/*
 * lwftpc.c
 *
 *  Created on: Feb 20, 2024
 *      Author: "SeungJu Lim"
 */

#include "lwftpc.h"

/**
 *=============================================
 *                 Debugging
 *=============================================
 */

/*
 * @brief Debug print for LwFTP
 */
void debugPrint(const char *format, ...) {
#ifdef LWFTP_DEBUG
	va_list args;
	va_start(args, format);
	vprintf(format, args);
	va_end(args);
#endif
}


/**
 *=============================================
 *                 Debugging
 *=============================================
 */

/**
 * @brief Send command to connected FTP connection
 *
 * @param conn Target netconn structure
 * @param data
 */
err_t lwftp_send(struct netconn *conn, char *data) {
	err_t err = 0;
	if (strcmp(data, "\r\n") == 0)
		debugPrint(">> lwftp: ----> send <CRLF>\r\n");
	else
		debugPrint(">> lwftp: ----> send %s", data);
	err = netconn_write(conn, data, strlen(data), NETCONN_COPY);
	return err;
}

/*
 * @brief Send PASV command to server
 */
err_t lwftp_send_pasv(lwftp_session_t *s){
	s->ctrl_state = LWFTP_PASV_SENT;
	return lwftp_send(s->conn, "PASV\r\n");
}

/*
 * @brief Attempt login to the server
 */
err_t lwftp_login(lwftp_session_t *s) {
	char cmd[256];
	if (s->ctrl_state == LWFTP_CLOSED) {
		return ERR_CONN;
	} else if (s->ctrl_state == LWFTP_CONNECTED
			|| s->ctrl_state == LWFTP_LOGGED) {
		s->ctrl_state = LWFTP_USER_SENT;
		snprintf(cmd, sizeof(cmd), "USER %s\r\n", s->user);
		return lwftp_send(s->conn, cmd);
	}
	return ERR_USE;
}

/*
 * @brief
 */
err_t lwftp_data_open(lwftp_session_t *s, char *response) {
	err_t err = ERR_VAL;
	char *ptr;
	ip_addr_t addr_d;

	ptr = strchr(response, '(');
	if (!ptr) return ERR_BUF;
	do {
		unsigned int a = strtoul(ptr + 1, &ptr, 10);
		unsigned int b = strtoul(ptr + 1, &ptr, 10);
		unsigned int c = strtoul(ptr + 1, &ptr, 10);
		unsigned int d = strtoul(ptr + 1, &ptr, 10);
		IP4_ADDR(&addr_d, a, b, c, d);
	} while (0);
	s->data_port = strtoul(ptr + 1, &ptr, 10) << 8;
	s->data_port |= strtoul(ptr + 1, &ptr, 10) & 255;
	if (*ptr != ')') return ERR_BUF;

	debugPrint(">> lwftp: new data port: '%d'\r\n", s->data_port);

	// if data connection already exist:
	if (s->data_conn != NULL) {
		debugPrint(">> lwftp: existing data connection found, closing\r\n");
		netconn_close(s->data_conn);
		netconn_delete(s->data_conn);
		s->data_state = LWFTP_CLOSED;
		s->ctrl_state = LWFTP_LOGGED;
	}

	// create new data connection
	s->data_conn = netconn_new(NETCONN_TCP);
	if (s->data_conn == NULL) {
		debugPrint(">> lwftp: Failed to create new netconn for data connection\r\n");
		return ERR_MEM;
	}

	// do connect
	err = netconn_connect(s->data_conn, &addr_d, s->data_port);
	return err;
}

/**
 *=============================================
 *               FTP Commands
 *=============================================
 */

/*
 * @brief Close FTP connection
 */
err_t lwftp_close(lwftp_session_t *s) {
	err_t err;
	if (s->data_conn != NULL && s->data_state != LWFTP_DATA_CLOSED) {
		netconn_close(s->data_conn);
		err = netconn_delete(s->data_conn);
		if (err != ERR_OK) {
			debugPrint(">> lwftp: cannot close data connection with code %d\r\n", err);
			return err;
		}
		debugPrint(">> lwftp: data connection closed successfully\r\n");
		s->data_state = LWFTP_CLOSED;
	}
	if (s->conn != NULL && s->ctrl_state != LWFTP_CLOSED) {
		netconn_close(s->conn);
		err = netconn_delete(s->conn);
		if (err != ERR_OK) {
			debugPrint(">> lwftp: cannot close control connection with code %d\r\n", err);
			return err;
		}
		debugPrint(">> lwftp: control connection closed successfully\r\n");
		s->ctrl_state = LWFTP_CLOSED;
	}
	return err;
}


