/*
 * history.c
 * 
 * Simple non-readline hooks for the cli library
 */
#include <string.h>
#include <stdio.h>
#include <assert.h>

#include "private.h"
#include "lub/string.h"
#include <stdlib.h>

#include "tinyrl/history.h"

struct _tinyrl_history
{
    tinyrl_history_entry_t **entries;   /* pointer entries */
    unsigned     length;    /* Number of elements within this array */
    unsigned     size;      /* Number of slots allocated in this array */
    unsigned     current_index;
    unsigned     stifle;
};

/*------------------------------------- */
void
tinyrl_history_init(tinyrl_history_t *this,
                    unsigned          stifle)
{
    this->entries       = NULL;
    this->stifle        = stifle;
    this->current_index = 1;
    this->length        = 0;
    this->size          = 0;
}
/*------------------------------------- */
void
tinyrl_history_fini(tinyrl_history_t *this)
{
    tinyrl_history_entry_t *entry;
    tinyrl_history_iterator_t iter;
    
    /* release the resource associated with each entry */
    for(entry = tinyrl_history_getfirst(this,&iter);
        entry;
        entry = tinyrl_history_getnext(&iter))
    {
        tinyrl_history_entry_delete(entry);
    }
    /* release the list */
    free(this->entries);
    this->entries = NULL;
}
/*------------------------------------- */
tinyrl_history_t *
tinyrl_history_new(unsigned stifle)
{
    tinyrl_history_t *this = malloc(sizeof(tinyrl_history_t));
    if(NULL != this)
    {
        tinyrl_history_init(this,stifle);
    }
    return this;
}
/*------------------------------------- */
void
tinyrl_history_delete(tinyrl_history_t *this)
{
    tinyrl_history_fini(this);
    free(this);
}

/*
HISTORY LIST MANAGEMENT 
*/
/*------------------------------------- */
/* insert a new entry at the current offset */
static void
insert_entry(tinyrl_history_t *this,
             const char       *line)
{
    tinyrl_history_entry_t *new_entry = tinyrl_history_entry_new(line,this->current_index++);
    assert(this->length);
    assert(this->entries);
    if(new_entry)
    {
        this->entries[this->length-1] = new_entry;
    }
}
/*------------------------------------- */
/*
 * This frees the specified entries from the 
 * entries vector. NB it doesn't perform any shuffling.
 * This function is inclusive of start and end
 */
static void
free_entries(const tinyrl_history_t *this,
             unsigned                start,
             unsigned                end)
{
    unsigned i;
    assert(start <= end);
    assert(end < this->length);
        
    for(i  = start;
        i <= end;
        i++)
    {
        tinyrl_history_entry_t *entry = this->entries[i];
        tinyrl_history_entry_delete(entry);
        entry = NULL;
    }
}
/*------------------------------------- */
/*
 * This removes the specified entries from the 
 * entries vector. Shuffling up the array as necessary 
 * This function is inclusive of start and end
 */
static void
remove_entries(tinyrl_history_t *this,
               unsigned          start,
               unsigned          end)
{
    unsigned delta = (end - start) + 1; /* number of entries being deleted */
    /* number of entries to shuffle */
    unsigned num_entries = (this->length - end) - 1; 
    assert(start <= end);
    assert(end < this->length);

    if(num_entries)
    {
        /* move the remaining entries down to close the array */
        memmove(&this->entries[start],
                &this->entries[end+1],
                sizeof(tinyrl_history_entry_t *) * num_entries);
    }
    /* now fix up the length variables */
    this->length -= delta;
}
/*------------------------------------- */
/* 
Search the current history buffer for the specified 
line and if found remove it.
*/
static bool_t
remove_duplicate(tinyrl_history_t *this,
                 const char       *line)
{
    bool_t result = BOOL_FALSE;
    unsigned i;
        
    for(i  = 0;
        i < this->length;
        i++)
    {
        tinyrl_history_entry_t *entry = this->entries[i];
        if(0 == strcmp(line,tinyrl_history_entry__get_line(entry)))
        {
            free_entries(this,i,i);
            remove_entries(this,i,i);
            result = BOOL_TRUE;
            break;
        }
    }
    return result;
}
/*------------------------------------- */
/* 
add an entry to the end of the current array 
if there is no space returns -1 else 0
*/
static void
append_entry(tinyrl_history_t *this,
             const char       *line)
{
    if(this->length < this->size)
    {
        this->length++;

        insert_entry(this,line);
    }
}
/*------------------------------------- */
/*
 add a new history entry replacing the oldest one 
 */
static void
add_n_replace(tinyrl_history_t *this,
              const char       *line)
{
    if(BOOL_FALSE == remove_duplicate(this,line))
    {
        /* free the oldest entry */
        free_entries(this,0,0);
        /* shuffle the array */
        remove_entries(this,0,0);
    }
    /* add the new entry */
    append_entry(this,line);
}
/*------------------------------------- */
/* add a new history entry growing the array if necessary */
static void
add_n_grow(tinyrl_history_t *this,
           const char       *line)
{
    if(this->size == this->length)
    {
        /* increment the history memory by 10 entries each time we grow */
        unsigned                 new_size = this->size + 10;
        size_t                   nbytes;
        tinyrl_history_entry_t **new_entries;
        
        nbytes      = sizeof(tinyrl_history_entry_t *)*new_size;
        new_entries = realloc(this->entries,nbytes);
        if(NULL != new_entries)
        {
            this->size    = new_size;
            this->entries = new_entries;
        }
    }
    (void)remove_duplicate(this,line);
    append_entry(this,line);
}
/*------------------------------------- */
void
tinyrl_history_add(tinyrl_history_t *this,
                   const char       *line)
{
    if(this->length && (this->length == this->stifle))
    {
        add_n_replace(this,line);
    }
    else
    {
        add_n_grow(this,line);
    }
}
/*------------------------------------- */
tinyrl_history_entry_t *
tinyrl_history_remove(tinyrl_history_t *this,
                      unsigned          offset)
{
    tinyrl_history_entry_t *result = NULL;
    
