#!/usr/bin/env python3
import argparse
import os
import sys
import hashlib
import shutil
import re
import collections
import urllib.parse
import multiprocessing
from configparser import ConfigParser

import requests

parser = argparse.ArgumentParser(
    description="A Simple Git-Based Modpack Manager",
    formatter_class=argparse.RawDescriptionHelpFormatter,
    epilog='''\
Available commands:
    install          : Downloads mods listed in version.txt and populates the mods folder specified in pack-location.txt
    apply_updates    : Using the urls in mods.txt, repopulates version.txt to reflect the most recent mod versions
    check_updates    : Compares version.txt and mods.txt to see if any mods can be updated
''')

parser.add_argument('command',
    nargs='?',
    default='install',
    help="The action to perform (default: install)")
parser.add_argument('filename',
    nargs='?',
    default="mods.txt",
    help="Optional filename to specify latest mods (default: mods.txt)")
parser.add_argument('--version-file',
    type=str,
    default="version.txt",
    help="Optional custom version file to download mods from (default: version.txt)")
parser.add_argument('--pack-location',
    type=str,
    help="Optional custom modpack folder location (default: read from pack-location.txt)")
parser.add_argument('--whitelist-file',
    type=str,
    default="whitelist.txt",
    help="Optional custom whitelist file that tells 'install' which files not to remove (default: whitelist.txt)")
parser.add_argument("--game-version",
    type=str,
    default=None,
    help="The maximum game version to update mods to")

## loaded from version.txt
VERSION = 0

def load_config():
    config = ConfigParser()
    config.read("pack.ini")
    config["pack"]["sanitized_name"] = sanitize_text(config["pack"]["name"])
    # return the whole config file, pack configuration and modlist
    return config

# take a string and only keep filename-friendly parts
def sanitize_text(text):
    sanitized = ""
    replacement_map = {" ": "-"}
    for char in text:
        if char.isalnum():
            sanitized += char.lower()
        elif char in replacement_map:
            sanitized += replacement_map[char]
    return sanitized


def read_file(fil):
    """
    Given a filename, read its contents in as a list of tuples.
    This function strips out comment lines and whitespaces.
    """
    strings = []
    with open(fil) as f:
        for line in f:
            string = line.strip().split()
            if len(line) > 1 and line[0] != '#':
                    # run strip on each element
                    string = tuple(map(lambda x: x.strip(), string))
                    strings.append(string)

    return strings

# Apply updates to the actual mod pack
def install(args):
    print("Updating pack with version " + str(VERSION) + "...")
    print()
    # (fname, checksum, url)
    mods = read_file(args.version_file)
    names = [mod[0] for mod in mods]
    # whitelist client mods (e.g. optifine)
    names += [line[0] for line in read_file(args.whitelist_file)]

    i = 0
    for mod in mods:
        mod_path = os.path.join(args.pack_location, mod[0])
        i += 1
        if os.path.exists(mod_path) and os.path.isfile(mod_path) and \
        hashlib.sha1(open(mod_path, 'rb').read()).hexdigest() == mod[1]:
            print("Skipping {mod[0]}, already up to date".format(mod=mod))
        else:
            print('Installing {mod[0]} from {mod[2]}...'.format(mod=mod))
            print(' ({i} of {x})'.format(i=i,x=len(mods)), end='\r')
            download_obj = requests.get(mod[2], stream=True)
            with open(mod_path, "wb") as write_file:
                shutil.copyfileobj(download_obj.raw, write_file)
            print("Done!" + " " * 8)

    print()
    print("Removing old mods...")
    for jar in os.listdir(args.pack_location):
        if jar not in names and os.path.splitext(jar)[1] == ".jar":
            os.remove(os.path.join(args.pack_location, jar))
            print("Removing '{jar}'".format(jar=jar))

    print()
    print("Finished installing mods!")


