/*
 * Copyright (C) 2014 BlueKitchen GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 * 4. Any redistribution, use, or modification is done solely for
 *    personal benefit and not for any commercial purpose or for
 *    monetary gain.
 *
 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
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 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * Please inquire about commercial licensing options at 
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 */

/*
 *  hci_h4_transport.c
 *
 *  HCI Transport API implementation for basic H4 protocol over POSIX
 *
 *  Created by Matthias Ringwald on 4/29/09.
 */

#include "btstack_config.h"

#include <termios.h>  /* POSIX terminal control definitions */
#include <fcntl.h>    /* File control definitions */
#include <unistd.h>   /* UNIX standard function definitions */
#include <stdio.h>
#include <string.h>
#include <pthread.h> 

#include "btstack_debug.h"
#include "hci.h"
#include "hci_transport.h"
#include "btstack_uart_posix.h"

#ifdef HAVE_EHCILL
#error "HCI Transport H4 POSIX does not support eHCILL yet. Please remove HAVE_EHCILL from your btstack-config.h"
#endif 

// assert pre-buffer for packet type is available
#if !defined(HCI_OUTGOING_PRE_BUFFER_SIZE) || (HCI_OUTGOING_PRE_BUFFER_SIZE == 0)
#error HCI_OUTGOING_PRE_BUFFER_SIZE not defined. Please update hci.h
#endif

static void h4_process(btstack_data_source_t *ds, btstack_data_source_callback_type_t callback_type);
static void dummy_handler(uint8_t packet_type, uint8_t *packet, uint16_t size); 

typedef enum {
    H4_W4_PACKET_TYPE,
    H4_W4_EVENT_HEADER,
    H4_W4_ACL_HEADER,
    H4_W4_SCO_HEADER,
    H4_W4_PAYLOAD,
} H4_STATE;

typedef struct hci_transport_h4 {
    hci_transport_t transport;
    btstack_data_source_t *ds;
    int uart_fd;    // different from ds->fd for HCI reader thread
    /* power management support, e.g. used by iOS */
    btstack_timer_source_t sleep_timer;
} hci_transport_h4_t;


// single instance
static hci_transport_h4_t * hci_transport_h4 = NULL;

static hci_transport_config_uart_t * hci_transport_config_uart = NULL;

static  void (*packet_handler)(uint8_t packet_type, uint8_t *packet, uint16_t size) = dummy_handler;

// packet reader state machine
static  H4_STATE h4_state;
static int bytes_to_read;
static int read_pos;

// packet writer state
static int             write_bytes_len;
static const uint8_t * write_bytes_data;


static uint8_t hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE + 1 + HCI_PACKET_BUFFER_SIZE]; // packet type + max(acl header + acl payload, event header + event data)
static uint8_t * hci_packet = &hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE];

static int    h4_set_baudrate(uint32_t baudrate){
    log_info("h4_set_baudrate %u", baudrate);
    int fd = btstack_run_loop_get_data_source_fd(hci_transport_h4->ds);
    return btstack_uart_posix_set_baudrate(fd, baudrate);
}

static void h4_init(const void * transport_config){
    // check for hci_transport_config_uart_t
    if (!transport_config) {
        log_error("hci_transport_h4_posix: no config!");
        return;
    }
    if (((hci_transport_config_t*)transport_config)->type != HCI_TRANSPORT_CONFIG_UART) {
        log_error("hci_transport_h4_posix: config not of type != HCI_TRANSPORT_CONFIG_UART!");
        return;
    }
    hci_transport_config_uart = (hci_transport_config_uart_t*) transport_config;
}

static int h4_open(void){

    int fd = btstack_uart_posix_open(hci_transport_config_uart->device_name, hci_transport_config_uart->flowcontrol, hci_transport_config_uart->baudrate_init);
    if (fd < 0){
        return fd;
    }

   // set up data_source
    hci_transport_h4->ds = (btstack_data_source_t*) malloc(sizeof(btstack_data_source_t));
    if (!hci_transport_h4->ds) return -1;
    hci_transport_h4->uart_fd = fd;
    btstack_run_loop_set_data_source_fd(hci_transport_h4->ds, fd);
    btstack_run_loop_set_data_source_handler(hci_transport_h4->ds, &h4_process);
    btstack_run_loop_enable_data_source_callbacks(hci_transport_h4->ds, DATA_SOURCE_CALLBACK_READ);
    btstack_run_loop_add_data_source(hci_transport_h4->ds);

    // init state machine
    bytes_to_read = 1;
    h4_state = H4_W4_PACKET_TYPE;
    read_pos = 0;    
    return 0;
}

static int h4_close(void){
    // first remove run loop handler
	btstack_run_loop_remove_data_source(hci_transport_h4->ds);
    
    // close device 
    int fd = btstack_run_loop_get_data_source_fd(hci_transport_h4->ds);
    close(fd);

    // free struct
    free(hci_transport_h4->ds);
    hci_transport_h4->ds = NULL;
    return 0;
}

static void h4_register_packet_handler(void (*handler)(uint8_t packet_type, uint8_t *packet, uint16_t size)){
    packet_handler = handler;
}

static void h4_reset_statemachine(void){
    h4_state = H4_W4_PACKET_TYPE;
    read_pos = 0;
    bytes_to_read = 1;
}

static void   h4_deliver_packet(void){
    if (read_pos < 3) return; // sanity check
    packet_handler(hci_packet[0], &hci_packet[1], read_pos-1);
    h4_reset_statemachine();
}

