/*
	qwaq-debug.c

	Debugging support

	Copyright (C) 2020 Bill Currie <bill@taniwha.org>

	Author: Bill Currie <bill@taniwha.org>
	Date: 2020/03/24

	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 <sys/ioctl.h>
#include <ctype.h>
#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>

#include "QF/dstring.h"
#include "QF/hash.h"
#include "QF/keys.h"
#include "QF/sys.h"

#include "qwaq.h"
#include "event.h"
#include "qwaq-curses.h"
#include "qwaq-debug.h"

typedef struct qwaq_target_s {
	progs_t    *pr;
	struct qwaq_debug_s *debugger;
	int         handle;
	prdebug_t   event;
	rwcond_t    run_cond;
} qwaq_target_t;

typedef struct qwaq_debug_s {
	progs_t    *pr;
	qwaq_resources_t *qwaq;	// to communicate with the debugger thread
	PR_RESMAP (qwaq_target_t) targets;
} qwaq_debug_t;

#define always_inline inline __attribute__((__always_inline__))

static qwaq_target_t *
target_new (qwaq_debug_t *debug)
{
	PR_RESNEW (qwaq_target_t, debug->targets);
}

static void
target_free (qwaq_debug_t *debug, qwaq_target_t *target)
{
	PR_RESFREE (qwaq_target_t, debug->targets, target);
}

static void
target_reset (qwaq_debug_t *debug)
{
	PR_RESRESET (qwaq_target_t, debug->targets);
}

static inline qwaq_target_t *
target_get (qwaq_debug_t *debug, unsigned index)
{
	PR_RESGET (debug->targets, index);
}

static inline int
target_index (qwaq_debug_t *debug, qwaq_target_t *target)
{
	PR_RESINDEX (debug->targets, target);
}

static always_inline qwaq_target_t * __attribute__((pure))
get_target (qwaq_debug_t *debug, const char *name, int handle)
{
	qwaq_target_t *target = target_get (debug, handle);

	if (!target || !target->debugger) {
		PR_RunError (debug->pr, "invalid target passed to %s", name + 4);
	}
	return target;
}

static void
qwaq_debug_handler (prdebug_t debug_event, void *data)
{
	__auto_type target = (qwaq_target_t *) data;
	qwaq_debug_t *debug = target->debugger;
	qwaq_event_t event = {};
	int         ret;

	target->event = debug_event;
	event.what = qe_debug_event;
	event.message.pointer_val = target->handle;

	while ((ret = qwaq_add_event (debug->qwaq, &event)) == ETIMEDOUT) {
		// spin
	}
	if (ret == EINVAL) {
		Sys_Error ("event queue broke");
	}
	pthread_mutex_lock (&target->run_cond.mut);
	pthread_cond_wait (&target->run_cond.rcond, &target->run_cond.mut);
	pthread_mutex_unlock (&target->run_cond.mut);
	if (debug_event == prd_runerror || debug_event == prd_error) {
		pthread_exit ((void *) target->pr->error_string);
	}
}

static void
qwaq_debug_clear (progs_t *pr, void *data)
{
	__auto_type debug = (qwaq_debug_t *) data;
	target_reset (debug);
}

static void
qwaq_target_clear (progs_t *pr, void *data)
{
	qwaq_target_t *target = pr->debug_data;
	target_free (target->debugger, target);
}

//FIXME need a better way to get this from one thread to the others
static qwaq_debug_t *qwaq_debug_data;

static int
qwaq_target_load (progs_t *pr)
{
	qwaq_target_t *target = target_new (qwaq_debug_data);
	target->pr = pr;
	target->debugger = qwaq_debug_data;
	target->handle = target_index (qwaq_debug_data, target);
	qwaq_init_cond (&target->run_cond);

	pr->debug_handler = qwaq_debug_handler;
	pr->debug_data = target;

	// start tracing immediately so the debugger has a chance to start up
	// before the target progs begin running
	pr->pr_trace = 1;
	pr->pr_trace_depth = -1;

	return 1;
}

static void
qdb_set_trace (progs_t *pr)
{
	__auto_type debug = PR_Resources_Find (pr, "qwaq-debug");
	pointer_t   handle = P_INT (pr, 0);
	int         state = P_INT (pr, 1);
	qwaq_target_t *target = get_target (debug, __FUNCTION__, handle);
	progs_t    *tpr = target->pr;

	tpr->pr_trace = state;
}

static void
qdb_set_breakpoint (progs_t *pr)
{
	__auto_type debug = PR_Resources_Find (pr, "qwaq-debug");
	pointer_t   handle = P_INT (pr, 0);
	unsigned    staddr = P_INT (pr, 1);
	qwaq_target_t *target = get_target (debug, __FUNCTION__, handle);
	progs_t    *tpr = target->pr;

