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

#include <tls.h>
#include <ncurses.h>

const char towrite[] = "gemini://tilde.club/\r\n";

typedef struct ll {
  void *data;
  struct ll *next;
  struct ll *prev; /* optional */
} ll;

char *tls_incremental_line_read(struct tls *context) {
  char buffer;
  int bufsize = 40;
  int current = 0;
  int read;
  char *initial = malloc(bufsize);
  for(;;) {
    if(!(read = tls_read(context, &buffer, 1))) {
      free(initial);
      return NULL;
    }
    switch(buffer) {
      case '\n':
      case '\r':
      case '\0':
        initial[current] = '\0';
        return initial;
    }
    initial[current++] = buffer;
    if(current == bufsize - 2) {
      initial = realloc(initial, bufsize *= 2);
    }
  }
}

struct tls_config *tls_defconfig(void) {
  struct tls_config *r = tls_config_new();
  tls_config_insecure_noverifycert(r);
  tls_config_insecure_noverifyname(r);

  return r;
}

struct tls *dial(char *addr, char *port) {
  struct tls_config *t = tls_defconfig();
  struct tls *client = tls_client();

  tls_configure(client, t);
  tls_connect(client, addr, port);
  tls_config_free(t);

  return client;
}

void ncurses_init(void) {
  initscr();
  keypad(stdscr, TRUE);
  nonl();
  cbreak();
  noecho();

  if(has_colors()) {
    init_pair(COLOR_BLACK, COLOR_BLACK, COLOR_BLACK);
    init_pair(COLOR_GREEN, COLOR_GREEN, COLOR_BLACK);
    init_pair(COLOR_RED, COLOR_RED, COLOR_BLACK);
    init_pair(COLOR_CYAN, COLOR_CYAN, COLOR_BLACK);
    init_pair(COLOR_WHITE, COLOR_WHITE, COLOR_BLACK);
    init_pair(COLOR_MAGENTA, COLOR_MAGENTA, COLOR_BLACK);
    init_pair(COLOR_BLUE, COLOR_BLUE, COLOR_BLACK);
    init_pair(COLOR_YELLOW, COLOR_YELLOW, COLOR_BLACK);
  }
}

void ncurses_cleanup(void) {
  endwin();
}

void manager(void *newdata, ll **ptr, ll **head) {
  if(*ptr == NULL) {
    *ptr = malloc(sizeof **ptr);
    *head = *ptr;
    (*ptr)->prev = NULL;
  } else {
    (*ptr)->next = malloc(sizeof **ptr);
    (*ptr)->next->prev = *ptr;
    *ptr = (*ptr)->next;
  }

  (*ptr)->next = NULL;
  (*ptr)->data = newdata;
}

int is_link(char *c) {
  return c[0] == '=' && c[1] == '>';
}

ll *scroll_ll(int direction, ll *current) {
  if(direction) {
    if(current->next) {
      return current->next;
    }
  } else {
    if(current->prev) {
      return current->prev;
    }
  }
  return current;
}

void render(int yinit, int ymax, ll *data) {
  ll *ptr2 = data;
  erase();
  while(ptr2) {
    mvprintw(yinit++, 0, "%s", ptr2->data);
    ptr2 = ptr2->next;
    if(yinit == ymax) break;
  }
}

ll *fetch_and_render(struct tls *ctx, int yinit, int ymax, char *url) {
  tls_write(ctx, url, strlen(url));
  tls_write(ctx, "\r\n", 2);
  ll *doc = NULL, *dochead = NULL, *links = NULL, *linkhead = NULL;
  char *c;
  int to_screen = 0;

  while(c = tls_incremental_line_read(ctx)) {
    manager(c, &doc, &dochead);
    if(is_link(c)) manager(c, &links, &linkhead);
    if(!to_screen) {
      mvwprintw(stdscr, yinit++, 0, "%s", c);
    } else if(to_screen == 1) {
      refresh();
      to_screen++;
    }
    if(yinit == ymax) to_screen = 1;
  }

  ll *document = malloc(sizeof *document);
  ll *rlinks = malloc(sizeof *rlinks);

  document->data = dochead;
  document->next = rlinks;
  document->prev = NULL;

  rlinks->data = linkhead;
  rlinks->next = NULL;
  rlinks->prev = document;

  return document;
}

int main(void) {
  struct tls *ctx = dial("tilde.club", "1965");
  int tx, ty;
  getmaxyx(stdscr, ty, tx);
  char getchb;
  ll *ptr = NULL, *head = NULL;

  tls_write(ctx, &towrite, sizeof towrite);

  ncurses_init();
  ll *docdata = fetch_and_render(ctx, 1, ty, "gemini://tilde.club/");

  ptr = docdata->data;

  while(ptr) {
    getchb = getch();
    if(getchb == 'k') {
      ptr = scroll_ll(TRUE, ptr);
    } else if(getchb == 'q') {
      ptr = NULL;
    } else {
      ptr = scroll_ll(FALSE, ptr);
    }
    render(1, ty, ptr);
  }

  ncurses_cleanup();

  return 0;
}