/* 
 * libdivecomputer
 * 
 * Copyright (C) 2008 Jef Driesen
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */

#include <string.h> // memcmp, memcpy
#include <stdlib.h> // malloc, free
#include <assert.h> // assert

#include "device-private.h"
#include "suunto_d9.h"
#include "serial.h"
#include "utils.h"
#include "ringbuffer.h"
#include "checksum.h"
#include "array.h"

#define MAXRETRIES 2

#define MIN(a,b)	(((a) < (b)) ? (a) : (b))
#define MAX(a,b)	(((a) > (b)) ? (a) : (b))

#define WARNING(expr) \
{ \
	message ("%s:%d: %s\n", __FILE__, __LINE__, expr); \
}

#define EXITCODE(rc) \
( \
	rc == -1 ? DEVICE_STATUS_IO : DEVICE_STATUS_TIMEOUT \
)

#define MINIMUM 8

#define RB_PROFILE_BEGIN			0x019A
#define RB_PROFILE_END				SUUNTO_D9_MEMORY_SIZE - 2
#define RB_PROFILE_DISTANCE(a,b)	ringbuffer_distance (a, b, RB_PROFILE_BEGIN, RB_PROFILE_END)

#define FP_OFFSET 0x15
#define FP_SIZE   7

typedef struct suunto_d9_device_t {
	device_t base;
	struct serial *port;
	unsigned char fingerprint[FP_SIZE];
} suunto_d9_device_t;

static device_status_t suunto_d9_device_set_fingerprint (device_t *abstract, const unsigned char data[], unsigned int size);
static device_status_t suunto_d9_device_version (device_t *abstract, unsigned char data[], unsigned int size);
static device_status_t suunto_d9_device_read (device_t *abstract, unsigned int address, unsigned char data[], unsigned int size);
static device_status_t suunto_d9_device_write (device_t *abstract, unsigned int address, const unsigned char data[], unsigned int size);
static device_status_t suunto_d9_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result);
static device_status_t suunto_d9_device_foreach (device_t *abstract, dive_callback_t callback, void *userdata);
static device_status_t suunto_d9_device_close (device_t *abstract);

static const device_backend_t suunto_d9_device_backend = {
	DEVICE_TYPE_SUUNTO_D9,
	suunto_d9_device_set_fingerprint, /* set_fingerprint */
	NULL, /* handshake */
	suunto_d9_device_version, /* version */
	suunto_d9_device_read, /* read */
	suunto_d9_device_write, /* write */
	suunto_d9_device_dump, /* dump */
	suunto_d9_device_foreach, /* foreach */
	suunto_d9_device_close /* close */
};

static int
device_is_suunto_d9 (device_t *abstract)
{
	if (abstract == NULL)
		return 0;

    return abstract->backend == &suunto_d9_device_backend;
}


device_status_t
suunto_d9_device_open (device_t **out, const char* name)
{
	if (out == NULL)
		return DEVICE_STATUS_ERROR;

	// Allocate memory.
	suunto_d9_device_t *device = (suunto_d9_device_t *) malloc (sizeof (suunto_d9_device_t));
	if (device == NULL) {
		WARNING ("Failed to allocate memory.");
		return DEVICE_STATUS_MEMORY;
	}

	// Initialize the base class.
	device_init (&device->base, &suunto_d9_device_backend);

	// Set the default values.
	device->port = NULL;
	memset (device->fingerprint, 0, FP_SIZE);

	// Open the device.
	int rc = serial_open (&device->port, name);
	if (rc == -1) {
		WARNING ("Failed to open the serial port.");
		free (device);
		return DEVICE_STATUS_IO;
	}

	// Set the serial communication protocol (9600 8N1).
	rc = serial_configure (device->port, 9600, 8, SERIAL_PARITY_NONE, 1, SERIAL_FLOWCONTROL_NONE);
	if (rc == -1) {
		WARNING ("Failed to set the terminal attributes.");
		serial_close (device->port);
		free (device);
		return DEVICE_STATUS_IO;
	}

	// Set the timeout for receiving data (3000 ms).
	if (serial_set_timeout (device->port, 3000) == -1) {
		WARNING ("Failed to set the timeout.");
		serial_close (device->port);
		free (device);
		return DEVICE_STATUS_IO;
	}

	// Set the DTR line (power supply for the interface).
	if (serial_set_dtr (device->port, 1) == -1) {
		WARNING ("Failed to set the DTR line.");
		serial_close (device->port);
		free (device);
		return DEVICE_STATUS_IO;
	}

	// Give the interface 100 ms to settle and draw power up.
	serial_sleep (100);