	if (staddr >= tpr->progs->numstatements) {
		R_INT (pr) = -1;
		return;
	}
	tpr->pr_statements[staddr].op |= OP_BREAK;
	R_INT (pr) = 0;
}

static void
qdb_clear_breakpoint (progs_t *pr)
{
	__auto_type debug = PR_Resources_Find (pr, "qwaq-debug");
	pointer_t   handle = P_INT (pr, 0);
	unsigned    staddr = P_UINT (pr, 1);
	qwaq_target_t *target = get_target (debug, __FUNCTION__, handle);
	progs_t    *tpr = target->pr;

	if (staddr >= tpr->progs->numstatements) {
		R_INT (pr) = -1;
		return;
	}
	tpr->pr_statements[staddr].op &= ~OP_BREAK;
	R_INT (pr) = 0;
}

static void
qdb_set_watchpoint (progs_t *pr)
{
	__auto_type debug = PR_Resources_Find (pr, "qwaq-debug");
	pointer_t   handle = P_INT (pr, 0);
	pointer_t   offset = P_UINT (pr, 1);
	qwaq_target_t *target = get_target (debug, __FUNCTION__, handle);
	progs_t    *tpr = target->pr;

	if (offset >= tpr->globals_size) {
		R_INT (pr) = -1;
		return;
	}
	tpr->watch = &tpr->pr_globals[offset];
	R_INT (pr) = 0;
}

static void
qdb_clear_watchpoint (progs_t *pr)
{
	__auto_type debug = PR_Resources_Find (pr, "qwaq-debug");
	pointer_t   handle = P_INT (pr, 0);
	qwaq_target_t *target = get_target (debug, __FUNCTION__, handle);
	progs_t    *tpr = target->pr;

	tpr->watch = 0;
	R_INT (pr) = 0;
}

static void
qdb_continue (progs_t *pr)
{
	__auto_type debug = PR_Resources_Find (pr, "qwaq-debug");
	pointer_t   handle = P_INT (pr, 0);
	qwaq_target_t *target = get_target (debug, __FUNCTION__, handle);

	pthread_mutex_lock (&target->run_cond.mut);
	pthread_cond_signal (&target->run_cond.rcond);
	pthread_mutex_unlock (&target->run_cond.mut);
}

static void
qdb_get_state (progs_t *pr)
{
	__auto_type debug = PR_Resources_Find (pr, "qwaq-debug");
	pointer_t   handle = P_INT (pr, 0);
	qwaq_target_t *target = get_target (debug, __FUNCTION__, handle);
	progs_t    *tpr = target->pr;
	pr_lineno_t *lineno;
	pr_auxfunction_t *f;
	string_t    file = 0;
	unsigned    line = 0;
	unsigned    staddr = tpr->pr_xstatement;
	func_t      func = tpr->pr_xfunction - tpr->function_table;

	lineno = PR_Find_Lineno (tpr, staddr);
	if (lineno) {
		f = PR_Get_Lineno_Func (pr, lineno);
		file = pr->pr_functions[f->function].s_file;
		func = f->function;
		line = PR_Get_Lineno_Line (pr, lineno);
		line += f->source_line;
	}

	qdb_state_t state = {};
	state.staddr = staddr;
	state.func = func;
	state.file = file;
	state.line = line;

	R_PACKED (pr, qdb_state_t) = state;
}

static builtin_t builtins[] = {
	{"qdb_set_trace",			qdb_set_trace,			-1},
	{"qdb_set_breakpoint",		qdb_set_breakpoint,		-1},
	{"qdb_clear_breakpoint",	qdb_clear_breakpoint,	-1},
	{"qdb_set_watchpoint",		qdb_set_watchpoint,		-1},
	{"qdb_clear_watchpoint",	qdb_clear_watchpoint,	-1},
	{"qdb_continue",			qdb_continue,			-1},
	{"qdb_get_state",			qdb_get_state,			-1},
	{}
};

void
QWAQ_Debug_Init (progs_t *pr)
{
	qwaq_debug_t *debug = calloc (sizeof (*debug), 1);
	qwaq_debug_data = debug;	// FIXME ? see decl
	debug->pr = pr;
	debug->qwaq = PR_Resources_Find (pr, "qwaq");

	PR_Resources_Register (pr, "qwaq-debug", debug, qwaq_debug_clear);
	PR_RegisterBuiltins (pr, builtins);
}

void
QWAQ_DebugTarget_Init (progs_t *pr)
{
	PR_AddLoadFunc (pr, qwaq_target_load);
	PR_Resources_Register (pr, "qwaq-target", 0, qwaq_target_clear);
}