# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

# Note: This script was written to follow the same business logic
#  as make_incremental_update.sh and funsize logic. There are many
#  opportunities for refactoring and improving how this works.
# Some improvement ideas:
# - The script diffs xz-compressed files. This is not optimal,
#      if we change XZ compression options, this will cause the
#      partial to have unnecessary updates.
# - Only decompress the target complete mar once
# - Separate this script into a python module with multiple files (ie: download, validation, diffing)
# - Implement caching of diffs. (Keeping in mind SCCACHE needs to
#      move away from AWS)
#      https://bugzilla.mozilla.org/show_bug.cgi?id=1842209
# - Writing of the manifest file could be done at the very end
#      instead of multiple writes
# - Check file signature
# - Check ALLOWED_URL_PREFIXES
# - Check mar channel ids

import argparse
import configparser
import functools
import glob
import hashlib
import json
import logging
import os
import re
import shutil
import subprocess
import sys
import traceback
import urllib.error
import urllib.request
from concurrent.futures import ProcessPoolExecutor
from tempfile import NamedTemporaryFile

# import multiprocessing

# Additional flags for XZ compression
BCJ_OPTIONS = {
    "x86": ["--x86"],
    "x86_64": ["--x86"],
    "aarch64": [],
    "macos-x86_64-aarch64": [],
}

logging.basicConfig(level=logging.INFO)


# TODO: use logging context instead of this
#   https://docs.python.org/3/howto/logging-cookbook.html#context-info
def log(msg, func=""):
    logging.info(f"[pid: {os.getpid()}] {func}: {msg}")


def xz_compression_options(arch):
    return (
        "--compress",
        "-T1",
        "-7e",
        *BCJ_OPTIONS.get(arch, []),
        "--lzma2",
        "--format=xz",
        "--check=crc64",
        "--force",
    )


# Copied from scriptworker
def get_hash(path):
    h = hashlib.new("sha512")
    with open(path, "rb") as f:
        for chunk in iter(functools.partial(f.read, 4096), b""):
            h.update(chunk)
    return h.hexdigest()


# The thread-safety of this function should be ok, given that each thread only reads it's own from_mar
#   and the main thread reads the to_mar
@functools.cache
def get_text_from_compressed(path):
    proc = subprocess.run(
        ("xz", "-d", "-c", path),
        capture_output=True,
        text=True,
        check=True,
    )
    return proc.stdout


def get_option_from_compressed(directory, filename, section, option):
    """Gets an option from an XZ compressed config file"""
    log(
        f"Extracting [{section}]: {option} from {directory}/**/{filename}",
        "get_option_from_compressed",
    )
    files = list(glob.glob(f"{directory}/**/{filename}", recursive=True))
    if not files:
        raise Exception(f"Could not find {filename} in {directory}")
    f = files.pop()
    contents = get_text_from_compressed(f)
    config = configparser.ConfigParser()
    config.read_string(contents)
    rv = config.get(section, option)
    log(f"Found {section}.{option}: {rv}", "get_option_from_compressed")
    return rv


def check_for_forced_update(force_list, file_path):
    """Check for files that are forced to update. Note: .chk files are always force updated"""
    # List of files that are always force updated
    always_force_updated = (
        "precomplete",
        "Contents/Resources/precomplete",
        "removed-files",
        "Contents/Resources/removed-files",
        "Contents/CodeResources",
    )
    return (
        file_path in always_force_updated
        or file_path.endswith(".chk")
        or file_path in force_list
    )


def list_files_and_dirs(dir_path):
    files = []
    dirs = []
    for root, directories, filenames in os.walk(dir_path):
        for directory in directories:
            dirs.append(os.path.relpath(os.path.join(root, directory), dir_path))
        for filename in filenames:
            files.append(os.path.relpath(os.path.join(root, filename), dir_path))
    return files, dirs


def make_add_instruction(filename, manifest):
    """Adds an instruction to the update manifest file."""
    # Check if the path is an extension directory
    is_extension = re.search(r"distribution/extensions/.*/", filename) is not None

    if is_extension:
        # Extract the subdirectory to test before adding
        testdir = re.sub(r"(.*distribution/extensions/[^/]*)/.*", r"\1", filename)
        with open(manifest, "a") as file:
            file.write(f'add-if "{testdir}" "{filename}"\n')
    else:
        with open(manifest, "a") as file:
            file.write(f'add "{filename}"\n')


def check_for_add_if_not_update(filename):
    basename = os.path.basename(filename)
    return (
        basename in {"channel-prefs.js", "update-settings.ini"}
        or re.search(r"(^|/)ChannelPrefs\.framework/", filename)
        or re.search(r"(^|/)UpdateSettings\.framework/", filename)
    )


