/**
 * Copyright (c) 2017-2018 Tara Keeling
 *				 2020 Philippe G.
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include <esp_heap_caps.h>
#include <esp_log.h>

#include "gds.h"
#include "gds_private.h"

#define SHADOW_BUFFER
#define USE_IRAM
#define PAGE_BLOCK	1024

#define min(a,b) (((a) < (b)) ? (a) : (b))

static char TAG[] = "SSD132x";

enum { SSD1326, SSD1327 };

struct PrivateSpace {
	uint8_t *iRAM, *Shadowbuffer;
	uint8_t ReMap, PageSize;
	uint8_t Model;
};

static const unsigned char BitReverseTable256[] = 
{
  0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0, 
  0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, 
  0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, 
  0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, 
  0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, 
  0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
  0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, 
  0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,
  0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
  0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9, 
  0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,
  0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
  0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3, 
  0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,
  0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, 
  0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
};

// Functions are not declared to minimize # of lines

static void SetColumnAddress( struct GDS_Device* Device, uint8_t Start, uint8_t End ) {
	Device->WriteCommand( Device, 0x15 );
	Device->WriteCommand( Device, Start );
	Device->WriteCommand( Device, End );
}
static void SetRowAddress( struct GDS_Device* Device, uint8_t Start, uint8_t End ) {
	// can be by row, not by page (see Update Optimization)
	Device->WriteCommand( Device, 0x75 );
	Device->WriteCommand( Device, Start );
	Device->WriteCommand( Device, End );
}

static void Update4( struct GDS_Device* Device ) {
	struct PrivateSpace *Private = (struct PrivateSpace*) Device->Private;
		
	// always update by full lines
	SetColumnAddress( Device, 0, Device->Width / 2 - 1);
	
#ifdef SHADOW_BUFFER
	uint16_t *optr = (uint16_t*) Private->Shadowbuffer, *iptr = (uint16_t*) Device->Framebuffer;
	bool dirty = false;
	
	for (int r = 0, page = 0; r < Device->Height; r++) {
		// look for change and update shadow (cheap optimization = width always / by 2)
		for (int c = Device->Width / 2 / 2; --c >= 0;) {
			if (*optr != *iptr) {
				dirty = true;
				*optr = *iptr;
			}
			iptr++; optr++;
		}
		
		// one line done, check for page boundary
		if (++page == Private->PageSize) {
			if (dirty) {
				SetRowAddress( Device, r - page + 1, r );
				// own use of IRAM has not proven to be much better than letting SPI do its copy
				if (Private->iRAM) {
					memcpy(Private->iRAM, Private->Shadowbuffer + (r - page + 1) * Device->Width / 2, page * Device->Width / 2 );
					Device->WriteData( Device, Private->iRAM, Device->Width * page / 2 );
				} else	{
					Device->WriteData( Device, Private->Shadowbuffer + (r - page + 1) * Device->Width / 2, page * Device->Width / 2 );					
				}	
				dirty = false;
			}	
			page = 0;
		}	
	}	
#else
	for (int r = 0; r < Device->Height; r += Private->PageSize) {
		SetRowAddress( Device, r, r + Private->PageSize - 1 );
		if (Private->iRAM) {
			memcpy(Private->iRAM, Device->Framebuffer + r * Device->Width / 2, Private->PageSize * Device->Width / 2 );
			Device->WriteData( Device, Private->iRAM, Private->PageSize * Device->Width / 2 );
		} else	{
			Device->WriteData( Device, Device->Framebuffer + r * Device->Width / 2, Private->PageSize * Device->Width / 2 );
		}	
	}	
#endif	
}

/* 
 We have to make a choice here: either we go by row one by one and send lots of 
 small packets on the serial interface or we do a page of N rows once at least
 a change has been detected. So far, choice is to go one-by-one
*/ 
static void Update1( struct GDS_Device* Device ) {
#ifdef SHADOW_BUFFER
	struct PrivateSpace *Private = (struct PrivateSpace*) Device->Private;
	// not sure the compiler does not have to redo all calculation in for loops, so local it is
	int width = Device->Width / 8, rows = Device->Height;
	uint8_t *optr = Private->Shadowbuffer, *iptr = Device->Framebuffer;
	int CurrentRow = -1, FirstCol = -1, LastCol = -1;
	
	// by row, find first and last columns that have been updated
	for (int r = 0; r < rows; r++) {
		uint8_t first = 0, last;	
		for (int c = 0; c < width; c++) {
			if (*iptr != *optr) {
				if (!first) first = c + 1;
				last = c ;
			}	
			*optr++ = *iptr++;
		}
		
		// now update the display by "byte rows"
		if (first--) {
			// only set column when useful, saves a fair bit of CPU
			if (first > FirstCol && first <= FirstCol + 4 && last < LastCol && last >= LastCol - 4) {
				first = FirstCol;
				last = LastCol;
			} else {	
				SetColumnAddress( Device, first, last );
				FirstCol = first;
				LastCol = last;
			}
			
