#include <dlfcn.h>
#include <jsmn.h>
#include <stdio.h>
#include <stdlib.h>
#include <uv.h>

#include "module.h"
#include "module_database.h"
#include "runtime.h"
#include "types.h"

/*************************
 * Private Static Inline *
 ************************/

/**
 * Start the module as a server listening at module->port
 * @param module
 */
static inline void
module_listen(struct module *module)
{
	/* Allocate a new socket */
	int socket_descriptor = socket(AF_INET, SOCK_STREAM, 0);
	assert(socket_descriptor > 0);

	/* Configure socket address as [all addresses]:[module->port] */
	module->socket_address.sin_family      = AF_INET;
	module->socket_address.sin_addr.s_addr = htonl(INADDR_ANY);
	module->socket_address.sin_port        = htons((unsigned short)module->port);

	/* Configure the socket to allow multiple sockets to bind to the same host and port */
	int optval = 1;
	setsockopt(socket_descriptor, SOL_SOCKET, SO_REUSEPORT, &optval, sizeof(optval));
	optval = 1;
	setsockopt(socket_descriptor, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval));

	/* Bind to the interface */
	if (bind(socket_descriptor, (struct sockaddr *)&module->socket_address, sizeof(module->socket_address)) < 0) {
		perror("bind");
		assert(0);
	}

	/* Listen to the interface? Check that it is live? */
	if (listen(socket_descriptor, MODULE_MAX_PENDING_CLIENT_REQUESTS) < 0) assert(0);


	/* Set the socket descriptor and register with our global epoll instance to monitor for incoming HTTP
	requests */
	module->socket_descriptor = socket_descriptor;
	struct epoll_event accept_evt;
	accept_evt.data.ptr = (void *)module;
	accept_evt.events   = EPOLLIN;
	if (epoll_ctl(runtime_epoll_file_descriptor, EPOLL_CTL_ADD, module->socket_descriptor, &accept_evt) < 0)
		assert(0);
}

/***************************************
 * Public Methods
 ***************************************/

/**
 * Module Mega Teardown Function
 * Closes the socket and dynamic library, and then frees the module
 * Returns harmlessly if there are outstanding references
 *
 * TODO: Untested Functionality. Unsure if this will work
 * @param module - the module to teardown
 */
void
module_free(struct module *module)
{
	if (module == NULL) return;
	if (module->dynamic_library_handle == NULL) return;

	/* Do not free if we still have oustanding references */
	if (module->reference_count) return;

	/* TODO: What about the module database? Do we need to do any cleanup there? */

	close(module->socket_descriptor);
	dlclose(module->dynamic_library_handle);
	free(module);
}


/**
 * Module Contructor
 * Creates a new module, invokes initialize_tables to initialize the indirect table, adds it to the module DB, and
 *starts listening for HTTP Requests
 *
 * @param name
 * @param path
 * @param argument_count
 * @param stack_size
 * @param max_memory
 * @param relative_deadline_us
 * @param port
 * @param request_size
 * @returns A new module or NULL in case of failure
 */
struct module *
module_new(char *name, char *path, i32 argument_count, u32 stack_size, u32 max_memory, u32 relative_deadline_us,
           int port, int request_size, int response_size)
{
	struct module *module = (struct module *)malloc(sizeof(struct module));
	if (!module) return NULL;

	memset(module, 0, sizeof(struct module));

	/* Load the dynamic library *.so file with lazy function call binding and deep binding */
	module->dynamic_library_handle = dlopen(path, RTLD_LAZY | RTLD_DEEPBIND);
	if (module->dynamic_library_handle == NULL) goto dl_open_error;

	/* Resolve the symbols in the dynamic library *.so file */
	module->main = (mod_main_fn_t)dlsym(module->dynamic_library_handle, MODULE_MAIN);
	if (module->main == NULL) goto dl_error;

	module->initialize_globals = (mod_glb_fn_t)dlsym(module->dynamic_library_handle, MODULE_INITIALIZE_GLOBALS);
	if (module->initialize_globals == NULL) goto dl_error;

	module->initialize_memory = (mod_mem_fn_t)dlsym(module->dynamic_library_handle, MODULE_INITIALIZE_MEMORY);
	if (module->initialize_memory == NULL) goto dl_error;

	module->initialize_tables = (mod_tbl_fn_t)dlsym(module->dynamic_library_handle, MODULE_INITIALIZE_TABLE);
	if (module->initialize_tables == NULL) goto dl_error;

	module->initialize_libc = (mod_libc_fn_t)dlsym(module->dynamic_library_handle, MODULE_INITIALIZE_LIBC);
	if (module->initialize_libc == NULL) goto dl_error;