# Using the latest urls, update downloads.txt to match and have the correct sha1
def apply_updates(args):
    if args.game_version is not None:
        version = tuple(int(x) for x in args.game_version.split('.'))
    else:
        version = (2, 0, 0)
    print("Populating version file...")
    mods = read_file(args.filename)
    print("Getting new versions of all mods...")
    mod_urls = find_updated_urls([x[1] for x in mods], version)
    print("Downloading and checksumming all mods...")
    checksums = find_checksums(mod_urls)

    # Write information out to version.txt
    with open(args.version_file, 'w') as f:
        f.write('# Format: <jarname> <hex digested sha1> <direct download url>\n')
        f.write("#VERSION " + str(VERSION + 1) + "\n")
        for name, checksum, url in zip((mod[0] for mod in mods), checksums, mod_urls):
            f.write(f'{name} {checksum} {url}\n')

    print()
    print("Done!")
    print("Updates applied to {args.version_file}".format(args=args))
    print("New pack version is " + str(VERSION + 1))
    print("[!] No mods were installed. To update your mods folder, run 'update.py install'")


# Find if any updates are available
def check_updates(args):
    if args.game_version is not None:
        version = tuple(int(x) for x in args.game_version.split('.'))
    else:
        version = (2, 0, 0)
    print("Checking for updates to version " + str(VERSION) + "...")
    latest = read_file(args.filename)
    old = read_file(args.version_file)
    old_urls = [mod[2] for mod in old]
    num_updates = 0

    print("Checking updates...")
    ffx = firefox()

    for mod in latest:
        print("Checking for updates to {mod[0]}...".format(mod=mod), end="")
        sys.stdout.flush()  # takes care of line-buffered terminals
        if 'curseforge' in mod[1]:
            url = find_cdn(ffx, mod[1], version)
        else:
            url = requests.get(mod[1]).url
        if url in old_urls:
            print(" No updates")
        else:
            print(" Found update: " + url.split('/')[-1])
            num_updates += 1
    ffx.close()
    
    print("Finished checking for updates.  {num} mods can be updated".format(num=num_updates))
    if num_updates >= 0:
        print("Run 'python update.py apply_updates' to create a new version with these updates applied.")


def threaded_find_url(homepage_url, game_version):
    """
    Helper function that finds a single mod URL based on the homepage.
    """
    if 'curseforge' in homepage_url:
        ffx = firefox()
        final_url = find_cdn(ffx, homepage_url, game_version)
        ffx.close()
    else:
        final_url = requests.get(homepage_url).url
    return final_url


def find_updated_urls(forge_urls, game_version, threads=20):
    """
    Given a list of mod homepage URLs, find all of their direct download links in parallel.
    """

    # First, check that we can successfully open a Firefox instance in the main thread.
    # This provides us with a much nicer error message and quicker feedback.
    f = firefox()
    f.close()

    with multiprocessing.Pool(threads) as pool:
        # No progress indicator possible
        # return pool.map(threaded_find_url, forge_urls)

        # Much longer, but allows us to do a nice progress indicator
        result_futures = []
        for url in forge_urls:
            result_futures.append(pool.apply_async(threaded_find_url, (url, game_version)))

        results = []
        for i,f in enumerate(result_futures):
            results.append(f.get())
            print(f'\r{i+1}/{len(result_futures)} URLs updated ({round((i+1)/len(result_futures)*100)}%)', end='')
        print()

        return results


def threaded_calc_sha1(direct_url):
    """
    Helper function that downloads and calculates a single SHA1 hash from a direct download URL.
    """
    resp = requests.get(direct_url)
    hsh = hashlib.sha1(resp.content).hexdigest()
    return hsh


def find_checksums(direct_urls, threads=8):
    """
    Given a list of direct download URLs, download them all and calculate the SHA1 checksum of the file at that location.
    """
    
    with multiprocessing.Pool(threads) as pool:
        # Much longer, but allows us to do a nice progress indicator
        result_futures = []
        for url in direct_urls:
            result_futures.append(pool.apply_async(threaded_calc_sha1, (url,)))

        results = []
        for i,f in enumerate(result_futures):
            results.append(f.get())
            print(f'\r{i+1}/{len(result_futures)} checksums calculated ({round((i+1)/len(result_futures)*100)}%)', end='')
        print()

