/*
   swebs - a simple web server
   Copyright (C) 2022  Nate Choe
   
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/
#include <errno.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <swebs/util.h>
#include <swebs/runner.h>
#include <swebs/sitefile.h>
#include <swebs/responses.h>
#include <swebs/connections.h>

int newConnection(Stream *stream, Connection *ret, int portind) {
	struct timespec currentTime;

	ret->stream = stream;
	ret->progress = RECEIVE_REQUEST;

	ret->currLineAlloc = 30;
	ret->currLineLen = 0;
	ret->currLine = malloc(ret->currLineAlloc);
	if (ret->currLine == NULL)
		return 1;

	ret->allocatedFields = 10;
	ret->fields = malloc(sizeof(Field) * ret->allocatedFields);
	if (ret->fields == NULL) {
		free(ret->currLine);
		return 1;
	}
	ret->fieldCount = 0;

	ret->allocatedPathFields = 10;
	ret->pathFields = malloc(ret->allocatedPathFields * sizeof(PathField));
	if (ret->pathFields == NULL) {
		free(ret->currLine);
		free(ret->fields);
		return 1;
	}
	ret->pathFieldCount = 0;

	ret->body = NULL;
	/*
	 * pointers to things that are allocated within functions should be
	 * initialized to NULL so that free() doens't fail.
	 * */

	if (clock_gettime(CLOCK_MONOTONIC, &currentTime) < 0) {
		free(ret->currLine);
		free(ret->fields);
		free(ret->pathFields);
		return 1;
	}
	memcpy(&ret->lastdata, &currentTime, sizeof(struct timespec));

	ret->portind = portind;
	return 0;
}

void resetConnection(Connection *conn) {
	long i;
	conn->progress = RECEIVE_REQUEST;
	free(conn->body);
	conn->body = NULL;
	for (i = 0; i < conn->fieldCount; i++) {
		free(conn->fields[i].field);
		free(conn->fields[i].value);
	}
	conn->fieldCount = 0;
	for (i = 0; i < conn->pathFieldCount; i++) {
		free(conn->pathFields[i].var.data);
		free(conn->pathFields[i].value.data);
	}
	conn->pathFieldCount = 0;
}

void freeConnection(Connection *conn) {
	long i;
	freeStream(conn->stream);
	free(conn->currLine);
	free(conn->body);
	for (i = 0; i < conn->fieldCount; i++) {
		free(conn->fields[i].field);
		free(conn->fields[i].value);
	}
	for (i = 0; i < conn->pathFieldCount; i++) {
		free(conn->pathFields[i].var.data);
		free(conn->pathFields[i].value.data);
	}
	free(conn->pathFields);
	free(conn->fields);
}

static int createBinaryString(BinaryString *ret) {
	ret->allocatedLen = 50;
	ret->data = malloc(ret->allocatedLen);
	if (ret->data == NULL)
		return 1;
	ret->len = 0;
	return 0;
}

static int appendBinaryString(BinaryString *ret, char c) {
	if (ret->len >= ret->allocatedLen) {
		char *newdata;
		ret->allocatedLen *= 2;
		newdata = realloc(ret->data, ret->allocatedLen);
		if (newdata == NULL) {
			free(ret->data);
			return 1;
		}
		ret->data = newdata;
	}
	ret->data[ret->len++] = c;
	return 0;
}

static int hexval(char c) {
	if (isdigit(c))
		return c - '0';
	if ('a' <= c && c <= 'f')
		return c - 'a' + 10;
	if ('A' <= c && c <= 'F')
		return c - 'A' + 10;
	return -1;
}

static int getBinaryString(BinaryString *ret, char *path, char stop,
		long *lenReturn) {
	long i;
	createBinaryString(ret);
	for (i = 0; path[i] != stop && path[i] != '\0'; i++) {
		char c;
		if (path[i] == '%') {
			int v;
			v = hexval(path[i + 1]);
			if (v < 0) {
				free(ret->data);
				return 1;
			}
			c = v << 4;
			v = hexval(path[i + 2]);
			if (v < 0) {
				free(ret->data);
				return 1;
			}
			c |= v;
			i += 2;
		}
		else
			c = path[i];
		appendBinaryString(ret, c);
	}
	appendBinaryString(ret, '\0');
	*lenReturn = i;
	return 0;
}

static int processPath(Connection *conn, char *path) {
	long len;
	if (getBinaryString(&conn->path, path, '?', &len))
		return 1;
	path += len;
	while (path[0] != '\0') {
		if (conn->pathFieldCount >= conn->allocatedPathFields) {
			PathField *newPathFields;

			conn->allocatedPathFields *= 2;
			newPathFields = realloc(conn->pathFields,
						conn->allocatedPathFields *
						sizeof(PathField));
			if (newPathFields == NULL)
				goto error;
			conn->pathFields = newPathFields;
		}

		path++;
		if (getBinaryString(
				&conn->pathFields[conn->pathFieldCount].var,
				path, '=', &len))
			goto error;
		path += len;
		if (path[0] == '\0') {
			free(conn->pathFields[conn->pathFieldCount].var.data);
			goto error;
		}
		path++;
		if (getBinaryString(
				&conn->pathFields[conn->pathFieldCount].value,
				path, '&', &len)) {
			free(conn->pathFields[conn->pathFieldCount].var.data);
			goto error;
		}
		conn->pathFieldCount++;
		path += len;
	}
	return 0;
error:
	{
		long i;
		for (i = 0; i < conn->fieldCount; i++) {
			free(conn->pathFields[i].var.data);
			free(conn->pathFields[i].value.data);
		}
		free(conn->pathFields);
		free(conn->path.data);
		return 1;
	}
}

