/**
 * @brief migrate - Relocate root filesystem to tmpfs
 *
 * Run as part of system startup to move the ext2 root ramdisk
 * into a flexible in-memory temporary filesystem, which allows
 * file creation and editing and is much faster than the using
 * the ext2 driver against the static in-memory ramdisk.
 *
 * Based on the original Python implementation.
 *
 * @copyright
 * This file is part of ToaruOS and is released under the terms
 * of the NCSA / University of Illinois License - see LICENSE.md
 * Copyright (C) 2018 K. Lange
 */
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <unistd.h>

#include <fcntl.h>
#include <sys/stat.h>
#include <sys/ioctl.h>

#include <toaru/trace.h>
#include <toaru/hashmap.h>
#define TRACE_APP_NAME "migrate"

#define TRACE_(...) do { \
	if (_splash) { char _trace_tmp[512]; sprintf(_trace_tmp, __VA_ARGS__); fprintf(_splash, ":%s", _trace_tmp); fflush(_splash); } \
	if (_debug) { TRACE(__VA_ARGS__); } \
} while (0)

#define CHUNK_SIZE 4096

static int _debug = 0;
static FILE * _splash = NULL;

void copy_link(char * source, char * dest, int mode, int uid, int gid) {
	//fprintf(stderr, "need to copy link %s to %s\n", source, dest);
	char tmp[1024];
	readlink(source, tmp, 1024);
	symlink(tmp, dest);
	//chmod(dest, mode); /* links don't have modes */
	chown(dest, uid, gid);
}

void copy_file(char * source, char * dest, int mode,int uid, int gid) {
	//fprintf(stderr, "need to copy file %s to %s %x\n", source, dest, mode);
	//TRACE_("Copying %s...", dest);

	int d_fd = open(dest, O_WRONLY | O_CREAT, mode);
	int s_fd = open(source, O_RDONLY);

	ssize_t length;

	length = lseek(s_fd, 0, SEEK_END);
	lseek(s_fd, 0, SEEK_SET);

	//fprintf(stderr, "%d bytes to copy\n", length);

	char buf[CHUNK_SIZE];

	while (length > 0) {
		size_t r = read(s_fd, buf, length < CHUNK_SIZE ? length : CHUNK_SIZE);
		//fprintf(stderr, "copying %d bytes from %s to %s\n", r, source, dest);
		write(d_fd, buf, r);
		length -= r;
		//fprintf(stderr, "%d bytes remaining\n", length);
	}

	close(s_fd);
	close(d_fd);

	chown(dest, uid, gid);
	chmod(dest, mode);
}

void copy_directory(char * source, char * dest, int mode, int uid, int gid) {
	DIR * dirp = opendir(source);
	if (dirp == NULL) {
		fprintf(stderr, "Failed to copy directory %s\n", source);
		return;
	}

	TRACE_("Copying %s/...", dest);
	//fprintf(stderr, "Creating %s\n", dest);
	if (!strcmp(dest, "/")) {
		dest = "";
	} else {
		mkdir(dest, mode);
	}

	struct dirent * ent = readdir(dirp);
	while (ent != NULL) {
		if (!strcmp(ent->d_name,".") || !strcmp(ent->d_name,"..")) {
			//fprintf(stderr, "Skipping %s\n", ent->d_name);
			ent = readdir(dirp);
			continue;
		}
		//fprintf(stderr, "not skipping %s/%s → %s/%s\n", source, ent->d_name, dest, ent->d_name);
		struct stat statbuf;
		char tmp[strlen(source)+strlen(ent->d_name)+2];
		sprintf(tmp, "%s/%s", source, ent->d_name);
		char tmp2[strlen(dest)+strlen(ent->d_name)+2];
		sprintf(tmp2, "%s/%s", dest, ent->d_name);
		//fprintf(stderr,"%s → %s\n", tmp, tmp2);
		lstat(tmp,&statbuf);
		if (S_ISLNK(statbuf.st_mode)) {
			copy_link(tmp, tmp2, statbuf.st_mode & 07777, statbuf.st_uid, statbuf.st_gid);
		} else if (S_ISDIR(statbuf.st_mode)) {
			copy_directory(tmp, tmp2, statbuf.st_mode & 07777, statbuf.st_uid, statbuf.st_gid);
		} else if (S_ISREG(statbuf.st_mode)) {
			copy_file(tmp, tmp2, statbuf.st_mode & 07777, statbuf.st_uid, statbuf.st_gid);
		} else {
			fprintf(stderr, " %s is not any of the required file types?\n", tmp);
		}
		ent = readdir(dirp);
	}
	closedir(dirp);

	chown(dest, uid, gid);
}

void free_ramdisk(char * path) {
	int fd = open(path, O_RDONLY);
	ioctl(fd, 0x4001, NULL);
	close(fd);
}

#include "../kernel/misc/args.c"
static hashmap_t * get_cmdline(void) {
	char * results = args_from_procfs();
	if (results) free(results);
	return kernel_args_map;
}

int main(int argc, char * argv[]) {

	hashmap_t * cmdline = get_cmdline();

	if (hashmap_has(cmdline, "logtoserial")) {
		_debug = 1;
	}

	_splash = fopen("/dev/pex/splash","r+");

	if (hashmap_has(cmdline, "root")) {
		TRACE_("Original root was %s", (char*)hashmap_get(cmdline, "root"));
	} else if (hashmap_has(cmdline,"init") && !strcmp(hashmap_get(cmdline,"init"),"/dev/ram0")) {
		TRACE_("Init is ram0, so this is probably a netboot image, going to assume root is /tmp/netboot.img");
		hashmap_set(cmdline,"root","/tmp/netboot.img");
	} else {
		TRACE_("Fatal: Don't know how to boot this. No root set.\n");
		return 1;
	}

	char * root = hashmap_get(cmdline,"root");

	char * start = hashmap_get(cmdline,"_start");
	if (!start) {
		start = "";
	}
	char * root_type = hashmap_get(cmdline,"root_type");
	if (!root_type) {
		root_type = "tar";
	}

	char tmp[1024];

	TRACE_("Remounting root to /dev/base");
	sprintf(tmp, "mount %s %s /dev/base", root_type, root);
	system(tmp);

	TRACE_("Mounting tmpfs to /");
	system("mount tmpfs x,755 /");

	TRACE_("Migrating root...");
	copy_directory("/dev/base","/",0660,0,0);
	system("mount tmpfs x,755 /dev/base");

	if (strstr(root, "/dev/ram") != NULL) {
		char * tmp = strdup(root);
		char * c = strchr(tmp, ',');
		if (c) {
			*c = '\0';
		}
		TRACE_("Freeing ramdisk at %s", tmp);
		free_ramdisk(tmp);
		free(tmp);
	}

	return 0;
}