static void h4_statemachine(void){
    switch (h4_state) {
            
        case H4_W4_PACKET_TYPE:
            switch (hci_packet[0]){
                case HCI_EVENT_PACKET:
                    bytes_to_read = HCI_EVENT_HEADER_SIZE;
                    h4_state = H4_W4_EVENT_HEADER;
                    break;
                case HCI_ACL_DATA_PACKET:
                    bytes_to_read = HCI_ACL_HEADER_SIZE;
                    h4_state = H4_W4_ACL_HEADER;
                    break;
                case HCI_SCO_DATA_PACKET:
                    bytes_to_read = HCI_SCO_HEADER_SIZE;
                    h4_state = H4_W4_SCO_HEADER;
                    break;
                default:
                    log_error("h4_process: invalid packet type 0x%02x", hci_packet[0]);
                    h4_reset_statemachine();
                    break;
            }
            break;
            
        case H4_W4_EVENT_HEADER:
            bytes_to_read = hci_packet[2];
            h4_state = H4_W4_PAYLOAD;
            break;
            
        case H4_W4_ACL_HEADER:
            bytes_to_read = little_endian_read_16( hci_packet, 3);
            // check ACL length
            if (HCI_ACL_HEADER_SIZE + bytes_to_read >  HCI_PACKET_BUFFER_SIZE){
                log_error("h4_process: invalid ACL payload len %u - only space for %u", bytes_to_read, HCI_PACKET_BUFFER_SIZE - HCI_ACL_HEADER_SIZE);
                h4_reset_statemachine();
                break;              
            }
            h4_state = H4_W4_PAYLOAD;
            break;
            
        case H4_W4_SCO_HEADER:
            bytes_to_read = hci_packet[3];
            h4_state = H4_W4_PAYLOAD;
            break;

        case H4_W4_PAYLOAD:
            h4_deliver_packet();
            break;

        default:
            break;
    }
}
static void h4_process_read(btstack_data_source_t *ds){
    if (hci_transport_h4->uart_fd == 0) return;

    int read_now = bytes_to_read;

    uint32_t start = btstack_run_loop_get_time_ms();
    
    // read up to bytes_to_read data in
    ssize_t bytes_read = read(hci_transport_h4->uart_fd, &hci_packet[read_pos], read_now);
    // log_info("h4_process: bytes read %u", bytes_read);
    if (bytes_read < 0) return;

    uint32_t end = btstack_run_loop_get_time_ms();
    if (end - start > 10){
        log_info("h4_process: read took %u ms", end - start);
    }
    
    bytes_to_read -= bytes_read;
    read_pos      += bytes_read;
    if (bytes_to_read > 0) return;
    
    h4_statemachine();
}

static void h4_process_write(btstack_data_source_t * ds){
    if (hci_transport_h4->uart_fd == 0) return;
    if (write_bytes_len == 0) return;

    uint32_t start = btstack_run_loop_get_time_ms();

    // write up to write_bytes_len to fd
    int bytes_written = write(hci_transport_h4->uart_fd, write_bytes_data, write_bytes_len);
    if (bytes_written < 0) {
        btstack_run_loop_enable_data_source_callbacks(ds, DATA_SOURCE_CALLBACK_WRITE);
        return;
    }

    uint32_t end = btstack_run_loop_get_time_ms();
    if (end - start > 10){
        log_info("h4_process: write took %u ms", end - start);
    }

    write_bytes_data += bytes_written;
    write_bytes_len  -= bytes_written;

    if (write_bytes_len){
        btstack_run_loop_enable_data_source_callbacks(ds, DATA_SOURCE_CALLBACK_WRITE);
        return;
    }

    btstack_run_loop_disable_data_source_callbacks(ds, DATA_SOURCE_CALLBACK_WRITE);

    // notify upper stack that it can send again
    uint8_t event[] = { HCI_EVENT_TRANSPORT_PACKET_SENT, 0};
    packet_handler(HCI_EVENT_PACKET, &event[0], sizeof(event));
}

static void h4_process(btstack_data_source_t *ds, btstack_data_source_callback_type_t callback_type) {
    switch (callback_type){
        case DATA_SOURCE_CALLBACK_READ:
            h4_process_read(ds);
            break;
        case DATA_SOURCE_CALLBACK_WRITE:
            h4_process_write(ds);
        default:
            break;
    }
}

static int h4_send_packet(uint8_t packet_type, uint8_t * packet, int size){
    if (hci_transport_h4->ds == NULL) return -1;
    if (hci_transport_h4->uart_fd == 0) return -1;

    // store packet type before actual data and increase size
    size++;
    packet--;
    *packet = packet_type;

    // register outgoing request
    write_bytes_data = packet;
    write_bytes_len = size;

    // start sending
    h4_process_write(hci_transport_h4->ds);

    return 0;
}

static int h4_can_send_now(uint8_t packet_type){
    return write_bytes_len == 0;
}

static void dummy_handler(uint8_t packet_type, uint8_t *packet, uint16_t size){
}

// get h4 singleton
const hci_transport_t * hci_transport_h4_instance(void) {
    if (hci_transport_h4 == NULL) {
        hci_transport_h4 = (hci_transport_h4_t*)malloc( sizeof(hci_transport_h4_t));
        memset(hci_transport_h4, 0, sizeof(hci_transport_h4_t));
        hci_transport_h4->ds                                      = NULL;
        hci_transport_h4->transport.name                          = "H4_POSIX";
        hci_transport_h4->transport.init                          = h4_init;
        hci_transport_h4->transport.open                          = h4_open;
        hci_transport_h4->transport.close                         = h4_close;
        hci_transport_h4->transport.register_packet_handler       = h4_register_packet_handler;
        hci_transport_h4->transport.can_send_packet_now           = h4_can_send_now;
        hci_transport_h4->transport.send_packet                   = h4_send_packet;
        hci_transport_h4->transport.set_baudrate                  = h4_set_baudrate;
    }
    return (const hci_transport_t *) hci_transport_h4;
}