// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @defgroup graphics Graphics
 *
 * @{
 */

/**
 * @file
 * @brief  Graphics drawing library
 */
#include <gfx/gfx.h>

#include <assert.h>
#include <err.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <zircon/compiler.h>
#include <zircon/syscalls.h>

#define TRACE 0

#if TRACE
#define xprintf(fmt...) printf(fmt)
#else
#define xprintf(fmt...) \
    do {                \
    } while (0)
#endif

// Convert a 32bit ARGB image to its respective gamma corrected grayscale value.
static uint32_t ARGB8888_to_Luma(uint32_t in) {
    uint8_t out;

    uint32_t blue = (in & 0xFF) * 74;
    uint32_t green = ((in >> 8) & 0xFF) * 732;
    uint32_t red = ((in >> 16) & 0xFF) * 218;

    uint32_t intensity = red + blue + green;

    out = (intensity >> 10) & 0xFF;

    return out;
}

static uint32_t ARGB8888_to_RGB565(uint32_t in) {
    uint16_t out;

    out = (in >> 3) & 0x1f;           // b
    out |= ((in >> 10) & 0x3f) << 5;  // g
    out |= ((in >> 19) & 0x1f) << 11; // r

    return out;
}

static uint32_t ARGB8888_to_RGB332(uint32_t in) {
    uint8_t out = 0;

    out = (in >> 6) & 0x3;          // b
    out |= ((in >> 13) & 0x7) << 2; // g
    out |= ((in >> 21) & 0x7) << 5; // r

    return out;
}

static uint32_t ARGB8888_to_RGB2220(uint32_t in) {
    uint8_t out = 0;

    out = ((in >> 6) & 0x3) << 2;
    out |= ((in >> 14) & 0x3) << 4;
    out |= ((in >> 22) & 0x3) << 6;

    return out;
}

/**
 * @brief  Copy a rectangle of pixels from one part of the display to another.
 */
void gfx_copyrect(gfx_surface* surface, unsigned x, unsigned y, unsigned width, unsigned height, unsigned x2, unsigned y2) {
    // trim
    if (x >= surface->width)
        return;
    if (x2 >= surface->width)
        return;
    if (y >= surface->height)
        return;
    if (y2 >= surface->height)
        return;
    if (width == 0 || height == 0)
        return;

    // clip the width to src or dest
    if (x + width > surface->width)
        width = surface->width - x;
    if (x2 + width > surface->width)
        width = surface->width - x2;

    // clip the height to src or dest
    if (y + height > surface->height)
        height = surface->height - y;
    if (y2 + height > surface->height)
        height = surface->height - y2;

    surface->copyrect(surface, x, y, width, height, x2, y2);
}

void gfx_copylines(gfx_surface* dst, gfx_surface* src, unsigned srcy, unsigned dsty, unsigned height) {
    if ((dst->stride != src->stride) || (dst->format != src->format)) {
        return;
    }
    if ((srcy >= src->height) || ((src->height - srcy) < height)) {
        return;
    }
    if ((dsty >= dst->height) || (dst->height - dsty) < height) {
        return;
    }
    memcpy(dst->ptr + dsty * dst->stride * dst->pixelsize,
           src->ptr + srcy * src->stride * src->pixelsize,
           height * src->stride * src->pixelsize);
}

/**
 * @brief  Fill a rectangle on the screen with a constant color.
 */
void gfx_fillrect(gfx_surface* surface, unsigned x, unsigned y, unsigned width, unsigned height, unsigned color) {
    xprintf("surface %p, x %u y %u w %u h %u c %u\n", surface, x, y, width, height, color);
    // trim
    if (unlikely(x >= surface->width))
        return;
    if (y >= surface->height)
        return;
    if (width == 0 || height == 0)
        return;

    // clip the width
    if (x + width > surface->width)
        width = surface->width - x;

    // clip the height
    if (y + height > surface->height)
        height = surface->height - y;

    surface->fillrect(surface, x, y, width, height, color);
}

/**
 * @brief  Write a single pixel to the screen.
 */
void gfx_putpixel(gfx_surface* surface, unsigned x, unsigned y, unsigned color) {
    if (unlikely(x >= surface->width))
        return;
    if (y >= surface->height)
        return;

    surface->putpixel(surface, x, y, color);
}

static void putpixel16(gfx_surface* surface, unsigned x, unsigned y, unsigned color) {
    uint16_t* dest = &((uint16_t*)surface->ptr)[x + y * surface->stride];

