/*
    Copyright (C) 2019-2020 Carl Hetherington <cth@carlh.net>

    This file is part of DCP-o-matic.

    DCP-o-matic 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.

    DCP-o-matic 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 DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.

*/


#include "compose.hpp"
#include "cross.h"
#include "dcpomatic_log.h"
#include "digester.h"
#include "disk_writer_messages.h"
#include "exceptions.h"
#include "ext.h"
#include "nanomsg.h"

#ifdef DCPOMATIC_LINUX
#include <linux/fs.h>
#include <sys/ioctl.h>
extern "C" {
#include <lwext4/file_dev.h>
}
#endif

#ifdef DCPOMATIC_OSX
extern "C" {
#include <lwext4/file_dev.h>
}
#endif

#ifdef DCPOMATIC_WINDOWS
extern "C" {
#include <lwext4/file_windows.h>
}
#endif

extern "C" {
#include <lwext4/ext4.h>
#include <lwext4/ext4_debug.h>
#include <lwext4/ext4_errno.h>
#include <lwext4/ext4_fs.h>
#include <lwext4/ext4_mbr.h>
#include <lwext4/ext4_mkfs.h>
}
#include <boost/filesystem.hpp>
#include <string>


using std::exception;
using std::min;
using std::string;
using std::vector;


#define SHORT_TIMEOUT 100
#define LONG_TIMEOUT 2000


/* Use quite a big block size here, as ext4's fwrite() has quite a bit of overhead */
static uint64_t const block_size = 4096 * 4096;


static
void
count (boost::filesystem::path dir, uint64_t& total_bytes)
{
	using namespace boost::filesystem;
	for (directory_iterator i = directory_iterator(dir); i != directory_iterator(); ++i) {
		if (is_directory(*i)) {
			count (*i, total_bytes);
		} else {
			total_bytes += file_size (*i);
		}
	}
}

static
string
write (boost::filesystem::path from, boost::filesystem::path to, uint64_t& total_remaining, uint64_t total, Nanomsg* nanomsg)
{
	ext4_file out;
	int r = ext4_fopen(&out, to.generic_string().c_str(), "wb");
	if (r != EOK) {
		throw CopyError (String::compose("Failed to open file %1", to.generic_string()), r);
	}

	FILE* in = fopen_boost (from, "rb");
	if (!in) {
		ext4_fclose (&out);
		throw CopyError (String::compose("Failed to open file %1", from.string()), 0);
	}

	uint8_t* buffer = new uint8_t[block_size];
	Digester digester;

	int progress_frequency = 1;
	int progress_count = 0;
	uint64_t remaining = file_size (from);
	while (remaining > 0) {
		uint64_t const this_time = min(remaining, block_size);
		size_t read = fread (buffer, 1, this_time, in);
		if (read != this_time) {
			fclose (in);
			ext4_fclose (&out);
			delete[] buffer;
			throw CopyError (String::compose("Short read; expected %1 but read %2", this_time, read), 0);
		}

		digester.add (buffer, this_time);

		size_t written;
		r = ext4_fwrite (&out, buffer, this_time, &written);
		if (r != EOK) {
			fclose (in);
			ext4_fclose (&out);
			delete[] buffer;
			throw CopyError ("Write failed", r);
		}
		if (written != this_time) {
			fclose (in);
			ext4_fclose (&out);
			delete[] buffer;
			throw CopyError (String::compose("Short write; expected %1 but wrote %2", this_time, written), 0);
		}
		remaining -= this_time;
		total_remaining -= this_time;

		++progress_count;
		if ((progress_count % progress_frequency) == 0 && nanomsg) {
			nanomsg->send(String::compose(DISK_WRITER_COPY_PROGRESS "\n%1\n", (1 - float(total_remaining) / total)), SHORT_TIMEOUT);
		}
	}

	fclose (in);
	ext4_fclose (&out);
	delete[] buffer;

	return digester.get ();
}


static
string
read (boost::filesystem::path from, boost::filesystem::path to, uint64_t& total_remaining, uint64_t total, Nanomsg* nanomsg)
{
	ext4_file in;
	LOG_DISK("Opening %1 for read", to.generic_string());
	int r = ext4_fopen(&in, to.generic_string().c_str(), "rb");
	if (r != EOK) {
		throw VerifyError (String::compose("Failed to open file %1", to.generic_string()), r);
	}
	LOG_DISK("Opened %1 for read", to.generic_string());