	/* Set fields in the module struct */
	strncpy(module->name, name, MODULE_MAX_NAME_LENGTH);
	strncpy(module->path, path, MODULE_MAX_PATH_LENGTH);

	module->argument_count       = argument_count;
	module->stack_size           = round_up_to_page(stack_size == 0 ? WASM_STACK_SIZE : stack_size);
	module->max_memory           = max_memory == 0 ? ((u64)WASM_PAGE_SIZE * WASM_MAX_PAGES) : max_memory;
	module->relative_deadline_us = relative_deadline_us;
	module->socket_descriptor    = -1;
	module->port                 = port;

	if (request_size == 0) request_size = MODULE_DEFAULT_REQUEST_RESPONSE_SIZE;
	if (response_size == 0) response_size = MODULE_DEFAULT_REQUEST_RESPONSE_SIZE;
	module->max_request_size  = request_size;
	module->max_response_size = response_size;
	if (request_size > response_size) {
		module->max_request_or_response_size = round_up_to_page(request_size);
	} else {
		module->max_request_or_response_size = round_up_to_page(response_size);
	}

	/* Table initialization calls a function that runs within the sandbox. Rather than setting the current sandbox,
	 * we partially fake this out by only setting the module_indirect_table and then clearing after table
	 * initialization is complete.
	 *
	 * assumption: This approach depends on module_new only being invoked at program start before preemption is
	 * enabled. We are check that local_sandbox_context_cache.module_indirect_table is NULL to gain confidence that
	 * we are not invoking this in a way that clobbers a current module.
	 *
	 * If we want to be able to do this later, we can possibly defer module_initialize_table until the first
	 * invocation
	 */

	assert(local_sandbox_context_cache.module_indirect_table == NULL);
	local_sandbox_context_cache.module_indirect_table = module->indirect_table;
	module_initialize_table(module);
	local_sandbox_context_cache.module_indirect_table = NULL;

	/* Add the module to the in-memory module DB */
	module_database_add(module);

	/* Start listening for requests */
	module_listen(module);

	return module;

dl_error:
	dlclose(module->dynamic_library_handle);

dl_open_error:
	free(module);
	debuglog("%s\n", dlerror());
	return NULL;
}

/**
 * Parses a JSON file and allocates one or more new modules
 * @param file_name The path of the JSON file
 * @return RC 0 on Success. -1 on Error
 */
int
module_new_from_json(char *file_name)
{
	/* Use stat to get file attributes and make sure file is there and OK */
	struct stat stat_buffer;
	memset(&stat_buffer, 0, sizeof(struct stat));
	if (stat(file_name, &stat_buffer) < 0) {
		perror("stat");
		return -1;
	}

	/* Open the file */
	FILE *module_file = fopen(file_name, "r");
	if (!module_file) {
		perror("fopen");
		return -1;
	}

	/* Initialize a Buffer, Read the file into the buffer, and then check that the buffer size equals the file
	size */
	char *file_buffer = malloc(stat_buffer.st_size);
	memset(file_buffer, 0, stat_buffer.st_size);
	int total_chars_read = fread(file_buffer, sizeof(char), stat_buffer.st_size, module_file);
	debuglog("size read: %d content: %s\n", total_chars_read, file_buffer);
	if (total_chars_read != stat_buffer.st_size) {
		perror("fread");
		return -1;
	}

	/* Close the file */
	fclose(module_file);

	/* Initialize the Jasmine Parser and an array to hold the tokens */
	jsmn_parser module_parser;
	jsmn_init(&module_parser);
	jsmntok_t tokens[JSON_MAX_ELEMENT_SIZE * JSON_MAX_ELEMENT_COUNT];

	/* Use Jasmine to parse the JSON */
	int total_tokens = jsmn_parse(&module_parser, file_buffer, strlen(file_buffer), tokens,
	                              sizeof(tokens) / sizeof(tokens[0]));
	if (total_tokens < 0) {
		debuglog("jsmn_parse: invalid JSON?\n");
		return -1;
	}

	int module_count = 0;
	for (int i = 0; i < total_tokens; i++) {
		assert(tokens[i].type == JSMN_OBJECT);

