/*
 * Copyright 2018 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdbool.h>
#include <dirent.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>

#include "scrape.h"
#include "util.h"

#define DEFAULT_DIR "/var/lib/prometheus/node-exporter"

void *textfile_init(int argc, char *argv[]);
void textfile_collect(scrape_req *req, void *ctx);

const struct collector textfile_collector = {
  .name = "textfile",
  .collect = textfile_collect,
  .init = textfile_init,
  .has_args = true,
};

void *textfile_init(int argc, char *argv[]) {
  char *dir = DEFAULT_DIR;

  for (int arg = 0; arg < argc; arg++) {
    if (strncmp(argv[arg], "dir=", 4) == 0) {
      dir = &argv[arg][4];
    } else {
      fprintf(stderr, "unknown argument for textfile collector: %s", argv[arg]);
      return 0;
    }
  }

  return dir;
}

void textfile_collect(scrape_req *req, void *ctx) {
  const char *dir = ctx;

  DIR *d = opendir(dir);
  if (!d)
    return;

  struct dirent *dent;
  char buf[4096];

  while ((dent = readdir(d))) {
    size_t name_len = strlen(dent->d_name);
    if (name_len < 6 || strcmp(dent->d_name + name_len - 5, ".prom") != 0)
      continue;

    snprintf(buf, sizeof buf, "%s/%s", dir, dent->d_name);
    FILE *f = fopen(buf, "r");
    if (!f)
      continue;

    bool has_newline = true;
    size_t len;
    while ((len = fread(buf, 1, sizeof buf, f)) > 0) {
      scrape_write_raw(req, buf, len);
      has_newline = buf[len - 1] == '\n';
    }
    if (!has_newline)
      scrape_write_raw(req, (char[]){'\n'}, 1);

    fclose(f);
  }

  closedir(d);
}