#include <ctype.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "cJSON_Utils.h"

static int cJSONUtils_strcasecmp(const char *s1, const char *s2)
{
    if (!s1)
    {
        return (s1 == s2) ? 0 : 1; /* both NULL? */
    }
    if (!s2)
    {
        return 1;
    }
    for(; tolower(*s1) == tolower(*s2); ++s1, ++s2)
    {
        if(*s1 == 0)
        {
            return 0;
        }
    }

    return tolower(*(const unsigned char *)s1) - tolower(*(const unsigned char *)s2);
}

/* JSON Pointer implementation: */
static int cJSONUtils_Pstrcasecmp(const char *a, const char *e)
{
    if (!a || !e)
    {
        return (a == e) ? 0 : 1; /* both NULL? */
    }
    for (; *a && *e && (*e != '/'); a++, e++) /* compare until next '/' */
    {
        if (*e == '~')
        {
            /* check for escaped '~' (~0) and '/' (~1) */
            if (!((e[1] == '0') && (*a == '~')) && !((e[1] == '1') && (*a == '/')))
            {
                /* invalid escape sequence or wrong character in *a */
                return 1;
            }
            else
            {
                e++;
            }
        }
        else if (tolower(*a) != tolower(*e))
        {
            return 1;
        }
    }
    if (((*e != 0) && (*e != '/')) != (*a != 0))
    {
        /* one string has ended, the other not */
        return 1;
    }

    return 0;
}

static int cJSONUtils_PointerEncodedstrlen(const char *s)
{
    int l = 0;
    for (; *s; s++, l++)
    {
        if ((*s == '~') || (*s == '/'))
        {
            l++;
        }
    }

    return l;
}

static void cJSONUtils_PointerEncodedstrcpy(char *d, const char *s)
{
    for (; *s; s++)
    {
        if (*s == '/')
        {
            *d++ = '~';
            *d++ = '1';
        }
        else if (*s == '~')
        {
            *d++ = '~';
            *d++ = '0';
        }
        else
        {
            *d++ = *s;
        }
    }

    *d = '\0';
}

char *cJSONUtils_FindPointerFromObjectTo(cJSON *object, cJSON *target)
{
    int type = object->type;
    int c = 0;
    cJSON *obj = 0;

    if (object == target)
    {
        /* found */
        return strdup("");
    }

    /* recursively search all children of the object */
    for (obj = object->child; obj; obj = obj->next, c++)
    {
        char *found = cJSONUtils_FindPointerFromObjectTo(obj, target);
        if (found)
        {
            if (type == cJSON_Array)
            {
                /* reserve enough memory for a 64 bit integer + '/' and '\0' */
                char *ret = (char*)malloc(strlen(found) + 23);
                sprintf(ret, "/%d%s", c, found); /* /<array_index><path> */
                free(found);

                return ret;
            }
            else if (type == cJSON_Object)
            {
                char *ret = (char*)malloc(strlen(found) + cJSONUtils_PointerEncodedstrlen(obj->string) + 2);
                *ret = '/';
                cJSONUtils_PointerEncodedstrcpy(ret + 1, obj->string);
                strcat(ret, found);
                free(found);

                return ret;
            }

            /* reached leaf of the tree, found nothing */
            free(found);
            return 0;
        }
    }

    /* not found */
    return 0;
}

cJSON *cJSONUtils_GetPointer(cJSON *object, const char *pointer)
{
    /* follow path of the pointer */
    while ((*pointer++ == '/') && object)
    {
        if (object->type == cJSON_Array)
        {
            int which = 0;
            /* parse array index */
            while ((*pointer >= '0') && (*pointer <= '9'))
            {
                which = (10 * which) + (*pointer++ - '0');
            }
            if (*pointer && (*pointer != '/'))
            {
                /* not end of string or new path token */
                return 0;
            }
            object = cJSON_GetArrayItem(object, which);
        }
        else if (object->type == cJSON_Object)
        {
            object = object->child;
            /* GetObjectItem. */
            while (object && cJSONUtils_Pstrcasecmp(object->string, pointer))
            {
                object = object->next;
            }
            /* skip to the next path token or end of string */
            while (*pointer && (*pointer != '/'))
            {
                pointer++;
            }
        }
        else
        {
            return 0;
        }
    }

    return object;
}

/* JSON Patch implementation. */
static void cJSONUtils_InplaceDecodePointerString(char *string)
{
    char *s2 = string;
    for (; *string; s2++, string++)
    {
        *s2 = (*string != '~')
            ? (*string)
            : ((*(++string) == '0')
                    ? '~'
                    : '/');
    }

