#include <parser.h>

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

#define MAX_VARS  32
#define MAX_STACK 32

char *strclone(const char *s)
{
	char *clone = (char *)malloc(strlen(s));
	strcpy(clone, s);
	return clone;
}

char *strnclone(const char *s, uint32_t n)
{
	char *clone = (char *)malloc(n);
	strncpy(clone, s, n);
	return clone;
}

void ifunc_set(interpreter *it);

variable *idoexpr(interpreter *interp, const char *line);

variable *itostring(variable *v);
variable *itoint(variable *v);
variable *itofloat(variable *v);

void iinit(interpreter *interp)
{
	interp->vars = (variable *)calloc(MAX_VARS, sizeof(variable));
	interp->vnames = (char **)calloc(MAX_VARS, sizeof(char *));
	interp->stack = (stack_t *)calloc(MAX_STACK, sizeof(stack_t));
	interp->stidx = 0;

	inew_cfunc(interp, "set", ifunc_set);
}

variable *interpreter_get_variable(interpreter *interp, const char *name)
{
	for (uint32_t i = 0; i < MAX_VARS; i++) {
		if (!interp->vars[i].used) {
			interp->vars[i].used = 1;
			interp->vars[i].valtype = FUNC;
			interp->vars[i].value = 0;
			interp->vnames[i] = strclone(name);
			return &interp->vars[i];
		} else if (interp->vnames[i] != 0 && !strcmp(interp->vnames[i], name)) {
			return &interp->vars[i];
		}
	}
	return 0;
}

char *interpreter_get_name(interpreter *interp, variable *v)
{
	for (uint32_t i = 0; i < MAX_VARS; i++) {
		if (v == &interp->vars[i])
			return interp->vnames[i];
	}
	return "(undefined)";
}

void inew_string(interpreter *interp, const char *name, char *value)
{
	variable *v = interpreter_get_variable(interp, name);
	if (v != 0) {
		v->valtype = STRING;
		v->value = (uint32_t)value;
	}
}

void inew_integer(interpreter *interp, const char *name, int32_t value)
{
	variable *v = interpreter_get_variable(interp, name);
	if (v != 0) {
		v->valtype = INTEGER;
		v->value = (uint32_t)value;
	}
}

void inew_float(interpreter *interp, const char *name, float value)
{
	variable *v = interpreter_get_variable(interp, name);
	if (v != 0) {
		v->valtype = FLOAT;
		v->value = (uint32_t)value;
	}
}

void inew_cfunc(interpreter *interp, const char *name, func_t func)
{
	variable *v = interpreter_get_variable(interp, name);
	if (v != 0) {
		v->fromc = 1;
		v->valtype = FUNC;
		v->value = (uint32_t)func;
	}
}

uint8_t eol(int c)
{
	return c == '\n' || c == '\0';
}

uint8_t eot(int c)
{
	return eol(c) || c == ' ';
}

uint8_t eoe(int c)
{
	return eol(c) || c == ')';
}

variable *make_var(interpreter *interp, const char *line, uint32_t *next)
{
	if (line[0] == '\"') { // string literal
		uint32_t end = 1;
		while (!eol(line[end])) {
			if (line[end] == '\"'/* && line[end - 1] != '\\'*/) {
				if (!eot(line[end + 1]))
					return 0;
				// TODO string breakdown
				variable *v = (variable *)malloc(sizeof(variable));
				v->valtype = STRING;
				v->value = (uint32_t)strnclone(line + 1, end - 1);
				*next = end + 1;
				return v;
			}
			end++;
		}
		return 0;
	} else if (line[0] == '(') { // equation literal
		uint32_t end = 1;
		while (!eol(line[end])) {
			if (line[end] == ')' && line[end - 1] != '\\') {
				if (!eot(line[end + 1]))
					return 0;
				// TODO string breakdown
				*next = end + 1;
				return idoexpr(interp, line + 1);
			}
			end++;
		}
	} else if (isalpha(line[0])) { // variable/func
		uint32_t end = 1;
		for (; isalnum(line[end]); end++);
		if (!eot(line[end]))
			return 0;
		char *name = (char *)malloc(end + 1);
		strncpy(name, line, end);
		name[end] = '\0';
		*next = end;
		return interpreter_get_variable(interp, name);
	} else if (isdigit(line[0])) { // number
		uint32_t end = 1;
		uint8_t dec = 0;
		for (; !eot(line[end]); end++) {
			if (!isdigit(line[end])) {
				if (line[end] == '.') {
					if (!dec)
						dec = 1;
					else
						return 0;
				} else {
					return 0;
				}
			}
		}
		variable *v = (variable *)malloc(sizeof(variable));
		if (dec) {
			v->valtype = FLOAT;
			*((float *)&v->value) = strtof(line, 0);
		} else {
			v->valtype = INTEGER;
			v->value = atoi(line);
		}
		*next = end;
		return v;
	}
	return 0;
}

int idoline(interpreter *interp, const char *line)
{
	variable *ops[8];
	uint32_t ooffset = 0;
	uint32_t offset = 0;
	uint32_t next;

	// step 1 - convert to tokens
	while (!eol(line[offset])) {
		ops[ooffset] = make_var(interp, line + offset, &next);
		if (ops[ooffset] == 0) {
			return -4;
		} else {
			ooffset++;
			offset += next;
		}

		// skip whitespace
		for (; line[offset] == ' ' && !eol(line[offset]); offset++);
	}

