#include "wasm_compile.h"
#include "wasm.h"
#include "stack_machine_instruction.h"

struct types {
	struct types *prev;
	char type; /* should be one of VALTYPE_* constants from wasm.h */
};

struct translation {
	FILE *handle;
	struct function *function;
	struct module *module;
	struct types *types_stack;
};

void free_types_stack(struct types *top)
{
	struct types *tmp;

	while (top) {
		tmp = top->prev;
		free(top);
		top = tmp;
	}
}

/* All functions, that go into one of function pointer arrays, start with _ */

/** DEFINE TRANSLATION FUNCTIONS **/

/* Translate complex - those routines have to be defined manually */
#define TC(wasm_opcode, name, argtypes, restype)

static int typecheck_call(struct translation *data, struct function *callee);

static int _translate_call(struct translation *data)
{
	uint32_t funcidx;
	struct function *func;
	struct instruction **target;

	if (leb_u32(data->handle, &funcidx)) {
		PRERR(MSG_BAD_NUM);
		return -1;
	}

	if (funcidx >= data->module->functions_count) {
		PRERR(MSG_BAD_IDX("funcidx"));
		return -1;
	}

	func = data->module->functions + funcidx;

	if (typecheck_call(data, func))
		return -1;

	target = &func->translated_body;

	return i_call(ptr(target), &data->function->translated_body);
}

static int typecheck_local_get(struct translation *data, uint32_t localidx);

static int _translate_local_get(struct translation *data)
{
	uint32_t localidx;
	uint32_t args_count = data->function->type->args.count;
	uint32_t locals_count = data->function->locals_count;
	uint32_t all_locals_count = args_count + locals_count;
	uint64_t offset_on_frame;
	struct instruction **expr = &data->function->translated_body;

	if (leb_u32(data->handle, &localidx)) {
		PRERR(MSG_BAD_NUM);
		return -1;
	}

	if (localidx >= all_locals_count) {
		PRERR(MSG_BAD_IDX("localidx"));
		return -1;
	}

	if (typecheck_local_get(data, localidx))
		return -1;

	offset_on_frame = all_locals_count - localidx + 1;

	if (localidx >= args_count)
		offset_on_frame -= 1;

	if (i_load  (im(STACK_FRAME_BACKUP_ADDR), expr) ||
	    i_load_p(im(4 * offset_on_frame),     expr))
		return -1;

	return 0;
}

static int _translate_const(struct translation *data)
{
	uint32_t constant;

	if (leb_u32(data->handle, &constant)) {
		PRERR(MSG_BAD_NUM);
		return -1;
	}

	return i_const(im(constant), &data->function->translated_body);
}

/* Translate Simple */
#define TS(wasm_opcode, sm_instr, argtypes, restype)			\
	static int _translate_##sm_instr(struct translation *data)	\
	{								\
		return i_##sm_instr(&data->function->translated_body);	\
	}

/* Translate load/store */
static int translate_load_store(struct translation *data,
				int (*instr_routine) (struct instruction_data,
						      struct instruction **))
{
	uint32_t align, offset;

	if (leb_u32(data->handle, &align) ||
	    leb_u32(data->handle, &offset)) {
		PRERR(MSG_BAD_NUM);
		return -1;
	}

	offset += MEMORY_BOTTOM_ADDR;

	return instr_routine(im(offset), &data->function->translated_body);
}

#define TLS(wasm_opcode, sm_instr, argtypes, restype)			\
	static int _translate_##sm_instr(struct translation *data)	\
	{								\
		return translate_load_store(data, i_##sm_instr);	\
	}

/* This inclusion defines functions using macros above */
#include "translate_xmacro.h"

#undef TS
#undef TLS
#undef TC

/** DEFINE TRANSLATION FUNCTIONS POINTER ARRAY **/

/* Translate complex */
#define TC(wasm_opcode, name, argtypes, restype) \
	[wasm_opcode] = _translate_##name,

/* Translate Simple */
#define TS(wasm_opcode, sm_instr, argtypes, restype) \
	TC(wasm_opcode, sm_instr, dummy, dummy)

/* Translate load/store */
#define TLS(wasm_opcode, sm_instr, argtypes, restype)	\
	TC(wasm_opcode, sm_instr, dummy, dummy)

/* The actual array of function pointers is defined here */
static int (*translation_routines[256]) (struct translation *) = {
#include "translate_xmacro.h"
};