    *s2 = '\0';
}

static cJSON *cJSONUtils_PatchDetach(cJSON *object, const char *path)
{
    char *parentptr = 0;
    char *childptr = 0;
    cJSON *parent = 0;
    cJSON *ret = 0;

    /* copy path and split it in parent and child */
    parentptr = strdup(path);
    childptr = strrchr(parentptr, '/'); /* last '/' */
    if (childptr)
    {
        /* split strings */
        *childptr++ = '\0';
    }
    parent = cJSONUtils_GetPointer(object, parentptr);
    cJSONUtils_InplaceDecodePointerString(childptr);

    if (!parent)
    {
        /* Couldn't find object to remove child from. */
        ret = 0;
    }
    else if (parent->type == cJSON_Array)
    {
        ret = cJSON_DetachItemFromArray(parent, atoi(childptr));
    }
    else if (parent->type == cJSON_Object)
    {
        ret = cJSON_DetachItemFromObject(parent, childptr);
    }
    free(parentptr);

    /* return the detachted item */
    return ret;
}

static int cJSONUtils_Compare(cJSON *a, cJSON *b)
{
    if (a->type != b->type)
    {
        /* mismatched type. */
        return -1;
    }
    switch (a->type)
    {
        case cJSON_Number:
            /* numeric mismatch. */
            return ((a->valueint != b->valueint) || (a->valuedouble != b->valuedouble)) ? -2 : 0;
        case cJSON_String:
            /* string mismatch. */
            return (strcmp(a->valuestring, b->valuestring) != 0) ? -3 : 0;
        case cJSON_Array:
            for (a = a->child, b = b->child; a && b; a = a->next, b = b->next)
            {
                int err = cJSONUtils_Compare(a, b);
                if (err)
                {
                    return err;
                }
            }
            /* array size mismatch? (one of both children is not NULL) */
            return (a || b) ? -4 : 0;
        case cJSON_Object:
            cJSONUtils_SortObject(a);
            cJSONUtils_SortObject(b);
            a = a->child;
            b = b->child;
            while (a && b)
            {
                int err;
                /* compare object keys */
                if (cJSONUtils_strcasecmp(a->string, b->string))
                {
                    /* missing member */
                    return -6;
                }
                err = cJSONUtils_Compare(a, b);
                if (err)
                {
                    return err;
                }
                a = a->next;
                b = b->next;
            }
            /* object length mismatch (one of both children is not null) */
            return (a || b) ? -5 : 0;

        default:
            break;
    }
    /* null, true or false */
    return 0;
}

static int cJSONUtils_ApplyPatch(cJSON *object, cJSON *patch)
{
    cJSON *op = 0;
    cJSON *path = 0;
    cJSON *value = 0;
    cJSON *parent = 0;
    int opcode = 0;
    char *parentptr = 0;
    char *childptr = 0;

    op = cJSON_GetObjectItem(patch, "op");
    path = cJSON_GetObjectItem(patch, "path");
    if (!op || !path)
    {
        /* malformed patch. */
        return 2;
    }

    /* decode operation */
    if (!strcmp(op->valuestring, "add"))
    {
        opcode = 0;
    }
    else if (!strcmp(op->valuestring, "remove"))
    {
        opcode = 1;
    }
    else if (!strcmp(op->valuestring, "replace"))
    {
        opcode = 2;
    }
    else if (!strcmp(op->valuestring, "move"))
    {
        opcode = 3;
    }
    else if (!strcmp(op->valuestring, "copy"))
    {
        opcode = 4;
    }
    else if (!strcmp(op->valuestring, "test"))
    {
        /* compare value: {...} with the given path */
        return cJSONUtils_Compare(cJSONUtils_GetPointer(object, path->valuestring), cJSON_GetObjectItem(patch, "value"));
    }
    else
    {
        /* unknown opcode. */
        return 3;
    }

    /* Remove/Replace */
    if ((opcode == 1) || (opcode == 2))
    {
        /* Get rid of old. */
        cJSON_Delete(cJSONUtils_PatchDetach(object, path->valuestring));
        if (opcode == 1)
        {
            /* For Remove, this is job done. */
            return 0;
        }
    }

    /* Copy/Move uses "from". */
    if ((opcode == 3) || (opcode == 4))
    {
        cJSON *from = cJSON_GetObjectItem(patch, "from");
        if (!from)
        {
            /* missing "from" for copy/move. */
            return 4;
        }

        if (opcode == 3)
        {
            /* move */
            value = cJSONUtils_PatchDetach(object, from->valuestring);
        }
        if (opcode == 4)
        {
            /* copy */
            value = cJSONUtils_GetPointer(object, from->valuestring);
        }
        if (!value)
        {
            /* missing "from" for copy/move. */
            return 5;
        }
        if (opcode == 4)
        {
            value = cJSON_Duplicate(value, 1);
        }
        if (!value)
        {
            /* out of memory for copy/move. */
            return 6;
        }
    }
    else /* Add/Replace uses "value". */
    {
        value = cJSON_GetObjectItem(patch, "value");
        if (!value)
        {
            /* missing "value" for add/replace. */
            return 7;
        }
        value = cJSON_Duplicate(value, 1);
        if (!value)
        {
            /* out of memory for add/replace. */
            return 8;
        }
    }