	// step 2 - execute
	if (ooffset == 0)
		return -1;

	if (ops[0]->valtype != FUNC)
		return -2;

	if (ops[0]->value == 0)
		return -3;

	for (uint32_t i = 0; i < ooffset - 1; i++, interp->stidx++)
		interp->stack[i] = ops[i + 1];

	((func_t)ops[0]->value)(interp);

	return 0;
}

typedef void (*operation_t)(variable *, variable *, variable *);

#define IOPS_COUNT 2
static char *iops[IOPS_COUNT] = {
	"+", "-"
};

void iop_add(variable *, variable *, variable *);
void iop_sub(variable *, variable *, variable *);

static operation_t iopfuncs[IOPS_COUNT] = {
	iop_add, iop_sub
};

variable *idoexpr(interpreter *interp, const char *line)
{
	static variable result;
	char *mline = line;
	void *ops[16];
	uint32_t ooffset = 0;
	uint32_t offset = 0;
	uint32_t next;

	// step 1 - break aprt line

	// skip whitespace
	for (; line[offset] == ' ' && !eol(line[offset]); offset++);
	while (!eoe(line[offset])) {
		uint32_t end = offset;
		char cend;
		if (line[offset] != '\"' && line[offset] != '(') {
			for (; isalnum(line[end]) || line[end] == '.'; end++);
			cend = line[end];
			mline[end] = ' ';
		}
		ops[ooffset] = make_var(interp, line + offset, &next);
		if (end != 0)
			mline[end] = cend;
		if (ops[ooffset] == 0)
			return 0;
		
		ooffset++;
		offset += next;

		// skip whitespace
		for (; line[offset] == ' ' && !eoe(line[offset]); offset++);
		if (eoe(line[offset]))
			break;

		for (uint32_t i = 0; i < IOPS_COUNT; i++) {
			int len = strlen(iops[i]);
			if (!strncmp(iops[i], line + offset, len)) {
				ops[ooffset] = (void *)(i + 1);
				offset += len;
				break;
			}
		}
		if (ops[ooffset] == 0)
			return 0;
		ooffset++;

		// skip whitespace
		for (; line[offset] == ' ' && !eol(line[offset]); offset++);
	}

	if (ooffset % 2 == 0)
		return 0;

	// step 2 - do operations
	result.valtype = ((variable *)ops[0])->valtype;
	result.value = ((variable *)ops[0])->value;
	for (uint32_t i = 1; i < ooffset; i += 2) {
		iopfuncs[(uint32_t)ops[i] - 1](&result, &result, ops[i + 1]);
	}

	return &result;
}

char *igetarg_string(interpreter *interp, uint32_t index)
{
	if (index >= interp->stidx)
		return 0;
	return (char *)itostring(interp->stack[index])->value;
}

int igetarg_integer(interpreter *interp, uint32_t index)
{
	if (index >= interp->stidx)
		return 0;
	return *((int32_t *)&itoint(interp->stack[index])->value);
}

float igetarg_float(interpreter *interp, uint32_t index)
{
	if (index >= interp->stidx)
		return 0;
	return *((float *)&itofloat(interp->stack[index])->value);
}

variable *itostring(variable *v)
{
	char *buf;
	switch (v->valtype) {
	case STRING:
		break;
	case INTEGER:
		buf = (char *)malloc(12);
		sprintf(buf, "%d", *((int32_t *)&v->value));
		v->valtype = STRING;
		v->value = (uint32_t)buf;
		break;
	case FLOAT:
		buf = (char *)malloc(24);
		sprintf(buf, "%f", *((float *)&v->value));
		v->valtype = STRING;
		v->value = (uint32_t)buf;
		break;
	case FUNC:
		// no
		break;
	}
	return v;
}

variable *itoint(variable *v)
{
	switch (v->valtype) {
	case STRING:
		v->valtype = INTEGER;
		*((int32_t *)&v->value) = atoi((char *)v->value);
		break;
	case INTEGER:
		break;
	case FLOAT:
		v->valtype = INTEGER;
		*((int32_t *)&v->value) = (int32_t)*((float *)&v->value);
		break;
	case FUNC:
		break;
	}
	return v;
}

variable *itofloat(variable *v)
{
	switch (v->valtype) {
	case STRING:
		v->valtype = FLOAT;
		*((float *)&v->value) = strtof((char *)v->value, 0);
		break;
	case INTEGER:
		v->valtype = FLOAT;
		*((float *)&v->value) = (float)*((int32_t *)&v->value);
		break;
	case FLOAT:
		break;
	case FUNC:
		break;
	}
	return v;
}

/*char *iget_string(interpreter *, const char *)
{

}

int iget_integer(interpreter *, const char *)
{

}

float iget_float(interpreter *, const char *)
{

}*/

/**
 * Builtin functions
 */

void ifunc_set(interpreter *it)
{
	char *v = igetarg_string(it, 1);
	if (v == 0)
		return;
	inew_string(it, interpreter_get_name(it, it->stack[0]), v);
}

/**
 * Builtin operations
 */

void iop_add(variable *r, variable *a, variable *b)
{
	itofloat(a);
	itofloat(b);
	*((float *)&r->value) = *((float *)&a->value) + *((float *)&b->value);
}

void iop_sub(variable *r, variable *a, variable *b)
{
	itofloat(a);
	itofloat(b);
	*((float *)r->value) = *((float *)&a->value) - *((float *)&b->value);
}