	// Make sure everything is in a sane state.
	serial_flush (device->port, SERIAL_QUEUE_BOTH);

	*out = (device_t*) device;

	return DEVICE_STATUS_SUCCESS;
}


static device_status_t
suunto_d9_device_close (device_t *abstract)
{
	suunto_d9_device_t *device = (suunto_d9_device_t*) abstract;

	if (! device_is_suunto_d9 (abstract))
		return DEVICE_STATUS_TYPE_MISMATCH;

	// Close the device.
	if (serial_close (device->port) == -1) {
		free (device);
		return DEVICE_STATUS_IO;
	}

	// Free memory.	
	free (device);

	return DEVICE_STATUS_SUCCESS;
}


static device_status_t
suunto_d9_send (suunto_d9_device_t *device, const unsigned char command[], unsigned int csize)
{
	// Clear RTS to send the command.
	serial_set_rts (device->port, 0);

	// Send the command to the dive computer and 
	// wait until all data has been transmitted.
	serial_write (device->port, command, csize);
	serial_drain (device->port);

	// Receive the echo.
	unsigned char echo[128] = {0};
	assert (sizeof (echo) >= csize);
	int n = serial_read (device->port, echo, csize);
	if (n != csize) {
		WARNING ("Failed to receive the echo.");
		return EXITCODE (n);
	}

	// Verify the echo.
	if (memcmp (command, echo, csize) != 0) {
		WARNING ("Unexpected echo.");
		return DEVICE_STATUS_PROTOCOL;
	}

	// Set RTS to receive the reply.
	serial_set_rts (device->port, 1);

	return DEVICE_STATUS_SUCCESS;
}


static device_status_t
suunto_d9_packet (suunto_d9_device_t *device, const unsigned char command[], unsigned int csize, unsigned char answer[], unsigned int asize, unsigned int size)
{
	// Send the command to the dive computer.
	device_status_t rc = suunto_d9_send (device, command, csize);
	if (rc != DEVICE_STATUS_SUCCESS) {
		WARNING ("Failed to send the command.");
		return rc;
	}

	// Receive the answer of the dive computer.
	int n = serial_read (device->port, answer, asize);
	if (n != asize) {
		WARNING ("Failed to receive the answer.");
		return EXITCODE (n);
	}

	// Verify the header of the package.
	answer[2] -= size; // Adjust the package size for the comparision.
	if (memcmp (command, answer, asize - size - 1) != 0) {
		WARNING ("Unexpected answer start byte(s).");
		return DEVICE_STATUS_PROTOCOL;
	}
	answer[2] += size; // Restore the package size again.

	// Verify the checksum of the package.
	unsigned char crc = answer[asize - 1];
	unsigned char ccrc = checksum_xor_uint8 (answer, asize - 1, 0x00);
	if (crc != ccrc) {
		WARNING ("Unexpected answer CRC.");
		return DEVICE_STATUS_PROTOCOL;
	}

	return DEVICE_STATUS_SUCCESS;
}


static device_status_t
suunto_d9_transfer (suunto_d9_device_t *device, const unsigned char command[], unsigned int csize, unsigned char answer[], unsigned int asize, unsigned int size)
{
	assert (asize >= size + 4);

	// Occasionally, the dive computer does not respond to a command. 
	// In that case we retry the command a number of times before 
	// returning an error. Usually the dive computer will respond 
	// again during one of the retries.

	unsigned int nretries = 0;
	device_status_t rc = DEVICE_STATUS_SUCCESS;
	while ((rc = suunto_d9_packet (device, command, csize, answer, asize, size)) != DEVICE_STATUS_SUCCESS) {
		// Automatically discard a corrupted packet,
		// and request a new one.
		if (rc != DEVICE_STATUS_TIMEOUT && rc != DEVICE_STATUS_PROTOCOL)
			return rc;

		// Abort if the maximum number of retries is reached.
		if (nretries++ >= MAXRETRIES)
			return rc;
	}

	return rc;
}


static device_status_t
suunto_d9_device_set_fingerprint (device_t *abstract, const unsigned char data[], unsigned int size)
{
	suunto_d9_device_t *device = (suunto_d9_device_t*) abstract;

	if (! device_is_suunto_d9 (abstract))
		return DEVICE_STATUS_TYPE_MISMATCH;

	if (size && size != FP_SIZE)
		return DEVICE_STATUS_ERROR;

	if (size)
		memcpy (device->fingerprint, data, FP_SIZE);
	else
		memset (device->fingerprint, 0, FP_SIZE);

