#!/usr/bin/env python3

import json
import argparse
import stat
import textwrap
import shutil
import subprocess
from tempfile import TemporaryDirectory
from pathlib import Path
import typing as T

image_namespace = 'mesonbuild'

image_def_file = 'image.json'
install_script = 'install.sh'

class ImageDef:
    def __init__(self, image_dir: Path) -> None:
        path = image_dir / image_def_file
        data = json.loads(path.read_text(encoding='utf-8'))

        assert isinstance(data, dict)
        assert all([x in data for x in ['base_image', 'env']])
        assert isinstance(data['base_image'], str)
        assert isinstance(data['env'],  dict)

        self.base_image: str = data['base_image']
        self.args: T.List[str] = data.get('args', [])
        self.env: T.Dict[str, str] = data['env']

class BuilderBase():
    def __init__(self, data_dir: Path, temp_dir: Path) -> None:
        self.data_dir = data_dir
        self.temp_dir = temp_dir

        self.common_sh = self.data_dir.parent / 'common.sh'
        self.common_sh = self.common_sh.resolve(strict=True)
        self.validate_data_dir()

        self.image_def = ImageDef(self.data_dir)

        self.docker = shutil.which('docker')
        self.git = shutil.which('git')
        if self.docker is None:
            raise RuntimeError('Unable to find docker')
        if self.git is None:
            raise RuntimeError('Unable to find git')

    def validate_data_dir(self) -> None:
        files = [
            self.data_dir / image_def_file,
            self.data_dir / install_script,
        ]
        if not self.data_dir.exists():
            raise RuntimeError(f'{self.data_dir.as_posix()} does not exist')
        for i in files:
            if not i.exists():
                raise RuntimeError(f'{i.as_posix()} does not exist')
            if not i.is_file():
                raise RuntimeError(f'{i.as_posix()} is not a regular file')

class Builder(BuilderBase):
    def gen_bashrc(self) -> None:
        out_file = self.temp_dir / 'env_vars.sh'
        out_data = ''

        # run_tests.py parameters
        self.image_def.env['CI_ARGS'] = ' '.join(self.image_def.args)

        for key, val in self.image_def.env.items():
            out_data += f'export {key}="{val}"\n'

        # Also add /ci to PATH
        out_data += 'export PATH="/ci:$PATH"\n'

        out_file.write_text(out_data, encoding='utf-8')

        # make it executable
        mode = out_file.stat().st_mode
        out_file.chmod(mode | stat.S_IEXEC)

    def gen_dockerfile(self) -> None:
        out_file = self.temp_dir / 'Dockerfile'
        out_data = textwrap.dedent(f'''\
            FROM {self.image_def.base_image}

            ADD install.sh  /ci/install.sh
            ADD common.sh   /ci/common.sh
            ADD env_vars.sh /ci/env_vars.sh
            RUN /ci/install.sh
        ''')

        out_file.write_text(out_data, encoding='utf-8')

    def do_build(self) -> None:
        # copy files
        for i in self.data_dir.iterdir():
            shutil.copy(str(i), str(self.temp_dir))
        shutil.copy(str(self.common_sh), str(self.temp_dir))

        self.gen_bashrc()
        self.gen_dockerfile()

        cmd_git = [self.git, 'rev-parse', '--short', 'HEAD']
        res = subprocess.run(cmd_git, cwd=self.data_dir, stdout=subprocess.PIPE)
        if res.returncode != 0:
            raise RuntimeError('Failed to get the current commit hash')
        commit_hash = res.stdout.decode().strip()

        cmd = [
            self.docker, 'build',
            '-t', f'{image_namespace}/{self.data_dir.name}:latest',
            '-t', f'{image_namespace}/{self.data_dir.name}:{commit_hash}',
            '--pull',
            self.temp_dir.as_posix(),
        ]
        if subprocess.run(cmd).returncode != 0:
            raise RuntimeError('Failed to build the docker image')

class ImageTester(BuilderBase):
    def __init__(self, data_dir: Path, temp_dir: Path, ci_root: Path) -> None:
        super().__init__(data_dir, temp_dir)
        self.meson_root = ci_root.parent.parent.resolve()

    def gen_dockerfile(self) -> None:
        out_file = self.temp_dir / 'Dockerfile'
        out_data = textwrap.dedent(f'''\
            FROM {image_namespace}/{self.data_dir.name}

            ADD meson /meson
        ''')

        out_file.write_text(out_data, encoding='utf-8')

    def copy_meson(self) -> None:
        shutil.copytree(
            self.meson_root,
            self.temp_dir / 'meson',
            ignore=shutil.ignore_patterns(
                '.git',
                '*_cache',
                '__pycache__',
                # 'work area',
                self.temp_dir.name,
            )
        )

    def do_test(self, tty: bool = False) -> None:
        self.copy_meson()
        self.gen_dockerfile()

        try:
            build_cmd = [
                self.docker, 'build',
                '-t', 'meson_test_image',
                self.temp_dir.as_posix(),
            ]
            if subprocess.run(build_cmd).returncode != 0:
                raise RuntimeError('Failed to build the test docker image')

            test_cmd = []
            if tty:
                test_cmd = [
                    self.docker, 'run', '--rm', '-t', '-i', 'meson_test_image',
                    '/bin/bash', '-c', ''
                    + 'cd meson;'
                    + 'source /ci/env_vars.sh;'
                    + f'echo -e "\\n\\nInteractive test shell in the {image_namespace}/{self.data_dir.name} container with the current meson tree";'
                    + 'echo -e "The file ci/ciimage/user.sh will be sourced if it exists to enable user specific configurations";'
                    + 'echo -e "Run the following command to run all CI tests: ./run_tests.py $CI_ARGS\\n\\n";'
                    + '[ -f ci/ciimage/user.sh ] && exec /bin/bash --init-file ci/ciimage/user.sh;'
                    + 'exec /bin/bash;'
                ]
            else:
                test_cmd = [
                    self.docker, 'run', '--rm', '-t', 'meson_test_image',
                    '/bin/bash', '-c', 'source /ci/env_vars.sh; cd meson; ./run_tests.py $CI_ARGS'
                ]

            if subprocess.run(test_cmd).returncode != 0 and not tty:
                raise RuntimeError('Running tests failed')
        finally:
            cleanup_cmd = [self.docker, 'rmi', '-f', 'meson_test_image']
            subprocess.run(cleanup_cmd).returncode

def main() -> None:
    parser = argparse.ArgumentParser(description='Meson CI image builder')
    parser.add_argument('what', type=str, help='Which image to build / test')
    parser.add_argument('-t', '--type', choices=['build', 'test', 'testTTY'], help='What to do', required=True)

    args = parser.parse_args()

    ci_root = Path(__file__).parent
    ci_data = ci_root / args.what

    with TemporaryDirectory(prefix=f'{args.type}_{args.what}_', dir=ci_root) as td:
        ci_build = Path(td)
        print(f'Build dir: {ci_build}')

        if args.type == 'build':
            builder = Builder(ci_data, ci_build)
            builder.do_build()
        elif args.type == 'test':
            tester = ImageTester(ci_data, ci_build, ci_root)
            tester.do_test()
        elif args.type == 'testTTY':
            tester = ImageTester(ci_data, ci_build, ci_root)
            tester.do_test(tty=True)

if __name__ == '__main__':
    main()
