/*
 * Copyright (c) 2016 Google, Inc
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <common.h>
#include <dm.h>
#include <video.h>
#include <video_console.h>

/* Functions needed by stb_truetype.h */
static int tt_floor(double val)
{
        if (val < 0)
                return (int)(val - 0.999);

        return (int)val;
}

static int tt_ceil(double val)
{
        if (val < 0)
                return (int)val;

        return (int)(val + 0.999);
}

static double frac(double val)
{
        return val - tt_floor(val);
}

static double tt_fabs(double x)
{
        return x < 0 ? -x : x;
}

 /*
  * Simple square root algorithm. This is from:
  * http://stackoverflow.com/questions/1623375/writing-your-own-square-root-function
  * Written by Chihung Yu
  * Creative Commons license
  * http://creativecommons.org/licenses/by-sa/3.0/legalcode
  * It has been modified to compile correctly, and for U-Boot style.
  */
static double tt_sqrt(double value)
{
        double lo = 1.0;
        double hi = value;

        while (hi - lo > 0.00001) {
                double mid = lo + (hi - lo) / 2;

                if (mid * mid - value > 0.00001)
                        hi = mid;
                else
                        lo = mid;
        }

        return lo;
}

#define STBTT_ifloor            tt_floor
#define STBTT_iceil             tt_ceil
#define STBTT_fabs              tt_fabs
#define STBTT_sqrt              tt_sqrt
#define STBTT_malloc(size, u)   ((void)(u), malloc(size))
#define STBTT_free(size, u)     ((void)(u), free(size))
#define STBTT_assert(x)
#define STBTT_strlen(x)         strlen(x)
#define STBTT_memcpy            memcpy
#define STBTT_memset            memset

#define STB_TRUETYPE_IMPLEMENTATION
#include "stb_truetype.h"

/**
 * struct pos_info - Records a cursor position
 *
 * @xpos_frac:  Fractional X position in pixels (multiplied by VID_FRAC_DIV)
 * @ypos:       Y position (pixels from the top)
 */
struct pos_info {
        int xpos_frac;
        int ypos;
};

/*
 * Allow one for each character on the command line plus one for each newline.
 * This is just an estimate, but it should not be exceeded.
 */
#define POS_HISTORY_SIZE        (CONFIG_SYS_CBSIZE * 11 / 10)

/**
 * struct console_tt_priv - Private data for this driver
 *
 * @font_size:  Vertical font size in pixels
 * @font_data:  Pointer to TrueType font file contents
 * @font:       TrueType font information for the current font
 * @pos:        List of cursor positions for each character written. This is
 *              used to handle backspace. We clear the frame buffer between
 *              the last position and the current position, thus erasing the
 *              last character. We record enough characters to go back to the
 *              start of the current command line.
 * @pos_ptr:    Current position in the position history
 * @baseline:   Pixel offset of the font's baseline from the cursor position.
 *              This is the 'ascent' of the font, scaled to pixel coordinates.
 *              It measures the distance from the baseline to the top of the
 *              font.
 * @scale:      Scale of the font. This is calculated from the pixel height
 *              of the font. It is used by the STB library to generate images
 *              of the correct size.
 */
struct console_tt_priv {
        int font_size;
        u8 *font_data;
        stbtt_fontinfo font;
        struct pos_info pos[POS_HISTORY_SIZE];
        int pos_ptr;
        int baseline;
        double scale;
};

static int console_truetype_set_row(struct udevice *dev, uint row, int clr)
{
        struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
        struct console_tt_priv *priv = dev_get_priv(dev);
        void *line;
        int pixels = priv->font_size * vid_priv->line_length;
        int i;

        line = vid_priv->fb + row * priv->font_size * vid_priv->line_length;
        switch (vid_priv->bpix) {
#ifdef CONFIG_VIDEO_BPP8
        case VIDEO_BPP8: {
                uint8_t *dst = line;

                for (i = 0; i < pixels; i++)
                        *dst++ = clr;
                break;
        }
#endif
#ifdef CONFIG_VIDEO_BPP16
        case VIDEO_BPP16: {
                uint16_t *dst = line;

                for (i = 0; i < pixels; i++)
                        *dst++ = clr;
                break;
        }
#endif
#ifdef CONFIG_VIDEO_BPP32
        case VIDEO_BPP32: {
                uint32_t *dst = line;

