/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>

#include <fcntl.h>
#include <stdio.h>

#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/types.h>

#include <linux/fb.h>
#include <linux/kd.h>

#include <time.h>

#include "font_10x18.h"
#include "minui.h"

typedef struct {
    GRSurface* texture;
    int cwidth;
    int cheight;
} GRFont;

static GRFont* gr_font = NULL;

static int overscan_percent = OVERSCAN_PERCENT;
static int overscan_offset_x = 0;
static int overscan_offset_y = 0;

static int gr_fb_fd = -1;
static int gr_vt_fd = -1;

static GRSurface gr_framebuffer[2];
static bool double_buffered;
static GRSurface* gr_draw = NULL;
static int displayed_buffer;

static unsigned char gr_current_r = 255;
static unsigned char gr_current_g = 255;
static unsigned char gr_current_b = 255;
static unsigned char gr_current_a = 255;

static struct fb_var_screeninfo vi;

static bool outside(int x, int y)
{
    return x < 0 || x >= gr_draw->width || y < 0 || y >= gr_draw->height;
}

static void set_displayed_framebuffer(unsigned n)
{
    if (n > 1 || !double_buffered) return;

    vi.yres_virtual = gr_framebuffer[0].height * 2;
    vi.yoffset = n * gr_framebuffer[0].height;
    vi.bits_per_pixel = gr_framebuffer[0].pixel_bytes * 8;
    if (ioctl(gr_fb_fd, FBIOPUT_VSCREENINFO, &vi) < 0) {
        perror("active fb swap failed");
    }
    displayed_buffer = n;
}

static int get_framebuffer()
{
    int fd;
    void *bits;

    struct fb_fix_screeninfo fi;

    fd = open("/dev/graphics/fb0", O_RDWR);
    if (fd < 0) {
        perror("cannot open fb0");
        return -1;
    }

    if (ioctl(fd, FBIOGET_FSCREENINFO, &fi) < 0) {
        perror("failed to get fb0 info");
        close(fd);
        return -1;
    }

    if (ioctl(fd, FBIOGET_VSCREENINFO, &vi) < 0) {
        perror("failed to get fb0 info");
        close(fd);
        return -1;
    }

    // We print this out for informational purposes only, but
    // throughout we assume that the framebuffer device uses an RGBX
    // pixel format.  This is the case for every development device I
    // have access to.  For some of those devices (eg, hammerhead aka
    // Nexus 5), FBIOGET_VSCREENINFO *reports* that it wants a
    // different format (XBGR) but actually produces the correct
    // results on the display when you write RGBX.
    //
    // If you have a device that actually *needs* another pixel format
    // (ie, BGRX, or 565), patches welcome...

    printf("fb0 reports (possibly inaccurate):\n"
           "  vi.bits_per_pixel = %d\n"
           "  vi.red.offset   = %3d   .length = %3d\n"
           "  vi.green.offset = %3d   .length = %3d\n"
           "  vi.blue.offset  = %3d   .length = %3d\n",
           vi.bits_per_pixel,
           vi.red.offset, vi.red.length,
           vi.green.offset, vi.green.length,
           vi.blue.offset, vi.blue.length);

    bits = mmap(0, fi.smem_len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    if (bits == MAP_FAILED) {
        perror("failed to mmap framebuffer");
        close(fd);
        return -1;
    }

    overscan_offset_x = vi.xres * overscan_percent / 100;
    overscan_offset_y = vi.yres * overscan_percent / 100;

    gr_framebuffer[0].width = vi.xres;
    gr_framebuffer[0].height = vi.yres;
    gr_framebuffer[0].row_bytes = fi.line_length;
    gr_framebuffer[0].pixel_bytes = vi.bits_per_pixel / 8;
    gr_framebuffer[0].data = bits;
    memset(gr_framebuffer[0].data, 0, gr_framebuffer[0].height * gr_framebuffer[0].row_bytes);

    /* check if we can use double buffering */
    if (vi.yres * fi.line_length * 2 <= fi.smem_len) {
        double_buffered = true;

        memcpy(gr_framebuffer+1, gr_framebuffer, sizeof(GRSurface));
        gr_framebuffer[1].data = gr_framebuffer[0].data +
            gr_framebuffer[0].height * gr_framebuffer[0].row_bytes;

        gr_draw = gr_framebuffer+1;

