#include "version.h"
#include "digest/digest.h"
#include "l2su.h"
#include "macros.h"
#include "endian.h"
#include "command.h"

#include <curl/curl.h>
#include <jansson.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <alloca.h>
#include <unistd.h>

const char *const l2_version__messages[] = {
  "Success",
  "Malformed version manifest",
  "Version manifest JSON error",
  "Allocation failed",
  "OS error",
  "Error downloading version manifest",
  "Version not found",
  "Max recursion depth exceeded",
  NULL
};

#define L2_VERSION_MANIFEST_ETAG_PATH "/.l2_vermanifest_etag"
#define L2_VERSION_MANIFEST_PATH "/version_manifest_v2.json"
#define L2_VERSION_MANIFEST_EXP_TIME ((time_t)120)

unsigned l2_version__load_manifest(json_t **out_json);
unsigned l2_version__load_all_from_json(json_t *json);

unsigned l2_version__add_remote(json_t *obj);

unsigned l2_version_load_remote(void)
{
  json_t *vers = NULL;
  unsigned r = l2_version__load_manifest(&vers);
  if (r != VERSION_SUCCESS) goto done;

  r = l2_version__load_all_from_json(vers);

done:
  json_decref(vers);
  return r;
}

void l2_version__load_local(const char *id, size_t expectsz, l2_sha1_digest_t *digest, json_t **ojson);
bool l2_version__download_remote(struct l2_version_remote *remote, json_t **ojson);

unsigned l2_version__load_or_download(const char *name, json_t **ojs)
{
  json_t *js = NULL;
  struct l2_version_remote *remote = NULL;
  
  for (struct l2_version_remote *cur = l2_state.ver_remote_head; cur; cur = cur->next) {
    if (!strcmp(cur->id, name)) {
      remote = cur;
      break;
    }
  }

  if (remote) {
    l2_version__load_local(remote->id, 0, &remote->sha1, &js);
    if (!js) {
      CMD_DEBUG0("local version not found, downloading");
      if (!l2_version__download_remote(remote, &js) || !js)
        return VERSION_EDOWNLOAD;
    }
  } else {
    l2_version__load_local(remote->id, 0, NULL, &js);
    if (!js) return VERSION_ENOTFOUND;
  }

  *ojs = js;
  return VERSION_SUCCESS;
}

unsigned l2_version__load_recursive(const char *name, json_t *target, int depth)
{
  json_t *other = NULL;
  json_t *inherit;

  if (depth <= 0) return VERSION_ERECURSE;

  unsigned res = l2_version__load_or_download(name, &other);

  if (res != VERSION_SUCCESS) return res;
  l2_json_merge_objects(target, other);

  inherit = json_object_get(other, "inheritsFrom");
  if (!json_is_string(inherit)) {
    json_decref(other);
    return VERSION_SUCCESS;
  }

  json_decref(other);
  return l2_version__load_recursive(json_string_value(inherit), target, depth - 1);
}

unsigned l2_version_load_local(const char *name, json_t **ojson)
{
  json_t *js = json_object();
  if (!js) return VERSION_EJSON;

  unsigned res = l2_version__load_recursive(name, js, 10);
  *ojson = js;
  return res;
}

void l2_version__load_local(const char *id, size_t expectsz, l2_sha1_digest_t *digest, json_t **ojson)
{
  char *path;
  size_t temp;
  L2_ASPRINTF(path, temp, "%s/versions/%s/%s.json", l2_state.paths.data, id, id);
 
  FILE *ver = fopen(path, "r");
  if (!ver) return;

  int res = l2_version_check_integrity(ver, digest, expectsz);
  if (res < 0) {
    CMD_WARN("Error checking version file integrity for %s", id);
    return;
  } else if (res == 0) {
    CMD_DEBUG("Version %s (%s) has bad integrity", id, path);
    return;
  }

  json_t *js;
  json_error_t jerr;

  rewind(ver);
  js = json_loadf(ver, JSON_REJECT_DUPLICATES, &jerr);
  if (!js) {
    CMD_WARN("JSON error loading %s: %s", id, jerr.text);
    return;
  }

