#include <u.h>
#include <libc.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>
#include <stdio.h>

/* clang-format off */

char  clca(char c) { return c >= 'A' && c <= 'Z' ? c + ('a' - 'A') : c; } /* char to lowercase */
char  cuca(char c) { return c >= 'a' && c <= 'z' ? c - ('a' - 'A') : c; } /* char to uppercase */
int   slen(char *s) { int i = 0; while(s[i] && s[++i]) { ; } return i; } /* string length */
char *st__(char *s, char (*fn)(char)) { int i = 0; char c; while((c = s[i])) s[i++] = fn(c); return s; }
char *stuc(char *s) { return st__(s, cuca); } /* string to uppercase */
char *stlc(char *s) { return st__(s, clca); } /* string to lowercase */
char *scpy(char *src, char *dst, int len) { int i = 0; while((dst[i] = src[i]) && i < len - 2) i++; dst[i + 1] = '\0'; return dst; } /* string copy */
int   scmp(char *a, char *b) { int i = 0; while(a[i] == b[i]) if(!a[i++]) return 1; return 0; } /* string compare */
char *scsw(char *s, char a, char b) { int i = 0; char c; while((c = s[i])) s[i++] = c == a ? b : c; return s; } /* string char swap */
char *scat(char *dst, const char *src) { char *ptr = dst + slen(dst); while(*src) *ptr++ = *src++; *ptr = '\0'; return dst; } /* string cat */
int   ssin(char *s, char *ss) { int a = 0, b = 0; while(s[a]) { if(s[a] == ss[b]) { if(!ss[b + 1]) return a - b; b++; } else b = 0; a++; } return -1; } /* string substring index */
char *ccat(char *dst, char c) { int len = slen(dst); dst[len] = c; dst[len + 1] = '\0'; return dst; }

/* clang-format on */

static char Ebad[] = "something bad happened";
static char Enomem[] = "no memory";

typedef struct Ramfile Ramfile;
struct Ramfile {
  char* data;
  int ndata;
};

void fsread(Req* r) {
  Ramfile* rf;
  vlong offset;
  long count;

  rf = r->fid->file->aux;
  offset = r->ifcall.offset;
  count = r->ifcall.count;

  /*print("read %ld %lld\n", *count, offset); */
  if (offset >= rf->ndata) {
    r->ofcall.count = 0;
    respond(r, nil);
    return;
  }

  if (offset + count >= rf->ndata)
    count = rf->ndata - offset;

  memmove(r->ofcall.data, rf->data + offset, count);
  r->ofcall.count = count;
  respond(r, nil);
}

void fswrite(Req* r) {
  void* v;
  Ramfile* rf;
  vlong offset;
  long count;

  rf = r->fid->file->aux;
  offset = r->ifcall.offset;
  count = r->ifcall.count;

  if (offset + count >= rf->ndata) {
    v = realloc(rf->data, offset + count);
    if (v == nil) {
      respond(r, Enomem);
      return;
    }
    rf->data = v;
    rf->ndata = offset + count;
    r->fid->file->dir.length = rf->ndata;
  }
  memmove(rf->data + offset, r->ifcall.data, count);
  r->ofcall.count = count;
  respond(r, nil);
}

void fscreate(Req* r) {
  Ramfile* rf;
  File* f;

  if (
    f = createfile(
      r->fid->file,
      r->ifcall.name,
      nil,
      r->ifcall.perm,
      nil)) {
    rf = emalloc9p(sizeof *rf);
    f->aux = rf;
    r->fid->file = f;
    r->ofcall.qid = f->dir.qid;
    respond(r, nil);
    return;
  }
  respond(r, Ebad);
}

void fsopen(Req* r) {
  Ramfile* rf;

  rf = r->fid->file->aux;

  if (rf && (r->ifcall.mode & OTRUNC)) {
    rf->ndata = 0;
    r->fid->file->dir.length = 0;
  }

  respond(r, nil);
}

void fsdestroyfile(File* f) {
  Ramfile* rf;

  /*fprint(2, "clunk\n"); */
  rf = f->aux;
  if (rf) {
    free(rf->data);
    free(rf);
  }
}

Srv fs = {
  .open = fsopen,
  .read = fsread,
  .write = fswrite,
  .create = fscreate,
};

int threadmaybackground(void) {
  return 1;
}

void threadmain(int argc, char* argv[]) {
  Tree* tree;
  char* mtpt = nil;
  char* usocket = nil;
  int i;

  /* if -m PATH is supplied, mount on PATH */
  /* if -s NAME is supplied, create a socket for the namespace */
  /* otherwise, just use srv() (for wrapping with socat or inetd) */

  if (argc >= 3) {
    for (i = 0; i < argc; i++) {
      if (scmp(argv[i], "-m")) {
        mtpt = argv[++i];
        printf("serving on %s", mtpt);
      } else if (scmp(argv[i], "-s")) {
        usocket = argv[++i];
        printf("serving socket namespace %s", usocket);
      }
    }
  }

  /* create a single file called 'hello'. reading it calls fsread() */

	fs.tree = alloctree(nil, nil, DMDIR|0777, fsdestroyfile);
	fs.foreground = 1;

  if (argc >= 3) {
    if (mtpt != nil && access(mtpt, AEXIST) < 0 && access(mtpt, AEXIST) < 0)
      sysfatal("mountpoint %s does not exist", mtpt);

    threadpostmountsrv(&fs, usocket, mtpt, MREPL | MCREATE);
    threadexits(0);
  } else {
    srv(&fs);
  }
}