    // colors come in in ARGB 8888 form, flatten them
    *dest = (uint16_t)(surface->translate_color(color));
}

static void putpixel32(gfx_surface* surface, unsigned x, unsigned y, unsigned color) {
    uint32_t* dest = &((uint32_t*)surface->ptr)[x + y * surface->stride];

    *dest = color;
}

static void putpixel8(gfx_surface* surface, unsigned x, unsigned y, unsigned color) {
    uint8_t* dest = &((uint8_t*)surface->ptr)[x + y * surface->stride];

    // colors come in in ARGB 8888 form, flatten them
    *dest = (uint8_t)(surface->translate_color(color));
}

#define MKPUTCHAR(FUNC,TYPE) \
static void FUNC(gfx_surface* surface, const gfx_font* font, unsigned ch, unsigned x, unsigned y, unsigned fg, unsigned bg) { \
    TYPE* dest = &((TYPE*)surface->ptr)[x + y * surface->stride]; \
    const uint16_t* cdata = font->data + ch * font->height; \
    unsigned fw = font->width; \
    for (unsigned i = font->height; i > 0; i--) { \
        uint16_t xdata = *cdata++; \
        for (unsigned j = fw; j > 0; j--) { \
            *dest++ = (xdata & 1) ? fg : bg; \
            xdata >>= 1; \
        } \
        dest += (surface->stride - fw); \
    } \
}

MKPUTCHAR(putchar8, uint8_t)
MKPUTCHAR(putchar16, uint16_t)
MKPUTCHAR(putchar32, uint32_t)

void gfx_putchar(gfx_surface* surface, const gfx_font* font, unsigned ch, unsigned x, unsigned y, unsigned fg, unsigned bg) {
    if (unlikely(ch > 127)) {
        return;
    }
    if (unlikely(x > (surface->width - font->width))) {
        return;
    }
    if (unlikely(y > (surface->height - font->height))) {
        return;
    }
    if (surface->translate_color) {
        fg = surface->translate_color(fg);
        bg = surface->translate_color(bg);
    }
    surface->putchar(surface, font, ch, x, y, fg, bg);
}

static void copyrect8(gfx_surface* surface, unsigned x, unsigned y, unsigned width, unsigned height, unsigned x2, unsigned y2) {
    // copy
    const uint8_t* src = &((const uint8_t*)surface->ptr)[x + y * surface->stride];
    uint8_t* dest = &((uint8_t*)surface->ptr)[x2 + y2 * surface->stride];
    unsigned stride_diff = surface->stride - width;

    if (dest < src) {
        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                *dest = *src;
                dest++;
                src++;
            }
            dest += stride_diff;
            src += stride_diff;
        }
    } else {
        // copy backwards
        src += (height-1) * surface->stride + (width-1);
        dest += (height-1) * surface->stride + (width-1);

        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                *dest = *src;
                dest--;
                src--;
            }
            dest -= stride_diff;
            src -= stride_diff;
        }
    }
}

static void fillrect8(gfx_surface* surface, unsigned x, unsigned y, unsigned width, unsigned height, unsigned color) {
    uint8_t* dest = &((uint8_t*)surface->ptr)[x + y * surface->stride];
    unsigned stride_diff = surface->stride - width;

    uint8_t color8 = (uint8_t)(surface->translate_color(color));

    unsigned i, j;
    for (i = 0; i < height; i++) {
        for (j = 0; j < width; j++) {
            *dest = color8;
            dest++;
        }
        dest += stride_diff;
    }
}

static void copyrect16(gfx_surface* surface, unsigned x, unsigned y, unsigned width, unsigned height, unsigned x2, unsigned y2) {
    // copy
    const uint16_t* src = &((const uint16_t*)surface->ptr)[x + y * surface->stride];
    uint16_t* dest = &((uint16_t*)surface->ptr)[x2 + y2 * surface->stride];
    unsigned stride_diff = surface->stride - width;

    if (dest < src) {
        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                *dest = *src;
                dest++;
                src++;
            }
            dest += stride_diff;
            src += stride_diff;
        }
    } else {
        // copy backwards
        src += (height-1) * surface->stride + (width-1);
        dest += (height-1) * surface->stride + (width-1);