#undef TS
#undef TLS
#undef TC

/** DEFINE ARGUMENT TYPECHECK FUNCTIONS **/

static int _argcheck_empty(struct types **types_stack)
{
	return 0;
}

static int argcheck_generic_noremove(struct types *types_stack, char expected)
{
	char *name;

	name =
		expected == VALTYPE_F64 ? "f64" :
		expected == VALTYPE_F32 ? "f32" :
		expected == VALTYPE_I64 ? "i64" :
		"i32";

	if (!types_stack) {
		PRERR("Expected %s on stack, got nothing\n", name);
		return -1;
	}

	if (types_stack->type != VALTYPE_I32) {
		PRERR("Expected %s (0x%02hhx) on stack, got 0x%02hhx\n",
		      name, expected, types_stack->type);
		return -1;
	}

	return 0;
}

static int argcheck_generic(struct types **types_stack, char expected)
{
	struct types *top_type;

	if (argcheck_generic_noremove(*types_stack, expected))
		return -1;

	top_type = *types_stack;
	*types_stack = top_type->prev;
	free(top_type);

	return 0;
}

static int _argcheck_i32(struct types **types_stack)
{
	return argcheck_generic(types_stack, VALTYPE_I32);
}

static int _argcheck_i32_i32(struct types **types_stack)
{
	int i;

	for (i = 0; i < 2; i++) {
		if (argcheck_generic(types_stack, VALTYPE_I32))
			return -1;
	}

	return 0;
}

static int _argcheck_custom(struct types **types_stack)
{
	return 0; /* Translation function will handle argument checks */
}

/** DEFINE RESULT TYPECHECK FUNCTIONS **/

static int _rescheck_empty(struct types **types_stack)
{
	return 0;
}

static int rescheck_generic(struct types **types_stack, char returned)
{
	struct types *top;

	top = malloc(sizeof(struct types));

	if (!top) {
		PRERR(MSG_ALLOC_FAIL(sizeof(struct types)));
		return -1;
	}

	*top = (struct types) {.prev = *types_stack, .type = returned};
	*types_stack = top;

	return 0;
}

static int _rescheck_i32(struct types **types_stack)
{
	return rescheck_generic(types_stack, VALTYPE_I32);
}

static int _rescheck_custom(struct types **types_stack)
{
	return 0;
}

/** DEFINE TYPECHECK FUNCTION POINTER ARRAY **/

/* Translate complex */
#define TC(wasm_opcode, name, argtypes, restype)		\
	[wasm_opcode] = {.argcheck = _argcheck_##argtypes,	\
			 .rescheck = _rescheck_##restype},

/* Translate Simple */
#define TS(wasm_opcode, sm_instr, argtypes, restype)	\
	TC(wasm_opcode, dummy, argtypes, restype)

/* Translate load/store */
#define TLS(wasm_opcode, sm_instr, argtypes, restype)	\
	TC(wasm_opcode, dummy, argtypes, restype)

struct typecheck {
	int (*argcheck) (struct types **), (*rescheck) (struct types **);
};

/*static*/ struct typecheck typecheck_routines[256] = {
#include "translate_xmacro.h"
};

#undef TS
#undef TLS
#undef TC

/** DEFINE CUSTOM TYPECHECK FUNCTIONS **/

static int typecheck_call(struct translation *data, struct function *callee)
{
	uint32_t i;

	i = callee->type->args.count;

	while (i--) {
		if (argcheck_generic(&data->types_stack,
				     callee->type->args.types[i]))
			return -1;
	}

	for (i = 0; i < callee->type->results.count; i++) {
		if (rescheck_generic(&data->types_stack,
				     callee->type->results.types[i]))
			return -1;
	}

	return 0;
}

static int typecheck_local_get(struct translation *data, uint32_t localidx)
{
	uint32_t args_count = data->function->type->args.count;
	char type = localidx < args_count ?
		data->function->type->args.types[localidx] :
		data->function->locals[localidx - args_count];

	if (rescheck_generic(&data->types_stack, type))
		return -1;

	return 0;
}

/** REST OF THE CODE **/

static int translate_instr(struct translation *data, uint8_t wasm_opcode)
{
	struct typecheck *tc_routines;

	if (!translation_routines[wasm_opcode]) {
		PRERR("Unknown Wasm opcode: 0x%02x\n", wasm_opcode);
		return -1;
	}

