/*
 * Copyright (C) 2012-2025 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 "parser.h"
#include "error.h"
#include "undo.h"
#include "expressions.h"
#include "interface.h"
#include "cmdline.h"
#include "core-commands.h"
#include "stdio-commands.h"

/**
 * Check whether we are executing directly from the end of the command line.
 * This works \b only when invoked from the initial_cb.
 */
static inline gboolean
teco_cmdline_is_executing(teco_machine_main_t *ctx)
{
	return ctx == &teco_cmdline.machine &&
	       ctx->macro_pc == teco_cmdline.effective_len;
}

static gboolean is_executing = FALSE;

/**
 * Print number from stack in the given radix.
 *
 * It must be popped manually, so we can call it multiple times
 * on the same number.
 */
static gboolean
teco_print(teco_machine_main_t *ctx, guint radix, GError **error)
{
	if (!teco_expressions_eval(FALSE, error))
		return FALSE;
	if (!teco_expressions_args()) {
		teco_error_argexpected_set(error, "=");
		return FALSE;
	}

	/*
	 * teco_expressions_format() cannot easily be used
	 * to format __unsigned__ integers.
	 */
	const gchar *fmt = "%" TECO_INT_MODIFIER "d";
	switch (radix) {
	case 8:  fmt = "%" TECO_INT_MODIFIER "o"; break;
	case 16: fmt = "%" TECO_INT_MODIFIER "X"; break;
	}
	gchar buf[32];
	gint len = g_snprintf(buf, sizeof(buf), fmt, teco_expressions_peek_num(0));
	g_assert(len > 0);
	if (!teco_machine_main_eval_colon(ctx))
		buf[len++] = '\n';

	teco_interface_msg_literal(TECO_MSG_USER, buf, len);
	return TRUE;
}

/*$ "=" "==" "===" ":=" ":==" ":===" "print number"
 * <n>= -- Print integer as message
 * <n>==
 * <n>===
 * <n>:=
 * <n>:==
 * <n>:===
 *
 * Shows integer <n> as a message in the message line and/or
 * on the console.
 * One \(lq=\(rq formats the integer as a signed decimal number,
 * \(lq==\(rq formats as an unsigned octal number and
 * \(lq===\(rq as an unsigned hexadecimal number.
 * It is logged with the user-message severity.
 * The command fails if <n> is not given.
 *
 * A noteworthy quirk is that \(lq==\(rq and \(lq===\(rq
 * will print 2 or 3 numbers in succession when executed
 * from interactive mode at the end of the command line
 * in order to guarantee immediate feedback.
 *
 * If you want to print multiple values from the stack,
 * you have to put the \(lq=\(rq into a pass-through loop
 * or separate the commands with
 * whitespace (e.g. \(lq^Y= =\(rq).
 *
 * If colon-modified the number is printed without a trailing
 * linefeed.
 */
/*
 * In order to imitate TECO-11 closely, we apply the lookahead
 * strategy -- `=` and `==` are not executed immediately but only
 * when a non-`=` character is parsed (cf. `$$` and `^C^C`).
 * However, this would be very annoying during interactive
 * execution, therefore we still print the number immediately
 * and perhaps multiple times:
 * Typing `===` prints the number first in decimal,
 * then octal and finally in hexadecimal.
 * This won't happen e.g. in a loop that is closed on the command-line.
 */
TECO_DECLARE_STATE(teco_state_print_octal);

static gboolean
teco_state_print_decimal_initial(teco_machine_main_t *ctx, GError **error)
{
	if (ctx->flags.mode > TECO_MODE_NORMAL)
		return TRUE;
	is_executing = teco_cmdline_is_executing(ctx);
	if (G_LIKELY(!is_executing))
		return TRUE;
	/*
	 * Interactive invocation:
	 * don't yet pop number as we may have to print it repeatedly
	 */
	return teco_print(ctx, 10, error);
}

static teco_state_t *
teco_state_print_decimal_input(teco_machine_main_t *ctx, gunichar chr, GError **error)
{
	if (chr == '=')
		return &teco_state_print_octal;

	if (ctx->flags.mode == TECO_MODE_NORMAL) {
		if (G_LIKELY(!is_executing) && !teco_print(ctx, 10, error))
			return NULL;
		teco_expressions_pop_num(0);
	}
	return teco_state_start_input(ctx, chr, error);
}