  *ojson = js;
}

/* downloads a remote version */
bool l2_version__download_remote(struct l2_version_remote *remote, json_t **ojson)
{
  char *dirname;
  char *fname;
  size_t temp;
  FILE *save = NULL;
  json_t *js = NULL;
  L2_ASPRINTF(dirname, temp, "%s/versions/%s", l2_state.paths.data, remote->id);
  L2_ASPRINTF(fname, temp, "%s/%s.json", dirname, remote->id);

  if (l2_launcher_mkdir_parents(dirname) < 0) {
    CMD_ERROR("Could not create directory for %s: %s", remote->id, strerror(errno));
    return false;
  }

  CURL *cu = curl_easy_init();
  l2_sha1_state_t st;
  l2_sha1_digest_t dig;
  json_error_t err;
  if (!cu) return false;

  void *data = NULL;
  char errbuf[CURL_ERROR_SIZE];
  size_t sz;

  memset(errbuf, 0, CURL_ERROR_SIZE * sizeof(char));

  curl_easy_setopt(cu, CURLOPT_ERRORBUFFER, errbuf);
  CURLcode code = l2_launcher_download(cu, remote->url, &data, &sz);

  if (code != CURLE_OK) {
    CMD_WARN("Error downloading version %s: %s: %s", remote->id, curl_easy_strerror(code), errbuf);
    goto cleanup;
  }

  l2_sha1_init(&st);
  l2_sha1_update(&st, data, sz);
  l2_sha1_finalize(&st, &dig);

  if (l2_sha1_digest_compare(&dig, &remote->sha1)) {
    char d1[L2_SHA1_DIGESTLEN + 1];
    char d2[L2_SHA1_DIGESTLEN + 1];

    l2_sha1_digest_to_hex(&dig, d1);
    l2_sha1_digest_to_hex(&remote->sha1, d2);

    CMD_WARN("Downloaded file for %s has incorrect hash: expected %s, got %s!", remote->id, d2, d1);
    goto cleanup;
  }

  js = json_loadb(data, sz, JSON_REJECT_DUPLICATES, &err);
  if (!js) {
    CMD_WARN("JSON parse error reading version %s: %s", remote->id, err.text);
    goto cleanup;
  }

  save = fopen(fname, "w");
  if (!save) {
    CMD_WARN("Error opening version file %s", fname);
    goto cleanup;
  }

  if (fwrite(data, sz, 1, save) < 1) {
    CMD_WARN("Error saving version info to %s", fname);
    goto cleanup;
  }

  *ojson = js;

  curl_easy_cleanup(cu);
  fclose(save);
  free(data);
  return true;

cleanup:
  curl_easy_cleanup(cu);
  free(data);
  if (save) fclose(save);
  if (js) json_decref(js);
  return false;
}

char *l2_version__read_etag(time_t *lastmod)
{
  size_t dpathlen = strlen(l2_state.paths.data);
  char *etagpath;

  L2_ASTRCAT2(etagpath, l2_state.paths.data, dpathlen, L2_VERSION_MANIFEST_ETAG_PATH, L2_CSTRLEN(L2_VERSION_MANIFEST_ETAG_PATH));

  FILE *etagfp = fopen(etagpath, "rb");
  char *etag = NULL;
  uint32_t buf;
  uint64_t ts;

  CMD_DEBUG0("Reading etag file");

  if (!etagfp) {
    CMD_DEBUG0("Failed to open etag file");
    return NULL;
  }

  if (fread(&buf, sizeof(uint32_t), 1, etagfp) < 1) goto cleanup;
  if (fread(&ts, sizeof(uint64_t), 1, etagfp) < 1) goto cleanup;

  buf = l2_betoh32(buf);
  ts = l2_betoh64(ts);

  etag = calloc(buf + 1, 1);
  if (!etag) goto cleanup;

  if (fread(etag, 1, buf, etagfp) < buf) goto cleanup;
  etag[buf] = '\0';

