/*
	expr_construct.c

	type constructor expressions

	Copyright (C) 2024 Bill Currie <bill@taniwha.org>

	This program 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 2
	of the License, or (at your option) any later version.

	This program 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 this program; if not, write to:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <string.h>

#include "tools/qfcc/include/algebra.h"
#include "tools/qfcc/include/diagnostic.h"
#include "tools/qfcc/include/expr.h"
#include "tools/qfcc/include/rua-lang.h"
#include "tools/qfcc/include/symtab.h"
#include "tools/qfcc/include/type.h"
#include "tools/qfcc/include/value.h"

static const expr_t *
get_column (const expr_t *e, int i)
{
	auto t = get_type (e);
	if (!is_matrix (t)) {
		internal_error (e, "not a matrix");
	}
	if (i < 0 || i >= type_cols (t)) {
		internal_error (e, "invalid index");
	}

	auto ind = new_int_expr (i, false);
	auto a = new_array_expr (e, ind);
	a->array.type = column_type (t);
	return a;
}

static const expr_t *
get_value (const expr_t *e, int i, int j)
{
	auto t = get_type (e);

	if (i < 0 || i >= type_cols (t) || j < 0 || j >= type_rows (t)) {
		internal_error (e, "invalid index");
	}
	if (type_cols (t) > 1) {
		e = get_column (e, i);
	}
	if (type_rows (t) > 1) {
		auto ind = new_int_expr (j, false);
		auto a = new_array_expr (e, ind);
		a->array.type = base_type (t);
		e = a;
	}
	return e;
}

static const expr_t *
construct_by_components (const type_t *type, const expr_t *params,
						 const expr_t *e)
{
	auto base = base_type (type);
	int num_comp = type_rows (type) * type_cols (type);
	const expr_t *components[num_comp] = {};

	int num_param = list_count (&params->list);
	const expr_t *param_exprs[num_param + 1] = {};
	list_scatter_rev (&params->list, param_exprs);

	bool all_constant = true;
	bool all_implicit = true;

	int c = 0, p = 0;
	int err = -1;
	while (c < num_comp) {
		if (p < num_param) {
			auto pexpr = param_exprs[p++];
			auto ptype = get_type (pexpr);
			if (!ptype) {
				continue;
			}
			if (is_reference (ptype)) {
				pexpr = pointer_deref (pexpr);
				ptype = dereference_type (ptype);
			}
			if (!is_math (ptype)) {
				err = c++;
				components[err] = error (pexpr, "invalid type for conversion");
				continue;
			}
			for (int i = 0; i < type_cols (ptype) && c < num_comp; i++) {
				for (int j = 0; j < type_rows (ptype) && c < num_comp; j++) {
					auto val = get_value (pexpr, i, j);
					all_implicit = all_implicit && val->implicit;
					all_constant = all_constant && is_constant (val);
					components[c++] = cast_expr (base, val);
				}
			}
		} else {
			break;
		}
	}
	if (err >= 0) {
		return components[err];
	}
	if (c < num_comp) {
		return error (e, "too few parameters for %s", type->name);
	}
	if (p < num_param) {
		return error (e, "too may parameters for %s", type->name);
	}
	if (num_comp == 1) {
		return components[0];
	}
	if (all_constant) {
		if (is_matrix (type)) {
			return new_matrix_value (base, type_cols (type), type_rows (type),
									 num_comp, components, all_implicit);
		} else {
			return new_vector_value (base, type_width (type),
									 num_comp, components, all_implicit);
		}
	}

	if (is_matrix (type)) {
		auto ctype = column_type (type);
		int num_cols = type_cols (type);
		int num_rows = type_rows (type);
		const expr_t *columns[num_cols];
		const expr_t **col = components;
		for (int i = 0; i < num_cols; i++) {
			columns[i] = new_vector_list_gather (ctype, col, num_rows);
			col += num_rows;
		}
		return new_vector_list_gather (type, columns, num_cols);
	} else {
		return new_vector_list_gather (type, components, num_comp);
	}
}

static const expr_t *
construct_diagonal (const type_t *type, const expr_t *scalar, const expr_t *e)
{
	scoped_src_loc (scalar);
	int cols = type_cols (type);
	int rows = type_rows (type);
	const expr_t *components[cols * rows + 1] = {};
	auto zero = new_nil_expr ();

