/**
 * 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 2048
#define ENABLE_WRITE 0x5c

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

static char TAG[] = "SSD1351";

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

// Functions are not declared to minimize # of lines

static void WriteByte(struct GDS_Device* Device, uint8_t Data) { Device->WriteData(Device, &Data, 1); }

static void SetColumnAddress(struct GDS_Device* Device, uint8_t Start, uint8_t End) {
    Device->WriteCommand(Device, 0x15);
    WriteByte(Device, Start);
    WriteByte(Device, End);
}
static void SetRowAddress(struct GDS_Device* Device, uint8_t Start, uint8_t End) {
    Device->WriteCommand(Device, 0x75);
    WriteByte(Device, Start);
    WriteByte(Device, End);
}

static void Update16(struct GDS_Device* Device) {
    struct PrivateSpace* Private = (struct PrivateSpace*)Device->Private;

#ifdef SHADOW_BUFFER
    uint32_t *optr = (uint32_t*)Private->Shadowbuffer, *iptr = (uint32_t*)Device->Framebuffer;
    int FirstCol = Device->Width / 2, LastCol = 0, FirstRow = -1, LastRow = 0;

    for(int r = 0; r < Device->Height; r++) {
        // look for change and update shadow (cheap optimization = width is always a multiple of 2)
        for(int c = 0; c < Device->Width / 2; c++, iptr++, optr++) {
            if(*optr != *iptr) {
                *optr = *iptr;
                if(c < FirstCol) FirstCol = c;
                if(c > LastCol) LastCol = c;
                if(FirstRow < 0) FirstRow = r;
                LastRow = r;
            }
        }

        // wait for a large enough window - careful that window size might increase by more than a line at once !
        if(FirstRow < 0 || ((LastCol - FirstCol + 1) * (r - FirstRow + 1) * 4 < PAGE_BLOCK && r != Device->Height - 1)) continue;

        FirstCol *= 2;
        LastCol = LastCol * 2 + 1;
        SetRowAddress(Device, FirstRow, LastRow);
        SetColumnAddress(Device, FirstCol, LastCol);
        Device->WriteCommand(Device, ENABLE_WRITE);

        int ChunkSize = (LastCol - FirstCol + 1) * 2;

        // own use of IRAM has not proven to be much better than letting SPI do its copy
        if(Private->iRAM) {
            uint8_t* optr = Private->iRAM;
            for(int i = FirstRow; i <= LastRow; i++) {
                memcpy(optr, Private->Shadowbuffer + (i * Device->Width + FirstCol) * 2, ChunkSize);
                optr += ChunkSize;
                if(optr - Private->iRAM < PAGE_BLOCK && i < LastRow) continue;
                Device->WriteData(Device, Private->iRAM, optr - Private->iRAM);
                optr = Private->iRAM;
            }
        } else
            for(int i = FirstRow; i <= LastRow; i++) {
                Device->WriteData(Device, Private->Shadowbuffer + (i * Device->Width + FirstCol) * 2, ChunkSize);
            }

        FirstCol = Device->Width / 2;
        LastCol = 0;
        FirstRow = -1;
    }
#else
    // always update by full lines
    SetColumnAddress(Device, 0, Device->Width - 1);

    for(int r = 0; r < Device->Height; r += min(Private->PageSize, Device->Height - r)) {
        int Height = min(Private->PageSize, Device->Height - r);

        SetRowAddress(Device, r, r + Height - 1);
        Device->WriteCommand(Device, ENABLE_WRITE);

        if(Private->iRAM) {
            memcpy(Private->iRAM, Device->Framebuffer + r * Device->Width * 2, Height * Device->Width * 2);
            Device->WriteData(Device, Private->iRAM, Height * Device->Width * 2);
        } else {
            Device->WriteData(Device, Device->Framebuffer + r * Device->Width * 2, Height * Device->Width * 2);
        }
    }
#endif
}

static void Update24(struct GDS_Device* Device) {
    struct PrivateSpace* Private = (struct PrivateSpace*)Device->Private;
    int FirstCol = (Device->Width * 3) / 2, LastCol = 0, FirstRow = -1, LastRow = 0;

#ifdef SHADOW_BUFFER
    uint16_t *optr = (uint16_t*)Private->Shadowbuffer, *iptr = (uint16_t*)Device->Framebuffer;

    for(int r = 0; r < Device->Height; r++) {
        // look for change and update shadow (cheap optimization = width always / by 2)
        for(int c = 0; c < (Device->Width * 3) / 2; c++, optr++, iptr++) {
            if(*optr != *iptr) {
                *optr = *iptr;
                if(c < FirstCol) FirstCol = c;
                if(c > LastCol) LastCol = c;
                if(FirstRow < 0) FirstRow = r;
                LastRow = r;
            }
        }

        // do we have enough to send (cols are divided by 3/2)
        if(FirstRow < 0 || ((((LastCol - FirstCol + 1) * 2 + 3 - 1) / 3) * (r - FirstRow + 1) * 3 < PAGE_BLOCK && r != Device->Height - 1)) continue;

        FirstCol = (FirstCol * 2) / 3;
        LastCol = (LastCol * 2 + 1) / 3;
        SetRowAddress(Device, FirstRow, LastRow);
        SetColumnAddress(Device, FirstCol, LastCol);
        Device->WriteCommand(Device, ENABLE_WRITE);

        int ChunkSize = (LastCol - FirstCol + 1) * 3;