def make_patch_instruction(filename, manifest):
    with open(manifest, "a") as manifest_file:
        manifest_file.write(f'patch "{filename}"\n')


def add_remove_instructions(remove_array, manifest):
    with open(manifest, "a") as manifest_file:
        for file in remove_array:
            manifest_file.write(f'remove "{file}"\n')


def make_add_if_not_instruction(filename, manifest):
    with open(manifest, "a") as manifest_file:
        manifest_file.write(f'add-if-not "{filename}" "{filename}"\n')


def append_remove_instructions(newdir, manifest):
    removed_files_path = os.path.join(newdir, "removed-files")
    if os.path.exists(removed_files_path):
        with NamedTemporaryFile() as rmv, open(rmv.name) as f:
            xz_cmd(("--decompress",), removed_files_path, rmv.name)
            removed_files = f.readlines()
        with open(manifest, "a") as manifest_file:
            for file in removed_files:
                manifest_file.write(f'remove "{file.strip()}"\n')


def mar_extract(source_mar, destination):
    os.makedirs(destination, exist_ok=True)
    cmd = ("mar", "-C", os.path.abspath(destination), "-x", os.path.abspath(source_mar))
    log(f"Running mar extract command: {cmd}", "mar_extract")
    try:
        subprocess.run(cmd, check=True)
    except subprocess.CalledProcessError as e:
        log(f"Error extracting mar: {e.stderr}", "mar_extract")
        raise Exception(f"Mar failed with code {e.returncode}")


def xz_cmd(cmd, source_file, destination_file):
    """Run xz command via pipes to avoid file extension checks."""
    os.makedirs(os.path.dirname(destination_file), exist_ok=True)
    with open(destination_file, "wb") as dest_fd, open(source_file, "rb") as source_fd:
        try:
            subprocess.run(("xz", *cmd), stdin=source_fd, stdout=dest_fd, check=True)
        except subprocess.CalledProcessError as e:
            log(
                f"XZ Failure running xz {cmd} on {source_file} to {destination_file}: {e.stderr}",
                "xz_cmd",
            )
            raise Exception(f"XZ exited with code {e.returncode}")


def create_patch(from_file, to_file, destination_patch):
    """Create a patch between 2 xz compressed files"""
    log(f"{from_file} -> {destination_patch}", "create_patch")

    with (
        NamedTemporaryFile() as from_fd,
        NamedTemporaryFile() as to_fd,
        NamedTemporaryFile() as patch_fd,
    ):
        xz_cmd(("--decompress",), from_file, from_fd.name)

        # TODO: Potentially don't decompress to_mar files once per thread?
        xz_cmd(("--decompress",), to_file, to_fd.name)

        # args = f"zucchini -gen '{from_fd.name}' '{to_fd.name}' '{patch_fd.name}'"
        args = ["zucchini", "-gen", from_fd.name, to_fd.name, patch_fd.name]
        try:
            subprocess.run(args, check=True)
        except subprocess.CalledProcessError as e:
            log(f"Zucchini failed to create patch:\n{e.stderr}", "create_patch")
            raise Exception(f"Zucchini exited with code: {e.returncode}")

        xz_cmd(("--compress", "-9", "-e", "-c"), patch_fd.name, destination_patch)


def make_partial(from_mar_url, to_mar_dir, target_mar, workdir, arch="", force=None):
    # Download from_mar
    from_mar = os.path.join(workdir, "from.mar")
    download_file(from_mar_url, from_mar)

    requested_forced_updates = force or []
    # MacOS firefox binary is always forced update
    requested_forced_updates.append("Contents/MacOS/firefox")
    manifest_file = os.path.join(workdir, "updatev3.manifest")

    # Holds the relative path to all archive files to be added to the partial
    archivefiles = []

    # Mar extract
    from_mar_dir = os.path.join(workdir, "from_mar")
    mar_extract(from_mar, from_mar_dir)

    # Log current version for easier referencing
    from_version = get_option_from_compressed(
        from_mar_dir, "application.ini", "App", "Version"
    )
    log(f"Processing from_mar: {from_version}", "make_partial")

    partials_dir = os.path.abspath(os.path.join(workdir, "partials"))
    os.makedirs(partials_dir, exist_ok=True)

    # List files and directories
    oldfiles, olddirs = list_files_and_dirs(from_mar_dir)
    newfiles, newdirs = list_files_and_dirs(to_mar_dir)

    for newdir in newdirs:
        os.makedirs(os.path.join(partials_dir, newdir), exist_ok=True)

