/*
 * Copyright (C) 2020 Weber Yann
 * 
 * This file is part of pyrpn.
 * 
 * pyrpn is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 * 
 * pyrpn is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with pyrpn.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "python_rpnexpr.h"

PyMethodDef RPNExpr_methods[] = {
	{"eval", (PyCFunction)rpnexpr_eval, METH_FASTCALL, "Evaluate an expression"},
	{"reset_stack", (PyCFunction)rpnexpr_reset_stack, METH_NOARGS,
		"Reset stack memory storage (set all items to 0)"},
	{"__getstate__", (PyCFunction)rpnexpr_getstate, METH_NOARGS,
		"Pickling method. Return a bytes repr of tokenized expression \
and the stack state."},
	{"__setstate__", (PyCFunction)rpnexpr_setstate, METH_O,
		"Unpickling method"},
	{NULL} //Sentinel
};

PyMemberDef RPNExpr_members[] = {
	{NULL}
};

PyTypeObject RPNExprType = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"pyrpn.RPNExpr",                     /* tp_name */
	sizeof(PyRPNExpr_t),                        /* tp_basicsize */
	0,                                               /* tp_itemsize */
	(destructor)rpnexpr_del, /* tp_dealloc */
	0,                                               /* tp_print */
	0,                                               /* tp_getattr */
	0,                                               /* tp_setattr */
	0,                                               /* tp_reserved */
	rpnexpr_repr,                                    /* tp_repr */
	0,                                               /* tp_as_number */
	0,                                               /* tp_as_sequence */
	0,                              /* tp_as_mapping */
	0,                                               /* tp_hash  */
	0,                                               /* tp_call */
	rpnexpr_str,                                               /* tp_str */
	0,                                               /* tp_getattro */
	0,                                               /* tp_setattro */
	0,                                               /* tp_as_buffer */
	Py_TPFLAGS_DEFAULT |
	Py_TPFLAGS_BASETYPE,   /* tp_flags */
	"RPN expression evaluator",                /* tp_doc */
	0,                                               /* tp_traverse */
	0,                                               /* tp_clear */
	0,                                               /* tp_richcompare */
	0,                                               /* tp_weaklistoffset */
	0,                                               /* tp_iter */
	0,                                               /* tp_iternext */
	RPNExpr_methods,                        /* tp_methods */
	RPNExpr_members,                        /* tp_members */
	0,                                               /* tp_getset */
	0,                                               /* tp_base */
	0,                                               /* tp_dict */
	0,                                               /* tp_descr_get */
	0,                                               /* tp_descr_set */
	0,                                               /* tp_dictoffset */
	rpnexpr_init,          /* tp_init */
	0,                                               /* tp_alloc */
	rpnexpr_new,                            /* tp_new */
};

PyObject* rpnexpr_new(PyTypeObject *subtype, PyObject *args, PyObject* kwds)
{
	PyObject *ret, *err;
	PyRPNExpr_t *expr;
	ret = PyType_GenericNew(subtype, args, kwds);
	if((err = PyErr_Occurred()))
	{
		Py_DECREF(err);
		return ret;
	}
	expr = (PyRPNExpr_t*)ret;
	expr->rpn = NULL;
	expr->args = NULL;
	return ret;
}

int rpnexpr_init(PyObject *self, PyObject *args, PyObject *kwds)
{
	PyRPNExpr_t *expr_self;
	char *names[] = {"expression", "args_count", "stack_size", NULL};
	char err_str[256];
	const char *expr;
	long long int args_count, stack_size;

	expr_self = (PyRPNExpr_t*)self;

	stack_size = 16;
	expr_self->rpn = NULL;

	if(!PyArg_ParseTupleAndKeywords(args, kwds, "sL|L:RPNExpr.__init__", names, &expr,
		&args_count, &stack_size))
	{
		return -1;
	}

	if(strlen(expr) == 0)
	{
		PyErr_SetString(PyExc_ValueError,
			"RpnExpr.__init__() expect expression argument to be not empty");
		return -1;
	}

