import json
import cv2
import numpy as np

"""
dd if=mobitec-1682-r7-bib-01979-r3.bin of=mobitec-1682-r7-bib-01979-r3-fonts.bin skip=64 bs=1024
dd if=mobitec-01682-r7-bib-01369-r9.bin of=mobitec-01682-r7-bib-01369-r9-fonts.bin skip=64 bs=1024
dhex mobitec-1682-r7-bib-01979-r3-fonts.bin mobitec-01682-r7-bib-01369-r9-fonts.bin
"""

src = "mobitec-1682-r7-bib-01979-r3"
src = "mobitec-01682-r7-bib-01369-r9"

with open("firmware/%s.bin" % src, "rb") as fh:
    buf = fh.read()[65536:]


def scan_fonts(buf):
    """
    Font start markers seem to be ascii character a..z followed by at least 60 nulls
    """
    font_index = buf[0]
    assert font_index == 0x61
    prev = 0
    done = False
    while not done:
        needle = b"%c" % (font_index + 1)
        needle += 50 * b"\x00"
        try:
            font_offset = buf.index(needle)
        except ValueError:
            break
            font_body = buf[prev:]
            done = True
        else:
            font_body = buf[prev:font_offset]
        if done:
            break
        font_marker_length = len(needle)
        font_body = font_body[font_marker_length:]
        while font_body.startswith(b"\x00"):
            font_body = font_body[1:]
            font_marker_length += 1
        yield font_index, font_body, font_marker_length
        prev = font_offset
        font_index += 1


meta = []
for font_index, font_body, font_marker_length in scan_fonts(buf):
    print()
    print("Parsing font %02x" % font_index)

    # Looks like yet another marker
    assert font_body[0] == 3
    assert font_body[1] == 1

    # Look up table consists of 95 16-bit integers
    glyph_offsets = np.frombuffer(font_body[2:192], dtype=np.uint16)
    prev = 0
    slices = []
    errors = set()

    for index, glyph_offset in enumerate(glyph_offsets):
        if glyph_offset != 0:
            glyph_offset -= font_marker_length
            print("Found %d undecoded bytes between lookup table and first glyph" % len(font_body[192:192 + glyph_offset]))
            break

    characters_present = ""

    for index, glyph_offset in enumerate(glyph_offsets):
        if glyph_offset == 0:
            characters_present += "_"
            # No glyph
            meta.append(None)
            continue
        else:
            # The index goes from space (32) up to ~ (126)
            character = chr(index + 32)
            characters_present += "+"

        # Glyphs are relative to the font marker start
        glyph_offset -= font_marker_length

        try:
            height, width = font_body[glyph_offset], font_body[glyph_offset + 1]
        except IndexError:
            print("Failed to look up glyph for %s", repr(character))
        else:
            jah = np.frombuffer((font_body[glyph_offset + 2:])[::-1], dtype=np.uint8)[::-1]
            a = np.unpackbits(jah, axis=0)
            try:
                img = a[:width * 16].reshape((width, 16, 1))
                img = np.hstack([img[:, 8:, :], img[:, :8, :]])
                meta.append({
                    "width": width,
                    "height": height,
                    "bitmap": img.tolist()
                })
                img = 255 * img

                slices.append(img)
            except ValueError:
                pass
            else:
                blank_image = np.zeros((1, 16, 1), np.uint8)
                blank_image[::] = 0
                slices.append(blank_image)

        if glyph_offset <= prev:
            print("Glyph offsets not ordered")
        prev = glyph_offset
    print("Glyphs present:", characters_present)
    img = np.vstack(slices)

    img = np.flip(np.swapaxes(img, 1, 0), 0)
    s = img.shape * np.array(5)
    img = cv2.resize(img, dsize=(s[1], s[0]), interpolation=cv2.INTER_NEAREST)
    cv2.imwrite("samples/%s-%02x.png" % (src, font_index), img)
    with open("samples/%s-%02x.json" % (src, font_index), "w") as fh:
        fh.write(json.dumps({"glyphs": meta}))