#include <math.h>
#include <time.h>
#include <string.h>
#include <stdio.h>

#include "lib.h"
#include "state.h"
#include "val.h"
#include "util.h"
#include "mem.h"

static Val fn_clock(State *S, int nargs, Val *args) {
	return VAL_NUM((double)clock() / CLOCKS_PER_SEC);
}

static Val fn_write(State *S, int nargs, Val *args) {
	CHECK(nargs>0, "need 1 arg to write");
	for (int i = 0; i < nargs; i++) print_val(args[i]);
	return VAL_NIL;
}
static Val fn_say(State *S, int nargs, Val *args) {
	CHECK(nargs>0, "need 1 arg to say");
	for (int i = 0; i < nargs; i++) println_val(args[i]);
	return VAL_NIL;
}

static uint8_t num_to_u8(Val v) {
	CHECK(IS_NUM(v), "can't convert non-num to u8");
	return (uint8_t)AS_NUM(v);
}
static Val fn_writebytes(State *S, int nargs, Val *args) {
	CHECK(nargs == 1, "need exactly 1 arg to writebytes");
	CHECK(IS_ARR(args[0]), "need array arg to writebytes");
	ObjArr *a = AS_ARR(args[0]);
	uint8_t *buf = malloc(1 * a->len);
	for (int i = 0; i < a->len; i++) {
		buf[i] = num_to_u8(a->d[i]);
	}
	fwrite(buf, 1, a->len, stdout);
	return VAL_NIL;
}

static Val fn_readstring(State *S, int nargs, Val *args){
	CHECK(nargs == 1, "need exactly 1 arg to readstring");
	CHECK(IS_STRING(args[0]), "need string arg to readstring");
	FILE *f = fopen(AS_CSTRING(args[0]), "r");
	CHECK(f != NULL, "io error (fopen)");
	fseek(f, 0L, SEEK_END);
	long flen = ftell(f);
	char *buf = NEW_ARR(S, char, flen+1);
	rewind(f); fread(buf, 1, flen, f);
		CHECK(!ferror(f), "file error");
	buf[flen] = '\0';
	return VAL_OBJ(objstring_take(S, buf, flen));
}


// lists
static Val fn_arr(State *S, int nargs, Val *args) {
	CHECK(nargs == 0, "need 0 args to arr");
	ObjArr *o = objarr_new(S);
	return VAL_OBJ(o);
}
static Val fn_append(State *S, int nargs, Val *args) {
	CHECK(nargs == 2, "need 2 args to append!");
	CHECK(IS_ARR(args[0]), "can only append to arr");
	ObjArr *a = AS_ARR(args[0]);
	objarr_append(S, a, args[1]);
	return args[0];
}
static Val fn_delete(State *S, int nargs, Val *args) {
	CHECK(nargs == 2, "need 2 args to delete!");
	CHECK(IS_ARR(args[0]), "can only delete from arr");
	CHECK(IS_NUM(args[1]), "can only delete using num index");
	ObjArr *a = AS_ARR(args[0]);
	size_t ix = (size_t)AS_NUM(args[1]);
	objarr_delete(S, a, ix);
	return args[0];
}
static Val fn_len(State *S, int nargs, Val *args) {
	CHECK(nargs == 1, "need 1 arg to len");
	CHECK(IS_ARR(args[0]), "can only take length of arr");
	ObjArr *a = AS_ARR(args[0]);
	return VAL_NUM(a->len);
}
static Val fn_pend(State *S, int nargs, Val *args) {
	CHECK(nargs > 0, "need at least 1 arg to ,");
	ObjArr *a = objarr_new(S);
	for (int i = 0; i < nargs; i++) {
		Val v = args[i];
		if (!IS_ARR(v))
			objarr_append(S, a, v);
		else {
			ObjArr *b = AS_ARR(v);
			for (int j = 0; j < b->len; j++) 
				objarr_append(S, a, b->d[j]);
		}
	}
	return VAL_OBJ(a);
}


// strings
static Val fn_spend(State *S, int nargs, Val *args) {
	size_t len = 0;
	for (int i = 0; i < nargs; i++) {
		CHECK(IS_STRING(args[i]), "can only spend strings");
		len += AS_STRING(args[i])->len;
	}
	char *new = NEW_ARR(S, char, len+1);
	char *cur = new;
	for (int i = 0; i < nargs; i++) {
		ObjString *s = AS_STRING(args[i]);
		memcpy(cur, s->d, s->len); 
		cur += s->len;
	}
	new[len] = '\0';
	return VAL_OBJ(objstring_take(S, new, len));
}
static Val fn_spendsplat(State *S, int nargs, Val *args) {
	CHECK(nargs==1, "need exactly 1 arg for spendsplat");
	CHECK(IS_ARR(args[0]), "need arr arg for spendsplat");
	ObjArr *a = AS_ARR(args[0]);
	return fn_spend(S, a->len, a->d);
}
static Val fn_ssub(State *S, int nargs, Val *args) {
	CHECK(nargs == 2, "need exactly 2 args for ssub?");
	CHECK(IS_STRING(args[0]) && IS_STRING(args[1]), "need 2 strings for ssub?");
	ObjString *needle = AS_STRING(args[0]);
	ObjString *haystack = AS_STRING(args[1]);
	int maxoff = haystack->len - needle->len;
	for (int i = 0; i <= maxoff; i++)
		if (0 == memcmp(needle->d, haystack->d + i, needle->len))
			return VAL_TRUE;
	return VAL_FALSE;
}


