "Switching Protocols",
  [102] = "Processing",
  [200] = "OK",
  [201] = "Created",
  [202] = "Accepted",
  [203] = "Non-authoritative Information",
  [204] = "No Content",
  [205] = "Reset Content",
  [206] = "Partial Content",
  [207] = "Multi-Status",
  [208] = "Already Reported",
  [226] = "IM Used",
  [300] = "Multiple Choices",
  [301] = "Moved Permanently",
  [302] = "Found",
  [303] = "See Other",
  [304] = "Not Modified",
  [305] = "Use Proxy",
  [307] = "Temporary Redirect",
  [308] = "Permanent Redirect",
  [400] = "Bad Request",
  [401] = "Unauthorized",
  [402] = "Payment Required",
  [403] = "Forbidden",
  [404] = "Not Found",
  [405] = "Method Not Allowed",
  [406] = "Not Acceptable",
  [407] = "Proxy Authentication Required",
  [408] = "Request Timeout",
  [409] = "Conflict",
  [410] = "Gone",
  [411] = "Length Required",
  [412] = "Precondition Failed",
  [413] = "Payload Too Large",
  [414] = "Request-URI Too Long",
  [415] = "Unsupported Media Type",
  [416] = "Requested Range Not Satisfiable",
  [417] = "Expectation Failed",
  [418] = "I'm a teapot",
  [421] = "Misdirected Request",
  [422] = "Unprocessable Entity",
  [423] = "Locked",
  [424] = "Failed Dependency",
  [426] = "Upgrade Required",
  [428] = "Precondition Required",
  [429] = "Too Many Requests",
  [431] = "Request Header Fields Too Large",
  [444] = "Connection Closed Without Response",
  [451] = "Unavailable For Legal Reasons",
  [499] = "Client Closed Request",
  [500] = "Internal Server Error",
  [501] = "Not Implemented",
  [502] = "Bad Gateway",
  [503] = "Service Unavailable",
  [504] = "Gateway Timeout",
  [505] = "HTTP Version Not Supported",
  [506] = "Variant Also Negotiates",
  [507] = "Insufficient Storage",
  [508] = "Loop Detected",
  [510] = "Not Extended",
  [511] = "Network Authentication Required",
  [599] = "Network Connect Timeout Error",
}

function push_headers(headers, add)
  for k,v in pairs(add) do
    headers[k] = v
  end
  return headers
end

function get_content_length(body)
  return {["Content-Length"] = #body+1}
end

function get_content_type(body)
  return {["Content-Type"] = "text/html"}
end

local header_functions = {
  get_content_length,
  get_content_type
}

function hlib.parse_request(r)
  local request = {
    method = nil,
    path = nil,
    version = nil,
    headers = {}
  }
  local lines = string.gmatch(r, "[^\n]+")
  local head_msg = lines()
  local _, _, method, path, version = string.find(head_msg, "(%u+) ([%w/]+) ([%w/%.]+)")
  request.method = method
  request.path = path
  request.version = version

  for line in lines do
    local _, _, a, b = string.find(line, "([%w-]+): (.+)")
    if a then
      request.headers[a] = b
    end
  end
  return request
end

function hlib.response(path, status, body)
  local resp = {
    version = fmt("HTTP/%s", g_version),
    status = status,
    status_msg = g_status_msg[status],
    body = body,
    headers = {}
  }

  for k,v in pairs(header_functions) do
    resp.headers = push_headers(resp.headers, v(body))
  end
  local r = fmt(
[[%s %s %s
Content-Length: %d

%s
]], resp.version, resp.status, resp.status_msg, #resp.body+1, resp.body)
  return r
end

return hlib