/*
 * Copyright (C) 2012-2026 Robin Haberkorn
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <glib.h>

#include "sciteco.h"
#include "undo.h"
#include "qreg.h"
#include "lexer.h"
#include "ring.h"
#include "parser.h"
#include "interface.h"
#include "expressions.h"
#include "core-commands.h"
#include "number-commands.h"

static teco_state_t teco_state_number;

static gboolean
teco_state_number_end_of_macro(teco_machine_main_t *ctx, GError **error)
{
	teco_undo_guint(ctx->number.radix) = 0; /* default */
	guint divisor = ctx->number.divisor;
	teco_undo_guint(ctx->number.divisor) = 0; /* default */

	if (ctx->flags.mode > TECO_MODE_NORMAL)
		return TRUE;

	if (divisor)
		/* floating point number */
		teco_expressions_push((teco_float_t)ctx->number.value / divisor);
	else
		teco_expressions_push(ctx->number.value);
	teco_undo_int(ctx->number.value) = 0;
	return TRUE;
}

teco_state_t *
teco_state_number_input(teco_machine_main_t *ctx, gunichar chr, GError **error)
{
	/*
	 * If you have several dots, the second one will push the current buffer position.
	 * E.g. 23.0. is equivalent to 23.0,.
	 */
	if (chr == '.' && !ctx->number.divisor) {
		/* floating point number */
		if (ctx->number.radix == 8 && ctx->number.value == 0)
			/* otherwise 0.1 would be parsed in octal */
			teco_undo_guint(ctx->number.radix) = 10;
		teco_undo_guint(ctx->number.divisor) = 1;
		return &teco_state_number;
	}

	/*
	 * Hexadecimal constants (@[0-9][0-9a-zA-Z]*) are terminated by any non-hexadecimal character.
	 * This means you may have to append a space or braces to stop parsing if the next
	 * command would begin with such a letter (e.g. `@0ff D`).
	 */
	gboolean end_of_number = chr <= 0xFF && (ctx->number.radix == 16 ? !g_ascii_isxdigit(chr)
	                                                                 : !g_ascii_isdigit(chr));
	if (end_of_number) {
		teco_state_number_end_of_macro(ctx, error);
		return teco_state_start_input(ctx, chr, error);
	}

	if (!ctx->number.radix) {
		if (teco_machine_main_eval_at(ctx))
			/* @[0-9] starts a hexadecimal constant */
			teco_undo_guint(ctx->number.radix) = 16;
		else if (!ctx->number.value && chr == '0')
			/* a leading zero starts an octal constant */
			teco_undo_guint(ctx->number.radix) = 8;
	}

	if (ctx->flags.mode > TECO_MODE_NORMAL)
		return &teco_state_number;

	teco_int_t radix = ctx->number.radix;
	if (!radix)
		/*
		 * The ^R radix is only considered if we do not
		 * syntactically signify the radix (octal or hex constants).
		 *
		 * FIXME: We could just access qreg->number.i here since
		 * we can assume that "^R" is a plain register.
		 */
		teco_qreg_get_integer(ctx->qreg_table_locals->radix, &radix, NULL);

	chr = teco_ascii_toupper(chr);
	guint digit = 'A' <= chr && chr <= 'F' ? chr-'A'+10 : chr-'0';
	if (digit >= radix) {
		g_set_error(error, TECO_ERROR, TECO_ERROR_FAILED,
		            "Digit \"%c\" not allowed in radix %" TECO_INT_FORMAT,
		            (gchar)chr, radix);
		return NULL;
	}

	teco_undo_int(ctx->number.value) = ctx->number.value*radix + digit;
	if (ctx->number.divisor)
		teco_undo_guint(ctx->number.divisor) *= radix;

	return &teco_state_number;
}

/*
 * FIXME: This has to be a "command" since we chain to teco_state_start_input()
 * and want case-folding to work properly.
 * On the downside, this will also case-fold the hexadecimal constants (A-F).
 * There would be cumbersome workarounds with custom process_edit_cmd callbacks,
 * though.
 */
static TECO_DEFINE_STATE_START(teco_state_number,
	.input_cb = (teco_state_input_cb_t)teco_state_number_input,
	.end_of_macro_cb = (teco_state_end_of_macro_cb_t)teco_state_number_end_of_macro,
	.style = SCE_SCITECO_NUMBER,
	.is_start = FALSE
);