    # Check if precomplete file exists in the new directory
    if not os.path.exists(
        os.path.join(to_mar_dir, "precomplete")
    ) and not os.path.exists(
        os.path.join(to_mar_dir, "Contents/Resources/precomplete")
    ):
        log("precomplete file is missing!", "make_partial")
        return 1

    # Create update manifest
    with open(manifest_file, "w") as manifest_fd:
        manifest_fd.write('type "partial"\n')

    remove_array = []

    # Process files for patching
    # Note: these files are already XZ compressed
    for rel_path in oldfiles:
        new_file_abs = os.path.join(to_mar_dir, rel_path)
        old_file_abs = os.path.join(from_mar_dir, rel_path)

        if os.path.exists(new_file_abs):
            patch_file = os.path.join(partials_dir, rel_path)
            if check_for_add_if_not_update(old_file_abs):
                make_add_if_not_instruction(rel_path, manifest_file)
                shutil.copy2(new_file_abs, patch_file)
                archivefiles.append(rel_path)
            elif check_for_forced_update(requested_forced_updates, rel_path):
                make_add_instruction(rel_path, manifest_file)
                shutil.copy2(new_file_abs, patch_file)
                archivefiles.append(rel_path)
            elif (
                # TODO: !!! This check will always trigger if we switch XZ options!
                subprocess.run(
                    ("diff", old_file_abs, new_file_abs),
                    check=False,
                ).returncode
                != 0
            ):
                # Check for smaller patch or full file size and choose the smaller of the two to package
                create_patch(old_file_abs, new_file_abs, f"{patch_file}.patch")
                if (
                    os.stat(f"{patch_file}.patch").st_size
                    > os.stat(new_file_abs).st_size
                ):
                    make_add_instruction(rel_path, manifest_file)
                    os.unlink(f"{patch_file}.patch")
                    shutil.copy2(new_file_abs, patch_file)
                    archivefiles.append(rel_path)
                else:
                    make_patch_instruction(patch_file, manifest_file)
                    path_relpath = os.path.relpath(patch_file, partials_dir)
                    archivefiles.append(f"{path_relpath}.patch")

        else:
            remove_array.append(rel_path)

    # Newly added files
    for newfile_rel in newfiles:
        new_file_abs = os.path.join(to_mar_dir, newfile_rel)
        if newfile_rel not in oldfiles:
            patch_file = os.path.join(partials_dir, newfile_rel)
            make_add_instruction(newfile_rel, manifest_file)
            archivefiles.append(newfile_rel)
            shutil.copy2(new_file_abs, patch_file)

    # Remove files
    add_remove_instructions(remove_array, manifest_file)

    # Add directory removal instructions from removed-files
    append_remove_instructions(to_mar_dir, manifest_file)

    # Compress manifest file and add to list of archived files
    compressed_manifest = os.path.join(partials_dir, "updatev3.manifest")
    xz_cmd(xz_compression_options(arch), manifest_file, compressed_manifest)
    archivefiles.append("updatev3.manifest")

    # Use
    mar_channel_id = os.environ.get("MAR_CHANNEL_ID", "unknown")
    version = get_option_from_compressed(
        to_mar_dir, "application.ini", "App", "Version"
    )
    # from_version = get_option_from_compressed(from_mar_dir, "application.ini", "App", "Version")

    log(f"Archive files: {' '.join(archivefiles)}", "make_partial")

    mar_cmd = (
        "mar",
        "-H",
        mar_channel_id,
        "-V",
        version,
        "-c",
        target_mar,
        *archivefiles,
    )
    log(f"Running mar command with: {' '.join(mar_cmd)}", "make_partial")
    try:
        subprocess.run(mar_cmd, cwd=partials_dir, check=True)
    except subprocess.CalledProcessError as e:
        log(f"Error creating mar:\n{e.stderr}")
        raise Exception(f"Mar exited with code {e.returncode}")

    return {
        "MAR_CHANNEL_ID": mar_channel_id,
        "appName": get_option_from_compressed(
            from_mar_dir, filename="application.ini", section="App", option="Name"
        ),
        "from_size": os.path.getsize(from_mar),
        "from_hash": get_hash(from_mar),
        "from_buildid": get_option_from_compressed(
            from_mar_dir, filename="application.ini", section="App", option="BuildID"
        ),
        "mar": os.path.basename(target_mar),
        "size": os.path.getsize(target_mar),
        "from_mar": from_mar_url,
    }


def download_file(url, save_path):
    """
    Downloads a file from a given URL and saves it to disk.