    if(offset < this->length)
    {
        result = this->entries[offset];
        /* do the biz */
        remove_entries(this,offset,offset);
    }
    return result;
}
/*------------------------------------- */
void
tinyrl_history_clear(tinyrl_history_t *this)
{
    /* free all the entries */
    free_entries(this,0,this->length-1);
    /* and shuffle the array */
    remove_entries(this,0,this->length-1);
}
/*------------------------------------- */
void
tinyrl_history_stifle(tinyrl_history_t *this,
                      unsigned          stifle)
{
    /* 
     * if we are stifling (i.e. non zero value) then 
     * delete the obsolete entries
     */
    if(stifle)
    {
        if(stifle < this->length)
        {
            unsigned num_deletes = this->length - stifle;
            /* free the entries */
            free_entries(this,0,num_deletes-1);
            /* shuffle the array shut */
            remove_entries(this,0,num_deletes-1);
        }
        this->stifle = stifle;
    }
}
/*------------------------------------- */
unsigned
tinyrl_history_unstifle(tinyrl_history_t *this)
{
    unsigned result = this->stifle;

    this->stifle = 0;

    return result;
}
/*------------------------------------- */
bool_t
tinyrl_history_is_stifled(const tinyrl_history_t *this)
{
    return this->stifle ? BOOL_TRUE : BOOL_FALSE;
}
/*
INFORMATION ABOUT THE HISTORY LIST 
*/    
tinyrl_history_entry_t *
tinyrl_history_get(const tinyrl_history_t *this,
                   unsigned                position)
{
    unsigned i;
    tinyrl_history_entry_t *entry = NULL;
    for(i = 0;
        i < this->length;
        i++)
    {
        entry = this->entries[i];
        if(position == tinyrl_history_entry__get_index(entry))
        {
            /* found it */
            break;
        }
        entry = NULL;
    }
    return entry;
}
/*------------------------------------- */
tinyrl_history_expand_t
tinyrl_history_expand(const tinyrl_history_t *this,
                      const char             *string, 
                      char                  **output)
{
    tinyrl_history_expand_t result = tinyrl_history_NO_EXPANSION; /* no expansion */
    const char             *p,*start;
    char                   *buffer = NULL;
    unsigned                len;
    
    for(p = string,start=string,len=0;
        *p;
        p++,len++)
    {
        /* perform pling substitution */
        if(*p == '!')
        {
            /* assume the last command to start with... */
            unsigned                offset = this->current_index - 1;
            unsigned                skip;
            tinyrl_history_entry_t *entry;
         
            /* this could be an escape sequence */
            if(p[1] != '!')
            {
                int tmp;
                int res;
                /* read the numeric identifier */
                res = sscanf(p,"!%d",&tmp);
                if((0 == res) || (EOF == res))
                {
                    /* error so ignore it */
                    break;
                }
                
                if(tmp < 0)
                {
                    /* this is a relative reference */
                    /*lint -e737 Loss of sign in promotion from int to unsigend int */
                    offset += tmp; /* adding a negative substracts... */
                    /*lint +e737 */
                }
                else
                {
                    /* this is an absolute reference */
                    offset = (unsigned)tmp;
                }
            }
            if(len > 0)
            {
                /* we need to add in some previous plain text */
                lub_string_catn(&buffer,start,len);
            }
            
            /* skip the escaped chars */
            p += skip = strspn(p,"!-0123456789");

            /* try and find the history entry */
            entry = tinyrl_history_get(this,offset);
            if(NULL != entry)
            {
                /* reset the non-escaped references */
                start = p;
                len   = 0;
                /* add the expanded text to the buffer */
                result = tinyrl_history_EXPANDED;
                lub_string_cat(&buffer,tinyrl_history_entry__get_line(entry));
            }
            else
            {
                /* we simply leave the unexpanded sequence */
                len += skip;
            }
        }
    }
    /* add any left over plain text */
    lub_string_catn(&buffer,start,len);
    *output = buffer;
    
    return result;
}
/*-------------------------------------*/
tinyrl_history_entry_t *
tinyrl_history_getfirst(const tinyrl_history_t    *this,
                        tinyrl_history_iterator_t *iter)
{
    tinyrl_history_entry_t *result = NULL;

    iter->history = this;
    iter->offset  = 0;

    if(this->length)
    {
        result = this->entries[iter->offset];
    }    
    return result;
}
/*-------------------------------------*/
tinyrl_history_entry_t *
tinyrl_history_getnext(tinyrl_history_iterator_t *iter)
{
    tinyrl_history_entry_t *result = NULL;

    if(iter->offset < iter->history->length - 1)
    {
        iter->offset++;
        result = iter->history->entries[iter->offset];
    }

    return result;
}
/*-------------------------------------*/
tinyrl_history_entry_t *
tinyrl_history_getlast (const tinyrl_history_t    *this,
                        tinyrl_history_iterator_t *iter)
{
    iter->history = this;
    iter->offset  = this->length;
    
    return tinyrl_history_getprevious(iter);
}
/*-------------------------------------*/
tinyrl_history_entry_t *
tinyrl_history_getprevious(tinyrl_history_iterator_t *iter)
{
    tinyrl_history_entry_t *result = NULL;

    if(iter->offset)
    {
        iter->offset--;
        result = iter->history->entries[iter->offset];
    }

    return result;    
}
/*-------------------------------------*/