        // own use of IRAM has not proven to be much better than letting SPI do its copy
        if(Private->iRAM) {
            uint8_t* optr = Private->iRAM;
            for(int i = FirstRow; i <= LastRow; i++) {
                memcpy(optr, Private->Shadowbuffer + (i * Device->Width + FirstCol) * 3, ChunkSize);
                optr += ChunkSize;
                if(optr - Private->iRAM < PAGE_BLOCK && i < LastRow) continue;
                Device->WriteData(Device, Private->iRAM, optr - Private->iRAM);
                optr = Private->iRAM;
            }
        } else
            for(int i = FirstRow; i <= LastRow; i++) {
                Device->WriteData(Device, Private->Shadowbuffer + (i * Device->Width + FirstCol) * 3, ChunkSize);
            }

        FirstCol = (Device->Width * 3) / 2;
        LastCol = 0;
        FirstRow = -1;
    }
#else
    // always update by full lines
    SetColumnAddress(Device, 0, Device->Width - 1);

    for(int r = 0; r < Device->Height; r += min(Private->PageSize, Device->Height - r)) {
        int Height = min(Private->PageSize, Device->Height - r);

        SetRowAddress(Device, r, r + Height - 1);
        Device->WriteCommand(Device, ENABLE_WRITE);

        if(Private->iRAM) {
            memcpy(Private->iRAM, Device->Framebuffer + r * Device->Width * 3, Height * Device->Width * 3);
            Device->WriteData(Device, Private->iRAM, Height * Device->Width * 3);
        } else {
            Device->WriteData(Device, Device->Framebuffer + r * Device->Width * 3, Height * Device->Width * 3);
        }
    }
#endif
}

static void SetLayout(struct GDS_Device* Device, struct GDS_Layout* Layout) {
    struct PrivateSpace* Private = (struct PrivateSpace*)Device->Private;
    Private->ReMap = Layout->HFlip ? (Private->ReMap & ~(1 << 1)) : (Private->ReMap | (1 << 1));
    Private->ReMap = Layout->VFlip ? (Private->ReMap | (1 << 4)) : (Private->ReMap & ~(1 << 4));
    Device->WriteCommand(Device, 0xA0);
    WriteByte(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, 0xC7);
    WriteByte(Device, Contrast >> 4);
}

static bool Init(struct GDS_Device* Device) {
    struct PrivateSpace* Private = (struct PrivateSpace*)Device->Private;
    int Depth = (Device->Depth + 8 - 1) / 8;

    Private->PageSize = min(8, PAGE_BLOCK / (Device->Width * Depth));

#ifdef SHADOW_BUFFER
    Private->Shadowbuffer = malloc(Device->FramebufferSize);
    memset(Private->Shadowbuffer, 0xFF, Device->FramebufferSize);
#endif
#ifdef USE_IRAM
    Private->iRAM = heap_caps_malloc((Private->PageSize + 1) * Device->Width * Depth, MALLOC_CAP_INTERNAL | MALLOC_CAP_DMA);
#endif

    ESP_LOGI(TAG, "SSD1351 with bit depth %u, page %u, iRAM %p", Device->Depth, Private->PageSize, Private->iRAM);

    // unlock (specially 0xA2)
    Device->WriteCommand(Device, 0xFD);
    WriteByte(Device, 0xB1);

    // set clocks
    /*
    Device->WriteCommand( Device, 0xB3 );
    WriteByte( Device, ( 0x08 << 4 ) | 0x00 );
	*/

    // need to be off and disable display RAM
    Device->DisplayOff(Device);

    // need COM split (5)
    Private->ReMap = (1 << 5);

    // Display Offset
    Device->WriteCommand(Device, 0xA2);
    WriteByte(Device, 0x00);

    // Display Start Line
    Device->WriteCommand(Device, 0xA1);
    WriteByte(Device, 0x00);

    // set flip modes & contrast
    Device->SetContrast(Device, 0x7F);
    struct GDS_Layout Layout = {};
    Device->SetLayout(Device, &Layout);

    // set Adressing Mode Horizontal
    Private->ReMap |= (0 << 2);
    // set screen depth (16/18)
    if(Device->Depth == 24) Private->ReMap |= (0x02 << 6);
    // write ReMap byte
    Device->WriteCommand(Device, 0xA0);
    WriteByte(Device, Private->ReMap);

    // no Display Inversion
    Device->WriteCommand(Device, 0xA6);

    // gone with the wind
    Device->DisplayOn(Device);
    Device->Update(Device);

    return true;
}

static const struct GDS_Device SSD1351 = {
    .DisplayOn = DisplayOn,
    .DisplayOff = DisplayOff,
    .SetContrast = SetContrast,
    .SetLayout = SetLayout,
    .Update = Update16,
    .Init = Init,
    .Mode = GDS_RGB565,
    .Depth = 16,
};

struct GDS_Device* SSD1351_Detect(sys_display_config* Driver, struct GDS_Device* Device) {
    int Depth;

    if(Driver->common.driver != sys_display_drivers_SSD1351) return NULL;

    if(!Device) Device = calloc(1, sizeof(struct GDS_Device));

    *Device = SSD1351;
    Depth = Driver->common.bitDepth != 0 ? Driver->common.bitDepth : 18;

    if(Depth == 18) {
        Device->Mode = GDS_RGB666;
        Device->Depth = 24;
        Device->Update = Update24;
    }

    return Device;
}