/***************************************************************************
 *   Copyright (C) 2020 by Federico Amedeo Izzo IU2NUO,                    *
 *                         Niccolò Izzo IU2KIN                             *
 *                         Frederik Saraci IU2NRO                          *
 *                         Silvano Seva IU2KWO                             *
 *                                                                         *
 *   This program 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 3 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program 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 this program; if not, see <http://www.gnu.org/licenses/>   *
 ***************************************************************************/

#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <os.h>
#include "gpio.h"
#include "display.h"
#include "delays.h"
#include "hwconfig.h"

/*
 * LCD framebuffer, allocated on the heap by display_init().
 * Pixel format is black and white, one bit per pixel
 */
static uint8_t *frameBuffer;

void sendByteToController(uint8_t value)
{
    for(uint8_t i = 0; i < 8; i++)
    {
        gpio_clearPin(LCD_CLK);

        if(value & 0x80)
        {
            gpio_setPin(LCD_DAT);
        }
        else
        {
            gpio_clearPin(LCD_DAT);
        }

        gpio_setPin(LCD_CLK);
        value <<= 1;
    }
}

void display_init()
{
    /* Framebuffer size, in bytes */
    unsigned int fbSize = (SCREEN_HEIGHT * SCREEN_WIDTH)/8;
    if((fbSize * 8) < (SCREEN_HEIGHT * SCREEN_WIDTH)) fbSize += 1; /* Compensate for eventual truncation error in division */
    fbSize *= sizeof(uint8_t);

    /* Allocate framebuffer */
    frameBuffer = (uint8_t *) malloc(fbSize);
    if(frameBuffer == NULL)
    {
        printf("*** LCD ERROR: cannot allocate framebuffer! ***");
        return;
    }

    /* Clear framebuffer, setting all pixels to 0x00 makes the screen white */
    memset(frameBuffer, 0x00, fbSize);

    gpio_setMode(LCD_CS,  OUTPUT);
    gpio_setMode(LCD_RST, OUTPUT);
    gpio_setMode(LCD_RS,  OUTPUT);
    gpio_setMode(LCD_CLK, OUTPUT);
    gpio_setMode(LCD_DAT, OUTPUT);

    gpio_setPin(LCD_CS);
    gpio_clearPin(LCD_RS);
    gpio_clearPin(LCD_CLK);
    gpio_clearPin(LCD_DAT);

    gpio_clearPin(LCD_RST);     /* Reset controller                */
    delayMs(1);
    gpio_setPin(LCD_RST);
    delayMs(5);

    gpio_clearPin(LCD_CS);

    gpio_clearPin(LCD_RS);      /* RS low -> command mode          */
//     sendByteToController(0xE2); /* System Reset                    */
    sendByteToController(0x2F); /* Voltage Follower On             */
    sendByteToController(0x81); /* Set Electronic Volume = 15      */
    sendByteToController(0x3F); /* Full contrast                   */
    sendByteToController(0xA2); /* Set Bias = 1/9                  */
    sendByteToController(0xA1); /* A0 Set SEG Direction            */
    sendByteToController(0xC0); /* Set COM Direction               */
    sendByteToController(0xA4); /* White background, black pixels  */
    sendByteToController(0xAF); /* Set Display Enable              */
}

void display_terminate()
{
    if(frameBuffer != NULL)
    {
        free(frameBuffer);
    }
}

void display_renderRows(uint8_t startRow, uint8_t endRow)
{
    if(frameBuffer == NULL) return;

    uint8_t *rowPos = (frameBuffer + startRow * SCREEN_WIDTH);

    for(uint8_t row = startRow; row < endRow; row++)
    {
        gpio_clearPin(LCD_RS);            /* RS low -> command mode */
        sendByteToController(0xB0 | row); /* Set Y position         */
        sendByteToController(0x10);       /* Set X position         */
        sendByteToController(0x04);

        gpio_setPin(LCD_RS);              /* RS high -> data mode   */

        for(size_t x = 0; x < SCREEN_WIDTH; x++)
        {
            sendByteToController(*rowPos);
            rowPos++;
        }
    }
}

void display_render()
{
    display_renderRows(0, SCREEN_HEIGHT);
}

bool display_renderingInProgress()
{
    /*
     * Rendering is in progress if display's chip select is low or a DMA
     * transfer is in progress.
     */
}

void *display_getFrameBuffer()
{
    return (void *)(frameBuffer);
}