/*
 * Due to the deferred nature of `=`,
 * it is valid to end in this state as well.
 */
static gboolean
teco_state_print_decimal_end_of_macro(teco_machine_main_t *ctx, GError **error)
{
	if (ctx->flags.mode > TECO_MODE_NORMAL)
		return TRUE;
	if (G_UNLIKELY(is_executing))
		return TRUE;
	if (!teco_print(ctx, 10, error))
		return FALSE;
	teco_expressions_pop_num(0);
	return TRUE;
}

TECO_DEFINE_STATE_START(teco_state_print_decimal,
	.initial_cb = (teco_state_initial_cb_t)teco_state_print_decimal_initial,
	.end_of_macro_cb = (teco_state_end_of_macro_cb_t)
	                   teco_state_print_decimal_end_of_macro
);

static gboolean
teco_state_print_octal_initial(teco_machine_main_t *ctx, GError **error)
{
	if (ctx->flags.mode > TECO_MODE_NORMAL)
		return TRUE;
	is_executing = teco_cmdline_is_executing(ctx);
	if (G_LIKELY(!is_executing))
		return TRUE;
	/*
	 * Interactive invocation:
	 * don't yet pop number as we may have to print it repeatedly
	 */
	return teco_print(ctx, 8, error);
}

static teco_state_t *
teco_state_print_octal_input(teco_machine_main_t *ctx, gunichar chr, GError **error)
{
	if (chr == '=') {
		if (ctx->flags.mode == TECO_MODE_NORMAL) {
			if (!teco_print(ctx, 16, error))
				return NULL;
			teco_expressions_pop_num(0);
		}
		return &teco_state_start;
	}

	if (ctx->flags.mode == TECO_MODE_NORMAL) {
		if (G_LIKELY(!is_executing) && !teco_print(ctx, 8, error))
			return NULL;
		teco_expressions_pop_num(0);
	}
	return teco_state_start_input(ctx, chr, error);
}

/*
 * Due to the deferred nature of `==`,
 * it is valid to end in this state as well.
 */
static gboolean
teco_state_print_octal_end_of_macro(teco_machine_main_t *ctx, GError **error)
{
	if (ctx->flags.mode > TECO_MODE_NORMAL)
		return TRUE;
	if (G_UNLIKELY(is_executing))
		return TRUE;
	if (!teco_print(ctx, 8, error))
		return FALSE;
	teco_expressions_pop_num(0);
	return TRUE;
}

TECO_DEFINE_STATE_START(teco_state_print_octal,
	.initial_cb = (teco_state_initial_cb_t)teco_state_print_octal_initial,
	.end_of_macro_cb = (teco_state_end_of_macro_cb_t)
	                   teco_state_print_octal_end_of_macro
);

static gboolean
teco_state_print_string_initial(teco_machine_main_t *ctx, GError **error)
{
	/*
	 * ^A differs from all other string-taking commands in having
	 * a default ^A escape char.
	 */
	if (ctx->parent.must_undo)
		teco_undo_gunichar(ctx->expectstring.machine.escape_char);
	ctx->expectstring.machine.escape_char = TECO_CTL_KEY('A');

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

	teco_machine_stringbuilding_set_codepage(&ctx->expectstring.machine,
	                                         teco_machine_main_eval_colon(ctx)
	                                         ? SC_CHARSET_ANSI : teco_default_codepage());
	return TRUE;
}

static teco_state_t *
teco_state_print_string_done(teco_machine_main_t *ctx, const teco_string_t *str, GError **error)
{
	teco_interface_msg_literal(TECO_MSG_USER, str->data, str->len);
	return &teco_state_start;
}

/*$ "^A" ":^A" print "print string"
 * ^A<string>^A -- Print string as message
 * @^A/string/
 * :^A<string>^A
 *
 * Print <string> as a message, i.e. in the message line
 * in interactive mode and if possible on the terminal (stdout) as well.
 *
 * \fB^A\fP differs from all other commands in the way <string>
 * is terminated.
 * It is terminated by ^A (CTRL+A, ASCII 1) by default.
 * While the initial \fB^A\fP can be written with upcarets,
 * the terminating ^A must always be ASCII 1.
 * You can however overwrite the <string> terminator as usual
 * by \fB@\fP-modifying the command.
 *
 * String-building characters are enabled for this command.
 * \fB^A\fP outputs strings in the default codepage,
 * but when colon modified raw ANSI encoding is enforced.
 */
/*
 * NOTE: Codepage is among other things important for
 * ^EUq, ^E<...> and case folding.
 */
TECO_DEFINE_STATE_EXPECTSTRING(teco_state_print_string,
	.initial_cb = (teco_state_initial_cb_t)teco_state_print_string_initial
);