	if(args_count < 0 || args_count > 255)
	{
		snprintf(err_str, 128,
			"Argument count should be in [4..255] but %lld given",
			args_count);
		PyErr_SetString(PyExc_ValueError, err_str);
		return -1;
	}

	if(stack_size < 4 || stack_size > 255)
	{
		snprintf(err_str, 128,
			"Stack size should be in [0..255] but %lld given",
			stack_size);
		PyErr_SetString(PyExc_ValueError, err_str);
		return -1;
	}

	expr_self->rpn = malloc(sizeof(rpn_expr_t));
	if(!expr_self->rpn)
	{
		snprintf(err_str, 256,
			"Expression memory allocation error : %s",
			strerror(errno));
	}
	bzero(expr_self->rpn, sizeof(rpn_expr_t));

	if(rpn_expr_init(expr_self->rpn, stack_size, args_count) < 0)
	{
		snprintf(err_str, 256,
			"Expression init error : %s",
			expr_self->rpn->err_reason);
		PyErr_SetString(PyExc_ValueError, err_str);
		return -1;
	}

	expr_self->args = malloc(sizeof(rpn_value_t) * args_count);
	if(!expr_self->args)
	{
		snprintf(err_str, 256,
			"Error allocating arguments memory : %s",
			strerror(errno));
		return -1;
	}

	if(rpn_expr_compile(expr_self->rpn, expr))
	{
		PyErr_SetString(PyExc_ValueError, expr_self->rpn->err_reason);
		return -1;
	}

	return 0;
}

void rpnexpr_del(PyObject *self)
{
	PyRPNExpr_t *expr_self;

	expr_self = (PyRPNExpr_t*)self;
	if(expr_self->rpn)
	{
		rpn_expr_close(expr_self->rpn);
		free(expr_self->rpn);
		expr_self->rpn = NULL;
	}
	if(expr_self->args)
	{
		free(expr_self->args);
		expr_self->args = NULL;
	}
}


PyObject* rpnexpr_getstate(PyObject *self, PyObject *noargs)
{
	PyObject *res, *part;
	PyRPNExpr_state_t resbuf;
	PyRPNExpr_t *expr_self;
	size_t total_sz;
	char err_str[128];

	expr_self = (PyRPNExpr_t*)self;

	if(expr_self->rpn->state != RPN_READY)
	{
		snprintf(err_str, 128, 
			"RPNExpr.__getstate__() instance in bad state : %s",
			expr_self->rpn->state==RPN_ERROR?"error":"init");
		PyErr_SetString(PyExc_ValueError, err_str);
		return NULL;
	}

	total_sz = sizeof(PyRPNExpr_state_t);
	total_sz += expr_self->rpn->toks.tokens_sz * sizeof(rpn_token_t);
	total_sz += expr_self->rpn->stack_sz * sizeof(rpn_value_t);

	resbuf.total_sz = total_sz;
	resbuf.argc = expr_self->rpn->args_count;
	resbuf.stack_sz = expr_self->rpn->stack_sz;
	resbuf.token_sz = expr_self->rpn->toks.tokens_sz;

	if(!(res = PyBytes_FromStringAndSize((char*)&resbuf, sizeof(resbuf))))
	{
		return NULL;
	}
	if(resbuf.stack_sz)
	{
		if(!(part=PyBytes_FromStringAndSize(
				(char*)expr_self->rpn->stack,
				sizeof(rpn_value_t) * resbuf.stack_sz)))
		{
			return NULL;
		}
		PyBytes_ConcatAndDel(&res, part);
		if(!res)
		{
			return NULL;
		}
	}
	if(resbuf.token_sz)
	{
		if(!(part=PyBytes_FromStringAndSize(
				(char*)expr_self->rpn->toks.tokens,
				sizeof(rpn_token_t) * resbuf.token_sz)))
		{
			return NULL;
		}
		PyBytes_ConcatAndDel(&res, part);
		if(!res)
		{
			return NULL;
		}
	}
	return res;
}

