#!/bin/bash
# bdf-to-c.sh — Convert a BDF font file to a C header with embedded glyph data
# Usage: ./bdf-to-c.sh input.bdf > output.h
#
# Extracts ASCII glyphs (32-126) with variable-width support.

set -euo pipefail

BDF="$1"
FONT_NAME="${2:-bdf_font}"

cat << EOF
// Auto-generated from $(basename "$BDF") — do not edit
// Generated by bdf-to-c.sh

#ifndef AC_FONT_${FONT_NAME^^}_H
#define AC_FONT_${FONT_NAME^^}_H

#include <stdint.h>

#define ${FONT_NAME^^}_MAX_W 16
#define ${FONT_NAME^^}_MAX_H 16

typedef struct {
    uint8_t width;      // glyph pixel width (BBX w)
    uint8_t height;     // glyph pixel height (BBX h)
    int8_t  xoff;       // x offset from origin
    int8_t  yoff;       // y offset from baseline
    uint8_t dwidth;     // advance width (device width)
    uint8_t rows[${FONT_NAME^^}_MAX_H]; // bitmap rows (MSB = leftmost pixel)
} BDFGlyph;

EOF

# Parse BDF and emit glyph data
awk -v name="$FONT_NAME" '
BEGIN {
    font_ascent = 8
    max_h = 0
}

/^FONT_ASCENT / { font_ascent = $2 }

/^STARTCHAR / { char_name = $2; in_char = 1; in_bitmap = 0; row_idx = 0 }
/^ENCODING /  { encoding = $2 }
/^DWIDTH /    { dwidth = $2 }
/^BBX /       { bbx_w = $2; bbx_h = $3; bbx_xoff = $4; bbx_yoff = $5; if (bbx_h > max_h) max_h = bbx_h }
/^BITMAP$/    { in_bitmap = 1; next }
/^ENDCHAR/    {
    if (encoding >= 32 && encoding <= 126) {
        glyphs[encoding] = 1
        g_w[encoding] = bbx_w
        g_h[encoding] = bbx_h
        g_xoff[encoding] = bbx_xoff
        g_yoff[encoding] = bbx_yoff
        g_dw[encoding] = dwidth
        g_rows[encoding] = row_idx
        for (r = 0; r < row_idx; r++) {
            g_data[encoding, r] = rows[r]
        }
    }
    in_char = 0; in_bitmap = 0
}

in_bitmap && in_char {
    rows[row_idx++] = "0x" $0
}

END {
    printf "static const int %s_ascent = %d;\n\n", name, font_ascent
    printf "static const BDFGlyph %s_glyphs[95] = {\n", name
    for (enc = 32; enc <= 126; enc++) {
        if (enc in glyphs) {
            printf "    // %c (%d) — %dpx wide\n", enc, enc, g_w[enc]
            printf "    {%d, %d, %d, %d, %d, {", g_w[enc], g_h[enc], g_xoff[enc], g_yoff[enc], g_dw[enc]
            for (r = 0; r < g_rows[enc]; r++) {
                if (r > 0) printf ", "
                printf "%s", g_data[enc, r]
            }
            printf "}},\n"
        } else {
            printf "    // (missing %d)\n    {0, 0, 0, 0, 4, {0}},\n", enc
        }
    }
    printf "};\n\n"
    printf "#endif\n"
}
' "$BDF"