        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                *dest = *src;
                dest--;
                src--;
            }
            dest -= stride_diff;
            src -= stride_diff;
        }
    }
}

static void fillrect16(gfx_surface* surface, unsigned x, unsigned y, unsigned width, unsigned height, unsigned color) {
    uint16_t* dest = &((uint16_t*)surface->ptr)[x + y * surface->stride];
    unsigned stride_diff = surface->stride - width;

    uint16_t color16 = (uint16_t)(surface->translate_color(color));

    unsigned i, j;
    for (i = 0; i < height; i++) {
        for (j = 0; j < width; j++) {
            *dest = color16;
            dest++;
        }
        dest += stride_diff;
    }
}

static void copyrect32(gfx_surface* surface, unsigned x, unsigned y, unsigned width, unsigned height, unsigned x2, unsigned y2) {
    // copy
    const uint32_t* src = &((const uint32_t*)surface->ptr)[x + y * surface->stride];
    uint32_t* dest = &((uint32_t*)surface->ptr)[x2 + y2 * surface->stride];
    unsigned stride_diff = surface->stride - width;

    if (dest < src) {
        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                *dest = *src;
                dest++;
                src++;
            }
            dest += stride_diff;
            src += stride_diff;
        }
    } else {
        // copy backwards
        src += (height-1) * surface->stride + (width-1);
        dest += (height-1) * surface->stride + (width-1);

        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                *dest = *src;
                dest--;
                src--;
            }
            dest -= stride_diff;
            src -= stride_diff;
        }
    }
}

static void fillrect32(gfx_surface* surface, unsigned x, unsigned y, unsigned width, unsigned height, unsigned color) {
    uint32_t* dest = &((uint32_t*)surface->ptr)[x + y * surface->stride];
    unsigned stride_diff = surface->stride - width;

    unsigned i, j;
    for (i = 0; i < height; i++) {
        for (j = 0; j < width; j++) {
            *dest = color;
            dest++;
        }
        dest += stride_diff;
    }
}

void gfx_line(gfx_surface* surface, unsigned x1, unsigned y1, unsigned x2, unsigned y2, unsigned color) {
    if (unlikely(x1 >= surface->width))
        return;
    if (unlikely(x2 >= surface->width))
        return;

    if (y1 >= surface->height)
        return;
    if (y2 >= surface->height)
        return;

    int dx = x2 - x1;
    int dy = y2 - y1;

    int sdx = (0 < dx) - (dx < 0);
    int sdy = (0 < dy) - (dy < 0);

    unsigned dxabs = (dx > 0) ? dx : -dx;
    unsigned dyabs = (dy > 0) ? dy : -dy;

    unsigned x = dyabs >> 1;
    unsigned y = dxabs >> 1;

    unsigned px = x1;
    unsigned py = y1;

    if (dxabs >= dyabs) {
        // mostly horizontal line.
        for (unsigned i = 0; i < dxabs; i++) {
            y += dyabs;
            if (y >= dxabs) {
                y -= dxabs;
                py += sdy;
            }
            px += sdx;
            surface->putpixel(surface, px, py, color);
        }
    } else {
        // mostly vertical line.
        for (unsigned i = 0; i < dyabs; i++) {
            x += dxabs;
            if (x >= dyabs) {
                x -= dyabs;
                px += sdx;
            }
            py += sdy;
            surface->putpixel(surface, px, py, color);
        }
    }
}

uint32_t alpha32_add_ignore_destalpha(uint32_t dest, uint32_t src) {
    uint32_t cdest[3];
    uint32_t csrc[3];

    uint32_t srca;
    uint32_t srcainv;

    srca = (src >> 24) & 0xff;
    if (srca == 0) {
        return dest;
    } else if (srca == 255) {
        return src;
    }
    srca++;
    srcainv = (255 - srca);

    cdest[0] = (dest >> 16) & 0xff;
    cdest[1] = (dest >> 8) & 0xff;
    cdest[2] = (dest >> 0) & 0xff;

    csrc[0] = (src >> 16) & 0xff;
    csrc[1] = (src >> 8) & 0xff;
    csrc[2] = (src >> 0) & 0xff;

    //    if (srca > 0)
    //        printf("s %d %d %d d %d %d %d a %d ai %d\n", csrc[0], csrc[1], csrc[2], cdest[0], cdest[1], cdest[2], srca, srcainv);

    uint32_t cres[3];

    cres[0] = ((csrc[0] * srca) / 256) + ((cdest[0] * srcainv) / 256);
    cres[1] = ((csrc[1] * srca) / 256) + ((cdest[1] * srcainv) / 256);
    cres[2] = ((csrc[2] * srca) / 256) + ((cdest[2] * srcainv) / 256);

    return (srca << 24) | (cres[0] << 16) | (cres[1] << 8) | (cres[2]);
}

/**
 * @brief  Copy pixels from source to dest.
 *
 * Currently does not support alpha channel.
 */
void gfx_surface_blend(struct gfx_surface* target, struct gfx_surface* source, unsigned destx, unsigned desty) {
    gfx_blend(target, source, 0, 0, source->width, source->height, destx, desty);
}

