/**
 * This CGI program renders the oper.io blog
 * Copyright (C) 2024 Aaron Ball <nullspoon@oper.io>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "common.h"
#include "cgi.h"
#include "j2.h"


int handle_special(char* querystring) {
  if(strncmp(querystring, "ip", 2) == 0) {
    // If the IP address was requested
    cgi_print_header("text/plain", 200);
    puts(cgi_remote_ip());
    return 0;

  } else if(strncmp(querystring, "agent", 5) == 0) {
    // If the remote agent was requested
    cgi_print_header("text/plain", 200);
    puts(cgi_user_agent());
    return 0;

  } else if(strncmp(querystring, "headers", 5) == 0) {
    // If client headers requested
    cgi_print_header("text/plain", 200);
    cgi_print_headers();
    return 0;
  }
  return -1;
}

int handle_page(char* querystring) {
  char path[512] = {0};
  int  status    = 200;
  // Space for title assembly
  char titlebuf[TITLE_MAX] = {'\0'};
  char title[TITLE_MAX + 2] = {'\0'};
  // Required environment variables
  char* header = getenv("INDEX_HEADER");
  char* footer = getenv("INDEX_FOOTER");
  char* posts  = getenv("INDEX_POSTS");

  // Assemble the page path
  sprintf(path, "%s/%s.html", posts, querystring);

  // If the file does not exist, attempt to read the 404 page instead
  // Return -1 if 404 page does not exist
  if(access(path, F_OK) != 0) {
    sprintf(path, "%s/404.html", posts);

    if(access(path, F_OK) != 0)
      return -1;

    status = 404;
    strcpy(title, ": 404");
  }

  // Anything below this gets printed. Make sure all variables are set and
  // logic completed before here.
  cgi_print_header("text/html", status);

  // The specified page exists, attempt to read the title
  html_read_title(path, titlebuf);
  sprintf(title, "%s", titlebuf);
  setenv("PAGE_TITLE", title, 1);

  j2_cat(header);
  j2_cat(path);
  j2_cat(footer);
  fflush(stdout);
  return 0;
}

int main(int argc, char* argv[], char* envp[]) {
  char buf[256] = {0};
  char* keys[] = {"q", "p", "title", "\0"}; // Supported query string key names
  struct querystring qs;
  // Parse the query string (if present)
  qs.qs  = getenv("QUERY_STRING");
  qs.pos = 0;

  // If no title specified (return non-zero), default to "index"
  if(cgi_qs_get_val(&qs, keys, buf) != 0)
    strcpy(buf, "index");

  if(handle_special(buf) == 0)
    return 0;
  if(handle_page(buf) == 0)
    return 0;

  // All attempts to recognize the request have failed. Return generic 404.
  cgi_print_header("text/html", 404);
  setenv("PAGE_TITLE", "404 Not Found", 1);
  puts("404 Not Found");
  fflush(stdout);

  return 0;
}