	uint8_t* buffer = new uint8_t[block_size];
	Digester digester;

	uint64_t remaining = file_size (from);
	while (remaining > 0) {
		uint64_t const this_time = min(remaining, block_size);
		size_t read;
		r = ext4_fread (&in, buffer, this_time, &read);
		if (read != this_time) {
			ext4_fclose (&in);
			delete[] buffer;
			throw VerifyError (String::compose("Short read; expected %1 but read %2", this_time, read), 0);
		}

		digester.add (buffer, this_time);
		remaining -= this_time;
		total_remaining -= this_time;
		if (nanomsg) {
			nanomsg->send(String::compose(DISK_WRITER_VERIFY_PROGRESS "\n%1\n", (1 - float(total_remaining) / total)), SHORT_TIMEOUT);
		}
	}

	ext4_fclose (&in);
	delete[] buffer;

	return digester.get ();
}


class CopiedFile
{
public:
	CopiedFile (boost::filesystem::path from_, boost::filesystem::path to_, string write_digest_)
		: from (from_)
		, to (to_)
		, write_digest (write_digest_)
	{}

	boost::filesystem::path from;
	boost::filesystem::path to;
	/** digest calculated from data as it was read from the source during write */
	string write_digest;
};


/** @param from File to copy from.
 *  @param to Directory to copy to.
 */
static
void
copy (boost::filesystem::path from, boost::filesystem::path to, uint64_t& total_remaining, uint64_t total, vector<CopiedFile>& copied_files, Nanomsg* nanomsg)
{
	LOG_DISK ("Copy %1 -> %2", from.string(), to.generic_string());

	using namespace boost::filesystem;

	path const cr = to / from.filename();

	if (is_directory(from)) {
		int r = ext4_dir_mk (cr.generic_string().c_str());
		if (r != EOK) {
			throw CopyError (String::compose("Failed to create directory %1", cr.generic_string()), r);
		}

		for (directory_iterator i = directory_iterator(from); i != directory_iterator(); ++i) {
			copy (i->path(), cr, total_remaining, total, copied_files, nanomsg);
		}
	} else {
		string const write_digest = write (from, cr, total_remaining, total, nanomsg);
		LOG_DISK ("Wrote %1 %2 with %3", from.string(), cr.generic_string(), write_digest);
		copied_files.push_back (CopiedFile(from, cr, write_digest));
	}
}


static
void
verify (vector<CopiedFile> const& copied_files, uint64_t total, Nanomsg* nanomsg)
{
	uint64_t total_remaining = total;
	for (auto const& i: copied_files) {
		string const read_digest = read (i.from, i.to, total_remaining, total, nanomsg);
		LOG_DISK ("Read %1 %2 was %3 on write, now %4", i.from.string(), i.to.generic_string(), i.write_digest, read_digest);
		if (read_digest != i.write_digest) {
			throw VerifyError ("Hash of written data is incorrect", 0);
		}
	}
}


static
void
format_progress (void* context, float progress)
{
	if (context) {
		reinterpret_cast<Nanomsg*>(context)->send(String::compose(DISK_WRITER_FORMAT_PROGRESS "\n%1\n", progress), SHORT_TIMEOUT);
	}
}


void
#ifdef DCPOMATIC_WINDOWS
dcpomatic::write (boost::filesystem::path dcp_path, string device, string, Nanomsg* nanomsg)
#else
dcpomatic::write (boost::filesystem::path dcp_path, string device, string posix_partition, Nanomsg* nanomsg)
#endif
try
{
	ext4_dmask_set (DEBUG_ALL);

	/* We rely on static initialization for these */
	static struct ext4_fs fs;
	static struct ext4_mkfs_info info;
	info.block_size = 4096;
	info.inode_size = 128;
	info.journal = false;

#ifdef WIN32
	file_windows_name_set(device.c_str());
	struct ext4_blockdev* bd = file_windows_dev_get();
#else
	file_dev_name_set (device.c_str());
	struct ext4_blockdev* bd = file_dev_get ();
#endif

	if (!bd) {
		throw CopyError ("Failed to open drive", 0);
	}
	LOG_DISK_NC ("Opened drive");

	struct ext4_mbr_parts parts;
	parts.division[0] = 100;
	parts.division[1] = 0;
	parts.division[2] = 0;
	parts.division[3] = 0;

