#include <git2/repository.h>
#include <git2/types.h>
#include <linux/limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <stdint.h>
#include <errno.h>

#include "hash.h"
#include "helpers.h"

#ifdef GITHASH
static uint64_t
murmur64(uint64_t k)
{
  k ^= k >> 33;
  k *= 0xff51afd7ed558ccdLLU;
  k ^= k >> 33;
  k *= 0xc4ceb9fe1a85ec53LLU;
  k ^= k >> 33;

  return k;
}

uint64_t
generate_hash(git_repository *repo)
{
  struct stat dir, index;
  char path[PATH_MAX] = { 0 };

  const char *gitpath = git_repository_path(repo);
  if (strlen(gitpath) + strlen("/..") > PATH_MAX - 1) {
    L("strlen: %s", strerror(errno));
    return -1;
  }

  strcat(path, gitpath);
  if (stat(path, &index) < 0) {
    return -1;
  }
  strcat(path, "/..");
  if (stat(path, &dir) < 0) {
    return -1;
  }
  return murmur64(dir.st_mtim.tv_nsec ^ index.st_mtim.tv_nsec);
}

repohash
*read_hash(git_repository *repo)
{
  FILE *f;
  uint64_t data;
  uint8_t changes;
  repohash *hash = malloc(sizeof(repohash));
  char path[PATH_MAX] = { 0 };

  const char *gitpath = git_repository_path(repo);
  if (strlen(gitpath) + strlen(XD_HASH_PATH) > PATH_MAX - 1) {
    L("strlen: %s", strerror(errno));
    return NULL;
  }
  strcat(path, gitpath);
  strcat(path, XD_HASH_PATH);

  f = fopen(path, "r");
  if (!f) {
    L("fopen: %s", strerror(errno));
    return NULL;
  }

  if (fread(&data, sizeof(uint64_t), 1, f) != 1) {
    L("fread: %s", strerror(errno));
    return NULL;
  }

  if (fseek(f, sizeof(uint64_t), SEEK_SET) < 0) {
    L("fseek: %s", strerror(errno));
    return NULL;
  }

  if (fread(&changes, sizeof(uint8_t), 1, f) != 1) {
    L("fread: %s", strerror(errno));
    return NULL;
  }
  fclose(f);

  hash->hash = data;
  hash->changes = changes;
  return hash;
}

int
write_hash(git_repository *repo, repohash hash)
{
  FILE *f;
  char path[PATH_MAX] = { 0 };

  const char *gitpath = git_repository_path(repo);
  if (strlen(gitpath) + strlen(XD_HASH_PATH) > PATH_MAX - 1) {
    L("strlen: %s", strerror(errno));
    return 1;
  }
  strcat(path, gitpath);
  strcat(path, XD_HASH_PATH);

  f = fopen(path, "wb");
  if (!f) {
    L("fopen: %s", strerror(errno));
    return 1;
  }

  if (fwrite(&hash.hash, sizeof(uint64_t), 1, f) != 1) {
    L("fwrite: %s", strerror(errno));
    return 1;
  }

  if (fseek(f, sizeof(uint64_t), SEEK_SET) < 0) {
    L("fseek: %s", strerror(errno));
    return 1;
  }

  if (fwrite(&hash.changes, sizeof(uint8_t), 1, f) != 1) {
    L("fwrite: %s", strerror(errno));
    return 1;
  }

  fclose(f);
  return 0;
}
#endif