#!python3
import freetype
import zlib
import sys
import re
import math
import argparse
from collections import namedtuple

# From: https://github.com/vroland/epdiy

parser = argparse.ArgumentParser(description="Generate a header file from a font to be used with epdiy.")
parser.add_argument("name", action="store", help="name of the font.")
parser.add_argument("size", type=int, help="font size to use.")
parser.add_argument("fontstack", action="store", nargs='+', help="list of font files, ordered by descending priority.")
parser.add_argument("--compress", dest="compress", action="store_true", help="compress glyph bitmaps.")
parser.add_argument("--additional-intervals", dest="additional_intervals", action="append", help="Additional code point intervals to export as min,max. This argument can be repeated.")
args = parser.parse_args()

GlyphProps = namedtuple("GlyphProps", ["width", "height", "advance_x", "left", "top", "compressed_size", "data_offset", "code_point"])

font_stack = [freetype.Face(f) for f in args.fontstack]
compress = args.compress
size = args.size
font_name = args.name

# inclusive unicode code point intervals
# must not overlap and be in ascending order
intervals = [
    ### Basic Latin ###
    # ASCII letters, digits, punctuation, control characters
    (0x0000, 0x007F),
    ### Latin-1 Supplement ###
    # Accented characters for Western European languages
    (0x0080, 0x00FF),
    ### Latin Extended-A ###
    # Eastern European and Baltic languages
    (0x0100, 0x017F),
    ### General Punctuation (core subset) ###
    # Smart quotes, en dash, em dash, ellipsis, NO-BREAK SPACE
    (0x2000, 0x206F),
    ### Basic Symbols From "Latin-1 + Misc" ###
    # dashes, quotes, prime marks
    (0x2010, 0x203A),
    # misc punctuation
    (0x2040, 0x205F),
    # common currency symbols
    (0x20A0, 0x20CF),
    ### Combining Diacritical Marks (minimal subset) ###
    # Needed for proper rendering of many extended Latin languages
    (0x0300, 0x036F),
    ### Greek & Coptic ###
    # Used in science, maths, philosophy, some academic texts
    # (0x0370, 0x03FF),
    ### Cyrillic ###
    # Russian, Ukrainian, Bulgarian, etc.
    # (0x0400, 0x04FF),
    ### Math Symbols (common subset) ###
    # General math operators
    (0x2200, 0x22FF),
    # Arrows
    (0x2190, 0x21FF),
    ### CJK ###
    # Core Unified Ideographs
    # (0x4E00, 0x9FFF),
    # # Extension A
    # (0x3400, 0x4DBF),
    # # Extension B
    # (0x20000, 0x2A6DF),
    # # Extension C–F
    # (0x2A700, 0x2EBEF),
    # # Extension G
    # (0x30000, 0x3134F),
    # # Hiragana
    # (0x3040, 0x309F),
    # # Katakana
    # (0x30A0, 0x30FF),
    # # Katakana Phonetic Extensions
    # (0x31F0, 0x31FF),
    # # Halfwidth Katakana
    # (0xFF60, 0xFF9F),
    # # Hangul Syllables
    # (0xAC00, 0xD7AF),
    # # Hangul Jamo
    # (0x1100, 0x11FF),
    # # Hangul Compatibility Jamo
    # (0x3130, 0x318F),
    # # Hangul Jamo Extended-A
    # (0xA960, 0xA97F),
    # # Hangul Jamo Extended-B
    # (0xD7B0, 0xD7FF),
    # # CJK Radicals Supplement
    # (0x2E80, 0x2EFF),
    # # Kangxi Radicals
    # (0x2F00, 0x2FDF),
    # # CJK Symbols and Punctuation
    # (0x3000, 0x303F),
    # # CJK Compatibility Forms
    # (0xFE30, 0xFE4F),
    # # CJK Compatibility Ideographs
    # (0xF900, 0xFAFF),
]

add_ints = []
if args.additional_intervals:
    add_ints = [tuple([int(n, base=0) for n in i.split(",")]) for i in args.additional_intervals]

def norm_floor(val):
    return int(math.floor(val / (1 << 6)))

def norm_ceil(val):
    return int(math.ceil(val / (1 << 6)))

def chunks(l, n):
    for i in range(0, len(l), n):
        yield l[i:i + n]

