#!/usr/bin/env python
from __future__ import print_function
import os
import re
import sys
import binascii
import time

assert len(sys.argv) > 2

start = time.time()
print("MEMFS: starting")

# Exclude experimental features e.g. GRIB3 and TAF
# The BUFR codetables is not used in the engine
EXCLUDED = ["grib3", "codetables", "taf", "stations"]
EXPECTED_FCOUNT = 6

pos = 1
if sys.argv[1] == "-exclude":
    product = sys.argv[2]
    if product == "bufr":
        EXCLUDED.append(product)
        EXPECTED_FCOUNT = 4
    elif product == "grib":
        EXCLUDED.extend(["grib1", "grib2"])
        EXPECTED_FCOUNT = 2
    else:
        assert False, "Invalid product %s" % product
    pos = 3

dirs = [os.path.realpath(x) for x in sys.argv[pos:-1]]
print("Directories: ", dirs)
print("Excluding: ", EXCLUDED)

FILES = {}
SIZES = {}
NAMES = []
CHUNK = 16 * 1024 * 1024  # chunk size in bytes

# Binary to ASCII function. Different in Python 2 and 3
try:
    str(b"\x23\x20", "ascii")
    ascii = lambda x: str(x, "ascii")  # Python 3
except:
    ascii = lambda x: str(x)  # Python 2


def get_outfile_name(base, count):
    return base + "_" + str(count).zfill(3) + ".c"


# The last argument is the base name of the generated C file(s)
output_file_base = sys.argv[-1]

buffer = None
fcount = -1

for directory in dirs:

    # print("MEMFS: directory=", directory)
    dname = os.path.basename(directory)
    NAMES.append(dname)

    for dirpath, dirnames, files in os.walk(directory, followlinks=True):

        # Prune the walk by modifying the dirnames in-place
        dirnames[:] = [dirname for dirname in dirnames if dirname not in EXCLUDED]
        for name in files:

            if buffer is None:
                fcount += 1
                opath = get_outfile_name(output_file_base, fcount)
                print("MEMFS: Generating output:", opath)
                buffer = open(opath, "w")

            full = "%s/%s" % (dirpath, name)
            _, ext = os.path.splitext(full)
            if ext not in [".def", ".table", ".tmpl", ".list", ".txt"]:
                continue
            if name == "CMakeLists.txt":
                continue

            full = full.replace("\\", "/")
            fname = full[full.find("/%s/" % (dname,)) :]
            # print("MEMFS: Add ", fname)
            name = re.sub(r"\W", "_", fname)

            assert name not in FILES
            assert name not in SIZES
            FILES[name] = fname
            SIZES[name] = os.path.getsize(full)

            buffer.write("const unsigned char %s[] = {" % (name,))

            with open(full, "rb") as f:
                i = 0
                # Python 2
                # contents_hex = f.read().encode("hex")

                # Python 2 and 3
                contents_hex = binascii.hexlify(f.read())

                # Read two characters at a time and convert to C hex
                # e.g. 23 -> 0x23
                for n in range(0, len(contents_hex), 2):
                    twoChars = ascii(contents_hex[n : n + 2])
                    buffer.write("0x%s," % (twoChars,))
                    i += 1
                    if (i % 20) == 0:
                        buffer.write("\n")

            buffer.write("};\n")
            if buffer.tell() >= CHUNK:
                buffer.close()
                buffer = None


if buffer is not None:
    buffer.close()

# The number of generated C files is hard coded.
# See memfs/CMakeLists.txt
assert fcount == EXPECTED_FCOUNT, fcount
opath = output_file_base + "_final.c"
print("MEMFS: Generating output:", opath)
g = open(opath, "w")

f = open(os.path.join(os.path.dirname(__file__), "src", "memfs.c"))
for line in f.readlines():
    line = line.rstrip()
    if "<MARKER>" in line:
        # Write extern variables with sizes
        for k, v in SIZES.items():
            print("extern const unsigned char %s[%d];" % (k, v), file=g)

        print(
            "static struct entry entries[] = {",
            file=g,
        )
        items = [(v, k) for k, v in FILES.items()]
        for k, v in sorted(items):
            print(
                '{"/MEMFS%s", &%s[0], sizeof(%s) / sizeof(%s[0]) },' % (k, v, v, v),
                file=g,
            )
        print(
            "};",
            file=g,
        )

    else:
        print(line, file=g)


print("Finished")

print("MEMFS: done", time.time() - start)