#!/usr/bin/python3


import argparse
import contextlib
import os
import shutil
import subprocess
import sys


def format_title(title):
    box = {
        'tl': '╔', 'tr': '╗', 'bl': '╚', 'br': '╝', 'h': '═', 'v': '║',
    }
    hline = box['h'] * (len(title) + 2)

    return '\n'.join([
        f"{box['tl']}{hline}{box['tr']}",
        f"{box['v']} {title} {box['v']}",
        f"{box['bl']}{hline}{box['br']}",
    ])


def rm_rf(path):
    try:
        shutil.rmtree(path)
    except FileNotFoundError:
        pass


def sanitize_path(name):
    return name.replace('/', '-')


def get_current_revision():
    revision = subprocess.check_output(['git', 'rev-parse', '--abbrev-ref', 'HEAD'],
                                       encoding='utf-8').strip()

    if revision == 'HEAD':
        # This is a detached HEAD, get the commit hash
        revision = subprocess.check_output(['git', 'rev-parse', 'HEAD']).strip().decode('utf-8')

    return revision


@contextlib.contextmanager
def checkout_git_revision(revision):
    current_revision = get_current_revision()
    subprocess.check_call(['git', 'checkout', '-q', revision])

    try:
        yield
    finally:
        subprocess.check_call(['git', 'checkout', '-q', current_revision])


def build_install(revision):
    build_dir = '_build'
    dest_dir = os.path.abspath(sanitize_path(revision))
    print(format_title(f'# Building and installing {revision} in {dest_dir}'),
          end='\n\n', flush=True)

    with checkout_git_revision(revision):
        rm_rf(build_dir)
        rm_rf(revision)

        subprocess.check_call(['meson', build_dir,
                               '--prefix=/usr', '--libdir=lib',
                               '-Dx11-examples=false', '-Ddoc=false', '-Dgtk-examples=false'])
        subprocess.check_call(['ninja', '-v', '-C', build_dir])
        subprocess.check_call(['ninja', '-v', '-C', build_dir, 'install'],
                              env={'DESTDIR': dest_dir})

    return dest_dir


def compare(old_tree, new_tree):
    print(format_title(f'# Comparing the two ABIs'), end='\n\n', flush=True)

    old_headers = os.path.join(old_tree, 'usr', 'include')
    old_lib = os.path.join(old_tree, 'usr', 'lib', 'libfprint.so')

    new_headers = os.path.join(new_tree, 'usr', 'include')
    new_lib = os.path.join(new_tree, 'usr', 'lib', 'libfprint.so')

    subprocess.check_call([
        'abidiff', '--headers-dir1', old_headers, '--headers-dir2', new_headers,
        '--drop-private-types', '--fail-no-debug-info', '--no-added-syms', old_lib, new_lib])


if __name__ == '__main__':
    parser = argparse.ArgumentParser()

    parser.add_argument('old', help='the previous revision, considered the reference')
    parser.add_argument('new', help='the new revision, to compare to the reference')

    args = parser.parse_args()

    if args.old == args.new:
        print("Let's not waste time comparing something to itself")
        sys.exit(0)

    old_tree = build_install(args.old)
    new_tree = build_install(args.new)

    try:
        compare(old_tree, new_tree)

    except Exception:
        sys.exit(1)

    print(f'Hurray! {args.old} and {args.new} are ABI-compatible!')
