#include "sys/mman.h"
#include "sys/types.h"
#include "sys/stat.h"
#include "fcntl.h"
#include "system.h"
#include "heap.h"
#include "vm.h"

using namespace vm;

namespace {

class System: public vm::System {
 public:
  System(unsigned limit): limit(limit), count(0) { }

  virtual bool success(Status s) {
    return s == 0;
  }

  virtual void* allocate(unsigned* size) {
    if (count + *size > limit) {
      *size = limit - count;
    }

    uintptr_t* up = static_cast<uintptr_t*>(malloc(*size + sizeof(uintptr_t)));
    if (up == 0) abort();

    *up = *size;
    return up + 1;
  }

  virtual void free(const void* p) {
    if (p) {
      const uintptr_t* up = static_cast<const uintptr_t*>(p) - 1;
      count -= *up;
      ::free(const_cast<uintptr_t*>(up));
    }
  }

  virtual Status start(Thread*) {
    return 1;
  }

  virtual Status make(Monitor**) {
    return 1;
  }

  virtual void abort() {
    ::abort();
  }

  unsigned limit;
  unsigned count;
};

const char*
append(vm::System* s, const char* a, const char* b, const char* c)
{
  unsigned al = strlen(a);
  unsigned bl = strlen(b);
  unsigned cl = strlen(c);
  char* p = static_cast<char*>(s->allocate(al + bl + cl + 1));
  memcpy(p, a, al);
  memcpy(p + al, b, bl);
  memcpy(p + al + bl, c, cl + 1);
  return p;
}

class ClassFinder: public vm::ClassFinder {
 public:
  ClassFinder(vm::System* system, const char** path):
    system(system),
    path(path)
  { }

  class Data: public vm::ClassFinder::Data {
   public:
    Data(uint8_t* start, size_t length):
      start_(start),
      length_(length)
    { }

    virtual const uint8_t* start() {
      return start_;
    }

    virtual size_t length() {
      return length_;
    }

    virtual void dispose() {
      if (start_) {
        munmap(start_, length_);
      }
    }

    uint8_t* start_;
    size_t length_;
  };

  virtual Data* find(const char* className) {
    Data* d = new (system->allocate(sizeof(Data))) Data(0, 0);

    for (const char** p = path; *p; ++p) {
      const char* file = append(system, *p, "/", className);
      int fd = open(file, O_RDONLY);
      if (fd != -1) {
        struct stat s;
        int r = fstat(fd, &s);
        if (r != -1) {
          void* data = mmap(0, s.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
          if (data) {
            d->start_ = static_cast<uint8_t*>(data);
            d->length_ = s.st_size;
            return d;
          }
        }
      }
      system->free(file);
    }
    
    system->free(d);
    return 0;
  }

  vm::System* system;
  const char** path;
};

const char**
parsePath(vm::System* s, const char* path)
{
  class Tokenizer {
   public:
    class Token {
     public:
      Token(const char* s, unsigned length): s(s), length(length) { }

      const char* s;
      unsigned length;
    };

    Tokenizer(const char* s, char delimiter): s(s), delimiter(delimiter) { }

    bool hasMore() {
      while (*s == delimiter) ++s;
      return *s;
    }

    Token next() {
      const char* p = s;
      while (*s and *s != delimiter) ++s;
      return Token(p, s - p);
    }

    const char* s;
    char delimiter;
  };

  unsigned count = 0;
  for (Tokenizer t(path, ':'); t.hasMore();) ++ count;

  const char** v = static_cast<const char**>
    (s->allocate((count + 1) * sizeof(const char*)));

  unsigned i = 0;
  for (Tokenizer t(path, ':'); t.hasMore(); ++i) {
    Tokenizer::Token token(t.next());
    char* p = static_cast<char*>(s->allocate(token.length));
    memcpy(p, token.s, token.length);
    p[token.length] = 0;
    v[i] = p;
  }

  v[i] = 0;

  return v;
}

void
run(unsigned heapSize, const char* path, const char* class_, int argc,
    const char** argv)
{
  System s(heapSize);

  const char** pathv = parsePath(&s, path);
  ClassFinder cf(&s, pathv);

  Heap* heap = makeHeap(&s);

  run(&s, heap, &cf, class_, argc, argv);

  heap->dispose();

  for (const char** p = pathv; *p; ++p) {
    s.free(*p);
  }

  s.free(pathv);
}

void
usageAndExit(const char* name)
{
  fprintf(stderr, "usage: %s [-cp <classpath>] [-hs <maximum heap size>] "
          "<class name> [<argument> ...]", name);
  exit(-1);
}

} // namespace

int
main(int ac, const char** av)
{
  unsigned heapSize = 4 * 1024 * 1024;
  const char* path = ".";
  const char* class_ = 0;
  int argc = 0;
  const char** argv = 0;

  for (int i = 1; i < ac; ++i) {
    if (strcmp(av[i], "-cp") == 0) {
      path = av[++i];
    } else if (strcmp(av[i], "-hs") == 0) {
      heapSize = atoi(av[++i]);
    } else {
      class_ = av[i++];
      if (i < ac) {
        argc = ac - i;
        argv = av + i;
        i = ac;
      }
    }
  }

  if (class_ == 0) {
    usageAndExit(av[0]);
  }

  run(heapSize, path, class_, argc, argv);

  return 0;
}