#include <lladd/transactional.h>

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

typedef struct {
  short nextEntry;
  short keySize;
} pagedListEntry;

compensated_function recordid TpagedListAlloc(int xid) {
  recordid ret;
  try_ret(NULLRID) {
    ret = Talloc(xid, sizeof(pagedListHeader));
    pagedListHeader header;
    header.thisPage = 0;
    header.nextPage = NULLRID;
    Tset(xid, ret, &header);
  } end_ret(NULLRID);
  return ret;
}

compensated_function int TpagedListInsert(int xid, recordid list, const byte * key, int keySize, const byte * value, int valueSize) {
  int ret;
  try_ret(compensation_error()) {
    pagedListHeader header;
    Tread(xid, list, &header);
    recordid headerRid = list;

    byte * garbage;
    ret = (TpagedListFind(xid, list, key, keySize, &garbage) != -1);
    if(ret) {
      free(garbage);
      TpagedListRemove(xid, list, key, keySize);
    }
    int entrySize = sizeof(pagedListEntry) + keySize + valueSize;
    
    recordid rid = TallocFromPage(xid, headerRid.page, entrySize);
    DEBUG("Alloced rid: {%d %d %d}", rid.page, rid.slot, rid.size);
    
    // When the loop completes, header will contain the contents of the page header the entry will be inserted into, 
    // headerrid will contain the rid of that header, and rid will contain the newly allocated recordid
    while(rid.size == -1) {
      if(compensation_error()) { break; }
      if(header.nextPage.size == -1)  {
	header.nextPage = Talloc(xid, sizeof(pagedListHeader));
	DEBUG("allocing on new page %d\n", header.nextPage.page);
	Tset(xid, headerRid, &header);
	pagedListHeader newHead;
	newHead.thisPage = 0;
	newHead.nextPage.page =0;
	newHead.nextPage.slot =0;
	newHead.nextPage.size =-1;
	Tset(xid, header.nextPage, &newHead);
      }
      
      headerRid = header.nextPage;
      Tread(xid, header.nextPage, &header);
      rid = TallocFromPage(xid, headerRid.page, entrySize);
      DEBUG("Alloced rid: {%d %d %d}", rid.page, rid.slot, rid.size);
    }
    
    pagedListEntry * dat = malloc(entrySize);
    
    dat->keySize   = keySize;
    dat->nextEntry = header.thisPage;
    memcpy(dat+1, key, keySize);
    memcpy(((byte*)(dat+1))+keySize, value, valueSize);
    Tset(xid, rid, dat);
    
    header.thisPage = rid.slot;
    DEBUG("Header.thisPage = %d\n", rid.slot);
    Tset(xid, headerRid, &header);
    free(dat);
  } end_ret(compensation_error());
  return ret;
}

compensated_function int TpagedListFind(int xid, recordid list, const byte * key, int keySize, byte ** value) {
  try_ret(compensation_error()) { 
    pagedListHeader header;
    Tread(xid, list, &header);
    
    recordid rid;
    rid.page = list.page;
    rid.slot = header.thisPage;

    while(rid.slot || header.nextPage.size != -1) {
      if(compensation_error()) { break; }
      
      if(rid.slot) {
	rid.size = TrecordSize(xid, rid);
	pagedListEntry * dat;      
	if(compensation_error()) { break; }
	dat = malloc(rid.size);
	Tread(xid, rid, dat);
	
	if(!memcmp(dat+1, key, keySize)) {
	  int valueSize = rid.size - keySize - sizeof(pagedListEntry);
	  *value = malloc(valueSize);
	  memcpy(*value, ((byte*)(dat+1))+keySize, valueSize);
	  free(dat);
	  return valueSize;
	}
	//      if(dat->nextEntry) {          // another entry on this page
	rid.slot = dat->nextEntry;
	free(dat);	//      }
      } else if (header.nextPage.size != -1) {  // another page
	rid.page = header.nextPage.page;
	Tread(xid, header.nextPage, &header);
	rid.slot = header.thisPage;
      } else {                     // we've reached the end of the last page
	rid.slot = 0;
      }
    }
  } end_ret(compensation_error());
  return -1;
}

compensated_function int TpagedListRemove(int xid, recordid list, const byte * key, int keySize) {
  pagedListHeader header;
  int ret = 0;
  try_ret(compensation_error()) { 