			// Set row only when needed, otherwise let auto-increment work
			if (r != CurrentRow) SetRowAddress( Device, r, Device->Height - 1 );
			CurrentRow = r + 1;
			
			// actual write
			Device->WriteData( Device, Private->Shadowbuffer + r*width + first, last - first + 1 );
		}
	}	
#else	
	// automatic counter and end Row/Column
	SetColumnAddress( Device, 0, Device->Width / 8 - 1);
	SetRowAddress( Device, 0, Device->Height - 1);
	Device->WriteData( Device, Device->Framebuffer, Device->FramebufferSize );
#endif	
}

// in 1 bit mode, SSD1326 has a different memory map than SSD1306 and SH1106
static void IRAM_ATTR _DrawPixel1Fast( struct GDS_Device* Device, int X, int Y, int Color ) {
    uint32_t XBit = ( X & 0x07 );
    uint8_t* FBOffset = Device->Framebuffer + ( ( Y * Device->Width + X ) >> 3 );

    if ( Color == GDS_COLOR_XOR ) {
        *FBOffset ^= BIT( 7 - XBit );
    } else {
		// we might be able to save the 7-Xbit using BitRemap (A0 bit 2)
        *FBOffset = ( Color == GDS_COLOR_BLACK ) ?  *FBOffset & ~BIT( XBit ) : *FBOffset | BIT( XBit );
    }
}

static void ClearWindow( struct GDS_Device* Device, int x1, int y1, int x2, int y2, int Color ) {
	uint8_t _Color = Color == GDS_COLOR_BLACK ? 0: 0xff;
	int Width = Device->Width >> 3;
	uint8_t *optr = Device->Framebuffer;
	
	for (int r = y1; r <= y2; r++) {
		int c = x1;
		// for a row that is not on a boundary, not column opt can be done, so handle all columns on that line
		while (c & 0x07 && c <= x2) _DrawPixel1Fast( Device, c++, r, Color );
		// at this point we are aligned on column boundary
		int chunk = (x2 - c + 1) >> 3;
		memset(optr + Width * r + (c >> 3), _Color, chunk );
		c += chunk * 8;
		while (c <= x2) _DrawPixel1Fast( Device, c++, r, Color );
	}
}

static void DrawBitmapCBR(struct GDS_Device* Device, uint8_t *Data, int Width, int Height, int Color ) {
	if (!Height) Height = Device->Height;
	if (!Width) Width = Device->Width;
	int DWidth = Device->Width >> 3;
	
	// Two consecutive bits of source data are split over two different bytes of framebuffer
	for (int c = 0; c < Width; c++) {
		uint8_t shift = c & 0x07, bit = ~(1 << shift);
		uint8_t *optr = Device->Framebuffer + (c >> 3);
		
		// we need to linearize code to let compiler better optimize
		for (int r = Height >> 3; --r >= 0;) {
			uint8_t Byte = BitReverseTable256[*Data++];
			*optr = (*optr & bit) | ((Byte & 0x01) << shift); optr += DWidth; Byte >>= 1;
			*optr = (*optr & bit) | ((Byte & 0x01) << shift); optr += DWidth; Byte >>= 1;
			*optr = (*optr & bit) | ((Byte & 0x01) << shift); optr += DWidth; Byte >>= 1;
			*optr = (*optr & bit) | ((Byte & 0x01) << shift); optr += DWidth; Byte >>= 1;
			*optr = (*optr & bit) | ((Byte & 0x01) << shift); optr += DWidth; Byte >>= 1;
			*optr = (*optr & bit) | ((Byte & 0x01) << shift); optr += DWidth; Byte >>= 1;
			*optr = (*optr & bit) | ((Byte & 0x01) << shift); optr += DWidth; Byte >>= 1;
			*optr = (*optr & bit) | ((Byte & 0x01) << shift); optr += DWidth;
		}	
	}
}

static void SetLayout( struct GDS_Device* Device, struct GDS_Layout *Layout ) { 
	struct PrivateSpace *Private = (struct PrivateSpace*) Device->Private;
	if (Private->Model == SSD1326) {
		Private->ReMap = Layout->HFlip ? (Private->ReMap | ((1 << 0) | (1 << 2))) : (Private->ReMap & ~((1 << 0) | (1 << 2)));
		Private->ReMap = Layout->HFlip ? (Private->ReMap | (1 << 1)) : (Private->ReMap & ~(1 << 1));		
	} else {
		Private->ReMap = Layout->VFlip ? (Private->ReMap | ((1 << 0) | (1 << 1))) : (Private->ReMap & ~((1 << 0) | (1 << 1)));
		Private->ReMap = Layout->VFlip ? (Private->ReMap | (1 << 4)) : (Private->ReMap & ~(1 << 4));
	}	
	Device->WriteCommand( Device, 0xA0 );
	Device->WriteCommand( Device, Private->ReMap );
    Device->WriteCommand( Device, Layout->Invert ? 0xA7 : 0xA6 );	
}	

static void DisplayOn( struct GDS_Device* Device ) { Device->WriteCommand( Device, 0xAF ); }
static void DisplayOff( struct GDS_Device* Device ) { Device->WriteCommand( Device, 0xAE ); }

static void SetContrast( struct GDS_Device* Device, uint8_t Contrast ) {
    Device->WriteCommand( Device, 0x81 );
    Device->WriteCommand( Device, Contrast );
}

static bool Init( struct GDS_Device* Device ) {
	struct PrivateSpace *Private = (struct PrivateSpace*) Device->Private;
	
