args <- commandArgs(trailingOnly = TRUE)
routes <- readRDS(args[[1L]])
logfile <- args[[2L]]
readyfile <- args[[3L]]

server <- NULL
port <- NA_integer_
for (candidate in sample(20000:60000, 500L)) {
  server <- tryCatch(serverSocket(candidate), error = function(e) NULL)
  if (!is.null(server)) {
    port <- candidate
    break
  }
}
if (is.null(server)) {
  stop("no free port for the fake server")
}

state <- new.env(parent = emptyenv())
state$queues <- lapply(routes, function(route) route$responses)

pick <- function(path) {
  index <- NA_integer_
  for (i in seq_along(routes)) {
    if (identical(routes[[i]]$match, path)) {
      index <- i
      break
    }
  }
  if (is.na(index)) {
    for (i in seq_along(routes)) {
      if (startsWith(path, routes[[i]]$match)) {
        index <- i
        break
      }
    }
  }
  if (is.na(index)) {
    return(list(
      status = 404L,
      body = "{\"erro\":\"cep_nao_encontrado\"}",
      headers = list()
    ))
  }
  queue <- state$queues[[index]]
  if (length(queue) > 1L) {
    state$queues[[index]] <- queue[-1L]
  }
  queue[[1L]]
}

send <- function(connection, response) {
  body <- charToRaw(enc2utf8(response$body))
  head <- paste0("HTTP/1.1 ", response$status, " Response\r\n")
  for (name in names(response$headers)) {
    head <- paste0(head, name, ": ", response$headers[[name]], "\r\n")
  }
  head <- paste0(
    head,
    "Content-Type: text/plain; charset=utf-8\r\n",
    "Content-Length: ", length(body), "\r\n",
    "Connection: close\r\n\r\n"
  )
  try(
    {
      writeBin(c(charToRaw(head), body), connection)
      flush(connection)
    },
    silent = TRUE
  )
}

pending <- paste0(readyfile, ".tmp")
writeLines(as.character(port), pending)
file.rename(pending, readyfile)

repeat {
  if (!socketSelect(list(server), timeout = 60)) {
    break
  }
  connection <- socketAccept(server, blocking = TRUE, open = "r+b",
                             timeout = 10)
  path <- NA_character_
  repeat {
    line <- readLines(connection, n = 1L, warn = FALSE)
    if (length(line) == 0L) {
      break
    }
    line <- sub("\r$", "", line)
    if (!nzchar(line)) {
      break
    }
    if (is.na(path)) {
      path <- strsplit(line, " ", fixed = TRUE)[[1L]][2L]
    }
  }

  stopping <- FALSE
  if (!is.na(path)) {
    cat(path, "\n", sep = "", file = logfile, append = TRUE)
    if (identical(path, "/__shutdown__")) {
      stopping <- TRUE
      send(connection, list(status = 200L, body = "bye", headers = list()))
    } else {
      send(connection, pick(path))
    }
  }
  try(close(connection), silent = TRUE)
  if (stopping) {
    break
  }
}

close(server)