/*$ T type typeout
 * [lines]T -- Type out buffer contents as messages
 * -T
 * from,toT
 *
 * Type out the next or previous number of <lines> from the buffer
 * as a message, i.e. in the message line in interactive mode
 * and if possible on the terminal (stdout) as well.
 * If <lines> is omitted, the sign prefix is implied.
 * If two arguments are specified, the characters beginning
 * at position <from> up to the character at position <to>
 * are copied.
 *
 * The semantics of the arguments is analogous to the \fBK\fP
 * command's arguments.
 */
void
teco_state_start_typeout(teco_machine_main_t *ctx, GError **error)
{
	gsize from, len;

	if (!teco_get_range_args("T", &from, &len, error))
		return;

	/*
	 * NOTE: This may remove the buffer gap since we need a consecutive
	 * piece of memory to log as a single message.
	 * FIXME: In batch mode even this could theoretically be avoided.
	 * Need to add a function like teco_interface_is_batch().
	 * Still, this is probably more efficient than using a temporary
	 * allocation with SCI_GETTEXTRANGEFULL.
	 */
	const gchar *str = (const gchar *)teco_interface_ssm(SCI_GETRANGEPOINTER, from, len);
	teco_interface_msg_literal(TECO_MSG_USER, str, len);
}

/*$ "^T" ":^T" "typeout glyph" "get char"
 * <c1,c2,...>^T -- Type out the numeric arguments as a message or get character from user
 * <c1,c2,...>:^T
 * ^T -> codepoint
 * :^T -> byte
 *
 * Types out characters for all the values
 * on the argument stack (interpreted as codepoints) as messages,
 * i.e. in the message line in interactive mode
 * and if possible on the terminal (stdout) as well.
 * It does so in the order of the arguments, i.e.
 * <c1> is inserted before <c2>, ecetera.
 * By default the codepoints are expected to be in the default
 * codepage, but you can force raw ANSI encoding (for arbitrary
 * bytes) by colon-modifying the command.
 *
 * When called without any argument, \fB^T\fP reads a key from the
 * user (or from stdin) and returns the corresponding codepoint.
 * If the default encoding is UTF-8, this will not work
 * for function keys.
 * If the default encoding is raw ANSI or if the command is
 * colon-modified, \fB^T\fP returns raw bytes.
 * When run in batch mode, this will return whatever byte is
 * delivered by the attached terminal.
 * In case stdin is closed, -1 is returned.
 * In interactive mode, pressing CTRL+D or CTRL+C will also
 * return -1.
 */
void
teco_state_control_typeout(teco_machine_main_t *ctx, GError **error)
{
	if (!teco_expressions_eval(FALSE, error))
		return;

	gboolean utf8 = !teco_machine_main_eval_colon(ctx) &&
	                teco_default_codepage() == SC_CP_UTF8;

	guint args = teco_expressions_args();
	if (!args) {
		teco_expressions_push(teco_interface_getch(utf8));
		return;
	}

	if (!utf8) {
		/* assume raw ANSI byte output */
		g_autofree gchar *buf = g_malloc(args);
		gchar *p = buf+args;

		for (gint i = 0; i < args; i++) {
			teco_int_t chr = teco_expressions_pop_num(0);
			if (chr < 0 || chr > 0xFF) {
				teco_error_codepoint_set(error, "^T");
				return;
			}
			*--p = chr;
		}

		teco_interface_msg_literal(TECO_MSG_USER, p, args);
		return;
	}

	/* 4 bytes should be enough for UTF-8, but we better follow the documentation */
	g_autofree gchar *buf = g_malloc(args*6);
	gchar *p = buf;

	for (gint i = args; i > 0; i--) {
		teco_int_t chr = teco_expressions_peek_num(i-1);
		if (chr < 0 || !g_unichar_validate(chr)) {
			teco_error_codepoint_set(error, "^T");
			return;
		}
		p += g_unichar_to_utf8(chr, p);
	}
	/* we pop only now since we had to peek in reverse order */
	for (gint i = 0; i < args; i++)
		teco_expressions_pop_num(0);

	teco_interface_msg_literal(TECO_MSG_USER, buf, p-buf);
}