	tc_routines = typecheck_routines + wasm_opcode;

	if (tc_routines->argcheck(&data->types_stack) ||
	    tc_routines->rescheck(&data->types_stack) ||
	    translation_routines[wasm_opcode](data))
		return -1;

	return 0;
}

static int translate_expr(struct translation *data, struct resulttype *args,
			  struct resulttype *results)
{
	struct types **tmp, *types_stack_rest;
	uint32_t i;
	int wasm_opcode;

	tmp = &data->types_stack;
	i = args ? args->count : 0;

	while (i--) {
		if (argcheck_generic_noremove(*tmp, args->types[i]))
			return -1;

		tmp = &(*tmp)->prev;
	}

	types_stack_rest = *tmp;
	*tmp = NULL;

	while (1) {
		wasm_opcode = fgetc(data->handle);

		if (wasm_opcode == EOF) {
			PRERR(MSG_EOF);
			goto fail;
		}

		if (wasm_opcode == WASM_END)
			break;

		if (translate_instr(data, wasm_opcode))
			goto fail;
	}

	tmp = &data->types_stack;
	i = results ? results->count : 0;

	while (i--) {
		if (argcheck_generic_noremove(*tmp, results->types[i]))
			goto fail;

		tmp = &(*tmp)->prev;
	}

	if (*tmp) {
		PRERR("Expression produces too many result values\n");
		goto fail;
	}

	*tmp = types_stack_rest;
	return 0;

fail:
	free_types_stack(data->types_stack);
	data->types_stack = types_stack_rest;

	return -1;
}

int translate(FILE *handle, struct function *function, struct module *module)
{
	struct instruction **expr = &function->translated_body;
	uint32_t args_count = function->type->args.count;
	uint32_t locals_count = function->locals_count;
	uint32_t all_locals_count = args_count + locals_count;
	size_t i;
	struct translation data = {.handle = handle,
				   .function = function,
				   .module = module,
				   .types_stack = NULL};

	if (locals_count + (uint64_t) args_count > STACK_TOP_ADDR * 4) {
		PRERR("Too many locals in a function\n");
		goto fail;
	}

	for (i = locals_count + 3; i; i--) {
		if (i_const(im(0), expr))
			goto fail;
	}

	/* function prologue */
	if (i_get_frame(                             expr) ||
	    i_tee      (                             expr) ||
	    i_load     (im(STACK_FRAME_BACKUP_ADDR), expr) ||
	    i_store_p  (im(0x0),                     expr) ||
	    i_store    (im(STACK_FRAME_BACKUP_ADDR), expr))
		goto fail;

	/* actual function body */
	if (translate_expr(&data, NULL, &function->type->results))
		goto fail;

        /* function epilogue */
	if (function->type->results.count) {
		if (i_load   (im(STACK_FRAME_BACKUP_ADDR),        expr) ||
		    i_swap   (                                    expr) ||
		    i_store_p(im(4 * (2 + all_locals_count - 1)), expr) ||
		    i_load   (im(STACK_FRAME_BACKUP_ADDR),        expr) ||
		    i_tee    (                                    expr) ||
		    i_tee    (                                    expr) ||
		    i_load_p (im(4 * (1 + locals_count)),         expr) ||
		    i_store_p(im(4 * (2 + all_locals_count - 2)), expr) ||
		    i_load_p (im(0),                              expr) ||
		    i_store  (im(STACK_FRAME_BACKUP_ADDR),        expr))
			goto fail;
	} else {
		/* It's a bit shorter if we don't return anything */
		if (i_load   (im(STACK_FRAME_BACKUP_ADDR),        expr) ||
		    i_tee    (                                    expr) ||
		    i_tee    (                                    expr) ||
		    i_load_p (im(4 * (1 + locals_count)),         expr) ||
		    i_store_p(im(4 * (2 + all_locals_count - 1)), expr) ||
		    i_load_p (im(0),                              expr) ||
		    i_store  (im(STACK_FRAME_BACKUP_ADDR),        expr))
			goto fail;

	}

	i = locals_count + args_count + 2;

	if (!function->type->results.count)
		i++;

	while (i--) {
		if (i_drop(expr))
			goto fail;
	}

	if (i_ret(expr))
		goto fail;

	return 0;

fail:
	PRERR("Couldn't translate function to stack machine\n");

	free_expr(*expr);
	function->translated_body = NULL;

	return -1;
}