/* json beautifier
	default: print readable json
	-p: print each string/number/boolean/null value
		prefixed with a hierarchical path of object/array labels
	-u: transform the above format back into json
*/
#include <u.h>
#include <libc.h>
#include <json.h>
void*
gimme(void *p, ulong n){
	p = realloc(p, n);
	if(p == nil)
		sysfatal("realloc: %r");
	setrealloctag(p, getcallerpc(&n));
	return p;
}
void
cout(int c){
	static char b[7654];
	static int n;
	if(c == 0 || n == sizeof b){
		write(1, b, n);
		n = 0;
	}
	b[n++] = c;
}
void
sout(char *s){
	while(*s)
		cout(*s++);
}
void
cpath(int c){
	static char *s;
	static int u, a;
	if(c == -1){
		while(u && s[--u] != '[' && s[u] != '/')
			;
		return;
	}
	if(c == '/' && u == 0)
		return;
	if(u == a)
		s = gimme(s, a += 234);
	s[u++] = c;
	if(c == 0)
		sout(s);
}
void
number(void (*putc)(int), double n){
	char b[25];
	int i;
	i = n;
	if(i == n)
		seprint(b, b + sizeof b, "%d", i);
	else
		seprint(b, b + sizeof b, "%g", n);
	for(i = 0; b[i]; i++)
		putc(b[i]);
}
void
string(void (*putc)(int), char *s){
	for(; *s; s++)
		switch(*s){
		case '"': putc('\\'); putc('"'); break;
		case '\\': putc('\\'); putc('\\'); break;
		case '\b': putc('\\'); putc('b'); break;
		case '\t': putc('\\'); putc('t'); break;
		case '\f': putc('\\'); putc('f'); break;
		case '\n': putc('\\'); putc('n'); break;
		case '\r': putc('\\'); putc('r'); break;
		case '/':
		case '[':
		case ']':
		case ':':
			if(putc == cpath)
				goto hex;
		default:
			if(*s & 0xe0)
				putc(*s);
			else{
		hex:
				putc('\\');
				putc('u');
				putc('0');
				putc('0');
				putc('0' + (*s >> 4));
				putc((*s & 15) > 9 ? 'A' - 10 + (*s & 15) : '0' + (*s & 15));
			}
			break;
		}
}
void
index(int i){
	int m;
	cpath('[');
	for(m = 10; i / m; m *= 10)
		;
	while(m > 1){
		m /= 10;
		cpath('0' + i / m);
		i %= m;
	}
	cpath(']');
}
void
pretty(JSON *j, int d){
	JSONEl *e;
	int i;
	switch(j->t){
	case JSONNull:
		sout("null");
		break;
	case JSONBool:
		sout(j->n == 0 ? "false" : "true");
		break;
	case JSONNumber:
		number(cout, j->n);
		break;
	case JSONString:
		cout('"');
		string(cout, j->s);
		cout('"');
		break;
	case JSONArray:
		cout('[');
		for(e = j->first; e != nil; e = e->next){
			cout('\n');
			for(i = 0; i < d; i++)
				cout('\t');
			pretty(e->val, d + 1);
			if(e->next != nil)
				cout(',');
		}
		cout('\n');
		for(i = 1; i < d; i++)
			cout('\t');
		cout(']');
		break;
	case JSONObject:
		cout('{');
		for(e = j->first; e != nil; e = e->next){
			cout('\n');
			for(i = 0; i < d; i++)
				cout('\t');
			cout('"');
			string(cout, e->name);
			cout('"');
			cout(':');
			cout(' ');
			pretty(e->val, d + 1);
			if(e->next != nil)
				cout(',');
		}
		cout('\n');
		for(i = 1; i < d; i++)
			cout('\t');
		cout('}');
		break;
	}
}
void
path(JSON *j){
	JSONEl *e;
	int i;
	switch(j->t){
	case JSONNull:
		cpath(0);
		sout(": null\n");
		break;
	case JSONBool:
		cpath(0);
		sout(j->n == 0 ? ": false\n" : ": true\n");
		break;
	case JSONNumber:
		cpath(0);
		cout(':');
		cout(' ');
		number(cout, j->n);
		cout('\n');
		break;
	case JSONString:
		cpath(0);
		cout(':');
		cout(' ');
		string(cout, j->s);
		cout('\n');
		break;
	case JSONArray:
		for(i = 0, e = j->first; e != nil; e = e->next){
			index(i++);
			path(e->val);
			cpath(-1);
		}
		break;
	case JSONObject:
		for(e = j->first; e != nil; e = e->next){
			cpath('/');
			string(cpath, e->name);
			path(e->val);
			cpath(-1);
		}
		break;
	}
}
Rune
rune(char *s){
	Rune r;
	int i;
	for(r = i = 0; i < 4; i++)
		if(*s >= '0' && *s <= '9')