    } else {
        double_buffered = false;

        // Without double-buffering, we allocate RAM for a buffer to
        // draw in, and then "flipping" the buffer consists of a
        // memcpy from the buffer we allocated to the framebuffer.

        gr_draw = (GRSurface*) malloc(sizeof(GRSurface));
        memcpy(gr_draw, gr_framebuffer, sizeof(GRSurface));
        gr_draw->data = (unsigned char*) malloc(gr_draw->height * gr_draw->row_bytes);
        if (!gr_draw->data) {
            perror("failed to allocate in-memory surface");
            return -1;
        }
    }

    memset(gr_draw->data, 0, gr_draw->height * gr_draw->row_bytes);
    gr_fb_fd = fd;
    set_displayed_framebuffer(0);

    return fd;
}

void gr_flip(void)
{
    if (double_buffered) {
        // Change gr_draw to point to the buffer currently displayed,
        // then flip the driver so we're displaying the other buffer
        // instead.
        gr_draw = gr_framebuffer + displayed_buffer;
        set_displayed_framebuffer(1-displayed_buffer);
    } else {
        // Copy from the in-memory surface to the framebuffer.
        memcpy(gr_framebuffer[0].data, gr_draw->data,
               gr_draw->height * gr_draw->row_bytes);
    }
}

int gr_measure(const char *s)
{
    return gr_font->cwidth * strlen(s);
}

void gr_font_size(int *x, int *y)
{
    *x = gr_font->cwidth;
    *y = gr_font->cheight;
}

static void text_blend(unsigned char* src_p, int src_row_bytes,
                       unsigned char* dst_p, int dst_row_bytes,
                       int width, int height)
{
    int i, j;
    for (j = 0; j < height; ++j) {
        unsigned char* sx = src_p;
        unsigned char* px = dst_p;
        for (i = 0; i < width; ++i) {
            unsigned char a = *sx++;
            if (gr_current_a < 255) a = ((int)a * gr_current_a) / 255;
            if (a == 255) {
                *px++ = gr_current_r;
                *px++ = gr_current_g;
                *px++ = gr_current_b;
                px++;
            } else if (a > 0) {
                *px = (*px * (255-a) + gr_current_r * a) / 255;
                ++px;
                *px = (*px * (255-a) + gr_current_g * a) / 255;
                ++px;
                *px = (*px * (255-a) + gr_current_b * a) / 255;
                ++px;
                ++px;
            } else {
                px += 4;
            }
        }
        src_p += src_row_bytes;
        dst_p += dst_row_bytes;
    }
}


void gr_text(int x, int y, const char *s, int bold)
{
    GRFont *font = gr_font;
    unsigned off;

    if (!font->texture) return;
    if (gr_current_a == 0) return;

    bold = bold && (font->texture->height != font->cheight);

    x += overscan_offset_x;
    y += overscan_offset_y;

    while((off = *s++)) {
        off -= 32;
        if (outside(x, y) || outside(x+font->cwidth-1, y+font->cheight-1)) break;
        if (off < 96) {

            unsigned char* src_p = font->texture->data + (off * font->cwidth) +
                (bold ? font->cheight * font->texture->row_bytes : 0);
            unsigned char* dst_p = gr_draw->data + y*gr_draw->row_bytes + x*gr_draw->pixel_bytes;

            text_blend(src_p, font->texture->row_bytes,
                       dst_p, gr_draw->row_bytes,
                       font->cwidth, font->cheight);

