#!/usr/bin/env python3
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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
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#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
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# under the License.
import argparse
import configparser
import datetime
import difflib
import re
import textwrap
from dataclasses import dataclass
from pathlib import Path

import jinja2

REPO_ROOT = Path(__file__).resolve().parent.parent.parent
JENKINS_DIR = REPO_ROOT / "ci" / "jenkins"
TEMPLATES_DIR = JENKINS_DIR / "templates"
GENERATED_DIR = JENKINS_DIR / "generated"
DOCKER_IMAGES_INI = JENKINS_DIR / "docker-images.ini"

# Platform mapping for the CI image registry. The ini section names are the
# image names; this dict pins their Jenkins agent label. Keep in sync with
# the [jenkins] section of docker-images.ini when adding/removing images.
_IMAGE_PLATFORMS = {
    "ci_arm": "ARM",
    "ci_cpu": "CPU",
    "ci_gpu": "GPU",
    "ci_wasm": "CPU",
}


def _build_render_context() -> dict:
    """Build the Jinja render context: image metadata + AWS endpoints."""
    config = configparser.ConfigParser()
    config.read(DOCKER_IMAGES_INI)
    images = [
        {"name": name, "platform": platform}
        for name, platform in _IMAGE_PLATFORMS.items()
        if config.has_option("jenkins", name)
    ]
    aws_default_region = "us-west-2"
    return {
        "images": images,
        "aws_default_region": aws_default_region,
        "aws_ecr_url": f"dkr.ecr.{aws_default_region}.amazonaws.com",
    }


data = _build_render_context()


class Change:
    IMAGES_ONLY = object()
    NONE = object()
    FULL = object()


@dataclass
class ChangeData:
    diff: str | None
    content: str
    destination: Path
    source: Path


def lines_without_generated_tag(content):
    return [
        line for line in content.splitlines(keepends=True) if not line.startswith("// Generated at")
    ]


def change_type(lines: list[str]) -> Change:
    """
    Return True if 'line' only edits an image tag or if 'line' is not a changed
    line in a diff
    """
    added_images = []
    removed_images = []
    diff_lines = []

    for line in lines[2:]:
        if not line.startswith("-") and not line.startswith("+"):
            # not a diff line, ignore it
            continue

        diff_lines.append(line)

    if len(diff_lines) == 0:
        # no changes made
        return Change.NONE

    for line in diff_lines:
        is_add = line.startswith("+")
        line = line.strip().lstrip("+").lstrip("-")
        match = re.search(
            r"^(ci_[a-zA-Z0-9]+) = \'.*\'$",
            line.strip().lstrip("+").lstrip("-"),
            flags=re.MULTILINE,
        )
        if match is None:
            # matched a non-image line, quit early
            return Change.FULL

        if is_add:
            added_images.append(match.groups()[0])
        else:
            removed_images.append(match.groups()[0])

    # make sure that the added image lines match the removed image lines
    if len(added_images) > 0 and added_images == removed_images:
        return Change.IMAGES_ONLY
    else:
        return Change.FULL


def update_jenkinsfile(source: Path) -> ChangeData:
    destination = GENERATED_DIR / source.stem

    data["generated_time"] = datetime.datetime.now().isoformat()
    if destination.exists():
        with open(destination) as f:
            old_generated_content = f.read()

        timestamp_match = re.search(
            r"^// Generated at (.*)$", old_generated_content, flags=re.MULTILINE
        )
        if not timestamp_match:
            raise RuntimeError(
                f"Could not find timestamp in Jenkinsfile: {destination.relative_to(TEMPLATES_DIR)}"
            )
        original_timestamp = timestamp_match.groups()[0]

    environment = jinja2.Environment(
        loader=jinja2.FileSystemLoader(TEMPLATES_DIR),
        undefined=jinja2.StrictUndefined,
        lstrip_blocks=True,
        trim_blocks=True,
        keep_trailing_newline=True,
    )
    template = environment.get_template(str(source.relative_to(TEMPLATES_DIR)))
    new_content = template.render(**data)

    if not destination.exists():
        # New file, create it from scratch
        return ChangeData(
            diff=new_content, content=new_content, source=source, destination=destination
        )

    diff = [
        line
        for line in difflib.unified_diff(
            lines_without_generated_tag(old_generated_content),
            lines_without_generated_tag(new_content),
        )
    ]
    change = change_type(diff)
    if (not args.force and change == Change.IMAGES_ONLY) or change == Change.NONE:
        if change != Change.NONE:
            print("Detected only Docker-image name changes, skipping timestamp update")
        new_content = new_content.replace(data["generated_time"], original_timestamp)

    diff = "".join(diff)

    return ChangeData(diff=diff, content=new_content, source=source, destination=destination)


if __name__ == "__main__":
    help = "Regenerate Jenkinsfile from template"
    parser = argparse.ArgumentParser(description=help)
    parser.add_argument("--force", action="store_true", help="always overwrite timestamp")
    parser.add_argument("--check", action="store_true", help="just verify the output didn't change")
    args = parser.parse_args()

    sources = TEMPLATES_DIR.glob("*_jenkinsfile.groovy.j2")
    changes = [update_jenkinsfile(source) for source in sources if source.name != "base.groovy.j2"]

    if args.check:
        if all(not data.diff for data in changes):
            print("Success, the newly generated Jenkinsfiles matched the ones on disk")
            exit(0)
        else:
            print(
                textwrap.dedent(
                    """
                Newly generated Jenkinsfiles did not match the ones on disk! If you have made
                edits to the Jenkinsfiles in generated/, move them to the corresponding source and
                regenerate the Jenkinsfiles from the templates with

                    python3 -m pip install -r jenkins/requirements.txt
                    python3 jenkins/generate.py

                Diffed changes:
            """
                ).strip()
            )
            for data in changes:
                if data.diff:
                    source = data.source.relative_to(REPO_ROOT)
                    print(source)
                    print(data.diff)

            exit(1)
    else:
        for data in changes:
            with open(data.destination, "w") as f:
                f.write(data.content)

            if not data.diff:
                print(f"Wrote output to {data.destination.relative_to(REPO_ROOT)}, no changes made")
            else:
                print(f"Wrote output to {data.destination.relative_to(REPO_ROOT)}, changes:")
                print(data.diff)