/*
 * @brief Store data to FTP server
 * caller func
 */
err_t lwftp_store(lwftp_session_t *s, char *filename, char *data) {
	err_t err;

	// init error state
	s->result = ERR_INPROGRESS;
	// set semaphore
	s->xfer_semaphore = xSemaphoreCreateBinary();

	// get data port and open it
	if (s->ctrl_state == LWFTP_LOGGED && s->data_state == LWFTP_DATA_CLOSED) {
		// set callback
		s->data_callback = lwftp_store_callback;
		s->filename = filename;
		s->data = data;
		lwftp_send_pasv(s);

	// send data immediately if data port is already opened
	} else if (s->ctrl_state == LWFTP_PASV_MODE && s->data_state == LWFTP_DATA_XFER_READY) {
		lwftp_store_callback(s, filename, data);

	// unexpected state - busy data port or something
	// need to code more exceptions
	} else {
		debugPrint(">> lwftp_ERROR: unexpected state\r\n");
		xSemaphoreGive(s->xfer_semaphore);
	}

	// wait semaphore - get result from callback
	if (xSemaphoreTake(s->xfer_semaphore, FTP_TIMEOUT) == pdTRUE) {
		err = s->result;
		s->result = ERR_OK;	// reset state
		vSemaphoreDelete(s->xfer_semaphore); // reset semaphore
		return err;
	}
	return ERR_TIMEOUT;
}

/*
 * @brief Store command callback
 * callback func
 */
void lwftp_store_callback(lwftp_session_t *s, char *filename, char *data) {
	err_t err;
	char cmd[256];
	size_t data_len = strlen(data);

	// send STOR command
	snprintf(cmd, sizeof(cmd), "STOR %s\r\n", filename);
	err = lwftp_send(s->conn, cmd);

	if (err == ERR_OK) {
		err = netconn_write(s->data_conn, data, data_len, NETCONN_COPY);
		if (err == ERR_OK) {
			debugPrint(">> lwftp: data sent successfully\r\n");
			netconn_close(s->data_conn);
		} else {
			debugPrint(">> lwftp_ERROR: send data failed with code %d\r\n", err);
		}
	} else {
		debugPrint(">> lwftp_ERROR: send command failed with code %d\r\n", err);
	}

	// Reset callback data from FTP server
	s->data_callback = NULL;
	s->filename = NULL;
	s->data = NULL;
	// return result to caller using FTP session structure
	s->result = err;
}

/*
 * @brief Retrieve data from
 * caller func
 */
err_t lwftp_retrieve(lwftp_session_t *s, char *filename) {
	char cmd[256];
	err_t err;

	// Init data portz
	if (s->ctrl_state == LWFTP_LOGGED) {
		s->data_callback = lwftp_retrieve_callback;
		s->filename = strdup(filename);
		lwftp_send(s->conn, "PASV\r\n");

	// Send data
	} else if (s->ctrl_state == LWFTP_PASV_SENT && s->data_state == LWFTP_DATA_XFER_READY) {
		snprintf(cmd, sizeof(cmd), "RETR %s\r\n", filename);
		err = lwftp_send(s->conn, cmd);
		if (err == ERR_OK) {
			debugPrint(">> lwftp: command sent successfully\r\n");
		} else {
			debugPrint(">> lwftp: send command failed with code %d\r\n", err);
		}

		// Init callback data
		s->data_callback = NULL;
		s->filename = NULL;
		s->data = NULL;
	}
	return err;
}

/*
 * @brief Retrieve command callback
 * callback func
 */
void lwftp_retrieve_callback(lwftp_session_t *s, char *filename, char *data) {
	lwftp_retrieve(s, filename);
}


/*
 * @brief Get a list of files in the root directory of the server.
 * caller func
 * @param s Session structure
 * @param outStr output parameter to return result of LIST command
 */
err_t lwftp_list(lwftp_session_t *s, char **outStr) {
	err_t err;

