/*
 *  SPL - The SPL Programming Language
 *  Copyright (C) 2004, 2005  Clifford Wolf <clifford@clifford.at>
 *
 *  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 2 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  httpsrc.c: A simple HTTP server engine with an empedded SPL engine
 *
 *  This is a HTTP/1.0 web server. Conformance to HTTP/1.1 is a long-term
 *  goal. But we reduce the troubles by returning HTTP/1.0 response headers
 *  for now.
 *
 *  http://www.w3.org/Protocols/rfc2616/rfc2616.html
 */

#define _GNU_SOURCE

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <ctype.h>
#include <time.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/stat.h>

#if !defined USECYGWINAPI && !defined USEMACOSXAPI && !defined USEWIN32API && !defined USEIRIXAPI && !defined USEBSDAPI
#  include <sys/sendfile.h>
#endif

#include "spl.h"
#include "webspl_common.h"
#include "compat.h"

static char *read_line_from_fd(int fd)
{
	int len = 64, count = 0, rc;
	char *line = malloc(len + 1);

	while (1) {
		if (len <= count) {
			len *= 2;
			line = realloc(line, len+1);
		}

		rc = read(fd, line+count, 1);

		if (rc != 1) break;

		if (line[count] == '\n') {
			if (count > 0 && line[count-1] == '\r') count--;
			break;
		}

		count++;
	}

	line[count] = 0;
	return line;
}

static char *read_block_from_fd(int fd, int len)
{
	char *data = malloc(len + 1);
	int count, rc;

	for (count = 0; count < len; count += rc) {
		rc = read(fd, data+count, len-count);
		if (rc < 1) break;
	}

	data[count] = 0;
	return data;
}

static void free_http_request(struct http_request *req)
{
	if (req->method) free(req->method);
	if (req->url)    free(req->url);
	if (req->query)  free(req->query);
	if (req->pver)   free(req->pver);
	if (req->peerip) free(req->peerip);

	if (req->data)      free(req->data);
	if (req->data_type) free(req->data_type);

	while (req->headers) {
		struct http_request_hdr *h = req->headers;
		if (h->name)  free(h->name);
		if (h->value) free(h->value);
		req->headers = h->next;
		free(h);
	}

	free(req);
}

static inline void strtoupper(char *p)
{
	for (; *p; p++)
		*p = toupper(*p);
}

static inline void strtolower(char *p)
{
	for (; *p; p++)
		*p = tolower(*p);
}

static struct http_request *read_http_request(int fd)
{
	struct http_request *req = calloc(1, sizeof(struct http_request));

	char *line, *p;
	int len;

	struct sockaddr_in peername;
	socklen_t peerlen = sizeof(struct sockaddr_in);

	getpeername(fd, (struct sockaddr*)&peername, &peerlen);
	req->peerip = strdup(inet_ntoa(peername.sin_addr));

	line = p = read_line_from_fd(fd);

	len = strcspn(p, " \t\r\n");
	req->method = my_strndup(line, len);
	p += len + strspn(p + len, " \t\r\n");

	len = strcspn(p, "? \t\r\n");
	req->url = my_strndup(p, len);
	p += len + strspn(p + len, " \t\r\n");

	if (*p == '?') {
		len = strcspn(++p, " \t\r\n");
		req->query = my_strndup(p, len);
		p += len + strspn(p + len, " \t\r\n");
	} else {
		req->query = strdup("");
	}

	len = strcspn(p, " \t\r\n");
	req->pver = my_strndup(p, len);
	p += len + strspn(p + len, " \t\r\n");

	free(line);

	strtoupper(req->method);
	strtoupper(req->pver);

	if (*req->pver == 0) {
		// FIXME: Howdy! This is an HTTP 0.9 request!
		// It is really hard to suppress the response headers,
		// so we just skip reading the request headers here..
		free(req->pver);
		req->pver = strdup("HTTP/0.9");
		return req;
	}

	while (1) {
		line = p = read_line_from_fd(fd);

		if (*line == 0) {
			free(line);
			break;
		}

		struct http_request_hdr *hdr = calloc(1, sizeof(struct http_request_hdr));

		len = strcspn(p, ": \t\r\n");
		hdr->name = my_strndup(p, len);
		p += len + strspn(p + len, ": \t\r\n");

		len = strcspn(p, " \t\r\n");
		hdr->value = strdup(p);

		strtolower(hdr->name);

		hdr->next = req->headers;
		req->headers = hdr;