                for (i = 0; i < pixels; i++)
                        *dst++ = clr;
                break;
        }
#endif
        default:
                return -ENOSYS;
        }

        return 0;
}

static int console_truetype_move_rows(struct udevice *dev, uint rowdst,
                                     uint rowsrc, uint count)
{
        struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
        struct console_tt_priv *priv = dev_get_priv(dev);
        void *dst;
        void *src;
        int i, diff;

        dst = vid_priv->fb + rowdst * priv->font_size * vid_priv->line_length;
        src = vid_priv->fb + rowsrc * priv->font_size * vid_priv->line_length;
        memmove(dst, src, priv->font_size * vid_priv->line_length * count);

        /* Scroll up our position history */
        diff = (rowsrc - rowdst) * priv->font_size;
        for (i = 0; i < priv->pos_ptr; i++)
                priv->pos[i].ypos -= diff;

        return 0;
}

static int console_truetype_putc_xy(struct udevice *dev, uint x, uint y,
                                    char ch)
{
        struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
        struct udevice *vid = dev->parent;
        struct video_priv *vid_priv = dev_get_uclass_priv(vid);
        struct console_tt_priv *priv = dev_get_priv(dev);
        stbtt_fontinfo *font = &priv->font;
        int width, height, xoff, yoff;
        double xpos, x_shift;
        int lsb;
        int width_frac, linenum;
        struct pos_info *pos;
        u8 *bits, *data;
        int advance;
        void *line;
        int row;

        /* First get some basic metrics about this character */
        stbtt_GetCodepointHMetrics(font, ch, &advance, &lsb);

        /*
         * First out our current X position in fractional pixels. If we wrote
         * a character previously, using kerning to fine-tune the position of
         * this character */
        xpos = frac(VID_TO_PIXEL((double)x));
        if (vc_priv->last_ch) {
                xpos += priv->scale * stbtt_GetCodepointKernAdvance(font,
                                                        vc_priv->last_ch, ch);
        }

        /*
         * Figure out where the cursor will move to after this character, and
         * abort if we are out of space on this line. Also calculate the
         * effective width of this character, which will be our return value:
         * it dictates how much the cursor will move forward on the line.
         */
        x_shift = xpos - (double)tt_floor(xpos);
        xpos += advance * priv->scale;
        width_frac = (int)VID_TO_POS(xpos);
        if (x + width_frac >= vc_priv->xsize_frac)
                return -EAGAIN;

        /* Write the current cursor position into history */
        if (priv->pos_ptr < POS_HISTORY_SIZE) {
                pos = &priv->pos[priv->pos_ptr];
                pos->xpos_frac = vc_priv->xcur_frac;
                pos->ypos = vc_priv->ycur;
                priv->pos_ptr++;
        }

        /*
         * Figure out how much past the start of a pixel we are, and pass this
         * information into the render, which will return a 8-bit-per-pixel
         * image of the character. For empty characters, like ' ', data will
         * return NULL;
         */
        data = stbtt_GetCodepointBitmapSubpixel(font, priv->scale, priv->scale,
                                                x_shift, 0, ch, &width, &height,
                                                &xoff, &yoff);
        if (!data)
                return width_frac;

        /* Figure out where to write the character in the frame buffer */
        bits = data;
        line = vid_priv->fb + y * vid_priv->line_length +
                VID_TO_PIXEL(x) * VNBYTES(vid_priv->bpix);
        linenum = priv->baseline + yoff;
        if (linenum > 0)
                line += linenum * vid_priv->line_length;

        /*
         * Write a row at a time, converting the 8bpp image into the colour
         * depth of the display. We only expect white-on-black or the reverse
         * so the code only handles this simple case.
         */
        for (row = 0; row < height; row++) {
                switch (vid_priv->bpix) {
#ifdef CONFIG_VIDEO_BPP16
                case VIDEO_BPP16: {
                        uint16_t *dst = (uint16_t *)line + xoff;
                        int i;

                        for (i = 0; i < width; i++) {
                                int val = *bits;
                                int out;