/*
 * Transition table callbacks
 */

/*$ \[rs]
 * n\\ -- Insert or read ASCII numbers
 * \\ -> n
 *
 * Backslash pops a value from the stack, formats it
 * according to the current radix and inserts it in the
 * current buffer or Q-Register at dot.
 * Floating point numbers are formatted without an exponent
 * and 6 significant digits (precision), but whout trailing
 * zeros.
 *
 * If <n> is omitted (empty stack), it does the reverse \(em
 * it reads from the current buffer position a number
 * in the current radix and pushes it onto the stack
 * (either as an integer or float).
 * Dot is not changed when reading numbers.
 *
 * In other words, the command serializes or deserializes
 * numbers as ASCII characters.
 */
void
teco_state_start_backslash(teco_machine_main_t *ctx, GError **error)
{
	if (!teco_expressions_eval(FALSE, error))
		return;

	if (teco_expressions_args()) {
		gboolean is_float;
		teco_number_t number = teco_expressions_pop_num(0, &is_float);

		gchar buffer[TECO_EXPRESSIONS_FORMAT_LEN];
		const gchar *str;
		str = is_float ? teco_expressions_format_float(buffer, number.f, 6)
		               : teco_expressions_format_int(buffer, number.i,
		                                             ctx->qreg_table_locals->radix);
		g_assert(*str != '\0');
		gsize len = strlen(str);

		teco_undo_int(teco_ranges[0].from) = teco_current_doc_get_dot();
		/*
		 * We can assume that `len` is already in glyphs,
		 * i.e. formatted numbers will never use multi-byte/Unicode characters.
		 */
		teco_undo_int(teco_ranges[0].to) = teco_ranges[0].from + len;
		teco_undo_guint(teco_ranges_count) = 1;

		teco_current_doc_set_dot(teco_ranges[0].to);

		if (teco_current_doc_must_undo())
			undo__teco_interface_ssm(SCI_DELETERANGE,
			                         teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0), len);
		teco_interface_ssm(SCI_ADDTEXT, len, (sptr_t)str);
		teco_ring_dirtify();
	} else {
		teco_int_t radix = 10;
		teco_qreg_get_integer(ctx->qreg_table_locals->radix, &radix, NULL);

		/*
		 * FIXME: Should we also support octal constants automatically when seeing
		 * a leading 0 or even hexadecimal via @[0-9]?
		 */
		uptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
		gchar c = (gchar)teco_interface_ssm(SCI_GETCHARAT, pos, 0);
		teco_int_t value = 0;
		guint divisor = 0;
		gint sign = 1;

		if (c == '-') {
			pos++;
			sign = -1;
		}

		for (;; pos++) {
			c = teco_ascii_toupper((gchar)teco_interface_ssm(SCI_GETCHARAT, pos, 0));

			if (c == '.') {
				/* floating point number */
				divisor = 1;
				continue;
			}

			if (c >= '0' && c <= '0' + MIN(radix, 10) - 1)
				value = (value*radix) + (c - '0');
			else if (c >= 'A' &&
				 c <= 'A' + MIN(radix - 10, 26) - 1)
				value = (value*radix) + 10 + (c - 'A');
			else
				break;

			if (divisor)
				divisor *= radix;
		}

		if (divisor)
			teco_expressions_push(sign * ((teco_float_t)value / divisor));
		else
			teco_expressions_push(sign * value);
	}
}