static int processRequest(Connection *conn) {
	char *line;
	long i;

	line = conn->currLine;
	/*
	 * line is not necessarily always conn->currentLine. It's the beginning
	 * of the currently parsing thing.
	 * */
	for (i = 0;; i++) {
		if (line[i] == ' ') {
			line[i] = '\0';
			conn->type = getType(line);
			if (conn->type == INVALID)
				return 1;
			line += i + 1;
			break;
		}
		if (line[i] == '\0') {
			return 1;
		}
	}
	for (i = 0;; i++) {
		if (line[i] == ' ') {
			line[i] = '\0';
			if (processPath(conn, line))
				return 1;
			line += i + 1;
			break;
		}
		if (line[i] == '\0') {
			return 1;
		}
	}
	if (strcmp(line, "HTTP/1.1"))
		return 1;
	conn->progress = RECEIVE_HEADER;
	conn->fieldCount = 0;

	return 0;
}

static int processField(Connection *conn) {
	long i;
	char *line, *split, *field, *value;
	size_t linelen;
	Field *newfields;
	if (conn->currLineLen == 0) {
		conn->progress = RECEIVE_BODY;
		for (i = 0; i < conn->fieldCount; i++) {
			if (strcmp(conn->fields[i].field,
			           "Content-Length") == 0) {
				conn->bodylen = atol(conn->fields[i].value);
				goto foundlen;
			}
		}
		conn->bodylen = 0;
		conn->body = NULL;
		goto lendone;
foundlen:
		conn->body = malloc(conn->bodylen);
		if (conn->body == NULL)
			return 1;
lendone:
		conn->receivedBody = 0;
		return 0;
	}

	if (conn->fieldCount >= conn->allocatedFields) {
		conn->allocatedFields *= 2;
		newfields = realloc(conn->fields, conn->allocatedFields *
		                                sizeof(char *[2]));
		if (newfields == NULL)
			return 1;
		conn->fields = newfields;
	}

	line = conn->currLine;
	split = strstr(line, ": ");
	linelen = conn->currLineLen;
	if (split == NULL)
		return 1;

	field = malloc(split - line + 1);
	if (field == NULL)
		return 1;
	memcpy(field, line, split - line);
	field[split - line] = '\0';

	linelen -= split - line + 2;
	line += split - line + 2;
	value = malloc(linelen + 1);
	if (value == NULL) {
		free(field);
		return 1;
	}
	memcpy(value, line, linelen + 1);

	conn->fields[conn->fieldCount].field = field;
	conn->fields[conn->fieldCount].value = value;

	conn->fieldCount++;

	return 0;
}

static int processChar(Connection *conn, char c, Sitefile *site) {
	if (conn->progress < RECEIVE_BODY) {
		if (conn->currLineLen >= conn->currLineAlloc) {
			char *newline;
			conn->currLineAlloc *= 2;
			newline = realloc(conn->currLine,
			                        conn->currLineAlloc);
			if (newline == NULL)
				return 1;
			conn->currLine = newline;
		}
		if (c == '\n') {
			if (--conn->currLineLen < 0)
				return 1;
			if (conn->currLine[conn->currLineLen] != '\r')
				return 1;
			conn->currLine[conn->currLineLen] = '\0';
			if (conn->progress == RECEIVE_REQUEST) {
				if (processRequest(conn))
					return 1;
			}
			else if (conn->progress == RECEIVE_HEADER) {
				if (processField(conn))
					return 1;
			}
			conn->currLineLen = 0;
		}
		else
			conn->currLine[conn->currLineLen++] = c;
	}
	else if (conn->progress == RECEIVE_BODY) {
		if (conn->receivedBody < conn->bodylen)
			conn->body[conn->receivedBody++] = c;
	}
	if (conn->progress == RECEIVE_BODY &&
	    conn->receivedBody >= conn->bodylen)
		if (sendResponse(conn, site))
			return 1;
	return 0;
}

static long diff(struct timespec *t1, struct timespec *t2) {
/* returns the difference in times in milliseconds */
	return (t2->tv_sec - t1->tv_sec) * 1000 +
		(t2->tv_nsec - t1->tv_nsec) / 1000000;
}

int updateConnection(Connection *conn, Sitefile *site) {
	size_t totalReceived = 0;
	for (;;) {
		char buff[300];
		ssize_t received;
		unsigned long i;
		struct timespec currentTime;
		const Port *port = site->ports + conn->portind;
		if (clock_gettime(CLOCK_MONOTONIC, &currentTime) < 0) {
			createLog("Error getting current time");
			return 1;
		}
		if (port->timeout > 0 &&
		    diff(&conn->lastdata, &currentTime) > port->timeout) {
			createLog("Connection timed out");
			return 1;
		}
		createFormatLog("Attempting to receive %ld bytes", sizeof buff);
		received = recvStream(conn->stream, buff, sizeof buff);
		createFormatLog("Received %ld bytes", received);
		if (received < 0)
			return errno != EAGAIN && totalReceived <= 0;
		if (received == 0)
			return 1;
		totalReceived += received;
		memcpy(&conn->lastdata, &currentTime, sizeof(struct timespec));
		for (i = 0; i < received; i++) {
			if (processChar(conn, buff[i], site))
				return 1;
		}
	}
}