		free(line);
	}

	return req;
}

static void http_cache_header(int fd)
{
	int expire_seconds = 600;
	time_t tm;
	struct tm *ptr;
	char buf[100];

	tm = time(NULL) + expire_seconds;
	ptr = gmtime(&tm);

	strftime(buf, 100, "%a, %d %b %Y %H:%M:%S", ptr);
	my_dprintf(fd, "Cache-Control: min-fresh = %d\r\n", expire_seconds);
	my_dprintf(fd, "Expires: %s GMT\r\n", buf);
}

static int http_response_file(int fd, const char *file, const char *type)
{
	int filefd = open(file, O_RDONLY|MY_O_BINARY);

	if ( filefd < 0 )
		return 0;

	struct stat filest;
	fstat(filefd, &filest);

	printf("Sending file as `%s'.\n", type);
	my_dprintf(fd, "HTTP/1.0 200 OK\r\n");
	http_cache_header(fd);
	my_dprintf(fd, "Content-Type: %s\r\n\r\n", type);

	for (off_t i=0; i<filest.st_size;) {
		int rc = my_sendfile(fd, filefd, &i, filest.st_size-i);
		if ( rc <= 0 ) break;
	}

	close(filefd);
	return 1;
}

static struct spl_code *default_filename_to_codepage(struct spl_vm *vm, const char *file)
{
	char *spl_source = spl_malloc_file(file, 0);
	if (!spl_source) {
		spl_report(SPL_REPORT_HOST, vm, "Can't read script file!\n");
		return 0;
	}

	struct spl_asm *as = spl_asm_create();
	as->vm = vm;

	if ( spl_compiler(as, spl_source, file, spl_malloc_file, 1) ) {
		spl_asm_destroy(as);
		free(spl_source);
		return 0;
	}

	spl_asm_add(as, SPL_OP_HALT, "1");
	spl_optimizer(as);

	struct spl_code *code = spl_asm_dump(as);
	spl_asm_destroy(as);
	free(spl_source);

	code->id = strdup(file);
	return code;
}

static int http_response_script(int fd, const char *file, struct http_request *req,
		struct spl_vm *(*vm_pool_get)(const char *session, int create),
		void (*vm_pool_put)(struct spl_vm *vm),
		struct spl_code *(*filename_to_codepage)(struct spl_vm *vm, const char *file))
{
	char *dir = strdup(file);
	char *lastslash = strrchr(dir, '/');

	if (lastslash)
		*lastslash = 0;
	else {
		free(dir);
		dir = strdup(".");
	}

	my_dprintf(fd, "HTTP/1.0 200 OK\r\n");

	my_dprintf(fd, "Cache-Control: no-cache, must-revalidate, no-store\r\n");
	my_dprintf(fd, "Pragma: nocache\r\n");
	my_dprintf(fd, "Expires: 0\r\n");

	struct cgi_config *cfg;
	{
		char currentdir[1024], script_file[1024];
		snprintf(script_file, 1024, "%s/%s", getcwd(currentdir, 1024), file);
		cfg = cgi_config_read(script_file);
	}

	struct cgi_context *ctx = spl_mod_cgi_get_cgi_ctx(req, cfg);
	ctx->outfile = fdopen(dup(fd), "r+");

	struct spl_vm *vm = 0;
	struct spl_task *task;

	if (ctx->session[0])
	{
		vm = vm_pool_get(ctx->session, 0);

		if ( !vm ) {
			if (cgi_config_get_int(cfg, "spl.respawnsessions"))
				goto respawn_this_session;
			const char *expirelocation = cgi_config_get_str(cfg, "spl.expirelocation");
			printf("This session timed out!\n");
			if (expirelocation)
				my_dprintf(fd,
					"Content-Type: text/html\r\n\r\n"
					"<script>location.href = '%s';</script>\n"
					"&nbsp;\n", expirelocation);
			else
				my_dprintf(fd,
					"Content-Type: text/html\r\n\r\n"
					"<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n"
					"<html><head>\n"
					"<title>This session timed out!</title>\n"
					"</head><body>\n"
					"<h1>This session timed out!</h1>\n"
					"<hr />\n"
					"<address>WebSPL Daemon</address>\n"
					"</body></html>\n");
			free(dir); dir = 0;
			goto exit_point;
		}

		if (vm->current_dir_name)
			free(vm->current_dir_name);
		vm->current_dir_name = dir;

		if (vm->cgi_ctx)
			spl_mod_cgi_free_cgi_ctx(vm->cgi_ctx);
		vm->cgi_ctx = ctx;

