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

#include "index.h"

struct Index* InitIndex()
{
  struct Index *index = (struct Index*)malloc(sizeof(struct Index));
  index->filelist = NULL;
  index->indexlist = NULL;
  index->relation = NULL;
  int i;
  for (i = 0; i < 26; i++)
  {
    index->indexidx[i] = NULL;
  }
  return index;
}

void DestroyIndex(struct Index *index)
{
  struct FileList *filetrav, *filelast;
  struct IndexList *indextrav, *indexlast;
  struct Relation *reltrav, *rellast;

  filetrav = index->filelist;
  while (filetrav != NULL)
  {
    filelast = filetrav;
    filetrav = filetrav->next;
    free(filelast->filename);
    free(filelast);
  }
  indextrav = index->indexlist;
  while (indextrav != NULL)
  {
    indexlast = indextrav;
    indextrav = indextrav->next;
    free(indexlast->keyword);
    free(indexlast);
  }
  reltrav = index->relation;
  while (reltrav != NULL)
  {
    rellast = reltrav;
    reltrav = reltrav->next;
    free(rellast);
  }

  free(index);
}

void Insert(struct Index *index, char *keyword, char *filename, int offset)
{
  assert(index);
  struct FileList *file = InsertFile(index, filename);
  struct IndexList *word = InsertKeyword(index, keyword);
  MakeRelation(index, word, file, offset);
}

struct IndexList* InsertKeyword(struct Index *index, char *keyword)
{
  struct IndexList *indextrav = index->indexlist, *indexlast = NULL;
  int i, j = keyword[0] - 'a';
  if (indextrav == NULL)								// empty list
  {
    indextrav = index->indexlist = (struct IndexList*)malloc(sizeof(struct IndexList));
    indextrav->next = NULL;
  }
  else if ((index->indexidx[j] == NULL) || (strcmp(index->indexidx[j]->keyword, keyword) > 0))	// index index needs updating
  {
    j -= 1;
    while ((j >= 0) && (index->indexidx[j] == NULL))
      j -= 1;

    if (j < 0)										// will become head of list
    {
      indextrav = (struct IndexList*)malloc(sizeof(struct IndexList));
      indextrav->next = index->indexlist;
      index->indexlist = indextrav;
    }
    else										// insert before first of same
    {
      indextrav = index->indexidx[j];
      while (indextrav->next != NULL)
      {
        if (indextrav->next->keyword[0] >= keyword[0])
          break;
        indextrav = indextrav->next;
      }
      indexlast = indextrav->next;
      indextrav->next = (struct IndexList*)malloc(sizeof(struct IndexList));
      indextrav = indextrav->next;
      indextrav->next = indexlast;
    }

    index->indexidx[keyword[0] - 'a'] = indextrav;
  }
  else
  {
    indextrav = index->indexidx[j];
    while (indextrav != NULL)
    {
      i = strcmp(indextrav->keyword, keyword);
      if (i == 0)
        return indextrav;
      if (i > 0)
      {
        indexlast = indexlast->next = (struct IndexList*)malloc(sizeof(struct IndexList));
        indexlast->next = indextrav;
        indextrav = indexlast;
        break;        
      }

      indexlast = indextrav;
      indextrav = indextrav->next;
    }
    if (indextrav == NULL)
    {
      indextrav = indexlast->next = (struct IndexList*)malloc(sizeof(struct IndexList));
      indextrav->next = NULL;
    }
  }

  indextrav->len = strlen(keyword) + 1;
  if ((indextrav->len % 4) != 0)
    indextrav->len += 4 - (indextrav->len % 4);
  indextrav->keyword = (char*)malloc(indextrav->len);
  strcpy(indextrav->keyword, keyword);
    
  return indextrav;
}

struct FileList* InsertFile(struct Index *index, char *filename)
{
  struct FileList *filetrav = index->filelist, *filelast;
  if (filetrav == NULL)
  {
    filetrav = index->filelist = (struct FileList*)malloc(sizeof(struct FileList));
    filetrav->next = NULL;
  }
  else
  {
    while (filetrav != NULL)
    {
      if (strcmp(filetrav->filename, filename) == 0)
        return filetrav;

      filelast = filetrav;
      filetrav = filetrav->next;
    }
    filetrav = (struct FileList*)malloc(sizeof(struct FileList));
    filetrav->next = index->filelist;
    index->filelist = filetrav;
  }

  filetrav->len = strlen(filename) + 1;
  if ((filetrav->len % 4) != 0)
    filetrav->len += 4 - (filetrav->len % 4);
  filetrav->filename = (char*)malloc(filetrav->len);
  strcpy(filetrav->filename, filename);

  return filetrav;
}

void MakeRelation(struct Index *index, struct IndexList *word, struct FileList *file, int offset)
{
  struct Relation *reltrav = index->relation;
  if (reltrav == NULL)
  {
    reltrav = index->relation = (struct Relation*)malloc(sizeof(struct Relation));
    reltrav->next = NULL;
  }
  else
  {
    reltrav = (struct Relation*)malloc(sizeof(struct Relation));
    reltrav->next = index->relation;
    index->relation = reltrav;
  }

  reltrav->word = word;
  reltrav->file = file;
  reltrav->offset = offset;
}

void Print(struct Index *index)
{
  struct FileList *filetrav = index->filelist;
  struct IndexList *indextrav = index->indexlist;
  struct Relation *reltrav = index->relation;

  printf("Filenames: ");
  if (filetrav == NULL)
    printf("** EMPTY **");
  else
    while (filetrav != NULL)
    {
      if (filetrav != index->filelist)
        printf(", ");
      printf("%s", filetrav->filename);
      filetrav = filetrav->next;
    }
  printf("\n");

  printf("Keywords: ");
  if (indextrav == NULL)
    printf("** EMPTY **");
  else
    while (indextrav != NULL)
    {
      if (indextrav != index->indexlist)
        printf(", ");
      printf("%s", indextrav->keyword);
      indextrav = indextrav->next;
    }
  printf("\n");

  printf("Relations: ");
  if (reltrav == NULL)
    printf("** EMPTY **");
  else
    while (reltrav != NULL)
    {
      if (reltrav != index->relation)
        printf(", ");
      printf("(%s,%s,%i)", reltrav->word->keyword, reltrav->file->filename, reltrav->offset);
      reltrav = reltrav->next;
    }
  printf("\n");
}