/*
 * Copyright (C) Andrew Clayton
 * Copyright (C) F5, Inc.
 */

#include <stdio.h>
#include <stdlib.h>

#include <wasm.h>
#include <wasi.h>
#include <wasmtime.h>

static void exit_with_error(const char *message, wasmtime_error_t *error,
			    wasm_trap_t *trap)
{
	wasm_byte_vec_t error_message;

	fprintf(stderr, "error: %s\n", message);
	if (error != NULL) {
		wasmtime_error_message(error, &error_message);
		wasmtime_error_delete(error);
	} else {
		wasm_trap_message(trap, &error_message);
		wasm_trap_delete(trap);
	}
	fprintf(stderr, "%.*s\n", (int) error_message.size, error_message.data);
	wasm_byte_vec_delete(&error_message);

	exit(EXIT_FAILURE);
}

static wasm_trap_t *dummy_func(void *env, wasmtime_caller_t *caller,
			       const wasmtime_val_t *args, size_t nargs,
			       wasmtime_val_t *results, size_t nresults)
{
	(void)env;
	(void)caller;
	(void)args;
	(void)nargs;
	(void)results;
	(void)nresults;

	return NULL;
}

static wasm_functype_t *create_wasm_func(const wasm_valkind_t *pk,
					 size_t nr_params,
					 const wasm_valkind_t *rk,
					 size_t nr_results)
{
	wasm_valtype_t *pt[14];
	wasm_valtype_t *rt[1];
	wasm_valtype_vec_t params;
	wasm_valtype_vec_t results;

	if (nr_params > 0) {
		for (size_t i = 0; i < nr_params; i++)
			pt[i] = wasm_valtype_new(pk[i]);
		wasm_valtype_vec_new(&params, nr_params, pt);
	} else {
		wasm_valtype_vec_new_empty(&params);
	}

	if (nr_results > 0) {
		for (size_t i = 0; i < nr_results; i++)
			rt[i] = wasm_valtype_new(rk[i]);
		wasm_valtype_vec_new(&results, nr_results, rt);
	} else {
		wasm_valtype_vec_new_empty(&results);
	}

	return wasm_functype_new(&params, &results);
}

static inline size_t rg(const char *s)
{
	return strlen(s);
}

/*
 * Argument counting macros gleamed from
 * https://gist.github.com/christophercrouzet/db9bbb07d427381253a91210e7ddc68d
 */
#define ARG( \
	_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, ...) \
	_14
#define COUNT_ARGS(...) \
	ARG(__VA_ARGS__, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0,)

#define SET_VALS(type, ...) \
	.type	   = { __VA_ARGS__ }, \
	.nr_##type = COUNT_ARGS(__VA_ARGS__)

#define SET_FUNC(function, function_name, module) \
	.func_name    = function_name, \
	.func_namelen = strlen(function_name), \
	.mod_name     = module, \
	.mod_namelen  = strlen(module), \
	.func	      = dummy_func

static void set_function_imports(wasmtime_linker_t *linker)
{
	static const struct {
		const char                *func_name;
		int			  func_namelen;
		const char		  *mod_name;
		int			  mod_namelen;

		wasmtime_func_callback_t  func;

		wasm_valkind_t            params[14];
		size_t			  nr_params;
		wasm_valkind_t            results[1];
		size_t			  nr_results;
	} import_functions[] = {
		{
			SET_FUNC(poll_oneoff, "poll-oneoff", "poll2"),
			SET_VALS(params, WASM_I32, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(read, "read", "streams2"),
			SET_VALS(params, WASM_I32, WASM_I64, WASM_I32),
		}, {
			SET_FUNC(blocking_read, "blocking-read", "streams2"),
			SET_VALS(params, WASM_I32, WASM_I64, WASM_I32),
		}, {
			SET_FUNC(subscribe_to_input_stream,
				 "subscribe-to-input-stream", "streams2"),
			SET_VALS(params, WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(write, "write", "streams2"),
			SET_VALS(params,
				 WASM_I32, WASM_I32, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(blocking_write, "blocking-write", "streams2"),
			SET_VALS(params,
				 WASM_I32, WASM_I32, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(subscribe_to_output_stream,
				 "subscribe-to-output-stream", "streams2"),
			SET_VALS(params, WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(handle, "handle", "default-outgoing-HTTP2"),
			SET_VALS(params,
				 WASM_I32, WASM_I32, WASM_I32, WASM_I32,
				 WASM_I32, WASM_I32, WASM_I32, WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(new_fields, "new-fields", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(fields_entries, "fields-entries", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(finish_incoming_stream,
				 "finish-incoming-stream", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(finish_outgoing_stream,
				 "finish-outgoing-stream", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(incoming_request_method,
				 "incoming-request-method", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(incoming_request_path_with_query,
				 "incoming-request-path-with-query", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(incoming_request_headers,
				 "incoming-request-headers", "types2"),
			SET_VALS(params, WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(incoming_request_consume,
				 "incoming-request-consume", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(new_outgoing_request, "new-outgoing-request",
				 "types2"),
			SET_VALS(params,
				 WASM_I32, WASM_I32, WASM_I32, WASM_I32,
				 WASM_I32, WASM_I32, WASM_I32, WASM_I32,
				 WASM_I32, WASM_I32, WASM_I32, WASM_I32,
				 WASM_I32, WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(outgoing_request_write,
				 "outgoing-request-write", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(set_response_outparam,
				 "set-response-outparam", "types2"),
			SET_VALS(params,
				 WASM_I32, WASM_I32, WASM_I32, WASM_I32,
				 WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(incoming_response_status,
				 "incoming-response-status", "types2"),
			SET_VALS(params, WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(incoming_response_headers,
				 "incoming-response-headers", "types2"),
			SET_VALS(params, WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(incoming_response_consume,
				 "incoming-response-consume", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(new_outgoing_response,
				 "new-outgoing-response", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
			SET_VALS(results, WASM_I32),
		}, {
			SET_FUNC(outgoing_response_write,
				 "outgoing-response-write", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(future_incoming_response-get,
				 "future-incoming-response-get", "types2"),
			SET_VALS(params, WASM_I32, WASM_I32),
		}, {
			SET_FUNC(listen_to_fauture_incoming_response,
				 "listen-to-future-incoming-response",
				 "types2"),
			SET_VALS(params, WASM_I32),
			SET_VALS(results, WASM_I32),
		},