static Val fn_ssplit(State *S, int nargs, Val *args) {
	CHECK(nargs==2,"need exactly 2 args for ssplit");
	CHECK(IS_STRING(args[0]) && IS_STRING(args[1]), "need two strings for ssplit");
	ObjString *delim = AS_STRING(args[0]);
	ObjString *text = AS_STRING(args[1]);
	CHECK(delim->len == 1, "need length-1 delimiter");
	char delimc = delim->d[0];

	ObjArr *out = objarr_new(S);
	int start = 0;
	for (int i = 0; i <= text->len; i++) {
		if (text->d[i] == delimc || i == text->len) {
			ObjString *new = objstring_copy(S, &text->d[start], i-start);
			objarr_append(S, out, VAL_OBJ(new));
			start = i + 1;
		}
	}

	return VAL_OBJ(out);
}
static Val fn_sbytes(State *S, int nargs, Val *args) {
	CHECK(nargs==1, "need exactly 1 args for sbytes");
	CHECK(IS_STRING(args[0]), "need string arg for sbytes");
	ObjString *s = AS_STRING(args[0]);
	ObjArr *a = objarr_new(S);
	for (int i = 0; i < s->len; i++)
		objarr_append(S, a, VAL_OBJ(objstring_copy(S, &s->d[i], 1)));
	return VAL_OBJ(a);
}

// math
static Val fn_sin(State *S, int nargs, Val *args) {
	CHECK(nargs == 1, "need exactly 1 arg for sin");
	CHECK(IS_NUM(args[0]), "need num for sin");
	double x = AS_NUM(args[0]);
	return VAL_NUM(sin(x));
}
static Val fn_cos(State *S, int nargs, Val *args) {
	CHECK(nargs == 1, "need exactly 1 arg for cos");
	CHECK(IS_NUM(args[0]), "need num for cos");
	double x = AS_NUM(args[0]);
	return VAL_NUM(cos(x));
}
static Val fn_ceil(State *S, int nargs, Val *args) {
	CHECK(nargs == 1, "need exactly 1 arg for ceil");
	CHECK(IS_NUM(args[0]), "need num for ceil");
	double x = AS_NUM(args[0]);
	return VAL_NUM(ceil(x));
}
static Val fn_floor(State *S, int nargs, Val *args) {
	CHECK(nargs == 1, "need exactly 1 arg for floor");
	CHECK(IS_NUM(args[0]), "need num for floor");
	double x = AS_NUM(args[0]);
	return VAL_NUM(floor(x));
}
static Val fn_abs(State *S, int nargs, Val *args) {
	CHECK(nargs == 1, "need exactly 1 arg for abs");
	CHECK(IS_NUM(args[0]), "need num for abs");
	double x = AS_NUM(args[0]);
	return VAL_NUM(abs(x));
}


typedef struct {
	char *name;
	CFunc func;
} BuiltinFunc;
static BuiltinFunc builtin_funcs[] = {
	{ "clock", fn_clock },
	{ "say", fn_say },
	{ "write", fn_write },
	{ "writebytes", fn_writebytes },
	{ "readstring", fn_readstring },

	{ "arr", fn_arr },
	{ "append!", fn_append },
	{ "delete!", fn_delete },
	{ "#", fn_len },
	{ ",", fn_pend },

	{ "s,", fn_spend },
	{ "s,@", fn_spendsplat },
	{ "ssub?", fn_ssub },
	{ "ssplit", fn_ssplit },
	{ "sbytes", fn_sbytes },

	{ "sin", fn_sin },
	{ "cos", fn_cos },
	{ "ceil", fn_ceil },
	{ "floor", fn_floor },
	{ "abs", fn_abs },
	{ 0 },
};

void load_stdlib(State *S) {
	for (BuiltinFunc *b = builtin_funcs; b->name != NULL; b++) {
		ObjString *oname = objstring_copy_cstr(S, b->name);
		ht_put(S, &S->globals, oname, VAL_CFUNC(b->func));
	}
}