  *lastmod = (time_t)ts;

  fclose(etagfp);

  CMD_DEBUG("Etag read: %s", etag);

  return etag;

cleanup:
  free(etag);
  fclose(etagfp);
  return NULL;
}

/* this function does not report errors on failure because its operation is not essential */
void l2_version__write_etag(time_t modtime, const char *etag)
{
  size_t dpathlen = strlen(l2_state.paths.data);
  char *etagpath;

  L2_ASTRCAT2(etagpath, l2_state.paths.data, dpathlen, L2_VERSION_MANIFEST_ETAG_PATH, L2_CSTRLEN(L2_VERSION_MANIFEST_ETAG_PATH));

  size_t etaglen = strlen(etag);
  uint32_t etaglenbe = l2_htobe32((uint32_t)etaglen);
  uint64_t mt_write = l2_htobe64((uint64_t)modtime);

  FILE *etagfp = fopen(etagpath, "wb");
  if (!etagfp) return;

  if (fwrite(&etaglenbe, sizeof(uint32_t), 1, etagfp) < 1) goto cleanup;
  if (fwrite(&mt_write, sizeof(uint64_t), 1, etagfp) < 1) goto cleanup;
  if (fwrite(etag, 1, etaglen, etagfp) < etaglen) goto cleanup;

cleanup:
  fclose(etagfp);
}

void l2_version__delete_etag(void)
{
  size_t dpathlen = strlen(l2_state.paths.data);
  char *etagpath;

  L2_ASTRCAT2(etagpath, l2_state.paths.data, dpathlen, L2_VERSION_MANIFEST_ETAG_PATH, L2_CSTRLEN(L2_VERSION_MANIFEST_ETAG_PATH));

  if (unlink(etagpath) < 0) {
    CMD_WARN("Failed to delete etag: %s", strerror(errno));
  }
}

int l2_version__read_manifest_file(json_t **manifest)
{
  size_t dpathlen = strlen(l2_state.paths.data);
  char *manpath;

  L2_ASTRCAT2(manpath, l2_state.paths.data, dpathlen, L2_VERSION_MANIFEST_PATH, L2_CSTRLEN(L2_VERSION_MANIFEST_PATH));

  json_error_t err;
  json_t *man = json_load_file(manpath, JSON_REJECT_DUPLICATES, &err);
  if (!man) {
    CMD_WARN("Error loading version manifest file: %s", err.text);
    return -1;
  }

  *manifest = man;
  return 0;
}

int l2_version__write_manifest_file(void *data, size_t d)
{
  size_t dpathlen = strlen(l2_state.paths.data);
  char *manpath;

  L2_ASTRCAT2(manpath, l2_state.paths.data, dpathlen, L2_VERSION_MANIFEST_PATH, L2_CSTRLEN(L2_VERSION_MANIFEST_PATH));

  FILE* fp = fopen(manpath, "w");
  if (!fp) return -2;

  if (fwrite(data, 1, d, fp) < d) {
    fclose(fp);
    return -1;
  }

  fclose(fp);
  return 0;
}

unsigned l2_version__load_manifest(json_t **omanifest)
{
  time_t lmod;
  char *etag = l2_version__read_etag(&lmod);
  time_t now = time(NULL);

  CMD_DEBUG("etag: %s, time: %jd", etag ? etag : "(null)", etag ? (uintmax_t)(now - lmod) : UINTMAX_C(0));
  if (etag && now - lmod < L2_VERSION_MANIFEST_EXP_TIME) {
    CMD_DEBUG0("Not downloading (cached).");
    if (l2_version__read_manifest_file(omanifest) == 0) {
      free(etag);
      return VERSION_SUCCESS; /* if it failed, redownload the file */
    }
  }