	// init
	s->result = ERR_INPROGRESS;
	*outStr = NULL;
	s->outStr = outStr;
	s->xfer_semaphore = xSemaphoreCreateBinary();

	// open data port
	if (s->ctrl_state == LWFTP_LOGGED && s->data_state == LWFTP_DATA_CLOSED) {
		s->data_callback = lwftp_list_callback;
		lwftp_send_pasv(s);

		// send data if data port already opened
	} else if (s->ctrl_state == LWFTP_PASV_SENT
			&& s->data_state == LWFTP_DATA_XFER_READY) {
		lwftp_list_callback(s, NULL, NULL);

		// unexpected state - busy data port or something
		// need to code more exceptions
	} else {
		debugPrint(">> lwftp_ERROR: data port is busy\r\n");
		xSemaphoreGive(s->xfer_semaphore);
	}

	// wait semaphore - get result from callback
	if (xSemaphoreTake(s->xfer_semaphore, FTP_TIMEOUT) == pdTRUE) {
		err = s->result;

		if (err == ERR_OK) {
			size_t length = strlen(*outStr);
			if (length == 0) {
				debugPrint(">> lwftp: server directory is empty.\r\n");
			}
		} else {
			debugPrint(">> lwftp_ERROR: failed to get file list.\r\n");
		}
		// reset session & semaphore
		resetSession(s);
		vSemaphoreDelete(s->xfer_semaphore);
		return err;
	}
	return ERR_TIMEOUT;
}

/*
 * @brief List command callback
 * callback func
 */
void lwftp_list_callback(lwftp_session_t *s, char *filename, char *data) {
	err_t err;

	// set state & send command
	s->ctrl_state = LWFTP_LIST_SENT;
	s->data_state = LWFTP_DATA_XFER_READY;
	err = lwftp_send(s->conn, "LIST\r\n");

	if (err == ERR_OK) {
		debugPrint(">> lwftp: command sent successfully\r\n");
		// the rest of the process will be done in the data thread.

	// failed to send command to the server.
	// event listener also will not catch anything.
	} else {
		debugPrint(">> lwftp_ERROR: send command failed with code %d\r\n", err);
		s->result = err;
		xSemaphoreGive(s->xfer_semaphore);
	}
}


/**
 *=============================================
 *        Data reception & processing
 *=============================================
 */

/**
 * @brief Called when data is finished receiving.
 * @param s Session structure
 * @param data Received data
 * @param size Size of received data (length)
 */
void onDataReceived(lwftp_session_t *s, void *data, size_t size) {
//	debugPrint(">> lwftp: Received data:\r\n%.*s\r\n", (int) size, (char*) data);
	printf(">> %d\r\n", s->data_state);
	if (s->data_state == LWFTP_DATA_XFERING) {
		if (s->ctrl_state == LWFTP_LIST_SENT || s->ctrl_state == LWFTP_RETR_SENT) {
			char *newData = (char*) malloc(size + 1);
			if (newData == NULL) {
				debugPrint(">> lwftp_ERROR: memory allocation failed\r\n");
				s->result = ERR_MEM;
			} else {
				memcpy(newData, data, size);
				newData[size] = '\0';

				if (*(s->outStr) != NULL) {
					free(*(s->outStr));
					*(s->outStr) = NULL;
				}
				*(s->outStr) = newData;
				s->result = ERR_OK;
			}
			s->ctrl_state = LWFTP_LOGGED;
			s->data_state = LWFTP_DATA_CLOSED;
			xSemaphoreGive(s->xfer_semaphore);
		}
	}
}


/**
 *=============================================
 *          Threads (Event listener)
 *=============================================
 */