/**
 * @brief  Copy pixels from source to dest.
 */
void gfx_blend(gfx_surface* target, gfx_surface* source, unsigned srcx, unsigned srcy, unsigned width, unsigned height, unsigned destx, unsigned desty) {
    assert(target->format == source->format);

    xprintf("target %p, source %p, srcx %u, srcy %u, width %u, height %u, destx %u, desty %u\n", target, source, srcx, srcy, width, height, destx, desty);

    if (destx >= target->width)
        return;
    if (desty >= target->height)
        return;

    if (srcx >= source->width)
        return;
    if (srcy >= source->height)
        return;

    if (destx + width > target->width)
        width = target->width - destx;
    if (desty + height > target->height)
        height = target->height - desty;

    if (srcx + width > source->width)
        width = source->width - srcx;
    if (srcy + height > source->height)
        height = source->height - srcy;

    // XXX total hack to deal with various blends
    if (source->format == ZX_PIXEL_FORMAT_RGB_565 && target->format == ZX_PIXEL_FORMAT_RGB_565) {
        // 16 bit to 16 bit
        const uint16_t* src = &((const uint16_t*)source->ptr)[srcx + srcy * source->stride];
        uint16_t* dest = &((uint16_t*)target->ptr)[destx + desty * target->stride];
        unsigned dest_stride_diff = target->stride - width;
        unsigned source_stride_diff = source->stride - width;

        xprintf("w %u h %u dstride %u sstride %u\n", width, height, dest_stride_diff, source_stride_diff);

        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                *dest = *src;
                dest++;
                src++;
            }
            dest += dest_stride_diff;
            src += source_stride_diff;
        }
    } else if (source->format == ZX_PIXEL_FORMAT_ARGB_8888 && target->format == ZX_PIXEL_FORMAT_ARGB_8888) {
        // both are 32 bit modes, both alpha
        const uint32_t* src = &((const uint32_t*)source->ptr)[srcx + srcy * source->stride];
        uint32_t* dest = &((uint32_t*)target->ptr)[destx + desty * target->stride];
        unsigned dest_stride_diff = target->stride - width;
        unsigned source_stride_diff = source->stride - width;

        xprintf("w %u h %u dstride %u sstride %u\n", width, height, dest_stride_diff, source_stride_diff);

        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                // XXX ignores destination alpha
                *dest = alpha32_add_ignore_destalpha(*dest, *src);
                dest++;
                src++;
            }
            dest += dest_stride_diff;
            src += source_stride_diff;
        }
    } else if (source->format == ZX_PIXEL_FORMAT_RGB_x888 && target->format == ZX_PIXEL_FORMAT_RGB_x888) {
        // both are 32 bit modes, no alpha
        const uint32_t* src = &((const uint32_t*)source->ptr)[srcx + srcy * source->stride];
        uint32_t* dest = &((uint32_t*)target->ptr)[destx + desty * target->stride];
        unsigned dest_stride_diff = target->stride - width;
        unsigned source_stride_diff = source->stride - width;

        xprintf("w %u h %u dstride %u sstride %u\n", width, height, dest_stride_diff, source_stride_diff);

        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                *dest = *src;
                dest++;
                src++;
            }
            dest += dest_stride_diff;
            src += source_stride_diff;
        }
    } else if (source->format == ZX_PIXEL_FORMAT_MONO_8 && target->format == ZX_PIXEL_FORMAT_MONO_8) {
        // both are 8 bit modes, no alpha
        const uint8_t* src = &((const uint8_t*)source->ptr)[srcx + srcy * source->stride];
        uint8_t* dest = &((uint8_t*)target->ptr)[destx + desty * target->stride];
        unsigned dest_stride_diff = target->stride - width;
        unsigned source_stride_diff = source->stride - width;

        xprintf("w %u h %u dstride %u sstride %u\n", width, height, dest_stride_diff, source_stride_diff);

        unsigned i, j;
        for (i = 0; i < height; i++) {
            for (j = 0; j < width; j++) {
                *dest = *src;
                dest++;
                src++;
            }
            dest += dest_stride_diff;
            src += source_stride_diff;
        }
    } else {
        xprintf("gfx_surface_blend: unimplemented colorspace combination (source %d target %d)\n", source->format, target->format);
        assert(0);
    }
}