  CMD_DEBUG0("Downloading");
  CURL *cu = curl_easy_init();
  struct curl_slist *headers = NULL;
  CURLcode cres;
  long httpres;
  unsigned retval = VERSION_EDOWNLOAD;

  char ebuf[CURL_ERROR_SIZE]; /* assuming CURL_ERROR_SIZE is small enough to fit on the stack... */
  memset(ebuf, 0, sizeof(ebuf));

  void *data = NULL;
  size_t dlen;

  if (!cu) {
    return VERSION_EDOWNLOAD;
  }

  if (etag) {
    char *headerstr;
    size_t etaglen = strlen(etag);
#define H_INM "If-None-Match: "
    L2_ASTRCAT2(headerstr, H_INM, L2_CSTRLEN(H_INM), etag, etaglen);
#undef H_INM

    headers = curl_slist_append(NULL, headerstr);
    if (!headers) {
      retval = VERSION_EDOWNLOAD;
      goto cleanup;
    }

    CMD_DEBUG("Adding etag header %s", etag);
    curl_easy_setopt(cu, CURLOPT_HTTPHEADER, headers);
  }

  curl_easy_setopt(cu, CURLOPT_ERRORBUFFER, ebuf);

  if ((cres = l2_launcher_download(cu, L2_URL_META_VERSION_MANIFEST, &data, &dlen)) != CURLE_OK) {
    CMD_ERROR("Error downloading version manifest: %s: %s", curl_easy_strerror(cres), ebuf);
    goto cleanup;
  }

  curl_easy_getinfo(cu, CURLINFO_RESPONSE_CODE, &httpres);
  if (httpres == 200) {
    CMD_DEBUG0("manifest download OK");
    /* yay we're good and *data contains our info */
    if (l2_version__write_manifest_file(data, dlen) < 0) {
      CMD_WARN0("Error writing version manifest");
    } else {
      struct curl_header *outh;
      if (curl_easy_header(cu, "etag", 0, CURLH_HEADER, 0, &outh) == CURLHE_OK) {
        l2_version__write_etag(time(NULL), outh->value);
        CMD_DEBUG("New etag returned: %s", outh->value);
      }
    }

    json_error_t err;
    json_t *js = json_loadb(data, dlen, JSON_REJECT_DUPLICATES, &err);
    if (!js) {
      CMD_ERROR("Failed to parse version manifest: %s", err.text);
      retval = VERSION_EJSON;
      goto cleanup;
    }

    *omanifest = js;
  } else if (httpres == 304) { /* not modified */
    CMD_DEBUG0("manifest download not modified");
    if (l2_version__read_manifest_file(omanifest) < 0) {
      CMD_WARN0("Could not read cached version manifest. Please try again.");
      l2_version__delete_etag();

      retval = VERSION_EJSON;
      goto cleanup;
    }

    /* write the new time because we know the file is good (at least valid json) */
    CMD_DEBUG0("writing new etag (read success)");
    l2_version__write_etag(time(NULL), etag); /* same etag but we know the file is still good */
  } else {
    CMD_ERROR("Received unexpected HTTP status code: %ld", httpres);
    goto cleanup;
  }

  free(data);
  free(etag);
  data = NULL;

  if (headers) curl_slist_free_all(headers);
  curl_easy_cleanup(cu);
  return VERSION_SUCCESS;

cleanup:
  if (headers) curl_slist_free_all(headers);
  if (cu) curl_easy_cleanup(cu);
  if (data) free(data);
  if (etag) free(etag);
  return retval;
}