                                if (vid_priv->colour_bg)
                                        val = 255 - val;
                                out = val >> 3 |
                                        (val >> 2) << 5 |
                                        (val >> 3) << 11;
                                if (vid_priv->colour_fg)
                                        *dst++ |= out;
                                else
                                        *dst++ &= out;
                                bits++;
                        }
                        break;
                }
#endif
                default:
                        free(data);
                        return -ENOSYS;
                }

                line += vid_priv->line_length;
        }
        free(data);

        return width_frac;
}

/**
 * console_truetype_erase() - Erase a character
 *
 * This is used for backspace. We erase a square of the display within the
 * given bounds.
 *
 * @dev:        Device to update
 * @xstart:     X start position in pixels from the left
 * @ystart:     Y start position in pixels from the top
 * @xend:       X end position in pixels from the left
 * @yend:       Y end position  in pixels from the top
 * @clr:        Value to write
 * @return 0 if OK, -ENOSYS if the display depth is not supported
 */
static int console_truetype_erase(struct udevice *dev, int xstart, int ystart,
                                  int xend, int yend, int clr)
{
        struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
        void *line;
        int pixels = xend - xstart;
        int row, i;

        line = vid_priv->fb + ystart * vid_priv->line_length;
        line += xstart * VNBYTES(vid_priv->bpix);
        for (row = ystart; row < yend; row++) {
                switch (vid_priv->bpix) {
#ifdef CONFIG_VIDEO_BPP8
                case VIDEO_BPP8: {
                        uint8_t *dst = line;

                        for (i = 0; i < pixels; i++)
                                *dst++ = clr;
                        break;
                }
#endif
#ifdef CONFIG_VIDEO_BPP16
                case VIDEO_BPP16: {
                        uint16_t *dst = line;

                        for (i = 0; i < pixels; i++)
                                *dst++ = clr;
                        break;
                }
#endif
#ifdef CONFIG_VIDEO_BPP32
                case VIDEO_BPP32: {
                        uint32_t *dst = line;

                        for (i = 0; i < pixels; i++)
                                *dst++ = clr;
                        break;
                }
#endif
                default:
                        return -ENOSYS;
                }
                line += vid_priv->line_length;
        }

        return 0;
}

/**
 * console_truetype_backspace() - Handle a backspace operation
 *
 * This clears the previous character so that the console looks as if it had
 * not been entered.
 *
 * @dev:        Device to update
 * @return 0 if OK, -ENOSYS if not supported
 */
static int console_truetype_backspace(struct udevice *dev)
{
        struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
        struct console_tt_priv *priv = dev_get_priv(dev);
        struct udevice *vid_dev = dev->parent;
        struct video_priv *vid_priv = dev_get_uclass_priv(vid_dev);
        struct pos_info *pos;
        int xend;

        /*
         * This indicates a very strange error higher in the stack. The caller
         * has sent out n character and n + 1 backspaces.
         */
        if (!priv->pos_ptr)
                return -ENOSYS;

        /* Pop the last cursor position off the stack */
        pos = &priv->pos[--priv->pos_ptr];

        /*
         * Figure out the end position for clearing. Normlly it is the current
         * cursor position, but if we are clearing a character on the previous
         * line, we clear from the end of the line.
         */
        if (pos->ypos == vc_priv->ycur)
                xend = VID_TO_PIXEL(vc_priv->xcur_frac);
        else
                xend = vid_priv->xsize;

        console_truetype_erase(dev, VID_TO_PIXEL(pos->xpos_frac), pos->ypos,
                               xend, pos->ypos + vc_priv->y_charsize,
                               vid_priv->colour_bg);

        /* Move the cursor back to where it was when we pushed this record */
        vc_priv->xcur_frac = pos->xpos_frac;
        vc_priv->ycur = pos->ypos;

        return 0;
}

static int console_truetype_entry_start(struct udevice *dev)
{
        struct console_tt_priv *priv = dev_get_priv(dev);

        /* A new input line has start, so clear our history */
        priv->pos_ptr = 0;

        return 0;
}

/*
 * Provides a list of fonts which can be obtained at run-time in U-Boot. These
 * are compiled in by the Makefile.
 *
 * At present there is no mechanism to select a particular font - the first
 * one found is the one that is used. But the build system and the code here
 * supports multiple fonts, which may be useful for certain firmware screens.
 */
struct font_info {
        char *name;
        u8 *begin;
        u8 *end;
};

#define FONT_DECL(_name) \
        extern u8 __ttf_ ## _name ## _begin[]; \
        extern u8 __ttf_ ## _name ## _end[];

