#!/usr/bin/env bash
set -euo pipefail

# ADR-0023 clause 1, and ONLY clause 1: an executable, instructed local git
# command in plugin skill or agent content is written `rtk git`, never bare
# `git`.
#
# WHY THIS IS NARROW ON PURPOSE. ADR-0023 has three clauses, and only the first
# is machine-decidable:
#
#   1. executable + instructed  -> `rtk git`     <- this hook
#   2. illustrative/referential -> bare `git`    <- undecidable, not gated
#   3. machine-parsed or interactive -> bare `git`, marked <- opt-out, below
#
# Clause 2 is a judgement about what a sentence is doing, not a pattern. "`git
# switch` refuses rather than clobbering conflicting local edits" and "run `git
# switch <branch>`" are the same token sequence in prose. A gate that guessed
# would fire on every doc paragraph in the corpus, and a gate that fires on
# correct content gets disabled. So this hook looks only at the two places where
# a `git` mention is unambiguously an instruction to execute:
#
#   (a) a line inside a fenced code block whose info string names a shell
#       (bash / sh / shell / zsh / console);
#   (b) the OPENING backticked span of a "Run" column cell in a markdown
#       dispatch table -- and only the opening span.
#
# (b) is that narrow because a Run cell routinely carries a command followed by
# prose about it, and that prose is clause 2. git-worktrees/SKILL.md has both
# shapes on adjacent rows: a cell reading `rtk git worktree add --track ...` --
# always correct. `git worktree add <path> <branch>` expands to exactly this
# (instruction first, reference second), and a `**Never** ...` row whose Run cell
# is entirely explanatory prose containing a bare `git push`. Checking every span
# flags both; checking only a leading span flags neither, and still catches the
# ordinary `| List | `git worktree list -v` |` case this gate exists for.
#
# Prose bullets, prose-leading Run cells, table cells outside a Run column, and
# fences tagged `text`, `yaml`, `json` etc. are NOT checked. That is a real
# coverage gap, recorded in docs/spec/gates.md rather than papered over.
#
# CLAUSE-3 OPT-OUT. A site that is deliberately bare because rtk rewrites the
# output the skill parses, or because the command is interactive, is exempted by
# putting the literal string `ADR-0023` on the SAME LINE — in a shell comment for
# a code line, in the cell text for a table row. Per-line, never per-block: a
# fenced block routinely mixes `rtk git` steps with one deliberately-bare
# command (references/push.md does exactly that), and a block-level marker would
# silently disarm the checked lines around the marked one.
#
# The marker is a bare substring match, so a line that merely *mentions*
# ADR-0023 for an unrelated reason is also exempt. That is accepted: the marker
# is an author's deliberate opt-out, not a security boundary, and a stricter
# form would only move the same trust to a different string.

if [[ $# -eq 0 ]]; then
  exit 0
fi

if ! command -v python3 > /dev/null 2>&1; then
  echo "ERROR: python3 is required for the ADR-0023 rtk-prefix gate but was not found on PATH." >&2
  echo "  Fix: install python3 (pre-commit itself is a Python application, so it is almost certainly already present)." >&2
  exit 1
fi

# No PyYAML here, unlike skill-size-check.sh: this gate never reads frontmatter,
# only the markdown body, so it has no folded scalar to measure.
exec python3 -u - "$@" <<'PY'
import re
import sys

MARKER = "ADR-0023"
SHELL_INFO = {"bash", "sh", "shell", "zsh", "console", "shell-session"}

FENCE_OPEN = re.compile(r"^\s*(?P<f>`{3,}|~{3,})\s*(?P<info>[^\s`]*)")
ASSIGNMENT = re.compile(r"^[A-Za-z_][A-Za-z0-9_]*=\S*\s+")
# Shell separators that begin a fresh command word.
SPLIT = re.compile(r"(?:\|\||&&|[;|&\n]|\$\(|`|\()")
BACKTICKED = re.compile(r"`([^`]+)`")


def strip_shell_comment(line: str) -> str:
    """Drop a trailing `#` comment, ignoring `#` inside single/double quotes."""
    out = []
    quote = None
    prev = ""
    for ch in line:
        if quote:
            if ch == quote and prev != "\\":
                quote = None
        elif ch in "'\"":
            quote = ch
        elif ch == "#" and (not out or out[-1].isspace()):
            break
        out.append(ch)
        prev = ch
    return "".join(out)


def bare_git_in_shell(code: str) -> bool:
    for segment in SPLIT.split(code):
        seg = segment.lstrip()
        if seg.startswith("$ "):          # a copied prompt
            seg = seg[2:].lstrip()
        while True:                        # VAR=x VAR2=y git ...
            m = ASSIGNMENT.match(seg)
            if not m:
                break
            seg = seg[m.end():]
        if re.match(r"git(\s|$)", seg):
            return True
    return False


def run_column(header: str):
    """Index of the 'Run' column in a markdown header row, or None."""
    cells = [c.strip().strip("`*_ ").lower() for c in header.strip().strip("|").split("|")]
    return cells.index("run") if "run" in cells else None


def check(path: str):
    problems = []
    try:
        lines = open(path, encoding="utf-8").read().splitlines()
    except (OSError, UnicodeDecodeError) as exc:
        # Unreadable is an error, never a silent pass.
        return [(0, f"could not read file: {exc}")]

    fence = None          # closing marker of the open fence, or None
    fence_is_shell = False
    run_col = None        # active Run-column index, or None
    pending_header = None

    for n, raw in enumerate(lines, start=1):
        if fence is not None:
            if re.match(r"^\s*" + re.escape(fence) + r"\s*$", raw):
                fence, fence_is_shell = None, False
                continue
            if fence_is_shell and MARKER not in raw:
                if bare_git_in_shell(strip_shell_comment(raw)):
                    problems.append((n, raw.strip()))
            continue

        m = FENCE_OPEN.match(raw)
        if m:
            fence = m.group("f")
            fence_is_shell = m.group("info").lower() in SHELL_INFO
            run_col, pending_header = None, None
            continue

        stripped = raw.strip()
        if not stripped.startswith("|"):
            run_col, pending_header = None, None
            continue

        # A markdown table: header row, delimiter row, then data rows.
        if run_col is None:
            if pending_header is not None and set(stripped) <= set("|-: "):
                run_col = run_column(pending_header)
                pending_header = None
            else:
                pending_header = stripped
                run_col = None
            continue

        if MARKER in raw:
            continue
        cells = stripped.strip("|").split("|")
        if run_col >= len(cells):
            continue
        cell = cells[run_col].strip()
        # Only a cell that OPENS with a backticked command is a dispatch entry.
        # A cell opening with prose is explanation, and explanation is clause 2.
        if not cell.startswith("`"):
            continue
        opening = BACKTICKED.match(cell)
        if opening and re.match(r"git(\s|$)", opening.group(1).strip()):
            problems.append((n, opening.group(1).strip()))

    return problems


failed = False
for path in sys.argv[1:]:
    for line_no, text in check(path):
        failed = True
        print(
            f"ADR-0023: {path}:{line_no}: executable git command is not prefixed with `rtk`: {text}",
            file=sys.stderr,
        )

if failed:
    print("", file=sys.stderr)
    print(
        "Fix: write `rtk git <subcommand>` (ADR-0023 clause 1). If this command must stay bare\n"
        "because rtk rewrites output the skill parses, or because it is interactive (clause 3),\n"
        "say so inline and put the literal string ADR-0023 on the same line to record the opt-out.",
        file=sys.stderr,
    )
    sys.exit(1)
PY