def load_glyph(code_point):
    face_index = 0
    while face_index < len(font_stack):
        face = font_stack[face_index]
        glyph_index = face.get_char_index(code_point)
        if glyph_index > 0:
            face.load_glyph(glyph_index, freetype.FT_LOAD_RENDER)
            return face
        face_index += 1
    print(f"code point {code_point} ({hex(code_point)}) not found in font stack!", file=sys.stderr)
    return None

unmerged_intervals = sorted(intervals + add_ints)
intervals = []
unvalidated_intervals = []
for i_start, i_end in unmerged_intervals:
    if len(unvalidated_intervals) > 0 and i_start + 1 <= unvalidated_intervals[-1][1]:
        unvalidated_intervals[-1] = (unvalidated_intervals[-1][0], max(unvalidated_intervals[-1][1], i_end))
        continue
    unvalidated_intervals.append((i_start, i_end))

for i_start, i_end in unvalidated_intervals:
    start = i_start
    for code_point in range(i_start, i_end + 1):
        face = load_glyph(code_point)
        if face is None:
            if start < code_point:
                intervals.append((start, code_point - 1))
            start = code_point + 1
    if start != i_end + 1:
        intervals.append((start, i_end))

for face in font_stack:
    # shift by 6 bytes, because sizes are given as 6-bit fractions
    # the display has about 150 dpi.
    face.set_char_size(size << 6, size << 6, 150, 150)

total_size = 0
total_packed = 0
all_glyphs = []

for i_start, i_end in intervals:
    for code_point in range(i_start, i_end + 1):
        face = load_glyph(code_point)
        bitmap = face.glyph.bitmap
        pixels = []
        px = 0
        for i, v in enumerate(bitmap.buffer):
            y = i / bitmap.width
            x = i % bitmap.width
            if x % 2 == 0:
                px = (v >> 4)
            else:
                px = px | (v & 0xF0)
                pixels.append(px);
                px = 0
            # eol
            if x == bitmap.width - 1 and bitmap.width % 2 > 0:
                pixels.append(px)
                px = 0

        packed = bytes(pixels);
        total_packed += len(packed)
        compressed = packed
        if compress:
            compressed = zlib.compress(packed)

        glyph = GlyphProps(
            width = bitmap.width,
            height = bitmap.rows,
            advance_x = norm_floor(face.glyph.advance.x),
            left = face.glyph.bitmap_left,
            top = face.glyph.bitmap_top,
            compressed_size = len(compressed),
            data_offset = total_size,
            code_point = code_point,
        )
        total_size += len(compressed)
        all_glyphs.append((glyph, compressed))

# pipe seems to be a good heuristic for the "real" descender
face = load_glyph(ord('|'))

glyph_data = []
glyph_props = []
for index, glyph in enumerate(all_glyphs):
    props, compressed = glyph
    glyph_data.extend([b for b in compressed])
    glyph_props.append(props)

print(f"/**\n * generated by fontconvert.py\n * name: {font_name}\n * size: {size}\n * compressed: {compress}\n */")
print("#pragma once")
print("#include \"EpdFontData.h\"\n")
print(f"static const uint8_t {font_name}Bitmaps[{len(glyph_data)}] = {{")
for c in chunks(glyph_data, 16):
    print ("    " + " ".join(f"0x{b:02X}," for b in c))
print ("};\n");

print(f"static const EpdGlyph {font_name}Glyphs[] = {{")
for i, g in enumerate(glyph_props):
    print ("    { " + ", ".join([f"{a}" for a in list(g[:-1])]),"},", f"// {chr(g.code_point) if g.code_point != 92 else '<backslash>'}")
print ("};\n");

print(f"static const EpdUnicodeInterval {font_name}Intervals[] = {{")
offset = 0
for i_start, i_end in intervals:
    print (f"    {{ 0x{i_start:X}, 0x{i_end:X}, 0x{offset:X} }},")
    offset += i_end - i_start + 1
print ("};\n");

print(f"static const EpdFontData {font_name} = {{")
print(f"    {font_name}Bitmaps,")
print(f"    {font_name}Glyphs,")
print(f"    {font_name}Intervals,")
print(f"    {len(intervals)},")
print(f"    {1 if compress else 0},")
print(f"    {norm_ceil(face.size.height)},")
print(f"    {norm_ceil(face.size.ascender)},")
print(f"    {norm_floor(face.size.descender)},")
print("};")