        return results


def find_cdn(ffx, url, version):
    """
    Given a mod home URL, finds the most up-to-date mod version compatible with the given game version.
    Returns the direct Forge CDN download URL
    """
    try:
        # This goes to the "all files" page, where we get a table view of all 
        ffx.get(url + '/files/all')
        mod_versions = ffx.find_elements_by_class_name("listing")[0].find_elements_by_xpath("tbody/tr") # extract the table of files from the page
        row_info = collections.namedtuple("row_info", ["type", "filename", "cdn_id", "game_version"]) # create a custom tuple because data
        rows = []
        for version_entry in mod_versions:
            # parse out the four fields that we use
            entry_cells = version_entry.find_elements_by_tag_name("td")
            release_type = entry_cells[0].text
            # Note that this is NOT the final filename - this is just the "release name".
            filename = urllib.parse.quote(entry_cells[1].find_elements_by_tag_name("a")[0].text)
            try:
                game_version = tuple([int(x) for x in entry_cells[4].find_element_by_class_name("mr-2").text.split(".")]) # get game version and convert to tuple
            except:
                game_version = (0, 0, 0)
            cdn_id = entry_cells[1].find_element_by_tag_name("a").get_property("href").split("/")[-1]

            #TODO make this configurable
            if 'fabric' not in filename.lower() or 'forge' in filename.lower():
                rows.append(row_info(release_type, filename, cdn_id, game_version))
        rows.sort(key=lambda x: x.game_version, reverse=True)
        best_row = next(x for x in rows if x.game_version <= version)

        # We need to find the real, ForgeCDN compatible filename now by going to the file page.
        ffx.get(f'{url}/files/{best_row.cdn_id}')
        # This will probably break in the future
        filename = ffx.find_elements_by_xpath("html/body/div/main/div/div/section/div/div/div/section/section/article/div/div/span")[1].text
        # URL escape the filename!
        filename = urllib.parse.quote(filename)

        # ForgeCDN requires that the leading zeroes are stripped from each portion of the CDN ID, hence the int() cast.
        return f'https://media.forgecdn.net/files/{int(best_row.cdn_id[:4])}/{int(best_row.cdn_id[4:])}/{filename}'

    except:
        print(url)
        open('temp.txt', 'a').write(url)
        import traceback; traceback.print_exc()
        return None


def firefox():
    """
    Start a headless Firefox instance and return the Selenium refrence to it.
    """
    #print("Starting Selenium...")
    try:
        from selenium.webdriver import Firefox
        from selenium.webdriver.firefox.options import Options
    except:
        print("Applying updates requires the `selenium` package")
        exit(0)
    options = Options()
    options.add_argument('-headless')
    options.add_argument('--window-size 1920,1080')
    return Firefox(executable_path='./geckodriver', options=options)

COMMAND_MAP = {
    'install': install,
    'apply_updates': apply_updates,
    'check_updates': check_updates,
}

if __name__ == "__main__":
    args = parser.parse_args()
    
    if not args.pack_location:
        # initialize from config
        with open("pack-location.txt", "r") as f:
            args.pack_location = f.read().strip()

    if not os.path.exists(args.version_file):
        print("Error: version file\"" + args.version_file + "\" does not exist.")
        parser.print_help()
        sys.exit(1)
    if not os.path.exists(args.pack_location):
        print("Error: mod folder \"" + args.pack_location + "\" does not exist.")
        parser.print_help()
        sys.exit(1)
    elif not os.path.isdir(args.pack_location):
        print("Error: mod folder \"" + args.pack_location + "\" is not actually a folder.")
        parser.print_help()
        sys.exit(1)
    if not os.path.exists(args.whitelist_file):
        print("Error: whitelist file \"" + args.whitelist_file + "\" does not exist.")
        sys.exit(1)
        
    if not (args.command in COMMAND_MAP):
        print("Error: command \"" + args.command + "\" does not exist")
        parser.print_help()
        sys.exit(1)
    
    # fetch version
    with open(args.version_file) as f:
        for line in f:
            if line.strip().split()[0] == "#VERSION":
                VERSION = int(line.strip().split()[1])
                break
    # run the command
    COMMAND_MAP[args.command](args)