        }
        x += font->cwidth;
    }
}

void gr_texticon(int x, int y, GRSurface* icon) {
    if (icon == NULL) return;

    if (icon->pixel_bytes != 1) {
        printf("gr_texticon: source has wrong format\n");
        return;
    }

    x += overscan_offset_x;
    y += overscan_offset_y;

    if (outside(x, y) || outside(x+icon->width-1, y+icon->height-1)) return;

    unsigned char* src_p = icon->data;
    unsigned char* dst_p = gr_draw->data + y*gr_draw->row_bytes + x*gr_draw->pixel_bytes;

    text_blend(src_p, icon->row_bytes,
               dst_p, gr_draw->row_bytes,
               icon->width, icon->height);
}

void gr_color(unsigned char r, unsigned char g, unsigned char b, unsigned char a)
{
    gr_current_r = r;
    gr_current_g = g;
    gr_current_b = b;
    gr_current_a = a;
}

void gr_clear()
{
    if (gr_current_r == gr_current_g &&
        gr_current_r == gr_current_b) {
        memset(gr_draw->data, gr_current_r, gr_draw->height * gr_draw->row_bytes);
    } else {
        int x, y;
        unsigned char* px = gr_draw->data;
        for (y = 0; y < gr_draw->height; ++y) {
            for (x = 0; x < gr_draw->width; ++x) {
                *px++ = gr_current_r;
                *px++ = gr_current_g;
                *px++ = gr_current_b;
                px++;
            }
            px += gr_draw->row_bytes - (gr_draw->width * gr_draw->pixel_bytes);
        }
    }
}

void gr_fill(int x1, int y1, int x2, int y2)
{
    x1 += overscan_offset_x;
    y1 += overscan_offset_y;

    x2 += overscan_offset_x;
    y2 += overscan_offset_y;

    if (outside(x1, y1) || outside(x2-1, y2-1)) return;

    unsigned char* p = gr_draw->data + y1 * gr_draw->row_bytes + x1 * gr_draw->pixel_bytes;
    if (gr_current_a == 255) {
        int x, y;
        for (y = y1; y < y2; ++y) {
            unsigned char* px = p;
            for (x = x1; x < x2; ++x) {
                *px++ = gr_current_r;
                *px++ = gr_current_g;
                *px++ = gr_current_b;
                px++;
            }
            p += gr_draw->row_bytes;
        }
    } else if (gr_current_a > 0) {
        int x, y;
        for (y = y1; y < y2; ++y) {
            unsigned char* px = p;
            for (x = x1; x < x2; ++x) {
                *px = (*px * (255-gr_current_a) + gr_current_r * gr_current_a) / 255;
                ++px;
                *px = (*px * (255-gr_current_a) + gr_current_g * gr_current_a) / 255;
                ++px;
                *px = (*px * (255-gr_current_a) + gr_current_b * gr_current_a) / 255;
                ++px;
                ++px;
            }
            p += gr_draw->row_bytes;
        }
    }
}

void gr_blit(GRSurface* source, int sx, int sy, int w, int h, int dx, int dy) {
    if (source == NULL) return;

    if (gr_draw->pixel_bytes != source->pixel_bytes) {
        printf("gr_blit: source has wrong format\n");
        return;
    }

    dx += overscan_offset_x;
    dy += overscan_offset_y;

    if (outside(dx, dy) || outside(dx+w-1, dy+h-1)) return;

    unsigned char* src_p = source->data + sy*source->row_bytes + sx*source->pixel_bytes;
    unsigned char* dst_p = gr_draw->data + dy*gr_draw->row_bytes + dx*gr_draw->pixel_bytes;

    int i;
    for (i = 0; i < h; ++i) {
        memcpy(dst_p, src_p, w * source->pixel_bytes);
        src_p += source->row_bytes;
        dst_p += gr_draw->row_bytes;
    }
}

unsigned int gr_get_width(GRSurface* surface) {
    if (surface == NULL) {
        return 0;
    }
    return surface->width;
}

unsigned int gr_get_height(GRSurface* surface) {
    if (surface == NULL) {
        return 0;
    }
    return surface->height;
}

static void gr_init_font(void)
{
    gr_font = calloc(sizeof(*gr_font), 1);

    int res = res_create_surface("font", &(gr_font->texture));
    if (res == 0) {
        // The font image should be a 96x2 array of character images.  The
        // columns are the printable ASCII characters 0x20 - 0x7f.  The
        // top row is regular text; the bottom row is bold.
        gr_font->cwidth = gr_font->texture->width / 96;
        gr_font->cheight = gr_font->texture->height / 2;
    } else {
        printf("failed to read font: res=%d\n", res);