PyObject* rpnexpr_setstate(PyObject *self, PyObject *state_bytes)
{
	PyObject *tmp, *tmp2;
	PyRPNExpr_state_t *state;
	PyRPNExpr_t *expr_self;
	rpn_value_t *stack;
	rpn_tokenized_t toks;
	const char *data;
	size_t bsize, csize;
	int err;
	char err_str[256];
	size_t i;

	expr_self = (PyRPNExpr_t*)self;
	
	if(!PyBytes_Check(state_bytes)) /* Arg check */
	{
		tmp2 = NULL;
		tmp = PyObject_Type(state_bytes);
		if(tmp)
		{
			tmp2 = PyObject_Str(tmp);
		}
		if(tmp2)
		{
			snprintf(err_str, 128, 
				"RPNExpr.__setstate__() expected a bytes as \
argument but %s found",
				PyUnicode_AsUTF8(tmp2));
			PyErr_SetString(PyExc_ValueError, err_str);
		}
		else
		{
			PyErr_SetString(PyExc_RuntimeError,
				"Failing to fetch arguments type will \
generating exception message !");
		}
		return NULL;
	}
	if(expr_self->rpn || expr_self->args) /* checking instance state */
	{
		PyErr_SetString(PyExc_ValueError,
			"RPNExpr.__getstate__() instance in bad state : \
should not be initialized");
		return NULL;
	}
	
	/* Checking data size */
	bsize = PyBytes_GET_SIZE(state_bytes);
	data = PyBytes_AS_STRING(state_bytes);
	state = (PyRPNExpr_state_t*)data;

	if(bsize < sizeof(size_t))
	{
		PyErr_SetString(PyExc_ValueError, "Invalid argument");
	}
	if(bsize != state->total_sz)
	{
		snprintf(err_str, 128,
			"RPNExpr.__setstate__() error : expected state to \
contains %ld bytes but %ld found",
			state->total_sz, bsize);
		PyErr_SetString(PyExc_ValueError, err_str);
	}

	/* Checking data "integrity" */
	csize = sizeof(PyRPNExpr_state_t) +
		state->token_sz * sizeof(rpn_token_t) +
		state->stack_sz * sizeof(rpn_value_t);
	if(state->total_sz != csize)
	{
		snprintf(err_str, 128,
			"RPNExpr.__setstate__() error : should have %ld as \
total size but %ld found",
			csize, state->total_sz);
		PyErr_SetString(PyExc_ValueError, err_str);
		return NULL;
	}


	/* Alloc and init rpn expression & args buffer*/
	if(!(expr_self->rpn = malloc(sizeof(rpn_expr_t))))
	{
		err = errno;
		snprintf(err_str, 128, 
			"RPNExpr.__setstate__() failed to allocate memory for \
rpn_expr_t : %s",
			strerror(err));
		PyErr_SetString(PyExc_MemoryError, err_str);
		return NULL;
	}
	bzero(expr_self->rpn, sizeof(rpn_expr_t));
	if(!(expr_self->args = malloc(sizeof(rpn_value_t)*state->argc)))
	{
		err = errno;
		snprintf(err_str, 128, 
			"RPNExpr.__setstate__() failed to allocate memory for \
args buffer : %s",
			strerror(err));
		PyErr_SetString(PyExc_MemoryError, err_str);
		return NULL;
	}

	if(rpn_expr_init(expr_self->rpn, state->stack_sz, state->argc) < 0)
	{
		snprintf(err_str, 256,
			"RPNExpr.__setstate__() failed to init RPN expression \
: %s",
			expr_self->rpn->err_reason);
		PyErr_SetString(PyExc_RuntimeError, err_str);
		goto free_err;
	}