	return DEVICE_STATUS_SUCCESS;
}


static device_status_t
suunto_d9_device_version (device_t *abstract, unsigned char data[], unsigned int size)
{
	suunto_d9_device_t *device = (suunto_d9_device_t*) abstract;

	if (! device_is_suunto_d9 (abstract))
		return DEVICE_STATUS_TYPE_MISMATCH;

	if (size < SUUNTO_D9_VERSION_SIZE) {
		WARNING ("Insufficient buffer space available.");
		return DEVICE_STATUS_MEMORY;
	}

	unsigned char answer[SUUNTO_D9_VERSION_SIZE + 4] = {0};
	unsigned char command[4] = {0x0F, 0x00, 0x00, 0x0F};
	device_status_t rc = suunto_d9_transfer (device, command, sizeof (command), answer, sizeof (answer), 4);
	if (rc != DEVICE_STATUS_SUCCESS)
		return rc;

	memcpy (data, answer + 3, SUUNTO_D9_VERSION_SIZE);

#ifndef NDEBUG
	message ("D9ReadVersion()=\"%02x %02x %02x %02x\"\n", data[0], data[1], data[2], data[3]);
#endif

	return DEVICE_STATUS_SUCCESS;
}


device_status_t
suunto_d9_device_reset_maxdepth (device_t *abstract)
{
	suunto_d9_device_t *device = (suunto_d9_device_t*) abstract;

	if (! device_is_suunto_d9 (abstract))
		return DEVICE_STATUS_TYPE_MISMATCH;

	unsigned char answer[4] = {0};
	unsigned char command[4] = {0x20, 0x00, 0x00, 0x20};
	device_status_t rc = suunto_d9_transfer (device, command, sizeof (command), answer, sizeof (answer), 0);
	if (rc != DEVICE_STATUS_SUCCESS)
		return rc;

#ifndef NDEBUG
	message ("D9ResetMaxDepth()\n");
#endif

	return DEVICE_STATUS_SUCCESS;
}


static device_status_t
suunto_d9_read (device_t *abstract, unsigned int address, unsigned char data[], unsigned int size, device_progress_t *progress)
{
	suunto_d9_device_t *device = (suunto_d9_device_t*) abstract;

	if (! device_is_suunto_d9 (abstract))
		return DEVICE_STATUS_TYPE_MISMATCH;

	// The data transmission is split in packages
	// of maximum $SUUNTO_D9_PACKET_SIZE bytes.

	unsigned int nbytes = 0;
	while (nbytes < size) {
		// Calculate the package size.
		unsigned int len = MIN (size - nbytes, SUUNTO_D9_PACKET_SIZE);
		
		// Read the package.
		unsigned char answer[SUUNTO_D9_PACKET_SIZE + 7] = {0};
		unsigned char command[7] = {0x05, 0x00, 0x03,
				(address >> 8) & 0xFF, // high
				(address     ) & 0xFF, // low
				len, // count
				0};  // CRC
		command[6] = checksum_xor_uint8 (command, 6, 0x00);
		device_status_t rc = suunto_d9_transfer (device, command, sizeof (command), answer, len + 7, len);
		if (rc != DEVICE_STATUS_SUCCESS)
			return rc;

		memcpy (data, answer + 6, len);

#ifndef NDEBUG
		message ("D9Read(0x%04x,%d)=\"", address, len);
		for (unsigned int i = 0; i < len; ++i) {
			message("%02x", data[i]);
		}
		message("\"\n");
#endif

		// Update and emit a progress event.
		if (progress) {
			progress->current += len;
			device_event_emit (abstract, DEVICE_EVENT_PROGRESS, progress);
		}

		nbytes += len;
		address += len;
		data += len;
	}

	return DEVICE_STATUS_SUCCESS;
}


static device_status_t
suunto_d9_device_read (device_t *abstract, unsigned int address, unsigned char data[], unsigned int size)
{
	return suunto_d9_read (abstract, address, data, size, NULL);
}


static device_status_t
suunto_d9_device_write (device_t *abstract, unsigned int address, const unsigned char data[], unsigned int size)
{
	suunto_d9_device_t *device = (suunto_d9_device_t*) abstract;

	if (! device_is_suunto_d9 (abstract))
		return DEVICE_STATUS_TYPE_MISMATCH;

	// The data transmission is split in packages
	// of maximum $SUUNTO_D9_PACKET_SIZE bytes.

	unsigned int nbytes = 0;
	while (nbytes < size) {
		// Calculate the package size.
		unsigned int len = MIN (size - nbytes, SUUNTO_D9_PACKET_SIZE);