    Args:
    url (str): The URL to download the file from.
    save_path (str): The path (including filename) where the file should be saved.
    """
    try:
        # Download the file and save it to the specified path
        urllib.request.urlretrieve(url, save_path)
        log(f"File downloaded successfully: {save_path}", "download_file")
    except urllib.error.URLError as e:
        log(f"Error downloading file: {url} -> {e}", "download_file")
        raise Exception("Failed to download file.")
    except Exception as e:
        log(f"An unexpected error occurred: {url} -> {e}", "download_file")
        raise Exception("Failed to download file.")


def process_single(
    update_number,
    from_mar_url,
    to_mar_dir,
    target_mar,
    workdir,
    arch,
    force,
):
    try:
        mar_manifest = make_partial(
            from_mar_url, to_mar_dir, target_mar, workdir, arch, force
        )
        mar_manifest["update_number"] = update_number
        return None, mar_manifest
    except Exception as e:
        log(traceback.format_exc(), "process_single")
        return e, None


def main():
    parser = argparse.ArgumentParser(
        description="Generate incremental update packages with zucchini."
    )
    parser.add_argument(
        "--from_url", help="Complete mar URLs", action="append", required=True
    )
    parser.add_argument("--to_mar", help="To complete mar", required=True)
    parser.add_argument(
        "--to_mar_url",
        help="To mar URL. Only used for filling the manifest.json file.",
        action="store",
        required=False,
        default="",
    )
    parser.add_argument("--target", help="Target partial mar location", required=True)
    parser.add_argument(
        "--workdir", help="Work directory", action="store", required=True
    )
    parser.add_argument("--locale", help="Build locale", action="store", required=True)
    parser.add_argument(
        "--arch",
        help="Target Architecture",
        action="store",
        choices=BCJ_OPTIONS.keys(),
        required=True,
    )
    parser.add_argument(
        "--force",
        help="Clobber this file in the installation. Must be a path to a file to clobber in the partial update.",
        action="append",
    )

    args = parser.parse_args()

    base_workdir = os.path.abspath(args.workdir)

    # Multithread one partial per CPU
    cpus = os.cpu_count()  # This isn't optimal, but will do for now
    log(f"CPUs available for parallel computing: {cpus}", "main")

    # Create target directory with locale
    target = os.path.abspath(args.target)
    os.makedirs(target, exist_ok=True)

    # Decompress to_mar early
    to_mar_dir = os.path.join(base_workdir, "to_mar")
    mar_extract(args.to_mar, to_mar_dir)

    futures = []
    futures_result = []

    def future_cb(f):
        if not f.cancelled():
            futures_result.append(f.result())
        else:
            futures_result.append(("Cancelled", None))

    with ProcessPoolExecutor(cpus) as executor:
        # TODO: should the update_number come from the task payload?
        for update_number, from_url in enumerate(args.from_url):
            process_workdir = os.path.join(base_workdir, str(update_number))
            os.makedirs(process_workdir, exist_ok=True)
            target_mar = os.path.join(target, f"target.partial-{update_number}.mar")
            future = executor.submit(
                process_single,
                update_number,
                from_url,
                to_mar_dir,
                target_mar,
                process_workdir,
                args.arch,
                args.force,
            )
            future.add_done_callback(future_cb)
            futures.append(future)

    log("Finished all processes.", "main")

    to_mar_info = {
        "locale": args.locale,
        # Use Gecko repo and rev from platform.ini, not application.ini
        "repo": get_option_from_compressed(
            to_mar_dir,
            filename="platform.ini",
            section="Build",
            option="SourceRepository",
        ),
        "revision": get_option_from_compressed(
            to_mar_dir, filename="platform.ini", section="Build", option="SourceStamp"
        ),
        "version": get_option_from_compressed(
            to_mar_dir, filename="platform.ini", section="Build", option="SourceStamp"
        ),
        "to_buildid": get_option_from_compressed(
            to_mar_dir, filename="application.ini", section="App", option="BuildID"
        ),
        "to_hash": get_hash(args.to_mar),
        "to_size": os.stat(args.to_mar).st_size,
        "to_mar": args.to_mar_url,
    }

    errd = False
    results = []
    for error, manifest in futures_result:
        if manifest:
            manifest.update(to_mar_info)
            results.append(manifest)
        else:
            errd = True
            log("Process raised an exception!", "main")
            print(error)
    if errd:
        sys.exit(1)

    # Write final task manifest
    with open(os.path.join(target, "manifest.json"), "w") as fd:
        fd.write(json.dumps(results))

    log("Finished writing final manifest.", "main")


if __name__ == "__main__":
    main()