#include <assert.h>
#include <stdio.h>
#include <stdint.h>
#include <libguile.h>
#include <string.h>

#include "riverguile.h"
#include "output.h"
#include "seat.h"

/**
 * ISO C forbids casting a function pointer to a void pointer because on some
 * architectures they have different sizes. However scm_c_define_gsubr() wants
 * a function pointer as a void pointer, which trips -Wpedantic. Compiling C
 * without pedantic errors is not a reasonable option in my opinion, so instead
 * we'll have to resort to this hack.
 */
#define scm_c_define_gsubr_fix(NAME, REQ, OPT, RST, FN) \
	{ const long int ptr = (long int)FN; scm_c_define_gsubr(NAME, REQ, OPT, RST, (void *)ptr); }

static uint32_t extract_ms_from_idle_key (SCM key)
{
	SCM key_split = scm_string_split(
		scm_symbol_to_string(key),
		scm_to_char_set(scm_from_utf8_string(":"))
	);
	if ( scm_to_uint32(scm_length(key_split)) != 2 )
		goto error;

	SCM maybe_number = scm_string_to_number(scm_cadr(key_split), scm_from_int(10));
	if ( scm_is_false(maybe_number) == 1 )
		goto error;

	int32_t ms = scm_to_int32(maybe_number);
	if ( ms < 0 )
		goto error;

	return (uint32_t)ms * 1000;

error:
	scm_error_scm(
		scm_from_utf8_symbol("wrong-type-arg"),
		scm_from_utf8_string("install-handler"),
		scm_from_utf8_string("First argument: Excpected 'idle:<positive integer>."),
		SCM_BOOL_F,
		scm_list_1(key)
	);
	return 0;
}

static SCM install_handler (SCM key, SCM proc)
{
	if ( scm_is_false(scm_symbol_p(key)) == 1 )
	{
		scm_error_scm(
			scm_from_utf8_symbol("wrong-type-arg"),
			scm_from_utf8_string("install-handler"),
			scm_from_utf8_string("First argument must be a symbol."),
			SCM_BOOL_F,
			scm_list_1(key)
		);
		return SCM_UNSPECIFIED;
	}

	// TODO check if the procedure has the right amount of arguments.
	if ( scm_is_false(scm_procedure_p(proc)) == 1 )
	{
		scm_error_scm(
			scm_from_utf8_symbol("wrong-type-arg"),
			scm_from_utf8_string("install-handler"),
			scm_from_utf8_string("Second argument must be a procedure."),
			SCM_BOOL_F,
			scm_list_1(proc)
		);
		return SCM_UNSPECIFIED;
	}

	if ( scm_is_eq(scm_from_utf8_symbol("layout-demand"), key) == 1 )
	{
		if ( context.layout_manager == NULL )
		{
			fputs("ERROR: Trying to install layout-demand handler but server does not support river-layout-v3.\n", stderr);
			fputs("INFO: This error is not fatal, but means riverguile will not provide any layout.\n", stderr);
			return SCM_BOOL_F;
		}

		context.mode = CONTINOUS;
		context.layout_demand_handler = proc;

		/* Configure all outputs to expose layouts. */
		struct Output *output;
		wl_list_for_each(output, &context.outputs, link)
			output_configure_layout(output);
	}
	else if ( scm_is_eq(scm_from_utf8_symbol("user-command"), key) == 1)
	{
		/* No need to check if the interface exists since it's only
		 * used when a layout-demand handler is configured.
		 */
		context.user_command_handler = proc;
	}
	else if ( scm_is_eq(scm_from_utf8_symbol("exit"), key) == 1)
		context.exit_handler = proc;
	else if ( scm_is_true(scm_string_prefix_p(scm_from_utf8_string("idle:"), scm_symbol_to_string(key),
		scm_from_int(0), scm_from_int(5),
		scm_from_int(0), scm_string_length(scm_symbol_to_string(key)))) == 1 )
	{
		if ( context.idle_notifier == NULL )
		{
			fputs("ERROR: Trying to install idle handler but server does not support ext-idle-notify-v1.\n", stderr);
			fputs("INFO: This error is not fatal, but means riverguile will not be able to call any idle handler.\n", stderr);
			return SCM_BOOL_F;
		}
		if ( wl_list_length(&context.seats) == 0 )
		{
			fputs("ERROR: Trying to install idle handler but server did not advertise any seats.\n", stderr);
			fputs("INFO: This error is not fatal, but means riverguile will not be able to call any idle handler.\n", stderr);
			return SCM_BOOL_F;
		}

		context.mode = CONTINOUS;

		/* Just use the first seat. River only supports a single one anyway. */
		struct Seat *seat;
		wl_list_for_each(seat, &context.seats, link)
			break;

		uint32_t ms = extract_ms_from_idle_key(key);

		if (!seat_add_idle(seat, proc, ms))
		{
			scm_error_scm(
				scm_from_utf8_symbol("memory-allocation-error"),
				scm_from_utf8_string("install-handler"),
				SCM_BOOL_F,
				SCM_BOOL_F,
				SCM_BOOL_F
			);
			return SCM_UNSPECIFIED;
		}
	}
	else
	{
		scm_error_scm(
			// TODO should this be 'misc-error instead?
			scm_from_utf8_symbol("out-of-range"),
			scm_from_utf8_string("install-handler"),
			scm_from_utf8_string("Unknown key: ~A"),
			scm_list_1(key),
			scm_list_1(key)
		);
		return SCM_UNSPECIFIED;
	}

	return SCM_BOOL_T;
}

static void *load_script_inner (void *data)
{
	const char *path = (char *)data;

	/* scm_primitive_load_path() searches guiles load-path when encountering
	 * a relative path. That should never happen here though.
	 */
	assert(path[0] == '/');

	return scm_primitive_load_path(scm_from_utf8_string(path));
}

void *load_script (void *data)
{
	/* Note: All guile objects are garbage collected. */

	scm_c_define_gsubr_fix("install-handler", 2, 0, 0, install_handler);

	/* Continuation barrier causes stack unwind on exceptions to stop here.
	 * Otherwise the entire stack created by scm_with_guile() would be
	 * unwound. This makes responding to exceptions nicer.
	 */
	SCM call_result = scm_c_with_continuation_barrier(
		load_script_inner, data
	);

	if ( call_result == NULL )
		return (void *)"ERROR: Fatal error while loading layout script.\n";

	/* Checked in the installer functions. */
	if ( context.layout_demand_handler != NULL )
		assert(scm_is_true(scm_procedure_p(context.layout_demand_handler)) == 1);
	if ( context.user_command_handler != NULL )
		assert(scm_is_true(scm_procedure_p(context.user_command_handler)) == 1);
	if ( context.exit_handler != NULL )
		assert(scm_is_true(scm_procedure_p(context.exit_handler)) == 1);

	return NULL;
}