/**
 * @brief Data connection event listener
 * @param arg Session structure
 */
void lwftp_data_thread(void *arg) {
	lwftp_session_t *s = (lwftp_session_t*) arg;
	static struct netbuf *d_buf;
	static char *total_data = NULL;
	static size_t total_len = 0;

	while (1) {
		if (s->data_conn != NULL) {
			while (netconn_recv(s->data_conn, &d_buf) == ERR_OK) {
				void *data;
				u16_t len;
				do {
					netbuf_data(d_buf, &data, &len);
					char *new_data = (char*) realloc(total_data, total_len + len);
					if (!new_data) {
						debugPrint("lwftp: memory reallocation failed\r\n");
						break;
					} else {
						total_data = new_data;
						memcpy(total_data + total_len, data, len);
						total_len += len;
					}
				} while (netbuf_next(d_buf) >= 0);
				netbuf_delete(d_buf);
			}
			if (total_data != NULL && total_len > 0) {
				onDataReceived(s, total_data, total_len);
				free(total_data);
				total_data = NULL;
				total_len = 0;
			}
		}
	}
}

/**
 * @brief Control connection event listener
 * @param arg Session structure
 */
void lwftp_ctrl_thread(void *arg) {
	lwftp_session_t *s = (lwftp_session_t*) arg;
	static struct netbuf *buf;
	uint response = 0;
	char cmd[256];
	err_t err;

	// check that the session data is valid.
	if ((s->ctrl_state != LWFTP_CLOSED) || s->data_state != LWFTP_DATA_CLOSED
			|| s->conn || s->data_conn || !s->user || !s->pass) {
		debugPrint(">> lwftp: invalid session data\r\n");
		return;
	}

	// create new TCP connection
	s->conn = netconn_new(NETCONN_TCP);
	err = netconn_bind(s->conn, &s->cli_ip, 0);

	if (err != ERR_OK) {
		debugPrint(">> lwftp: client IP binding failed with code %d\r\n", err);
		s->conn = NULL;
	} else {
		debugPrint(">> lwftp: client IP bind OK\r\n");
		err = netconn_connect(s->conn, &s->svr_ip, s->svr_port);

		// If the connection to the server is established, the following will continue, else delete the connection
		if (err != ERR_OK) {
			debugPrint(">> lwftp: server connection failed with code %d\r\n", err);
			s->conn = NULL;
		} else {

			while (1) {
				/* wait until the data is sent by the server*/
				if (netconn_recv(s->conn, &buf) == ERR_OK) {
					if (buf) {
						response = strtoul(buf->p->payload, NULL, 10);
						debugPrint("\n>> lwftp: <==== resp '%d'\r\n", response);

						/** ============================================ */
						/** ========= Response code processing ========= */

						/** [Response 220] Service ready for new user.*/
						if (response == 220) {
							if (s->ctrl_state == LWFTP_CLOSED) {
								debugPrint(">> lwftp: server connect OK\r\n");
								s->ctrl_state = LWFTP_CONNECTED;
								lwftp_login(s);
							}
						}

						/** [Response 331] User name okay, need password.*/
						else if (response == 331) {
						if (s->ctrl_state == LWFTP_USER_SENT) {
							s->ctrl_state = LWFTP_PASS_SENT;
							snprintf(cmd, sizeof(cmd), "PASS %s\r\n", s->pass);
								lwftp_send(s->conn, cmd);
							}
						}

						/** [Response 230] User logged in, proceed.*/
						else if (response == 230) {
							if (s->ctrl_state == LWFTP_PASS_SENT) {
								s->ctrl_state = LWFTP_LOGGED;
								debugPrint(">> lwftp: now logged in\r\n");
							}
						}

						/** [Response 227] Entering Passive Mode (h1,h2,h3,h4,p1,p2).*/
						else if (response == 227) {
							if (s->ctrl_state == LWFTP_PASV_SENT) {
								debugPrint(">> lwftp: entering passive Mode\r\n");
								err = lwftp_data_open(s, buf->p->payload);

								if (err == ERR_OK) {
									debugPrint(">> lwftp: data port connect OK\r\n");
									s->data_state = LWFTP_DATA_XFER_READY;
									// if callback exists, execute.
									if (s->data_callback != NULL) {
										s->data_callback(s, s->filename, s->data);
									}
								} else {
									debugPrint(">> lwftp_ERROR: failed to connect to server data port with code %d\r\n", err);
									netconn_delete(s->data_conn);
									s->data_conn = NULL;
									s->ctrl_state = LWFTP_LOGGED;
									s->data_state = LWFTP_DATA_CLOSED;
									// if callback exists, don't execute and release semaphore.
									if (s->data_callback != NULL) {
										xSemaphoreGive(s->xfer_semaphore);
									}
								}
							}
						}