/**
 * @brief  Ensure all graphics rendering is sent to display
 */
void gfx_flush(gfx_surface* surface) {
    if (surface->flags & GFX_FLAG_FLUSH_CPU_CACHE)
        zx_cache_flush(surface->ptr, surface->len, ZX_CACHE_FLUSH_DATA);

    if (surface->flush)
        surface->flush(0, surface->height - 1);
}

/**
 * @brief  Ensure that a sub-region of the display is up to date.
 */
void gfx_flush_rows(struct gfx_surface* surface, unsigned start, unsigned end) {
    if (start > end) {
        unsigned temp = start;
        start = end;
        end = temp;
    }

    if (start >= surface->height)
        return;
    if (end >= surface->height)
        end = surface->height - 1;

    if (surface->flags & GFX_FLAG_FLUSH_CPU_CACHE) {
        uint32_t runlen = surface->stride * surface->pixelsize;
        zx_cache_flush(surface->ptr + start * runlen,
                       (end - start + 1) * runlen, ZX_CACHE_FLUSH_DATA);
    }

    if (surface->flush)
        surface->flush(start, end);
}

/**
 * @brief  Create a new graphics surface object
 */
gfx_surface* gfx_create_surface(void* ptr, unsigned width, unsigned height,
                                unsigned stride, unsigned format, uint32_t flags) {
    gfx_surface* surface = calloc(1, sizeof(*surface));
    if (surface == NULL)
        return NULL;
    if (gfx_init_surface(surface, ptr, width, height, stride, format, flags)) {
        free(surface);
        return NULL;
    }
    return surface;
}

int gfx_init_surface(gfx_surface* surface, void* ptr, unsigned width, unsigned height,
                     unsigned stride, unsigned format, uint32_t flags) {
    assert(width > 0);
    assert(height > 0);
    assert(stride >= width);

    surface->flags = flags;
    surface->format = format;
    surface->width = width;
    surface->height = height;
    surface->stride = stride;
    surface->alpha = MAX_ALPHA;

    // set up some function pointers
    switch (format) {
    case ZX_PIXEL_FORMAT_RGB_565:
        surface->translate_color = &ARGB8888_to_RGB565;
        surface->copyrect = &copyrect16;
        surface->fillrect = &fillrect16;
        surface->putpixel = &putpixel16;
        surface->putchar = &putchar16;
        surface->pixelsize = 2;
        surface->len = (surface->height * surface->stride * surface->pixelsize);
        break;
    case ZX_PIXEL_FORMAT_RGB_x888:
    case ZX_PIXEL_FORMAT_ARGB_8888:
        surface->translate_color = NULL;
        surface->copyrect = &copyrect32;
        surface->fillrect = &fillrect32;
        surface->putpixel = &putpixel32;
        surface->putchar = &putchar32;
        surface->pixelsize = 4;
        surface->len = (surface->height * surface->stride * surface->pixelsize);
        break;
    case ZX_PIXEL_FORMAT_MONO_8:
        surface->translate_color = &ARGB8888_to_Luma;
        surface->copyrect = &copyrect8;
        surface->fillrect = &fillrect8;
        surface->putpixel = &putpixel8;
        surface->putchar = &putchar8;
        surface->pixelsize = 1;
        surface->len = (surface->height * surface->stride * surface->pixelsize);
        break;
    case ZX_PIXEL_FORMAT_RGB_332:
        surface->translate_color = &ARGB8888_to_RGB332;
        surface->copyrect = &copyrect8;
        surface->fillrect = &fillrect8;
        surface->putpixel = &putpixel8;
        surface->putchar = &putchar8;
        surface->pixelsize = 1;
        surface->len = (surface->height * surface->stride * surface->pixelsize);
        break;
    case ZX_PIXEL_FORMAT_RGB_2220:
        surface->translate_color = &ARGB8888_to_RGB2220;
        surface->copyrect = &copyrect8;
        surface->fillrect = &fillrect8;
        surface->putpixel = &putpixel8;
        surface->putchar = &putchar8;
        surface->pixelsize = 1;
        surface->len = (surface->height * surface->stride * surface->pixelsize);
        break;
    default:
        xprintf("invalid graphics format\n");
        return ZX_ERR_INVALID_ARGS;
    }

    if (ptr == NULL) {
        // allocate a buffer
        ptr = malloc(surface->len);
        if (ptr == NULL) {
            return ZX_ERR_NO_MEMORY;
        }
        assert(ptr);
        surface->flags |= GFX_FLAG_FREE_ON_DESTROY;
    }
    surface->ptr = ptr;
    return 0;
}

/**
 * @brief  Destroy a graphics surface and free all resources allocated to it.
 *
 * @param  surface  Surface to destroy.  This pointer is no longer valid after
 *    this call.
 */
void gfx_surface_destroy(struct gfx_surface* surface) {
    if (surface->flags & GFX_FLAG_FREE_ON_DESTROY)
        free(surface->ptr);
    free(surface);
}