#include <stdlib.h>
#include <string.h>

#include "url.h"

#define SET_STR(segment)                                                       \
  (segment) = malloc(i - start + 1);                                           \
  strncpy((segment), s + start, i - start);

#define MOVE(amount)                                                           \
  i += (amount);                                                               \
  start = i;

#define SET_AT_END(segment)                                                    \
  if (cur == '\0') {                                                           \
    state = END;                                                               \
    if (i - 1 > start) {                                                       \
      SET_STR(segment);                                                        \
    }                                                                          \
  }

enum state { SCHEME, HOST, PORT, PATH, QUERY, FRAGMENT, END };

int parse_url(struct url *url, char *s) {
  int i = 0;     // index into *s
  int start = 0; // index of current mode start
  enum state state = SCHEME;
  char cur;

  while (i < MAX_URL_LENGTH) {
    cur = s[i];

    if (cur == ' ')
      return INVALID_CHARACTER;

    switch (state) {
    case SCHEME:
      if (cur == ':') {
        state = HOST;
        SET_STR(url->scheme);

        MOVE(3); // skip the '://'
      }
      SET_AT_END(url->scheme);
      break;

    case HOST:
      if (cur == ':') {
        state = PORT;
        SET_STR(url->host);

        MOVE(1);
      }

      if (cur == '/') {
        state = PATH;
        SET_STR(url->host);

        MOVE(0);
      }
      SET_AT_END(url->host);
      break;

    case PORT:
      if (cur == '/') {
        state = PATH;
        char *port;
        SET_STR(port);

        url->port = atoi(port);

        MOVE(0);
      }
      if (cur == '\0') {
        state = END;

        char *port;
        SET_STR(port);

        url->port = atoi(port);
      }

      break;

    case PATH:
      if (cur == '?') {
        state = QUERY;
        SET_STR(url->path);

        MOVE(0);
      }

      if (cur == '#') {
        state = FRAGMENT;
        SET_STR(url->path);

        MOVE(0);
      }
      SET_AT_END(url->path);
      break;

    case QUERY:
      if (cur == '#') {
        state = FRAGMENT;
        SET_STR(url->query);

        MOVE(0);
      }
      SET_AT_END(url->query);
      break;

    case FRAGMENT:
      if (cur == '\0') {
        state = END;
        SET_STR(url->fragment);

        MOVE(0);
      }
      break;

    case END:
      break;
    }

    i++;

    if (cur == '\0')
      break;
    if (state == END)
      break;
  }

  if (url->host == NULL)
    return MISSING_HOST;
  if (url->port == 0)
    return MISSING_PORT;

  if (url->path == NULL) {
    url->path = malloc(2);
    strcpy(url->path, "/");
  }

  return 0;
}

struct url *init_url(void) {
  struct url *url = malloc(sizeof(struct url));

  url->scheme = NULL;
  url->host = NULL;
  url->port = 2693;

  url->path = NULL;

  url->query = NULL;
  url->fragment = NULL;

  return url;
}

void free_url(struct url *url) {
  free(url->scheme);
  free(url->host);
  free(url->path);
  free(url->fragment);
  free(url->query);
  free(url);
}

int len_url(struct url *url) {
  int len = 0;

  len += url->scheme != NULL ? strlen(url->scheme) : 0;
  len += url->host != NULL ? strlen(url->host) : 0;
  len += sizeof(url->port);
  len += url->path != NULL ? strlen(url->path) : 0;
  len += url->query != NULL ? strlen(url->query) : 0;
  len += url->fragment != NULL ? strlen(url->fragment) : 0;

  return len;
}