						/** [Response 125] Data connection already open; transfer starting.*/
						else if (response == 125) {
							printf(">>c: %d / d: %d\r\n", s->ctrl_state,s->data_state);
							if (s->data_state == LWFTP_DATA_XFER_READY) {
								s->data_state = LWFTP_DATA_XFERING;
								debugPrint(">> lwftp: data transfer starting.\r\n");
							}
						}

						/** [Response 226] Closing data connection. Requested file action successful*/
						else if (response == 226) {
//							if (s->data_state == LWFTP_DATA_XFERING) {}
								debugPrint(">> lwftp: transfer complete, closing connection\r\n");
						}

						/** [Response 332] Need account for login.*/
						else if (response == 332) {
							debugPrint("\n>> lwftp: need account for login.\r\n");
							s->ctrl_state = LWFTP_CONNECTED;
						}

						/** [Response 421] Service not available, closing.*/
						else if (response == 421) {
							debugPrint("\n>> lwftp: service not available, closing.\r\n");
							break;
						}

						/** [Response 500] Syntax error, command unrecognized.*/
						else if (response == 500 || response == 503) {
							debugPrint("\n>> lwftp: syntax error or bad sequence of commands\r\n");
							if (s->ctrl_state == LWFTP_USER_SENT || s->ctrl_state == LWFTP_PASS_SENT) {
								s->ctrl_state = LWFTP_CONNECTED;
							} else {
								s->ctrl_state = LWFTP_LOGGED;
							}
						}

						/** [Response 530] Not logged in.*/
						else if (response == 530) {
							if (s->ctrl_state == LWFTP_PASS_SENT) {
								s->ctrl_state = LWFTP_CONNECTED;
								debugPrint(">> lwftp: invalid user data or not logged in yet\r\n");
							}
						}
						/** ============================================ */
					}
				}
				memset(cmd, 0, sizeof(cmd));
				if (buf != NULL) {
					netbuf_delete(buf);
					buf = NULL;
				}
			}
		}
	}
	lwftp_close(s);
	return;
}


/**
 *=============================================
 *                  Utils
 *=============================================
 */

void resetSession(lwftp_session_t *s) {
	s->data_callback = NULL;
	s->filename = NULL;
	s->data = NULL;
	s->outStr = NULL;
	s->result = ERR_OK;
}

/** Extract file names from result of FTP LIST command */
char** extractFileNames(const char *input, int *fileCount) {
	int count = 0;
	char **fileNames = NULL;
	char *inputCopy = strdup(input);
	char *line = strtok(inputCopy, "\n");

	while (line != NULL) {
		char *fileName = strrchr(line, ' ');
		if (fileName && *(fileName + 1)) {
			fileName++;
			fileNames = realloc(fileNames, sizeof(char*) * (count + 1));
			fileNames[count++] = strdup(fileName);
		}
		line = strtok(NULL, "\n");
	}
	free(inputCopy);
//	*fileCount = count;
	return fileNames;
}

/** Generate unique file name if duplicate filenames exist */
char* genUniqFilName(char **fileNames, int fileCount, const char *targetFileName) {
	int suffix = 1;
	char baseFileName[256] = { 0 };
	char extension[256] = { 0 };
	char *newFileName = NULL;
	int nameExists;

	const char *dot = strrchr(targetFileName, '.');
	if (dot) {
		memcpy(baseFileName, targetFileName, dot - targetFileName);
		strcpy(extension, dot);
	} else {
		strcpy(baseFileName, targetFileName);
	}
	do {
		nameExists = 0;
		free(newFileName);
		newFileName = (char*) malloc(strlen(baseFileName) + strlen(extension) + 15);
		if (!newFileName) {
			debugPrint(">> lwftp: memory allocation failed\r\n");
			return NULL;
		}
		sprintf(newFileName, "%s(%d)%s", baseFileName, suffix, extension);
		for (int i = 0; i < fileCount; i++) {
			if (strcmp(fileNames[i], newFileName) == 0) {
				nameExists = 1;
				break;
			}
		}
		suffix++;
	} while (nameExists);
	return newFileName;
}