/* parses an instance of version_manifest_v2.json */
unsigned l2_version__load_all_from_json(json_t *json)
{
  if (!json_is_object(json)) {
    return VERSION_EFORMAT;
  }

  json_t *latest = json_object_get(json, "latest");
  json_t *versions = json_object_get(json, "versions");

  if (!json_is_object(latest) || !json_is_array(versions)) {
    return VERSION_EFORMAT;
  }

  const char *latestrel = json_string_value(json_object_get(latest, "release"));
  const char *latestsnap = json_string_value(json_object_get(latest, "snapshot"));
  size_t index;
  json_t *value;
  unsigned res;

  if (!latestrel || !latestsnap) {
    return VERSION_EFORMAT;
  }

  json_array_foreach(versions, index, value) {
    if ((res = l2_version__add_remote(value)) != VERSION_SUCCESS)
      return res;
  }

  return VERSION_SUCCESS;
}

unsigned l2_version__add_remote(json_t *js)
{
  struct l2_version_remote *ver = NULL;
  struct tm ts;
  json_t *val;

  unsigned res = VERSION_SUCCESS;
  
  if (!json_is_object(js)) {
    return VERSION_EFORMAT;
  }

  ver = calloc(1, sizeof(struct l2_version_remote));
  if (!ver) return VERSION_EALLOC;

  res = VERSION_EFORMAT;

  val = json_object_get(js, "id");
  if (!json_is_string(val)) goto cleanup;
  ver->id = strdup(json_string_value(val));

  val = json_object_get(js, "type");
  if (!json_is_string(val)) goto cleanup;
  ver->type = strdup(json_string_value(val));

  val = json_object_get(js, "url");
  if (!json_is_string(val)) goto cleanup;
  ver->url = strdup(json_string_value(val));

  val = json_object_get(js, "sha1");
  if (!json_is_string(val)) goto cleanup;
  if (l2_sha1_digest_from_hex(&ver->sha1, json_string_value(val)) < 0)
    goto cleanup;

  val = json_object_get(js, "complianceLevel");
  if (!json_is_number(val)) goto cleanup;
  ver->compliance_level = json_integer_value(val);

  val = json_object_get(js, "time");
  if (!json_is_string(val)) goto cleanup;
  memset(&ts, 0, sizeof(struct tm));
  if (!l2_launcher_parse_iso_time(json_string_value(val), &ts)) goto cleanup;
  ver->update_time = mktime(&ts);

  val = json_object_get(js, "releaseTime");
  if (!json_is_string(val)) goto cleanup;
  memset(&ts, 0, sizeof(struct tm));
  if (!l2_launcher_parse_iso_time(json_string_value(val), &ts)) goto cleanup;
  ver->release_time = mktime(&ts);

  /* add the thing to the global list */
  if (l2_state.ver_remote_tail) {
    l2_state.ver_remote_tail->next = ver;
    ver->prev = l2_state.ver_remote_tail;
    l2_state.ver_remote_tail = ver;
  } else {
    l2_state.ver_remote_head = l2_state.ver_remote_tail = ver;
  }

  return VERSION_SUCCESS;

cleanup:
  if (ver) {
    free(ver->id);
    free(ver->type);
    free(ver->url);
  }

  free(ver);

  return res;
}

int l2_version_check_integrity(FILE *fp, l2_sha1_digest_t *digest, size_t sz)
{
  #define VER_READBUF_SZ (1024)

  size_t len = 0, nread;
  uint8_t buf[VER_READBUF_SZ];
  l2_sha1_digest_t rdigest;
  l2_sha1_state_t st;

  l2_sha1_init(&st);

  while ((nread = fread(buf, 1, VER_READBUF_SZ, fp)) > 0) {
    len += nread;
    l2_sha1_update(&st, buf, nread);
  }

  if (ferror(fp)) return -1;

  l2_sha1_finalize(&st, &rdigest);

  if (sz > 0 && sz != len) return 0;

  if (digest) {
    return !l2_sha1_digest_compare(&rdigest, digest) ? 1 : 0;
  } else {
    return 1;
  }
}