#include <pic16f689.h>
#include <stdint.h>
#include <stdbool.h>
#include "delays.h"
#include "configuration.h"
#include "tickcounter.h"
#include "gprs_config.h"

// This is file-scope to conserve RAM.
static uint16_t start;

// Wait for string in input, up to timeout seconds.
bool gsm_expect(const char *expected, uint8_t timeout)
{   
    uint8_t pos = 0;
    start = get_ticks16();
    
    while (expected[pos])
    {
        while (!PIR1bits.RCIF)
        {
            if (get_ticks16() - start > timeout)
                return false;
        }
        
        if (expected[pos++] != (char)RCREG)
            pos = 0; // Mismatch, restart from beginning
    }
    
    return true;
}

void sleep(uint8_t seconds)
{
    start = get_ticks16();
    while (get_ticks16() - start < seconds);
}

static void gsm_flush()
{
    RCSTAbits.CREN = 0;
    __asm
    banksel RCREG
    movf RCREG, W
    movf RCREG, W
    __endasm;
    RCSTAbits.CREN = 1;
}

// Write a string to GSM
bool gsm_puts(const char *p)
{
    while (*p)
    {
        while (!PIR1bits.TXIF);
        TXREG = *p++;
    }
    gsm_flush(); // Clear overflow error due to echo
    return true;
}

// Start SMS sending
bool gsm_startsms()
{
    gsm_puts("AT+CMGF=1\r\n");
    if (!gsm_expect("OK", 5))
        return false;
        
    sleep(5);
    
    gsm_puts("AT+CMGS=\"" SMS_NUMBER "\"\r\n");
    return gsm_expect(">", 15);
}

bool gsm_endsms()
{
    gsm_puts("\r\n\x1a");
    return gsm_expect("OK", 15);
}

char GPRS_BATTERY_LEVEL[6];
static bool gsm_batterylevel()
{
    uint8_t pos = 0;
    start = get_ticks16();
    GPRS_BATTERY_LEVEL[0] = 0;
    
    gsm_puts("AT+CBC\r\n");
    if (!gsm_expect("\n+CBC: ", 5)) return false;

    do {
        while (!PIR1bits.RCIF)
        {
            if (get_ticks16() - start > 5) return false;
        }
        GPRS_BATTERY_LEVEL[pos++] = RCREG;
    } while (GPRS_BATTERY_LEVEL[pos - 1] != '\n' && pos < 6);
    GPRS_BATTERY_LEVEL[pos - 1] = 0;
    return gsm_expect("OK", 5);
}

char GPRS_CELL_ID[9];
// Wait for GSM connection and record cell id
static bool gsm_wait_connection()
{
    uint8_t i, byte;
    
    GPRS_CELL_ID[0] = 0;
    gsm_puts("AT+CREG=2\r\n");
    
    i = 0;
    while (!(gsm_puts("AT+CREG?\r\n") && gsm_expect("+CREG: 2, 1", 5)))
    {
        if (i++ > 30)
            return false;
    }
    
    i = 0;
    while (i < 8)
    {
        while (!PIR1bits.RCIF)
        {
            if (get_ticks16() - start > 5) return false;
        }
        
        byte = RCREG;
        
        if (byte >= '0')
            GPRS_CELL_ID[i++] = byte;
        else if (byte == '\n')
            break;
    }
    GPRS_CELL_ID[i] = 0;
    return true;
}

bool gprs_dial()
{
    uint8_t retries = 0;
    
    clrwdt();
    
    // Send the power-on pulse
    RCSTAbits.SPEN = 0;
    TRISBbits.TRISB7 = 0;
    GSM_TX = 0;
    delay_100ms(2);
    RCSTAbits.SPEN = 1;
    TRISBbits.TRISB7 = 1;
    
    // Assert CTS
    TRISCbits.TRISC7 = 0;
    GSM_CTS = 0;
    
    // Give the module time to wake up
    sleep(2);
    
    // Perform auto-baud initialization
    retries = 0;
    while (!(gsm_puts("AT\r\n") && gsm_expect("OK", 5)))
    {
        if (retries++ > 5)
            return false;
    }
    
    // Wait for GSM network connection
    gsm_wait_connection();
    
    // Get battery level information
    gsm_batterylevel();
    
    // Program the GPRS destination info
    if (gsm_puts("AT+CGDCONT=" GPRS_APN "\r\n") && gsm_expect("OK", FAST_TIMEOUT) &&
        gsm_puts("AT$DESTINFO=" GPRS_PROXY "\r\n") && gsm_expect("OK", FAST_TIMEOUT))
    {
        return true;
    }
    else
    {
        return false;
    }
}

// To post data, we use up to 255 byte HTTP requests
static uint8_t request_length;
bool gprs_startrequest()
{
    uint8_t tries = 0;
    do {
        if (tries++ > 3) return false;
        gsm_puts("AT\r\n");
    } while (!gsm_expect("OK", FAST_TIMEOUT));
    
    gsm_puts("ATD*97#\r\n");
    if (!gsm_expect("OK", GPRS_TIMEOUT)) return false;
    
    gsm_puts("POST " TRACKER_URL " HTTP/1.0\r\n");
    gsm_puts("Content-Length: 255\r\n\r\n");
    
    request_length = 255;
    
    return true;
}

// Put character
void gprs_putcrequest(char b)
{
    while (!PIR1bits.TXIF);
    TXREG = b;
    request_length--;
}

// Put string
void gprs_putsrequest(const char *p)
{
    while (*p)
    {
        while (!PIR1bits.TXIF);
        TXREG = *p++;
        request_length--;
    }
}

// Put hex value
void gprs_puthrequest(uint32_t w)
{
    uint8_t digit, pos;
    for (pos = 0; pos < 8; pos++)
    {
        digit = (w >> 28) & 15;
        if (digit >= 10)
            gprs_putcrequest('A' - 10 + digit);
        else
            gprs_putcrequest('0' + digit);
        
        w <<= 4;
    }
}

bool gprs_endrequest()
{
    while (request_length)
    {
        gprs_putcrequest(' ');
    }
    gsm_puts("\r\n");
    return gsm_expect("HTTP/1.0 200", GPRS_TIMEOUT);
}

void gprs_shutdown()
{
    gsm_puts("AT$POWEROFF\r\n");
    sleep(2);
    gsm_puts("AT$POWEROFF\r\n");
    sleep(2);
    TRISCbits.TRISC7 = 1;
}