#ifdef DCPOMATIC_LINUX
	PrivilegeEscalator e;
#endif

	/* XXX: not sure if disk_id matters */
	int r = ext4_mbr_write (bd, &parts, 0);
	if (r) {
		throw CopyError ("Failed to write MBR", r);
	}
	LOG_DISK_NC ("Wrote MBR");

	struct ext4_mbr_bdevs bdevs;
	r = ext4_mbr_scan (bd, &bdevs);
	if (r != EOK) {
		throw CopyError ("Failed to read MBR", r);
	}

#ifdef DCPOMATIC_LINUX
	/* Re-read the partition table */
	int fd = open(device.c_str(), O_RDONLY);
	ioctl(fd, BLKRRPART, NULL);
	close(fd);
#endif

	LOG_DISK ("Writing to partition at %1 size %2; bd part size is %3", bdevs.partitions[0].part_offset, bdevs.partitions[0].part_size, bd->part_size);

#ifdef DCPOMATIC_WINDOWS
	file_windows_partition_set (bdevs.partitions[0].part_offset, bdevs.partitions[0].part_size);
#else
	file_dev_name_set (posix_partition.c_str());
	bd = file_dev_get ();
#endif

	if (!bd) {
		throw CopyError ("Failed to open partition", 0);
	}
	LOG_DISK_NC ("Opened partition");

	r = ext4_mkfs(&fs, bd, &info, F_SET_EXT2, format_progress, nanomsg);
	if (r != EOK) {
		throw CopyError ("Failed to make filesystem", r);
	}
	LOG_DISK_NC ("Made filesystem");

	r = ext4_device_register(bd, "ext4_fs");
	if (r != EOK) {
		throw CopyError ("Failed to register device", r);
	}
	LOG_DISK_NC ("Registered device");

	r = ext4_mount("ext4_fs", "/mp/", false);
	if (r != EOK) {
		throw CopyError ("Failed to mount device", r);
	}
	LOG_DISK_NC ("Mounted device");

	uint64_t total_bytes = 0;
	count (dcp_path, total_bytes);

	uint64_t total_remaining = total_bytes;
	vector<CopiedFile> copied_files;
	copy (dcp_path, "/mp", total_remaining, total_bytes, copied_files, nanomsg);

	/* Unmount and re-mount to make sure the write has finished */
	r = ext4_umount("/mp/");
	if (r != EOK) {
		throw CopyError ("Failed to unmount device", r);
	}
	r = ext4_mount("ext4_fs", "/mp/", false);
	if (r != EOK) {
		throw CopyError ("Failed to mount device", r);
	}
	LOG_DISK_NC ("Re-mounted device");

	verify (copied_files, total_bytes, nanomsg);

	r = ext4_umount("/mp/");
	if (r != EOK) {
		throw CopyError ("Failed to unmount device", r);
	}

	ext4_device_unregister("ext4_fs");
	if (nanomsg && !nanomsg->send(DISK_WRITER_OK "\n", LONG_TIMEOUT)) {
		throw CommunicationFailedError ();
	}

	disk_write_finished ();
} catch (CopyError& e) {
	LOG_DISK("CopyError (from write): %1 %2", e.message(), e.number().get_value_or(0));
	if (nanomsg) {
		nanomsg->send(String::compose(DISK_WRITER_ERROR "\n%1\n%2\n", e.message(), e.number().get_value_or(0)), LONG_TIMEOUT);
	}
} catch (VerifyError& e) {
	LOG_DISK("VerifyError (from write): %1 %2", e.message(), e.number());
	if (nanomsg) {
		nanomsg->send(String::compose(DISK_WRITER_ERROR "\n%1\n%2\n", e.message(), e.number()), LONG_TIMEOUT);
	}
} catch (exception& e) {
	LOG_DISK("Exception (from write): %1", e.what());
	if (nanomsg) {
		nanomsg->send(String::compose(DISK_WRITER_ERROR "\n%1\n0\n", e.what()), LONG_TIMEOUT);
	}
}