		char  module_name[MODULE_MAX_NAME_LENGTH] = { 0 };
		char  module_path[MODULE_MAX_PATH_LENGTH] = { 0 };
		char *request_headers = (char *)malloc(HTTP_MAX_HEADER_LENGTH * HTTP_MAX_HEADER_COUNT);
		memset(request_headers, 0, HTTP_MAX_HEADER_LENGTH * HTTP_MAX_HEADER_COUNT);
		char *reponse_headers = (char *)malloc(HTTP_MAX_HEADER_LENGTH * HTTP_MAX_HEADER_COUNT);
		memset(reponse_headers, 0, HTTP_MAX_HEADER_LENGTH * HTTP_MAX_HEADER_COUNT);
		i32  request_size                                        = 0;
		i32  response_size                                       = 0;
		i32  argument_count                                      = 0;
		u32  port                                                = 0;
		u32  relative_deadline_us                                = 0;
		i32  is_active                                           = 0;
		i32  request_count                                       = 0;
		i32  response_count                                      = 0;
		int  j                                                   = 1;
		int  ntoks                                               = 2 * tokens[i].size;
		char request_content_type[HTTP_MAX_HEADER_VALUE_LENGTH]  = { 0 };
		char response_content_type[HTTP_MAX_HEADER_VALUE_LENGTH] = { 0 };

		for (; j < ntoks;) {
			int  ntks     = 1;
			char key[32]  = { 0 };
			char val[256] = { 0 };

			sprintf(val, "%.*s", tokens[j + i + 1].end - tokens[j + i + 1].start,
			        file_buffer + tokens[j + i + 1].start);
			sprintf(key, "%.*s", tokens[j + i].end - tokens[j + i].start,
			        file_buffer + tokens[j + i].start);
			if (strcmp(key, "name") == 0) {
				strcpy(module_name, val);
			} else if (strcmp(key, "path") == 0) {
				strcpy(module_path, val);
			} else if (strcmp(key, "port") == 0) {
				port = atoi(val);
			} else if (strcmp(key, "argsize") == 0) {
				argument_count = atoi(val);
			} else if (strcmp(key, "active") == 0) {
				is_active = (strcmp(val, "yes") == 0);
			} else if (strcmp(key, "relative-deadline-us") == 0) {
				relative_deadline_us = atoi(val);
			} else if (strcmp(key, "http-req-headers") == 0) {
				assert(tokens[i + j + 1].type == JSMN_ARRAY);
				assert(tokens[i + j + 1].size <= HTTP_MAX_HEADER_COUNT);

				request_count = tokens[i + j + 1].size;
				ntks += request_count;
				ntoks += request_count;
				for (int k = 1; k <= tokens[i + j + 1].size; k++) {
					jsmntok_t *g = &tokens[i + j + k + 1];
					char *     r = request_headers + ((k - 1) * HTTP_MAX_HEADER_LENGTH);
					assert(g->end - g->start < HTTP_MAX_HEADER_LENGTH);
					strncpy(r, file_buffer + g->start, g->end - g->start);
				}
			} else if (strcmp(key, "http-resp-headers") == 0) {
				assert(tokens[i + j + 1].type == JSMN_ARRAY);
				assert(tokens[i + j + 1].size <= HTTP_MAX_HEADER_COUNT);

				response_count = tokens[i + j + 1].size;
				ntks += response_count;
				ntoks += response_count;
				for (int k = 1; k <= tokens[i + j + 1].size; k++) {
					jsmntok_t *g = &tokens[i + j + k + 1];
					char *     r = reponse_headers + ((k - 1) * HTTP_MAX_HEADER_LENGTH);
					assert(g->end - g->start < HTTP_MAX_HEADER_LENGTH);
					strncpy(r, file_buffer + g->start, g->end - g->start);
				}
			} else if (strcmp(key, "http-req-size") == 0) {
				request_size = atoi(val);
			} else if (strcmp(key, "http-resp-size") == 0) {
				response_size = atoi(val);
			} else if (strcmp(key, "http-req-content-type") == 0) {
				strcpy(request_content_type, val);
			} else if (strcmp(key, "http-resp-content-type") == 0) {
				strcpy(response_content_type, val);
			} else {
				debuglog("Invalid (%s,%s)\n", key, val);
			}
			j += ntks;
		}
		i += ntoks;
		/* do not load if it is not active */
		if (is_active == 0) continue;

		/* Allocate a module based on the values from the JSON */
		struct module *module = module_new(module_name, module_path, argument_count, 0, 0, relative_deadline_us,
		                                   port, request_size, response_size);
		assert(module);
		module_set_http_info(module, request_count, request_headers, request_content_type, response_count,
		                     reponse_headers, response_content_type);
		module_count++;
		free(request_headers);
		free(reponse_headers);
	}

	free(file_buffer);
	assert(module_count);
	debuglog("Loaded %d module%s!\n", module_count, module_count > 1 ? "s" : "");

	return 0;
}