#include "compiler.h"

enum {
        MODE_GEN_INFO,
        MODE_GEN_DATA
};

typedef struct bitmap_s {               /* bitmap description */
        uint16_t width;
        uint16_t height;
        uint8_t palette[256*3];
        uint8_t *data;
} bitmap_t;

#define DEFAULT_CMAP_SIZE       16      /* size of default color map    */

void usage(const char *prog)
{
        fprintf(stderr, "Usage: %s [--gen-info|--gen-data] file\n", prog);
}

/*
 * Neutralize little endians.
 */
uint16_t le_short(uint16_t x)
{
    uint16_t val;
    uint8_t *p = (uint8_t *)(&x);

    val =  (*p++ & 0xff) << 0;
    val |= (*p & 0xff) << 8;

    return val;
}

void skip_bytes (FILE *fp, int n)
{
        while (n-- > 0)
                fgetc (fp);
}

__attribute__ ((__noreturn__))
int error (char * msg, FILE *fp)
{
        fprintf (stderr, "ERROR: %s\n", msg);

        fclose (fp);

        exit (EXIT_FAILURE);
}

void gen_info(bitmap_t *b, uint16_t n_colors)
{
        printf("/*\n"
                " * Automatically generated by \"tools/bmp_logo\"\n"
                " *\n"
                " * DO NOT EDIT\n"
                " *\n"
                " */\n\n\n"
                "#ifndef __BMP_LOGO_H__\n"
                "#define __BMP_LOGO_H__\n\n"
                "#define BMP_LOGO_WIDTH\t\t%d\n"
                "#define BMP_LOGO_HEIGHT\t\t%d\n"
                "#define BMP_LOGO_COLORS\t\t%d\n"
                "#define BMP_LOGO_OFFSET\t\t%d\n\n"
                "extern unsigned short bmp_logo_palette[];\n"
                "extern unsigned char bmp_logo_bitmap[];\n\n"
                "#endif /* __BMP_LOGO_H__ */\n",
                b->width, b->height, n_colors,
                DEFAULT_CMAP_SIZE);
}

int main (int argc, char *argv[])
{
        int     mode, i, x;
        FILE    *fp;
        bitmap_t bmp;
        bitmap_t *b = &bmp;
        uint16_t data_offset, n_colors, hdr_size;

        if (argc < 3) {
                usage(argv[0]);
                exit (EXIT_FAILURE);
        }

        if (!strcmp(argv[1], "--gen-info"))
                mode = MODE_GEN_INFO;
        else if (!strcmp(argv[1], "--gen-data"))
                mode = MODE_GEN_DATA;
        else {
                usage(argv[0]);
                exit(EXIT_FAILURE);
        }

        fp = fopen(argv[2], "rb");
        if (!fp) {
                perror(argv[2]);
                exit (EXIT_FAILURE);
        }

        if (fgetc (fp) != 'B' || fgetc (fp) != 'M')
                error ("Input file is not a bitmap", fp);

        /*
         * read width and height of the image, and the number of colors used;
         * ignore the rest
         */
        skip_bytes (fp, 8);
        if (fread (&data_offset, sizeof (uint16_t), 1, fp) != 1)
                error ("Couldn't read bitmap data offset", fp);
        skip_bytes(fp, 2);
        if (fread(&hdr_size,   sizeof(uint16_t), 1, fp) != 1)
                error("Couldn't read bitmap header size", fp);
        if (hdr_size < 40)
                error("Invalid bitmap header", fp);
        skip_bytes(fp, 2);
        if (fread (&b->width,   sizeof (uint16_t), 1, fp) != 1)
                error ("Couldn't read bitmap width", fp);
        skip_bytes (fp, 2);
        if (fread (&b->height,  sizeof (uint16_t), 1, fp) != 1)
                error ("Couldn't read bitmap height", fp);
        skip_bytes (fp, 22);
        if (fread (&n_colors, sizeof (uint16_t), 1, fp) != 1)
                error ("Couldn't read bitmap colors", fp);
        skip_bytes(fp, hdr_size - 34);

        /*
         * Repair endianess.
         */
        data_offset = le_short(data_offset);
        b->width = le_short(b->width);
        b->height = le_short(b->height);
        n_colors = le_short(n_colors);

        /* assume we are working with an 8-bit file */
        if ((n_colors == 0) || (n_colors > 256 - DEFAULT_CMAP_SIZE)) {
                /* reserve DEFAULT_CMAP_SIZE color map entries for default map */
                n_colors = 256 - DEFAULT_CMAP_SIZE;
        }

        if (mode == MODE_GEN_INFO) {
                gen_info(b, n_colors);
                goto out;
        }

        printf("/*\n"
                " * Automatically generated by \"tools/bmp_logo\"\n"
                " *\n"
                " * DO NOT EDIT\n"
                " *\n"
                " */\n\n\n"
                "#ifndef __BMP_LOGO_DATA_H__\n"
                "#define __BMP_LOGO_DATA_H__\n\n");

        /* allocate memory */
        if ((b->data = (uint8_t *)malloc(b->width * b->height)) == NULL)
                error ("Error allocating memory for file", fp);

        /* read and print the palette information */
        printf("unsigned short bmp_logo_palette[] = {\n");

        for (i=0; i<n_colors; ++i) {
                b->palette[(int)(i*3+2)] = fgetc(fp);
                b->palette[(int)(i*3+1)] = fgetc(fp);
                b->palette[(int)(i*3+0)] = fgetc(fp);
                x=fgetc(fp);

                printf ("%s0x0%X%X%X,%s",
                        ((i%8) == 0) ? "\t" : "  ",
                        (b->palette[(int)(i*3+0)] >> 4) & 0x0F,
                        (b->palette[(int)(i*3+1)] >> 4) & 0x0F,
                        (b->palette[(int)(i*3+2)] >> 4) & 0x0F,
                        ((i%8) == 7) ? "\n" : ""
                );
        }

        /* seek to offset indicated by file header */
        fseek(fp, (long)data_offset, SEEK_SET);

        /* read the bitmap; leave room for default color map */
        printf ("\n");
        printf ("};\n");
        printf ("\n");
        printf("unsigned char bmp_logo_bitmap[] = {\n");
        for (i=(b->height-1)*b->width; i>=0; i-=b->width) {
                for (x = 0; x < b->width; x++) {
                        b->data[i + x] = (uint8_t) fgetc(fp)
                                                + DEFAULT_CMAP_SIZE;
                }
        }

        for (i=0; i<(b->height*b->width); ++i) {
                if ((i%8) == 0)
                        putchar ('\t');
                printf ("0x%02X,%c",
                        b->data[i],
                        ((i%8) == 7) ? '\n' : ' '
                );
        }
        printf ("\n"
                "};\n\n"
                "#endif /* __BMP_LOGO_DATA_H__ */\n"
        );

out:
        fclose(fp);
        return 0;
}