		// Write the package.
		unsigned char answer[7] = {0};
		unsigned char command[SUUNTO_D9_PACKET_SIZE + 7] = {0x06, 0x00, 0x03,
				(address >> 8) & 0xFF, // high
				(address     ) & 0xFF, // low
				len, // count
				0};  // data + CRC
		memcpy (command + 6, data, len);
		command[len + 6] = checksum_xor_uint8 (command, len + 6, 0x00);
		device_status_t rc = suunto_d9_transfer (device, command, len + 7, answer, sizeof (answer), 0);
		if (rc != DEVICE_STATUS_SUCCESS)
			return rc;

#ifndef NDEBUG
		message ("D9Write(0x%04x,%d,\"", address, len);
		for (unsigned int i = 0; i < len; ++i) {
			message ("%02x", data[i]);
		}
		message ("\");\n");
#endif

		nbytes += len;
		address += len;
		data += len;
	}

	return DEVICE_STATUS_SUCCESS;
}


static device_status_t
suunto_d9_device_dump (device_t *abstract, unsigned char data[], unsigned int size, unsigned int *result)
{
	if (! device_is_suunto_d9 (abstract))
		return DEVICE_STATUS_TYPE_MISMATCH;

	if (size < SUUNTO_D9_MEMORY_SIZE) {
		WARNING ("Insufficient buffer space available.");
		return DEVICE_STATUS_MEMORY;
	}

	// Enable progress notifications.
	device_progress_t progress = DEVICE_PROGRESS_INITIALIZER;
	progress.maximum = SUUNTO_D9_MEMORY_SIZE;
	device_event_emit (abstract, DEVICE_EVENT_PROGRESS, &progress);

	device_status_t rc = suunto_d9_read (abstract, 0x00, data, SUUNTO_D9_MEMORY_SIZE, &progress);
	if (rc != DEVICE_STATUS_SUCCESS)
		return rc;

	if (result)
		*result = SUUNTO_D9_MEMORY_SIZE;

	return DEVICE_STATUS_SUCCESS;
}


static device_status_t
suunto_d9_device_foreach (device_t *abstract, dive_callback_t callback, void *userdata)
{
	suunto_d9_device_t *device = (suunto_d9_device_t*) abstract;

	if (! device_is_suunto_d9 (abstract))
		return DEVICE_STATUS_TYPE_MISMATCH;

	// Enable progress notifications.
	device_progress_t progress = DEVICE_PROGRESS_INITIALIZER;
	progress.maximum = RB_PROFILE_END - RB_PROFILE_BEGIN + 8 + 4 + (MINIMUM > 4 ? MINIMUM : 4);
	device_event_emit (abstract, DEVICE_EVENT_PROGRESS, &progress);

	// Read the version info.
	unsigned char version[4] = {0};
	device_status_t rc = suunto_d9_device_version (abstract, version, sizeof (version));
	if (rc != DEVICE_STATUS_SUCCESS) {
		WARNING ("Cannot read memory header.");
		return rc;
	}

	// Update and emit a progress event.
	progress.current += sizeof (version);
	device_event_emit (abstract, DEVICE_EVENT_PROGRESS, &progress);

	// Read the serial number.
	unsigned char serial[MINIMUM > 4 ? MINIMUM : 4] = {0};
	rc = suunto_d9_read (abstract, 0x0023, serial, sizeof (serial), NULL);
	if (rc != DEVICE_STATUS_SUCCESS) {
		WARNING ("Cannot read memory header.");
		return rc;
	}

	// Update and emit a progress event.
	progress.current += sizeof (serial);
	device_event_emit (abstract, DEVICE_EVENT_PROGRESS, &progress);

	// Emit a device info event.
	device_devinfo_t devinfo;
	devinfo.model = version[0];
	devinfo.firmware = array_uint24_be (version + 1);
	devinfo.serial = array_uint32_be (serial);
	device_event_emit (abstract, DEVICE_EVENT_DEVINFO, &devinfo);

	// Read the header bytes.
	unsigned char header[8] = {0};
	rc = suunto_d9_read (abstract, 0x0190, header, sizeof (header), NULL);
	if (rc != DEVICE_STATUS_SUCCESS) {
		WARNING ("Cannot read memory header.");
		return rc;
	}

	// Obtain the pointers from the header.
	unsigned int last  = array_uint16_le (header + 0);
	unsigned int count = array_uint16_le (header + 2);
	unsigned int end   = array_uint16_le (header + 4);
	unsigned int begin = array_uint16_le (header + 6);
	message ("Pointers: begin=%04x, last=%04x, end=%04x, count=%i\n", begin, last, end, count);

	// Memory buffer to store all the dives.