    Tread(xid, list, &header);
    recordid headerRid;
    recordid rid;
    rid.page = list.page;
    rid.slot = header.thisPage;
    short lastSlot = -1;
    headerRid = list;
    while(rid.slot || header.nextPage.size != -1) {
      if(compensation_error()) { break; }
      if(rid.slot) {
	rid.size = TrecordSize(xid, rid);
	if(compensation_error()) { break; };
	pagedListEntry * dat = malloc(rid.size);
	Tread(xid, rid, dat);
	
	if(!memcmp(dat+1, key, keySize)) {
	  
	  if(lastSlot != -1) {
	    recordid lastRid = rid;
	    lastRid.slot = lastSlot;
	    lastRid.size = TrecordSize(xid, lastRid);
	    if(compensation_error()) { free(dat); break; }
	    pagedListEntry * lastRidBuf = malloc(lastRid.size);
	    Tread(xid, lastRid, lastRidBuf);
	    lastRidBuf->nextEntry = dat->nextEntry;
	    Tset(xid, lastRid, lastRidBuf);
	    free(lastRidBuf);
	  } else {
	  header.thisPage = dat->nextEntry;
	  Tset(xid, headerRid, &header);
	  }
	  Tdealloc(xid, rid);
	  free(dat);
	  ret = 1;
	  break;
	}
	lastSlot = rid.slot;
	rid.slot = dat->nextEntry;
	free(dat);
      } else if (header.nextPage.size != -1) {  // another page
	lastSlot = -1;
	rid.page = header.nextPage.page;
	headerRid = header.nextPage;
	Tread(xid, header.nextPage, &header);
	rid.slot = header.thisPage;
      }
    }
  } end_ret(compensation_error());
  return ret;
}

compensated_function int TpagedListMove(int xid, recordid start_list, recordid end_list, const byte * key, int keySize) {
  byte * value = NULL;
  int ret;
  try_ret(compensation_error()) {
    int valueSize = TpagedListFind(xid, start_list, key, keySize, &value);
    if(valueSize != -1) {
      int ret = TpagedListRemove(xid, start_list, key, keySize);
      assert(ret);
      ret = TpagedListInsert(xid, end_list, key, keySize, value, valueSize);
      assert(!ret);
      if(value) { free(value); }
      ret = 1;
    } else { 
      ret = 0;
    }
  } end_ret(compensation_error());
  return ret;
}

compensated_function lladd_pagedList_iterator * TpagedListIterator(int xid, recordid list) { 
  pagedListHeader header;
  assert(list.size == sizeof(pagedListHeader));
  try_ret(NULL) { 
    Tread(xid, list, &header);
  } end_ret(NULL);

  lladd_pagedList_iterator * it = malloc(sizeof(lladd_pagedList_iterator));

  it->headerRid = header.nextPage;
  it->entryRid  = list;
  //  printf("slot <- %d\n", header.thisPage);
  it->entryRid.slot = header.thisPage;
  
  return it;
}

compensated_function int TpagedListNext(int xid, lladd_pagedList_iterator * it,
		   byte ** key, int * keySize,
		   byte ** value, int * valueSize) {
  while(it->entryRid.slot || it->headerRid.size != -1) {
    if(it->entryRid.slot) {
      try_ret(compensation_error()) {
	it->entryRid.size = TrecordSize(xid, it->entryRid);
      } end_ret(compensation_error());
      assert(it->entryRid.size != -1);

      pagedListEntry * entry = malloc(it->entryRid.size);
      begin_action_ret(free, entry, compensation_error()) {
	Tread(xid, it->entryRid, entry);
      } end_action_ret(compensation_error());
      
      *keySize = entry->keySize;
      *valueSize = it->entryRid.size - *keySize - sizeof(pagedListEntry);

      *key = malloc(*keySize);
      *value = malloc(*valueSize);

      memcpy(*key, entry+1, *keySize);
      memcpy(*value, ((byte*)(entry+1))+*keySize, *valueSize);
      
      it->entryRid.slot = entry->nextEntry;
      //      printf("slotA <- %d\n", it->entryRid.slot);

      free(entry);
      return 1;

    } else {  // move to next page.
      pagedListHeader header;
      try_ret(compensation_error()) {
	Tread(xid, it->headerRid, &header);
      } end_ret(compensation_error());
      it->entryRid.page = it->headerRid.page;
      it->headerRid = header.nextPage;
      it->entryRid.slot = header.thisPage;
      //      printf("slotB <- %d\n", it->entryRid.slot);
    }
  }
  return 0;
}