    /* Now, just add "value" to "path". */

    /* split pointer in parent and child */
    parentptr = strdup(path->valuestring);
    childptr = strrchr(parentptr, '/');
    if (childptr)
    {
        *childptr++ = '\0';
    }
    parent = cJSONUtils_GetPointer(object, parentptr);
    cJSONUtils_InplaceDecodePointerString(childptr);

    /* add, remove, replace, move, copy, test. */
    if (!parent)
    {
        /* Couldn't find object to add to. */
        free(parentptr);
        cJSON_Delete(value);
        return 9;
    }
    else if (parent->type == cJSON_Array)
    {
        if (!strcmp(childptr, "-"))
        {
            cJSON_AddItemToArray(parent, value);
        }
        else
        {
            cJSON_InsertItemInArray(parent, atoi(childptr), value);
        }
    }
    else if (parent->type == cJSON_Object)
    {
        cJSON_DeleteItemFromObject(parent, childptr);
        cJSON_AddItemToObject(parent, childptr, value);
    }
    else
    {
        cJSON_Delete(value);
    }
    free(parentptr);

    return 0;
}

int cJSONUtils_ApplyPatches(cJSON *object,cJSON *patches)
{
	int err;
	if (patches->type!=cJSON_Array) return 1;	/* malformed patches. */
	if (patches) patches=patches->child;
	while (patches)
	{
		if ((err=cJSONUtils_ApplyPatch(object,patches))) return err;
		patches=patches->next;
	}
	return 0;
}

static void cJSONUtils_GeneratePatch(cJSON *patches,const char *op,const char *path,const char *suffix,cJSON *val)
{
	cJSON *patch=cJSON_CreateObject();
	cJSON_AddItemToObject(patch,"op",cJSON_CreateString(op));
	if (suffix)
	{
		char *newpath=(char*)malloc(strlen(path)+cJSONUtils_PointerEncodedstrlen(suffix)+2);
		cJSONUtils_PointerEncodedstrcpy(newpath+sprintf(newpath,"%s/",path),suffix);
		cJSON_AddItemToObject(patch,"path",cJSON_CreateString(newpath));
		free(newpath);
	}
	else	cJSON_AddItemToObject(patch,"path",cJSON_CreateString(path));
	if (val) cJSON_AddItemToObject(patch,"value",cJSON_Duplicate(val,1));
	cJSON_AddItemToArray(patches,patch);
}

void cJSONUtils_AddPatchToArray(cJSON *array,const char *op,const char *path,cJSON *val)	{cJSONUtils_GeneratePatch(array,op,path,0,val);}

static void cJSONUtils_CompareToPatch(cJSON *patches,const char *path,cJSON *from,cJSON *to)
{
	if (from->type!=to->type)	{cJSONUtils_GeneratePatch(patches,"replace",path,0,to);	return;	}
	
	switch (from->type)
	{
	case cJSON_Number:	
		if (from->valueint!=to->valueint || from->valuedouble!=to->valuedouble)
			cJSONUtils_GeneratePatch(patches,"replace",path,0,to);
		return;
						
	case cJSON_String:	
		if (strcmp(from->valuestring,to->valuestring)!=0)
			cJSONUtils_GeneratePatch(patches,"replace",path,0,to);
		return;

	case cJSON_Array:
	{
		int c;char *newpath=(char*)malloc(strlen(path)+23);	/* Allow space for 64bit int. */
		for (c=0,from=from->child,to=to->child;from && to;from=from->next,to=to->next,c++){
										sprintf(newpath,"%s/%d",path,c);	cJSONUtils_CompareToPatch(patches,newpath,from,to);
		}
		for (;from;from=from->next,c++)	{sprintf(newpath,"%d",c);	cJSONUtils_GeneratePatch(patches,"remove",path,newpath,0);	}
		for (;to;to=to->next,c++)		cJSONUtils_GeneratePatch(patches,"add",path,"-",to);
		free(newpath);
		return;
	}

	case cJSON_Object:
	{
		cJSON *a,*b;
		cJSONUtils_SortObject(from);
		cJSONUtils_SortObject(to);
		