        // fall back to the compiled-in font.
        gr_font->texture = malloc(sizeof(*gr_font->texture));
        gr_font->texture->width = font.width;
        gr_font->texture->height = font.height;
        gr_font->texture->row_bytes = font.width;
        gr_font->texture->pixel_bytes = 1;

        unsigned char* bits = malloc(font.width * font.height);
        gr_font->texture->data = (void*) bits;

        unsigned char data;
        unsigned char* in = font.rundata;
        while((data = *in++)) {
            memset(bits, (data & 0x80) ? 255 : 0, data & 0x7f);
            bits += (data & 0x7f);
        }

        gr_font->cwidth = font.cwidth;
        gr_font->cheight = font.cheight;
    }
}

#if 0
// Exercises many of the gr_*() functions; useful for testing.
static void gr_test() {
    GRSurface** images;
    int frames;
    int result = res_create_multi_surface("icon_installing", &frames, &images);
    if (result < 0) {
        printf("create surface %d\n", result);
        gr_exit();
        return;
    }

    time_t start = time(NULL);
    int x;
    for (x = 0; x <= 1200; ++x) {
        if (x < 400) {
            gr_color(0, 0, 0, 255);
        } else {
            gr_color(0, (x-400)%128, 0, 255);
        }
        gr_clear();

        gr_color(255, 0, 0, 255);
        gr_surface frame = images[x%frames];
        gr_blit(frame, 0, 0, frame->width, frame->height, x, 0);

        gr_color(255, 0, 0, 128);
        gr_fill(400, 150, 600, 350);

        gr_color(255, 255, 255, 255);
        gr_text(500, 225, "hello, world!", 0);
        gr_color(255, 255, 0, 128);
        gr_text(300+x, 275, "pack my box with five dozen liquor jugs", 1);

        gr_color(0, 0, 255, 128);
        gr_fill(gr_draw->width - 200 - x, 300, gr_draw->width - x, 500);

        gr_flip();
    }
    printf("getting end time\n");
    time_t end = time(NULL);
    printf("got end time\n");
    printf("start %ld end %ld\n", (long)start, (long)end);
    if (end > start) {
        printf("%.2f fps\n", ((double)x) / (end-start));
    }
}
#endif

int gr_init(void)
{
    gr_init_font();

    gr_vt_fd = open("/dev/tty0", O_RDWR | O_SYNC);
    if (gr_vt_fd < 0) {
        // This is non-fatal; post-Cupcake kernels don't have tty0.
        perror("can't open /dev/tty0");
    } else if (ioctl(gr_vt_fd, KDSETMODE, (void*) KD_GRAPHICS)) {
        // However, if we do open tty0, we expect the ioctl to work.
        perror("failed KDSETMODE to KD_GRAPHICS on tty0");
        gr_exit();
        return -1;
    }

    if (get_framebuffer(&gr_framebuffer) < 0) {
        gr_exit();
        return -1;
    }

    printf("framebuffer: fd %d (%d x %d)\n",
           gr_fb_fd, gr_draw->width, gr_draw->height);

    gr_flip();
    gr_flip();

    gr_fb_blank(true);
    gr_fb_blank(false);

    return 0;
}

void gr_exit(void)
{
    close(gr_fb_fd);
    gr_fb_fd = -1;

    ioctl(gr_vt_fd, KDSETMODE, (void*) KD_TEXT);
    close(gr_vt_fd);
    gr_vt_fd = -1;

    if (!double_buffered) {
        if (gr_draw) free(gr_draw->data);
        free(gr_draw);
    }
}

int gr_fb_width(void)
{
    return gr_draw->width - 2*overscan_offset_x;
}

int gr_fb_height(void)
{
    return gr_draw->height - 2*overscan_offset_y;
}

void gr_fb_blank(bool blank)
{
    int ret;

    ret = ioctl(gr_fb_fd, FBIOBLANK, blank ? FB_BLANK_POWERDOWN : FB_BLANK_UNBLANK);
    if (ret < 0)
        perror("ioctl(): blank");
}