	for (int i = 0; i < cols; i++) {
		for (int j = 0; j < rows; j++) {
			components[i * rows + j] = i == j ? scalar : zero;
		}
	}
	auto params = new_list_expr (nullptr);
	list_gather (&params->list, components, cols * rows);
	return construct_by_components (type, params, e);
}

static const expr_t *
construct_matrix (const type_t *type, const expr_t *matrix, const expr_t *e)
{
	scoped_src_loc (e);
	int cols = type_cols (type);
	int rows = type_rows (type);
	int src_cols = type_cols (get_type (matrix));
	int src_rows = type_rows (get_type (matrix));

	if (src_rows >= rows) {
		char swizzle[] = "xyzw";
		swizzle[rows] = 0;
		const expr_t *columns[cols] = {};
		const expr_t *zero_column = nullptr;
		if (src_cols < cols) {
			auto ctype = column_type (type);
			const expr_t *zero_col[rows];
			auto zero = new_nil_expr ();
			for (int j = 0; j < rows; j++) {
				zero_col[j] = zero;
			}
			zero_column = new_vector_list_gather (ctype, zero_col, rows);
		}
		int i;
		for (i = 0; i < src_cols && i < cols; i++) {
			columns[i] = get_column (matrix, i);
			if (src_rows > rows) {
				columns[i] = new_swizzle_expr (columns[i], swizzle);
			}
		}
		for (; i < cols; i++) {
			columns[i] = zero_column;
		}
		return new_vector_list_gather (type, columns, cols);
	} else {
		const expr_t *components[cols * rows + 1] = {};
		auto zero = new_nil_expr ();

		for (int i = 0; i < cols; i++) {
			for (int j = 0; j < rows; j++) {
				const expr_t *val;
				if (i < src_cols && j < src_rows) {
					val = get_value (matrix, i, j);
				} else {
					val = zero;
				}
				components[i * rows + j] = val;
			}
		}
		auto params = new_list_expr (nullptr);
		list_gather (&params->list, components, cols * rows);
		return construct_by_components (type, params, e);
	}
}

static const expr_t *
construct_broadcast (const type_t *type, const expr_t *scalar, const expr_t *e)
{
	scoped_src_loc (e);
	int width = type_width (type);
	const expr_t *components[width + 1] = {};

	for (int i = 0; i < width; i++) {
		components[i] = scalar;
	}
	auto params = new_list_expr (nullptr);
	list_gather (&params->list, components, width);
	return construct_by_components (type, params, e);
}

static const expr_t *
math_constructor (const type_t *type, const expr_t *params, const expr_t *e)
{
	int num_param = list_count (&params->list);
	const expr_t *param_exprs[num_param + 1] = {};
	list_scatter_rev (&params->list, param_exprs);

	for (int i = 0; i < num_param; i++) {
		if (is_reference (get_type (param_exprs[i]))) {
			param_exprs[i] = pointer_deref (param_exprs[i]);
		}
	}

	if (num_param == 1 && is_scalar (get_type (param_exprs[0]))) {
		if (is_matrix (type)) {
			return construct_diagonal (type, param_exprs[0], e);
		}
		if (is_nonscalar (type)) {
			return construct_broadcast (type, param_exprs[0], e);
		}
	}
	if (num_param == 1 && is_matrix (get_type (param_exprs[0]))) {
		if (is_matrix (type)) {
			return construct_matrix (type, param_exprs[0], e);
		}
	}
	if (is_matrix (type) && num_param == type_cols (type)) {
		bool by_vector = true;
		for (int i = 0; i < type_cols (type); i++) {
			auto ptype = get_type (param_exprs[i]);
			if (!is_nonscalar (ptype)
				|| type_width (ptype) != type_rows (type)) {
				by_vector = false;
				break;
			}
		}
		if (by_vector) {
			scoped_src_loc (e);
			return new_vector_list_gather (type, param_exprs, type_cols (type));
		}
	}
	return construct_by_components (type, params, e);
}

const expr_t *
constructor_expr (const expr_t *e, const expr_t *params)
{
	auto type = e->typ.type;
	if (is_algebra (type)) {
		return error (e, "algebra not implemented");
	}
	if (is_math (type)) {
		return math_constructor (type, params, e);
	}
	return error (e, "not implemented");
}