		char *task_name = strchr(ctx->session, ':');
		if ( task_name ) task = spl_task_lookup(vm, task_name+1);
		else task = spl_task_lookup(vm, "main");

		if ( !task || !(task->flags & SPL_TASK_FLAG_PUBLIC) ) {
			spl_report(SPL_REPORT_HOST, vm, "Can't find task or task is not public!\n");
			goto exit_point;
		}

		task->flags &= ~SPL_TASK_FLAG_PAUSED;
		printf("Resuming session `%s'.\n", ctx->session);
		vm->cgi_ctx = ctx;
	}
	else
	{
respawn_this_session:
		free(ctx->session);
		ctx->session = get_new_session();
		printf("New session `%s'.\n", ctx->session);

		vm = vm_pool_get(ctx->session, 1);
		vm->current_dir_name = dir;
		vm->cgi_ctx = ctx;

		int file_len = strlen(file);
		if (file_len > 8 && !strcmp(file+file_len-8, ".websplb"))
		{
			struct spl_code *code = spl_code_get(0);
			code->code_type = SPL_CODE_MAPPED;
			code->code = spl_mmap_file(file, &code->size);
			if (!code->code) {
				spl_report(SPL_REPORT_HOST, vm, "Can't open bytecode file!\n");
				spl_code_put(code);
				goto exit_point;
			}
			task = spl_task_create(vm, "main");
			task->flags |= SPL_TASK_FLAG_PUBLIC;
			spl_task_setcode(task, code);
			task->code->id = strdup(file);
		}
		else
		{
			if (!filename_to_codepage)
				filename_to_codepage = default_filename_to_codepage;

			struct spl_code *code = filename_to_codepage(vm, file);
			if (!code) goto exit_point;

			task = spl_task_create(vm, "main");
			task->flags |= SPL_TASK_FLAG_PUBLIC;

			spl_task_setcode(task, code);
		}
	}

	while ( task && task->code ) {
		spl_gc_maybe(vm);
		task = spl_schedule(task);
		if ( spl_exec(task) < 0 ) break;
	}

exit_point:
	fflush(ctx->outfile);
	fclose(ctx->outfile);
	ctx->outfile = 0;
	ctx->req = 0;

	if (ctx->config) {
		cgi_config_free(ctx->config);
		ctx->config = 0;
	}

	spl_mod_cgi_free_cgi_ctx(ctx);
	if (vm && vm->cgi_ctx == ctx) vm->cgi_ctx = 0;

	if (vm && vm_pool_put)
		vm_pool_put(vm);

	return 1;
}

void handle_http_request(int fd,
		struct spl_vm *(*vm_pool_get)(const char *session, int create),
		void (*vm_pool_put)(struct spl_vm *vm),
		struct spl_code *(*filename_to_codepage)(struct spl_vm *vm, const char *file))
{
	struct http_request *req = read_http_request(fd);

	printf("Got a %s %s request for `%s'.\n",
			req->pver, req->method, req->url);

	if (!strcmp(req->method, "POST"))
	{
		int len = -1;

		struct http_request_hdr *hdr = req->headers;
		while (hdr) {
			if (!strcmp(hdr->name, "content-length")) {
				len = atoi(hdr->value);
			}
			if (!strcmp(hdr->name, "content-type")) {
				if (req->data_type) free(req->data_type);
				req->data_type = strdup(hdr->value);
			}
			hdr = hdr->next;
		}

		printf("Going to read %d bytes POST data of mime-type %s.\n",
			len, req->data_type ?: "*unknown*");

		if (len < 0) goto error_501;

		if (req->data) free(req->data);
		req->data = read_block_from_fd(fd, len);
		req->data_len = len;
	}
	else
	if (strcmp(req->method, "GET"))
	{
error_501:
		printf("Sending `501 Method Not Implemented'.\n");
		my_dprintf(fd, "HTTP/1.0 501 Method Not Implemented\r\n");
		my_dprintf(fd, "Content-Type: text/html\r\n\r\n");

		my_dprintf(fd,
			"<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n"
			"<html><head>\n"
			"<title>501 Method Not Implemented</title>\n"
			"</head><body>\n"
			"<h1>Method Not Implemented</h1>\n"
			"<p>The HTTP Method `%s' is not implemented.</p>\n"
			"<hr />\n"
			"<address>WebSPL Daemon</address>\n"
			"</body></html>\n", req->method);