			r = r << 4 | *s++ - '0';
		else if(*s >= 'A' && *s <= 'F')
			r = r << 4 | *s++ - 'A' + 10;
		else if(*s >= 'a' && *s <= 'f')
			r = r << 4 | *s++ - 'a' + 10;
		else
			return Runeerror;
	return r;
}
char*
unstring(char *s, char *e){
	char *ns, *ne;
	Rune r;
	if(s == nil)
		return nil;
	ne = ns = gimme(nil, e - s + 1);
	while(s < e){
		if(*s == '\\' && s + 1 < e)
			switch(s[1]){
			case '\\': *ne++ = '\\'; s += 2; continue;
			case '"': *ne++ = '"'; s += 2; continue;
			case 'b': *ne++ = '\b'; s += 2; continue;
			case 't': *ne++ = '\t'; s += 2; continue;
			case 'f': *ne++ = '\f'; s += 2; continue;
			case 'n': *ne++ = '\n'; s += 2; continue;
			case 'r': *ne++ = '\r'; s += 2; continue;
			case 'u':
				if(e - s < 6 || (r = rune(s + 2)) == Runeerror)
					break;
				s += 6;
				ne += runetochar(ne, &r);
				continue;
			}
		*ne++ = *s++;
	}
	*ne = 0;
	return ne - ns < e - s ? gimme(ns, ne - ns + 1) : ns;
}
JSONEl*
new(char *s){
	JSONEl *e;
	e = gimme(nil, sizeof *e);
	e->name = s;
	e->val = gimme(nil, sizeof(JSON));
	e->val->t = JSONNull;
	e->next = nil;
	return e;
}
void
usage(void){
	sysfatal("usage: %s [-p | -u] < data.json", argv0);
}
void
main(int argc, char **argv){
	JSON *r, *j;
	JSONEl **p;
	int a, u, n;
	char *s, *t, m;
	m = 0;
	ARGBEGIN{
	default: usage();
	case 'u': if(m) usage(); m = 'u'; break;
	case 'p': if(m) usage(); m = 'p'; break;
	}ARGEND
	if(argc)
		usage();
	s = nil;
	u = 0;
	a = 1999;
	while(9){
		if(a - u < 2000)
			s = gimme(s, a <<= 1);
		n = read(0, s + u, a - u);
		if(n < 1)
			break;
		u += n;
	}
	if(n)
		sysfatal("read: %r");
	s = gimme(s, u + 1);
	s[u] = 0;
#define err(msg) sysfatal("%s near #%d (byte %d)", msg, utfnlen(s, a), a);
	if(m == 'u'){
		r = gimme(nil, sizeof *r);
		r->t = JSONNull;
		a = 0;
		while(9){
			while(s[a] == '\n')
				a++;
			if(s[a] == 0)
				break;
			j = r;
			while(s[a] && s[a] != ':' && s[a] != '\n'){
				if(j->t == JSONNull){
					j->t = s[a] == '[' ? JSONArray : JSONObject;
					j->first = nil;
				}
				if(s[a] == '['){
					 if(j->t != JSONArray)
					 	err("not an array");
					n = 0;
					while(s[++a] >= '0' && s[a] <= '9')
						n = n * 10 + s[a] - '0';
					if(s[a++] != ']')
						err("bad array index");
					for(p = &j->first; n--; p = &(*p)->next)
						if(*p == nil)
							*p = new(nil);
					if(*p == nil)
						*p = new(nil);
				}else{
					if(j->t != JSONObject)
						err("not an object");
					if(s[a] == '/')
						a++;
					n = 0;
					while(s[a + n] != '/' && s[a + n] != '[' 
					&& s[a + n] && s[a + n] != ':' && s[a + n] != '\n')
					 	n++;
					if(n == 0)
						err("empty key string");
					t = unstring(s + a, s + a + n);
					for(p = &j->first; *p != nil && strcmp(t, (*p)->name); p = &(*p)->next)
						;
					if(*p == nil)
						*p = new(t);
					else
						free(t);
					a += n;
				}
				j = (*p)->val;
			}
			if(s[a++] != ':' || s[a++] != ' ')
				err("missing colon");
			if(j->t != JSONNull)
				err("new value assigned to old key");
			for(n = a; s[a] && s[a] != '\n'; a++)
				;
			if(a - n == 4 && !strncmp(s + n, "true", 4)){
				j->t = JSONBool;
				j->n = 1;
			}else if(a - n == 5 && !strncmp(s + n, "false", 5)){
				j->t = JSONBool;
				j->n = 0;
			}else if(a - n != 4 || strncmp(s + n, "null", 4)){
				j->n = strtod(s + n, &t);
				if(t == s + a)
					j->t = JSONNumber;
				else{
					j->t = JSONString;
					j->s = unstring(s + n, s + a);
				}
			}
		}
	}else if((r = jsonparse(s)) == nil)
			sysfatal("jsonparse: %r");
	free(s);
	if(m ==  'p')
		path(r);
	else{
		pretty(r, 1);
		cout('\n');
	}
	cout(0);
	exits(nil);
}