	/* restore stack & untokenize expression */
	stack = (rpn_value_t*)(state+1);
	memcpy(expr_self->rpn->stack, stack,
		sizeof(rpn_value_t)*state->stack_sz);

	toks.argc = state->argc;
	toks.tokens_sz = state->token_sz;
	toks.tokens = malloc(sizeof(rpn_token_t)*state->token_sz);
	if(!toks.tokens)
	{
		snprintf(err_str, 128,
			"RPNExpr.__setstate__() failed to allocate tokens \
: %s",
			strerror(errno));
		PyErr_SetString(PyExc_RuntimeError, err_str);
		goto close_err;
	}
	memcpy(toks.tokens, (rpn_token_t*)(stack+state->stack_sz),
		sizeof(rpn_token_t)*state->token_sz);

	for(i=0; i<toks.tokens_sz;i++)
	{
		// restore op pointers
		toks.tokens[i].op = &(rpn_ops[toks.tokens[i].op_n]);
	}
	
	
	if(rpn_expr_untokenize(expr_self->rpn, &toks, 0) < 0)
	{
		snprintf(err_str, 256,
			"RPNExpr.__setstate__() unable to untokenize : %s",
			expr_self->rpn->err_reason);
		PyErr_SetString(PyExc_RuntimeError, err_str);
		goto close_err;
	}

	Py_RETURN_NONE;
	close_err:
		rpn_expr_close(expr_self->rpn);
	free_err:
		return NULL;
}

PyObject* rpnexpr_eval(PyObject* self, PyObject** argv, Py_ssize_t argc)
{
	PyRPNExpr_t *expr_self;
	unsigned long res;
	char err_str[128];
	Py_ssize_t i;
	PyObject *cur, *ret;


	expr_self = (PyRPNExpr_t*)self;

	if((unsigned long)argc != expr_self->rpn->args_count)
	{
		snprintf(err_str, 128,
			"RPNExpr expected %ld arguments but %ld given",
			expr_self->rpn->args_count,
			argc);
		PyErr_SetString(PyExc_ValueError, err_str);
		return NULL;
	}

	for(i=0; i<argc; i++)
	{
		cur = argv[i];
		if(!PyLong_Check(cur))
		{
			snprintf(err_str, 128,
"RpnExpr.__call__ expect int as arguments but argument %ld is not",
				i+1);
			PyErr_SetString(PyExc_ValueError, err_str);
			return NULL;
		}
		expr_self->args[i] = PyLong_AsUnsignedLong(argv[i]);
		if((ret = PyErr_Occurred()))
		{
			Py_DECREF(ret);
			return NULL;
		}
	}

	res = rpn_expr_eval(expr_self->rpn, expr_self->args);
//dprintf(2, "[RES=%lu]\n", res);

	return PyLong_FromUnsignedLong(res);
}

PyObject* rpnexpr_reset_stack(PyObject *self, PyObject *noargs)
{
	rpn_expr_reset_stack(((PyRPNExpr_t*)self)->rpn);
	Py_RETURN_NONE;
}

PyObject* rpnexpr_str(PyObject *self)
{
	PyRPNExpr_t *expr_self;
	PyObject *res;

	expr_self = (PyRPNExpr_t*)self;
	res = Py_BuildValue("s", expr_self->rpn->expr);
	return res;
}

PyObject* rpnexpr_repr(PyObject *self)
{
	PyRPNExpr_t *expr_self;
	PyObject *res;
	size_t sz;
	char *buff, err_str[128];

	expr_self = (PyRPNExpr_t*)self;
	sz = snprintf(NULL, 0, "<RPNExpr argc:%ld stck_sz:%d '%s'>",
		expr_self->rpn->args_count, expr_self->rpn->stack_sz,
		expr_self->rpn->expr);
	buff = malloc(sizeof(char) * (sz + 1));
	if(!buff)
	{
		snprintf(err_str, 128,
			"Error allocating repr : %s",
			strerror(errno));
		PyErr_SetString(PyExc_RuntimeError, err_str);
		return NULL;
	}
	snprintf(buff, sz+1, "<RPNExpr argc:%ld stck_sz:%d '%s'>",
		expr_self->rpn->args_count, expr_self->rpn->stack_sz,
		expr_self->rpn->expr);
	res = Py_BuildValue("s", buff);
	free(buff);
	return res;
}