		{ }
	}, *imf;

	for (imf = import_functions; imf->func_name != NULL; imf++) {
		wasm_functype_t  *func_ty;

		printf("    [%s::%s]\n", imf->mod_name, imf->func_name);

		func_ty = create_wasm_func(imf->params, imf->nr_params,
					   imf->results, imf->nr_results);
		wasmtime_linker_define_func(linker,
					    imf->mod_name, imf->mod_namelen,
					    imf->func_name, imf->func_namelen,
					    func_ty,  imf->func, NULL, NULL);
		wasm_functype_delete(func_ty);
	}
}

int main(void)
{
	wasm_engine_t *engine;
	wasmtime_store_t *store;
	wasmtime_context_t *context;
	wasmtime_module_t *module = NULL;
	wasmtime_linker_t *linker;
	wasmtime_error_t *error;
	wasm_byte_vec_t wasm;
	wasmtime_extern_t item;
	wasi_config_t *wasi_config;
	FILE *file;
	size_t file_size;
	bool ok;

	printf("Initialising...\n");
	engine = wasm_engine_new();
	store = wasmtime_store_new(engine, NULL, NULL);
	context = wasmtime_store_context(store);

	linker = wasmtime_linker_new(engine);
	error = wasmtime_linker_define_wasi(linker);
	if (error != NULL)
		exit_with_error("failed to link wasi", error, NULL);

	printf("Loading binary...\n");
	file = fopen(WASM_MODULE, "r");
	if (!file) {
		printf("> Error loading file!\n");
		exit(EXIT_FAILURE);
	}
	fseek(file, 0L, SEEK_END);
	file_size = ftell(file);
	wasm_byte_vec_new_uninitialized(&wasm, file_size);
	fseek(file, 0L, SEEK_SET);
	if (fread(wasm.data, file_size, 1, file) != 1) {
		printf("> Error loading module!\n");
		exit(EXIT_FAILURE);
	}
	fclose(file);

	printf("Compiling module...\n");
	error = wasmtime_module_new(engine, (uint8_t*)wasm.data, wasm.size,
				    &module);
	if (!module)
		exit_with_error("failed to compile module", error, NULL);
	wasm_byte_vec_delete(&wasm);

	printf("Setting function imports...\n");
	set_function_imports(linker);

	printf("Initialising WASI...\n");
	wasi_config = wasi_config_new();
	wasi_config_inherit_env(wasi_config);
	wasi_config_inherit_stdin(wasi_config);
	wasi_config_inherit_stdout(wasi_config);
	wasi_config_inherit_stderr(wasi_config);
	error = wasmtime_context_set_wasi(context, wasi_config);
	if (error)
		exit_with_error("failed to initialise WASI", error, NULL);

	printf("Instantiating module...\n");
	error = wasmtime_linker_module(linker, context, "", 0, module);
	if (error != NULL)
		exit_with_error("failed to instantiate module", error, NULL);

	printf("Getting function exports...\n");
	ok = wasmtime_linker_get(linker, context, "", 0, "HTTP#handle", 11,
				 &item);
	if (!ok) {
		printf("> Error getting function export [HTTP#handle]\n");
		exit(EXIT_FAILURE);
	}
	printf("    [HTTP#handle]\n");

	ok = wasmtime_linker_get(linker, context, "", 0, "cabi_realloc", 12,
				 &item);
	if (!ok) {
		printf("> Error getting function export [cabi_realloc]\n");
		exit(EXIT_FAILURE);
	}
	printf("    [cabi_realloc]\n");

	printf("Shutting down...\n");
	wasmtime_module_delete(module);
	wasmtime_store_delete(store);
	wasm_engine_delete(engine);

	printf("Done.\n");

	exit(EXIT_SUCCESS);;
}