		a=from->child,b=to->child;
		while (a || b)
		{
			int diff=(!a)?1:(!b)?-1:cJSONUtils_strcasecmp(a->string,b->string);
			if (!diff)
			{
				char *newpath=(char*)malloc(strlen(path)+cJSONUtils_PointerEncodedstrlen(a->string)+2);
				cJSONUtils_PointerEncodedstrcpy(newpath+sprintf(newpath,"%s/",path),a->string);
				cJSONUtils_CompareToPatch(patches,newpath,a,b);
				free(newpath);
				a=a->next;
				b=b->next;
			}
			else if (diff<0)	{cJSONUtils_GeneratePatch(patches,"remove",path,a->string,0);	a=a->next;}
			else				{cJSONUtils_GeneratePatch(patches,"add",path,b->string,b);		b=b->next;}
		}
		return;
	}

	default:			break;
	}
}


cJSON* cJSONUtils_GeneratePatches(cJSON *from,cJSON *to)
{
	cJSON *patches=cJSON_CreateArray();	
	cJSONUtils_CompareToPatch(patches,"",from,to);
	return patches;
}


static cJSON *cJSONUtils_SortList(cJSON *list)
{
	cJSON *first=list,*second=list,*ptr=list;

	if (!list || !list->next) return list;	/* One entry is sorted already. */
	
	while (ptr && ptr->next && cJSONUtils_strcasecmp(ptr->string,ptr->next->string)<0) ptr=ptr->next;	/* Test for list sorted. */
	if (!ptr || !ptr->next) return list;	/* Leave sorted lists unmodified. */
	ptr=list;

	while (ptr) {second=second->next;ptr=ptr->next;if (ptr) ptr=ptr->next;}	/* Walk two pointers to find the middle. */
	if (second && second->prev) second->prev->next=0;	/* Split the lists */

	first=cJSONUtils_SortList(first);	/* Recursively sort the sub-lists. */
	second=cJSONUtils_SortList(second);
	list=ptr=0;

	while (first && second)	/* Merge the sub-lists */
	{		
		if (cJSONUtils_strcasecmp(first->string,second->string)<0)
		{
			if (!list) list=ptr=first;
			else	{ptr->next=first;first->prev=ptr;ptr=first;}
			first=first->next;
		}
		else 
		{
			if (!list) list=ptr=second;
			else	{ptr->next=second;second->prev=ptr;ptr=second;}
			second=second->next;
		}
	}
	if (first)	{	if (!list) return first;	ptr->next=first;	first->prev=ptr;	}	/* Append any tails. */
	if (second)	{	if (!list) return second;	ptr->next=second;	second->prev=ptr;	}

	return list;
}

void cJSONUtils_SortObject(cJSON *object)	{object->child=cJSONUtils_SortList(object->child);}

cJSON* cJSONUtils_MergePatch(cJSON *target, cJSON *patch)
{
	if (!patch || patch->type != cJSON_Object) {cJSON_Delete(target);return cJSON_Duplicate(patch,1);}
	if (!target || target->type != cJSON_Object) {cJSON_Delete(target);target=cJSON_CreateObject();}

	patch=patch->child;
	while (patch)
	{
		if (patch->type == cJSON_NULL) cJSON_DeleteItemFromObject(target,patch->string);
		else
		{
			cJSON *replaceme=cJSON_DetachItemFromObject(target,patch->string);
			cJSON_AddItemToObject(target,patch->string,cJSONUtils_MergePatch(replaceme,patch));
		}
		patch=patch->next;
	}
	return target;
}

cJSON *cJSONUtils_GenerateMergePatch(cJSON *from,cJSON *to)
{
	cJSON *patch=0;
	if (!to) return cJSON_CreateNull();
	if (to->type!=cJSON_Object || !from || from->type!=cJSON_Object) return cJSON_Duplicate(to,1);
	cJSONUtils_SortObject(from);
	cJSONUtils_SortObject(to);
	from=from->child;to=to->child;
	patch=cJSON_CreateObject();
	while (from || to)
	{
		int compare=from?(to?strcmp(from->string,to->string):-1):1;
		if (compare<0)
		{
			cJSON_AddItemToObject(patch,from->string,cJSON_CreateNull());
			from=from->next;
		}
		else if (compare>0)
		{
			cJSON_AddItemToObject(patch,to->string,cJSON_Duplicate(to,1));
			to=to->next;
		}
		else
		{
			if (cJSONUtils_Compare(from,to)) cJSON_AddItemToObject(patch,to->string,cJSONUtils_GenerateMergePatch(from,to));
			from=from->next;to=to->next;
		}
	}
	if (!patch->child) {cJSON_Delete(patch);return 0;}
	return patch;
}