#!/usr/bin/env python3

import os
import subprocess
import sys
from typing import Optional


MAX_DIFF_CHARS = 12000


def run_git_command(*args: str) -> str:
    result = subprocess.run(
        ["git", *args],
        check=True,
        capture_output=True,
        text=True,
    )
    return result.stdout.strip()


def try_git_command(*args: str) -> Optional[str]:
    try:
        return run_git_command(*args)
    except subprocess.CalledProcessError:
        return None


def resolve_base_commit() -> Optional[str]:
    for env_name in ("GIT_PREVIOUS_SUCCESSFUL_COMMIT", "GIT_PREVIOUS_COMMIT"):
        value = os.getenv(env_name)
        if value:
            return value

    change_target = os.getenv("CHANGE_TARGET")
    if change_target:
        base = try_git_command("merge-base", "HEAD", f"origin/{change_target}")
        if base:
            return base

    return try_git_command("rev-parse", "HEAD~1")


def collect_diff() -> str:
    base_commit = resolve_base_commit()
    if base_commit:
        diff = try_git_command("diff", f"{base_commit}..HEAD", "--")
        if diff:
            return diff

    staged_diff = try_git_command("diff", "--cached", "--")
    if staged_diff:
        return staged_diff

    working_tree_diff = try_git_command("diff", "--")
    if working_tree_diff:
        return working_tree_diff

    return ""


def build_prompt(diff_text: str) -> str:
    truncated_diff = diff_text[:MAX_DIFF_CHARS]
    suffix = ""
    if len(diff_text) > MAX_DIFF_CHARS:
        suffix = "\n\nDiff was truncated to fit the token budget."

    return (
        "Review the following git diff. Focus on correctness, regressions, missing validation, "
        "build/test issues, and security concerns. "
        "Return either 'No issues found.' or a short flat list where each item includes severity, file, and issue.\n\n"
        f"{truncated_diff}{suffix}"
    )


def request_review(diff_text: str) -> str:
    try:
        from openai import OpenAI
    except ImportError as exc:
        raise RuntimeError(
            "The 'openai' package is not installed. Install it with 'pip install openai'."
        ) from exc

    api_key = os.getenv("OPENAI_API_KEY")
    if not api_key:
        raise RuntimeError("OPENAI_API_KEY is not set.")

    model = os.getenv("CODEX_MODEL") or os.getenv("OPENAI_MODEL") or "gpt-4.1"
    client = OpenAI(api_key=api_key)

    response = client.responses.create(
        model=model,
        input=[
            {
                "role": "system",
                "content": [
                    {
                        "type": "input_text",
                        "text": (
                            "You are a strict CI code reviewer. Be concise, concrete, and prioritize real defects."
                        ),
                    }
                ],
            },
            {
                "role": "user",
                "content": [
                    {
                        "type": "input_text",
                        "text": build_prompt(diff_text),
                    }
                ],
            },
        ],
    )

    return response.output_text.strip()


def main() -> int:
    diff_text = collect_diff()
    if not diff_text:
        print("No git changes detected. Skipping AI review.")
        return 0

    try:
        review = request_review(diff_text)
    except Exception as exc:
        print(f"AI review failed: {exc}", file=sys.stderr)
        return 1

    print("AI review result:\n")
    print(review or "No issues found.")

    fail_on_findings = os.getenv("AI_REVIEW_FAIL_ON_FINDINGS", "false").lower() == "true"
    normalized = (review or "").strip().lower()
    no_findings = normalized == "no issues found."

    if fail_on_findings and not no_findings:
        return 1

    return 0


if __name__ == "__main__":
    sys.exit(main())