	// find a page size that is not too small is an integer of height
	Private->PageSize = min(8, PAGE_BLOCK / (Device->Width / 2));
	while (Private->PageSize && Device->Height != (Device->Height / Private->PageSize) * Private->PageSize) Private->PageSize--;
	
#ifdef SHADOW_BUFFER	
#ifdef USE_IRAM
	if (Device->IF == GDS_IF_SPI) {
		if (Device->Depth == 1) {
			Private->Shadowbuffer = heap_caps_malloc( Device->FramebufferSize, MALLOC_CAP_INTERNAL | MALLOC_CAP_DMA );
		} else {
			Private->Shadowbuffer = malloc( Device->FramebufferSize );	
			Private->iRAM = heap_caps_malloc( Private->PageSize * Device->Width / 2, MALLOC_CAP_INTERNAL | MALLOC_CAP_DMA );
		}	
	} else
#endif
	Private->Shadowbuffer = malloc( Device->FramebufferSize );	
	memset(Private->Shadowbuffer, 0xFF, Device->FramebufferSize);
#else
#ifdef USE_IRAM	
	if (Device->Depth == 4 && Device->IF == GDS_IF_SPI) Private->iRAM = heap_caps_malloc( Private->PageSize * Device->Width / 2, MALLOC_CAP_INTERNAL | MALLOC_CAP_DMA );
#endif	
#endif

	ESP_LOGI(TAG, "SSD1326/7 with bit depth %u, page %u, iRAM %p", Device->Depth, Private->PageSize, Private->iRAM);
			
	// need to be off and disable display RAM
	Device->DisplayOff( Device );
    Device->WriteCommand( Device, 0xA5 );
	
	// need COM split (6)
	Private->ReMap = 1 << 6;
	// MUX Ratio
    Device->WriteCommand( Device, 0xA8 );
    Device->WriteCommand( Device, Device->Height - 1);
	// Display Offset
    Device->WriteCommand( Device, 0xA2 );
    Device->WriteCommand( Device, 0 );
	// Display Start Line
    Device->WriteCommand( Device, 0xA1 );
	Device->WriteCommand( Device, 0x00 );
	Device->SetContrast( Device, 0x7F );
	// set flip modes
	struct GDS_Layout Layout = { };
	Device->SetLayout( Device, &Layout );
	// no Display Inversion
    Device->WriteCommand( Device, 0xA6 );
	// set Clocks
    Device->WriteCommand( Device, 0xB3 );
    Device->WriteCommand( Device, ( 0x08 << 4 ) | 0x00 );
	// set Adressing Mode Horizontal
	Private->ReMap |= (0 << 2);
	// set monotchrome mode if required
	if (Device->Depth == 1) Private->ReMap |= (1 << 4);
	// write ReMap byte
	Device->WriteCommand( Device, 0xA0 );
	Device->WriteCommand( Device, Private->ReMap );		
		
	// gone with the wind
	Device->WriteCommand( Device, 0xA4 );
	Device->DisplayOn( Device );
	Device->Update( Device );
	
	return true;
}	

static const struct GDS_Device SSD132x = {
	.DisplayOn = DisplayOn, .DisplayOff = DisplayOff, .SetContrast = SetContrast,
	.SetLayout = SetLayout,
	.Update = Update4, .Init = Init,
	.Mode = GDS_GRAYSCALE, .Depth = 4,
};	

struct GDS_Device* SSD132x_Detect(char *Driver, struct GDS_Device* Device) {
	uint8_t Model;
	int Depth;
		
	if (strcasestr(Driver, "SSD1326")) Model = SSD1326;
	else if (strcasestr(Driver, "SSD1327")) Model = SSD1327;
	else return NULL;
	
	if (!Device) Device = calloc(1, sizeof(struct GDS_Device));
	
	*Device = SSD132x;	
	struct PrivateSpace *Private = (struct PrivateSpace*) Device->Private;
	Private->Model = Model;
		
	sscanf(Driver, "%*[^:]:%u", &Depth);
		
	if (Model == SSD1326 && Depth == 1) {
		Device->Update = Update1;
		Device->DrawPixelFast = _DrawPixel1Fast;
		Device->DrawBitmapCBR = DrawBitmapCBR;
		Device->ClearWindow = ClearWindow;
		Device->Depth = 1;		
		Device->Mode = GDS_MONO;
#if !defined SHADOW_BUFFER && defined USE_IRAM	
		Device->Alloc = GDS_ALLOC_IRAM_SPI;
#endif	
	}
	
	return Device;
}