	unsigned char data[MINIMUM + RB_PROFILE_END - RB_PROFILE_BEGIN] = {0};

	// Calculate the total amount of bytes.

	unsigned int remaining = RB_PROFILE_DISTANCE (begin, end);

	// Update and emit a progress event.

	progress.maximum -= (RB_PROFILE_END - RB_PROFILE_BEGIN) - remaining;
	progress.current += sizeof (header);
	device_event_emit (abstract, DEVICE_EVENT_PROGRESS, &progress);

	// To reduce the number of read operations, we always try to read 
	// packages with the largest possible size. As a consequence, the 
	// last package of a dive can contain data from more than one dive. 
	// Therefore, the remaining data of this package (and its size) 
	// needs to be preserved for the next dive.

	unsigned int available = 0;

	// The ring buffer is traversed backwards to retrieve the most recent
	// dives first. This allows you to download only the new dives. During 
	// the traversal, the current pointer does always point to the end of
	// the dive data and we move to the "next" dive by means of the previous 
	// pointer.

	unsigned int ndives = 0;
	unsigned int current = end;
	unsigned int previous = last;
	while (current != begin) {
		// Calculate the size of the current dive.
		unsigned int size = RB_PROFILE_DISTANCE (previous, current);
		message ("Pointers: dive=%u, current=%04x, previous=%04x, size=%u, remaining=%u, available=%u\n",
			ndives + 1, current, previous, size, remaining, available);

		assert (size >= 4 && size <= remaining);

		unsigned int nbytes = available;
		unsigned int address = current - available;
		while (nbytes < size) {
			// Calculate the package size. Try with the largest possible 
			// size first, and adjust when the end of the ringbuffer or  
			// the end of the profile data is reached.
			unsigned int len = SUUNTO_D9_PACKET_SIZE;
			if (RB_PROFILE_BEGIN + len > address)
				len = address - RB_PROFILE_BEGIN; // End of ringbuffer.
			if (nbytes + len > remaining)
				len = remaining - nbytes; // End of profile.
			/*if (nbytes + len > size)
				len = size - nbytes;*/ // End of dive (for testing only).

			message ("Pointers: address=%04x, len=%u\n", address - len, len);

			// Always read at least the minimum amount of bytes, because 
			// reading fewer bytes is unreliable. The memory buffer is 
			// large enough to prevent buffer overflows, and the extra 
			// bytes are automatically ignored (due to reading backwards).
			unsigned int extra = 0;
			if (len < MINIMUM)
				extra = MINIMUM - len;

			message ("Pointers: extra=%u\n", extra);

			// Read the package.
			unsigned char *p = data + MINIMUM + remaining - nbytes;
			rc = suunto_d9_read (abstract, address - (len + extra), p - (len + extra), len + extra, NULL);
			if (rc != DEVICE_STATUS_SUCCESS) {
				WARNING ("Cannot read memory.");
				return rc;
			}

			// Update and emit a progress event.
			progress.current += len;
			device_event_emit (abstract, DEVICE_EVENT_PROGRESS, &progress);

			// Next package.
			nbytes += len;
			address -= len;
			if (address <= RB_PROFILE_BEGIN)
				address = RB_PROFILE_END;		
		}

		message ("Pointers: nbytes=%u\n", nbytes);

		// The last package of the current dive contains the previous and
		// next pointers (in a continuous memory area). It can also contain
		// a number of bytes from the next dive. The offset to the pointers
		// is equal to the number of bytes remaining after the current dive.

		remaining -= size;
		available = nbytes - size;

		unsigned int oprevious = array_uint16_le (data + MINIMUM + remaining + 0);
		unsigned int onext     = array_uint16_le (data + MINIMUM + remaining + 2);
		message ("Pointers: previous=%04x, next=%04x\n", oprevious, onext);
		assert (current == onext);

		// Next dive.
		current = previous;
		previous = oprevious;
		ndives++;

#ifndef NDEBUG
		message ("D9Profile()=\"");
		for (unsigned int i = 0; i < size - 4; ++i) {
			message ("%02x", data[MINIMUM + remaining + 4 + i]);
		}
		message ("\"\n");
#endif

		unsigned int offset = MINIMUM + remaining;
		if (memcmp (data + offset + FP_OFFSET, device->fingerprint, FP_SIZE) == 0)
			return DEVICE_STATUS_SUCCESS;

		if (callback && !callback (data + offset + 4, size - 4, userdata))
			return DEVICE_STATUS_SUCCESS;
	}
	assert (remaining == 0);
	assert (available == 0);

	return DEVICE_STATUS_SUCCESS;
}