		goto finished;
	}

#if 0
	if (!strcmp(req->url, "/dumprequest"))
	{
		printf("Sending Request Dump.\n");
		my_dprintf(fd, "HTTP/1.0 200 OK\r\n");
		my_dprintf(fd, "Content-Type: text/plain\r\n\r\n");

		my_dprintf(fd, "Method: %s\n", req->method);
		my_dprintf(fd, "URL:    %s\n", req->url);
		my_dprintf(fd, "Query:  %s\n", req->query);
		my_dprintf(fd, "PVer:   %s\n", req->pver);
		my_dprintf(fd, "\n");

		struct http_request_hdr *hdr = req->headers;

		while (hdr) {
			my_dprintf(fd, "[%s]\n%s\n\n", hdr->name, hdr->value);
			hdr = hdr->next;
		}

		goto finished;
	}
#endif

	if (strstr(req->url, "/.") || *req->url != '/')
		goto error_404;

	int url_len = strlen(req->url);

	if ( url_len && req->url[url_len - 1] == '/' )
	{
		char buffer[url_len+13];
		snprintf(buffer, url_len+13, "%sindex.html", req->url + 1);
		if (!access(buffer, F_OK)) {
			if (!http_response_file(fd, buffer, "text/html"))
				goto error_404;
			goto finished;
		}
		snprintf(buffer, url_len+13, "%sindex.websplb", req->url + 1);
		if (!access(buffer, F_OK)) {
			if (!http_response_script(fd, buffer, req, vm_pool_get, vm_pool_put, filename_to_codepage))
				goto error_404;
			goto finished;
		}
		snprintf(buffer, url_len+13, "%sindex.webspl", req->url + 1);
		if (!access(buffer, F_OK)) {
			if (!http_response_script(fd, buffer, req, vm_pool_get, vm_pool_put, filename_to_codepage))
				goto error_404;
			goto finished;
		}
		goto error_404;
	}

	if ( url_len > 4 && !strcmp(req->url + url_len - 4, ".gif") )
	{
		if (!http_response_file(fd, req->url + 1, "image/gif"))
			goto error_404;
		goto finished;
	}

	if ( url_len > 4 && !strcmp(req->url + url_len - 4, ".png") )
	{
		if (!http_response_file(fd, req->url + 1, "image/png"))
			goto error_404;
		goto finished;
	}

	if ( (url_len > 4 && !strcmp(req->url + url_len - 4, ".jpg")) ||
	     (url_len > 5 && !strcmp(req->url + url_len - 5, ".jpeg")))
	{
		if (!http_response_file(fd, req->url + 1, "image/jpeg"))
			goto error_404;
		goto finished;
	}

	if ( url_len > 4 && !strcmp(req->url + url_len - 4, ".ico") )
	{
		if (!http_response_file(fd, req->url + 1, "image/x-icon"))
			goto error_404;
		goto finished;
	}

	if ( (url_len > 4 && !strcmp(req->url + url_len - 4, ".htm")) ||
	     (url_len > 5 && !strcmp(req->url + url_len - 5, ".html")))
	{
		if (!http_response_file(fd, req->url + 1, "text/html"))
			goto error_404;
		goto finished;
	}

	if ( url_len > 4 && !strcmp(req->url + url_len - 4, ".css") )
	{
		if (!http_response_file(fd, req->url + 1, "text/css"))
			goto error_404;
		goto finished;
	}

	if ( url_len > 7 && !strcmp(req->url + url_len - 7, ".webspl"))
	{
		if (!http_response_script(fd, req->url + 1, req, vm_pool_get, vm_pool_put, filename_to_codepage))
			goto error_404;
		goto finished;
	}

	if ( url_len > 8 && !strcmp(req->url + url_len - 8, ".websplb"))
	{
		if (!http_response_script(fd, req->url + 1, req, vm_pool_get, vm_pool_put, filename_to_codepage))
			goto error_404;
		goto finished;
	}

error_404:
	printf("Sending `404 Not Found'.\n");
	my_dprintf(fd, "HTTP/1.0 404 Not Found\r\n");
	my_dprintf(fd, "Content-Type: text/html\r\n\r\n");

	my_dprintf(fd,
		"<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n"
		"<html><head>\n"
		"<title>404 Not Found</title>\n"
		"</head><body>\n"
		"<h1>Not Found</h1>\n"
		"<p>The requested URL was not found on this server.</p>\n"
		"<hr />\n"
		"<address>WebSPL Daemon</address>\n"
		"</body></html>\n");

finished:
	free_http_request(req);
}