/*
 * NOTE: This needs some extra code in teco_state_start_input().
 */
void
teco_state_start_mul(teco_machine_main_t *ctx, GError **error)
{
	teco_expressions_push_calc(TECO_OP_MUL, error);
}

void
teco_state_start_div(teco_machine_main_t *ctx, GError **error)
{
	teco_expressions_push_calc(TECO_OP_DIV, error);
}

void
teco_state_start_plus(teco_machine_main_t *ctx, GError **error)
{
	teco_expressions_push_calc(TECO_OP_ADD, error);
}

void
teco_state_start_minus(teco_machine_main_t *ctx, GError **error)
{
	if (!teco_expressions_args())
		teco_set_num_sign(-teco_num_sign);
	else
		teco_expressions_push_calc(TECO_OP_SUB, error);
}

void
teco_state_start_and(teco_machine_main_t *ctx, GError **error)
{
	teco_expressions_push_calc(TECO_OP_AND, error);
}

void
teco_state_start_or(teco_machine_main_t *ctx, GError **error)
{
	teco_expressions_push_calc(TECO_OP_OR, error);
}

void
teco_state_start_brace_open(teco_machine_main_t *ctx, GError **error)
{
	if (teco_num_sign < 0) {
		teco_set_num_sign(1);
		if (!teco_expressions_eval(FALSE, error))
			return;
		teco_expressions_push(-1);
		if (!teco_expressions_push_calc(TECO_OP_MUL, error))
			return;
	}
	teco_expressions_brace_open();
}

void
teco_state_start_brace_close(teco_machine_main_t *ctx, GError **error)
{
	teco_expressions_brace_close(error);
}

void
teco_state_start_comma(teco_machine_main_t *ctx, GError **error)
{
	if (!teco_expressions_eval(FALSE, error))
		return;
	teco_expressions_push_op(TECO_OP_NEW);
}

/*$ ^_ negate
 * n^_ -> ~n -- Binary negation
 *
 * Binary negates (complements) <n> and returns
 * the result.
 * Binary complements are often used to negate
 * \*(ST booleans.
 */
void
teco_state_control_negate(teco_machine_main_t *ctx, GError **error)
{
	if (!teco_expressions_eval(FALSE, error))
		return;

	if (!teco_expressions_args()) {
		teco_error_argexpected_set(error, "^_");
		return;
	}

	teco_expressions_push(~teco_expressions_pop_int(0));
}

void
teco_state_control_pow(teco_machine_main_t *ctx, GError **error)
{
	teco_expressions_push_calc(TECO_OP_POW, error);
}

void
teco_state_control_mod(teco_machine_main_t *ctx, GError **error)
{
	teco_expressions_push_calc(TECO_OP_MOD, error);
}

void
teco_state_control_xor(teco_machine_main_t *ctx, GError **error)
{
	teco_expressions_push_calc(TECO_OP_XOR, error);
}

/*$ ^O octal
 * ^O -- Set radix to 8 (octal)
 */
void
teco_state_control_octal(teco_machine_main_t *ctx, GError **error)
{
	teco_qreg_t *qreg = ctx->qreg_table_locals->radix;
	g_assert(qreg != NULL);
	if (!teco_qreg_set_integer(qreg, 8, NULL))
		return;
}

/*$ ^D decimal
 * ^D -- Set radix to 10 (decimal)
 */
void
teco_state_control_decimal(teco_machine_main_t *ctx, GError **error)
{
	teco_qreg_t *qreg = ctx->qreg_table_locals->radix;
	g_assert(qreg != NULL);
	if (!teco_qreg_set_integer(qreg, 10, NULL))
		return;
}

/*$ ^R radix
 * radix^R -- Set and get radix
 * ^R -> radix
 *
 * Set current radix to any value <radix> larger than or equal to 2.
 * If <radix> is omitted, the command instead
 * returns the current radix.
 *
 * An alternative way to access the radix is via the \(lq^R\(rq local Q-Register.
 * Consequently, the radix is local to the current macro invocation frame,
 * unless the macro call was colon-modified.
 */
void
teco_state_control_radix(teco_machine_main_t *ctx, GError **error)
{
	if (!teco_expressions_eval(FALSE, error))
		return;

	teco_qreg_t *qreg = ctx->qreg_table_locals->radix;
	g_assert(qreg != NULL);
	teco_int_t radix = 10;

	if (!teco_expressions_args()) {
		teco_qreg_get_integer(qreg, &radix, NULL);
		teco_expressions_push(radix);
	} else {
		if (!teco_qreg_set_integer(qreg, teco_expressions_pop_int(0), error))
			return;
	}
}