#define FONT_ENTRY(_name)               { \
        .name = #_name, \
        .begin = __ttf_ ## _name ## _begin, \
        .end = __ttf_ ## _name ## _end, \
        }

FONT_DECL(nimbus_sans_l_regular);
FONT_DECL(ankacoder_c75_r);
FONT_DECL(rufscript010);
FONT_DECL(cantoraone_regular);

static struct font_info font_table[] = {
#ifdef CONFIG_CONSOLE_TRUETYPE_NIMBUS
        FONT_ENTRY(nimbus_sans_l_regular),
#endif
#ifdef CONFIG_CONSOLE_TRUETYPE_ANKACODER
        FONT_ENTRY(ankacoder_c75_r),
#endif
#ifdef CONFIG_CONSOLE_TRUETYPE_RUFSCRIPT
        FONT_ENTRY(rufscript010),
#endif
#ifdef CONFIG_CONSOLE_TRUETYPE_CANTORAONE
        FONT_ENTRY(cantoraone_regular),
#endif
        {} /* sentinel */
};

#define FONT_BEGIN(name)        __ttf_ ## name ## _begin
#define FONT_END(name)          __ttf_ ## name ## _end
#define FONT_IS_VALID(name)     (abs(FONT_END(name) - FONT_BEGIN) > 4)

/**
 * console_truetype_find_font() - Find a suitable font
 *
 * This searched for the first available font.
 *
 * @return pointer to the font, or NULL if none is found
 */
static u8 *console_truetype_find_font(void)
{
        struct font_info *tab;

        for (tab = font_table; tab->begin; tab++) {
                if (abs(tab->begin - tab->end) > 4) {
                        debug("%s: Font '%s', at %p, size %lx\n", __func__,
                              tab->name, tab->begin,
                              (ulong)(tab->end - tab->begin));
                        return tab->begin;
                }
        }

        return NULL;
}

static int console_truetype_probe(struct udevice *dev)
{
        struct vidconsole_priv *vc_priv = dev_get_uclass_priv(dev);
        struct console_tt_priv *priv = dev_get_priv(dev);
        struct udevice *vid_dev = dev->parent;
        struct video_priv *vid_priv = dev_get_uclass_priv(vid_dev);
        stbtt_fontinfo *font = &priv->font;
        int ascent;

        debug("%s: start\n", __func__);
        if (vid_priv->font_size)
                priv->font_size = vid_priv->font_size;
        else
                priv->font_size = CONFIG_CONSOLE_TRUETYPE_SIZE;
        priv->font_data = console_truetype_find_font();
        if (!priv->font_data) {
                debug("%s: Could not find any fonts\n", __func__);
                return -EBFONT;
        }

        vc_priv->x_charsize = priv->font_size;
        vc_priv->y_charsize = priv->font_size;
        vc_priv->xstart_frac = VID_TO_POS(2);
        vc_priv->cols = vid_priv->xsize / priv->font_size;
        vc_priv->rows = vid_priv->ysize / priv->font_size;
        vc_priv->tab_width_frac = VID_TO_POS(priv->font_size) * 8 / 2;

        if (!stbtt_InitFont(font, priv->font_data, 0)) {
                debug("%s: Font init failed\n", __func__);
                return -EPERM;
        }

        /* Pre-calculate some things we will need regularly */
        priv->scale = stbtt_ScaleForPixelHeight(font, priv->font_size);
        stbtt_GetFontVMetrics(font, &ascent, 0, 0);
        priv->baseline = (int)(ascent * priv->scale);
        debug("%s: ready\n", __func__);

        return 0;
}

struct vidconsole_ops console_truetype_ops = {
        .putc_xy        = console_truetype_putc_xy,
        .move_rows      = console_truetype_move_rows,
        .set_row        = console_truetype_set_row,
        .backspace      = console_truetype_backspace,
        .entry_start    = console_truetype_entry_start,
};

U_BOOT_DRIVER(vidconsole_truetype) = {
        .name   = "vidconsole_tt",
        .id     = UCLASS_VIDEO_CONSOLE,
        .ops    = &console_truetype_ops,
        .probe  = console_truetype_probe,
        .priv_auto_alloc_size   = sizeof(struct console_tt_priv),
};