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

#include "lsm.h"
#include "lsm/store.h"
#include "lsm/store_internal.h"
#include "lsm/trie.h"

lsm_error lsm_store_init(lsm_store **ptr) {
  lsm_store *store = calloc(1, sizeof(lsm_store));

  if (store == NULL) {
    return lsm_error_failed_alloc;
  }

  lsm_error res = lsm_trie_init(&store->trie);

  if (res != lsm_error_ok) {
    free(store);

    return res;
  }

  *ptr = store;

  return lsm_error_ok;
}

lsm_error lsm_store_open(lsm_store **ptr, lsm_str *db_path,
                         lsm_str *data_path) {
  lsm_store *store;
  LSM_RES(lsm_store_init(&store));

  // TODO implement all of reading the db file

  store->db_path = db_path;
  store->data_path = data_path;

  *ptr = store;

  return lsm_error_ok;
}

lsm_error lsm_store_get_read(lsm_entry **out, lsm_store *store, lsm_str *key) {
  lsm_entry_wrapper *wrapper;

  LSM_RES(lsm_trie_search((void **)&wrapper, store->trie, key));

  // We don't want to block the thread
  if (pthread_rwlock_tryrdlock(&wrapper->lock) != 0) {
    return lsm_error_lock_busy;
  }

  lsm_entry *entry = wrapper->entry;

  // While the trie's data field will never be NULL, the actual entry pointer
  // might be
  if (entry == NULL) {
    pthread_rwlock_unlock(&wrapper->lock);

    return lsm_error_not_found;
  }

  // Open a new file descriptor if needed
  if (entry->data.on_disk && (entry->data.value.file == NULL)) {
    char path[store->data_path->len + entry->key->len + 2];
    sprintf(path, "%s/%s", lsm_str_ptr(store->data_path),
            lsm_str_ptr(entry->key));

    FILE *f = fopen(path, "rb");

    if (f == NULL) {
      return lsm_error_failed_io;
    }

    entry->data.value.file = f;
  }

  return lsm_error_ok;
}

lsm_error lsm_store_insert(lsm_entry **out, lsm_store *store, lsm_str *key) {
  lsm_entry_wrapper *wrapper;
  LSM_RES(lsm_entry_wrapper_init(&wrapper));

  lsm_entry *entry;
  LSM_RES(lsm_entry_init(&entry));

  entry->key = key;
  wrapper->entry = entry;
  pthread_rwlock_wrlock(&wrapper->lock);

  // TODO mem leak if already present
  LSM_RES(lsm_trie_insert(store->trie, key, wrapper));

  *out = entry;

  return lsm_error_ok;
}

lsm_error lsm_store_data_write(lsm_store *store, lsm_entry *entry,
                               lsm_str *data) {
  uint64_t new_len = entry->data.len + lsm_str_len(data);
  const char *data_s = lsm_str_ptr(data);

  // Data is in memory and still fits -> keep it in memory
  if ((new_len <= LSM_STORE_DISK_THRESHOLD) && (!entry->data.on_disk)) {
    char *buf = realloc(entry->data.value.ptr, new_len * sizeof(char));

    if (buf == NULL) {
      return lsm_error_failed_alloc;
    }

    memcpy(&buf[entry->data.len], data_s, lsm_str_len(data));
    entry->data.value.ptr = buf;
    entry->data.len = new_len;
  }
  // Data will end up on disk
  else {
    // Data is not yet on disk, so we create the file
    if (!entry->data.on_disk) {
      char path[store->data_path->len + entry->key->len + 2];
      sprintf(path, "%s/%s", lsm_str_ptr(store->data_path),
              lsm_str_ptr(entry->key));

      FILE *f = fopen(path, "w");

      if (f == NULL) {
        return lsm_error_failed_io;
      }

      entry->data.value.file = f;
      entry->data.on_disk = true;

      // TODO free old buff, write original data to file
    }

    size_t written = 0;

    // TODO what happens when I/O fails?
    while (written < data->len) {
      written += fwrite(&data_s[written], sizeof(char), data->len - written,
                        entry->data.value.file);
    }
  }

  return lsm_error_ok;
}