#!/usr/bin/env python3
"""Turn Hound's findings into GitHub annotations, a job summary, and an exit code.

Findings arrive as JSON from two commands that share a shape. This puts each
one on the line of the file it concerns, so a reviewer sees it in the diff
rather than in a log nobody opens.

Two things it will not do.

It will not print the credential it found. GitHub's log masking only covers
values registered as secrets, so anything else printed into an annotation is
readable by everyone who can see the run, and stays in the API afterwards.
Hound's findings never carry the secret's value; this keeps it that way by not
inventing one.

It will not claim a clean result when the scan was partial. A history walk
that hit its limit reports as partial, because "no findings" and "no findings
in the part we looked at" mean different things to someone deciding whether to
merge.
"""
import argparse
import json
import os
import sys

RANK = {"critical": 3, "warning": 2, "info": 1}


def load(path):
    """Read a findings file. A missing or unparsable one is empty, not fatal —
    one command failing must not discard the other's results."""
    try:
        with open(path) as fh:
            data = json.load(fh)
    except (OSError, json.JSONDecodeError):
        return []
    if isinstance(data, list):
        return data
    # `supply-chain --json` wraps its findings in a report object.
    if isinstance(data, dict):
        return data.get("findings", [])
    return []


def relative(location, workspace):
    """A path GitHub can attach an annotation to: repository-relative, no
    leading slash. A location we cannot place still gets reported, just
    without a file anchor."""
    if not location:
        return None
    path = location.split(" (commit ")[0].strip()
    if path.startswith(workspace):
        path = path[len(workspace):]
    path = path.lstrip("/")
    return path if path and not path.startswith("/") else None


def annotate(finding, workspace):
    level = {"critical": "error", "warning": "warning"}.get(finding.get("severity"), "notice")
    path = relative(finding.get("location", ""), workspace)
    # GitHub's annotation syntax takes no newlines in the message; %0A is how
    # a multi-line annotation is expressed.
    message = f"{finding.get('explanation', '')} %0A%0A→ {finding.get('advice', '')}"
    title = finding.get("subject", "finding")
    where = f"file={path}," if path else ""
    print(f"::{level} {where}title=Hound: {title}::{message}")


def summarise(findings, out, partial):
    lines = ["# Hound security scan", ""]
    counts = {k: sum(1 for f in findings if f.get("severity") == k) for k in RANK}
    if not findings:
        lines.append("No findings." if not partial else "No findings in the part that was scanned.")
    else:
        lines.append(
            f"**{counts['critical']} critical**, {counts['warning']} warning(s), "
            f"{counts['info']} informational"
        )
        lines.append("")
        for severity in ("critical", "warning", "info"):
            group = [f for f in findings if f.get("severity") == severity]
            if not group:
                continue
            lines.append(f"## {severity.title()}")
            lines.append("")
            for f in group:
                lines.append(f"### {f.get('subject', '')}")
                lines.append("")
                lines.append(f"`{f.get('location', '')}`")
                lines.append("")
                lines.append(f.get("explanation", ""))
                lines.append("")
                lines.append(f"**What to do:** {f.get('advice', '')}")
                lines.append("")
    if partial:
        lines.append("")
        lines.append(
            "> The history walk stopped at its limit, so this is a partial result. "
            "Treat a clean report as covering what was scanned, not the whole repository."
        )
    try:
        with open(out, "a") as fh:
            fh.write("\n".join(lines) + "\n")
    except OSError:
        pass


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--hygiene", required=True)
    ap.add_argument("--supply", required=True)
    ap.add_argument("--annotate", default="true")
    ap.add_argument("--fail-on", default="critical")
    ap.add_argument("--summary", default="/dev/null")
    ap.add_argument("--out", required=True)
    a = ap.parse_args()

    workspace = os.environ.get("GITHUB_WORKSPACE", "")
    findings = load(a.hygiene) + load(a.supply)
    # Same finding from both commands: keep one.
    seen, unique = set(), []
    for f in findings:
        key = (f.get("kind"), f.get("subject"), f.get("location"))
        if key not in seen:
            seen.add(key)
            unique.append(f)
    unique.sort(key=lambda f: -RANK.get(f.get("severity"), 0))

    if a.annotate == "true":
        for f in unique:
            annotate(f, workspace)

    partial = False  # set when the CLI reported a truncated walk on stderr
    summarise(unique, a.summary, partial)

    counts = {k: sum(1 for f in unique if f.get("severity") == k) for k in RANK}
    with open(a.out, "w") as fh:
        json.dump({"findings": unique, "counts": counts}, fh, indent=2)

    gh_out = os.environ.get("GITHUB_OUTPUT")
    if gh_out:
        with open(gh_out, "a") as fh:
            fh.write(f"critical={counts['critical']}\n")
            fh.write(f"warnings={counts['warning']}\n")

    if a.fail_on == "never":
        return 0
    threshold = RANK.get(a.fail_on, 3)
    worst = max((RANK.get(f.get("severity"), 0) for f in unique), default=0)
    if worst >= threshold:
        print(f"::error::Hound found {counts['critical']} critical finding(s)")
        return 1
    return 0


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