#!/usr/bin/env bash
# commit-msg hook: reject style tells in commit messages.
#
# Enforces github-discipline.md Rule 5.1 (no AI attribution) and
# Rule 5.2 (no em dashes U+2014) at the commit boundary.
#
# Tool-agnostic: synced from the canonical
# mihaela-agents/templates/git-hooks/commit-msg-style-check, plus an author /
# committer identity guard for AI-agent commit identities.
#
# Install (per repo): git config core.hooksPath .githooks
#
# Portable: uses only BSD-compatible grep (no -P, no \x escapes in patterns).

set -e

MSG_FILE="$1"
[ -z "$MSG_FILE" ] && exit 0
[ ! -f "$MSG_FILE" ] && exit 0

# Strip comment lines (lines starting with #) and the diff scissors block.
CONTENT=$(awk '
  /^# ------------------------ >8 ------------------------$/ { exit }
  /^[[:space:]]*#/ { next }
  { print }
' "$MSG_FILE")

FAIL=0

# Em dash U+2014 = UTF-8 bytes E2 80 94. Build the literal as a variable so the
# script source itself contains no em-dash character.
EMDASH=$(printf '\xe2\x80\x94')
if LC_ALL=C printf '%s' "$CONTENT" | grep -qF -- "$EMDASH"; then
  printf 'commit-msg: forbidden em dash (U+2014) in commit message.\n' >&2
  printf '  Replace with a comma, period, colon, semicolon, or restructure.\n' >&2
  printf '  Rule: github-discipline.md Rule 5.2\n' >&2
  printf '  Locations (line numbers in the cleaned message):\n' >&2
  LC_ALL=C printf '%s\n' "$CONTENT" | grep -nF -- "$EMDASH" | sed 's/^/    /' >&2
  FAIL=1
fi

# Rule 5.1: AI-attribution phrases. Tool-agnostic: any assistant or its vendor,
# not just the one in use. Bare tool names are NOT flagged (that would
# false-positive on legitimate text like "fix cursor blink"); only
# attribution-context mentions are. Case-insensitive, BSD-grep -E compatible.
AI_TOOLS='Claude|Anthropic|Codex|OpenAI|ChatGPT|GPT-[0-9]|Cursor|Copilot|Gemini|Google AI'
ATTRIB_REGEX="(Co-Authored-By|Co-authored-with|Generated (with|by)|Created (with|by)|Powered by|with help from|written by|authored by)[: ].*(${AI_TOOLS})"
if printf '%s' "$CONTENT" | grep -qiE -- "$ATTRIB_REGEX"; then
  printf 'commit-msg: forbidden AI-attribution phrase (names an AI tool/vendor).\n' >&2
  printf '  Rule: github-discipline.md Rule 5.1 (tool-agnostic)\n' >&2
  printf '  Matched lines:\n' >&2
  printf '%s\n' "$CONTENT" | grep -niE -- "$ATTRIB_REGEX" | sed 's/^/    /' >&2
  FAIL=1
fi

# Generic self-reference tells, independent of any vendor name.
GENERIC_PATTERNS=(
  'as an AI'
  'As an AI'
  'this commit was generated'
  'This commit was generated'
  'this change was generated'
  'This change was generated'
)
for p in "${GENERIC_PATTERNS[@]}"; do
  if printf '%s' "$CONTENT" | grep -qF -- "$p"; then
    printf 'commit-msg: forbidden AI-attribution phrase: %s\n' "$p" >&2
    printf '  Rule: github-discipline.md Rule 5.1\n' >&2
    FAIL=1
  fi
done

# Rule 5.1: AI-tell signature emojis used as flourish at end of line.
# Build emoji byte sequences in a variable so the script source stays clean.
EMOJI_TELLS=$(printf '\xf0\x9f\xa4\x96\n\xe2\x9c\xa8\n\xf0\x9f\xaa\x84\n\xf0\x9f\xa7\xa0\n\xf0\x9f\xa6\xbe\n\xf0\x9f\xa4\x9d')
while IFS= read -r emoji; do
  [ -z "$emoji" ] && continue
  if LC_ALL=C printf '%s' "$CONTENT" | grep -qF -- "$emoji"; then
    printf 'commit-msg: forbidden AI-signature emoji in commit message.\n' >&2
    printf '  Rule: github-discipline.md Rule 5.1\n' >&2
    FAIL=1
    break
  fi
done <<<"$EMOJI_TELLS"

# Rule 5.1: AI-tell preamble phrasings at start of any line.
PREAMBLE_PATTERNS=(
  "I'll now"
  "Let me "
  "Here is a quick summary"
  "Here's a quick summary"
)
for p in "${PREAMBLE_PATTERNS[@]}"; do
  if printf '%s' "$CONTENT" | grep -qE -- "^${p}"; then
    printf 'commit-msg: forbidden AI-tell preamble at line start: %s\n' "$p" >&2
    printf '  Rule: github-discipline.md Rule 5.1\n' >&2
    FAIL=1
  fi
done

# Author / committer identity must not be an AI agent. git var resolves the exact
# identity (including --author / GIT_*_IDENT overrides) this commit will record.
# Conservative on names (a human may be named Claude or Gemini); matches agent
# email domains and the Cursor agent identity, which injects itself in practice.
IDENT_REGEX='@cursor\.com|cursoragent|(^|[^[:alpha:]])[Cc]ursor [Aa]gent([^[:alpha:]]|$)'
for ident in "$(git var GIT_AUTHOR_IDENT 2>/dev/null)" "$(git var GIT_COMMITTER_IDENT 2>/dev/null)"; do
  [ -z "$ident" ] && continue
  if printf '%s' "$ident" | grep -qiE -- "$IDENT_REGEX"; then
    printf 'commit-msg: forbidden AI-agent identity as author/committer: %s\n' "$ident" >&2
    printf '  Fix: set git config user.name / user.email to your own identity.\n' >&2
    FAIL=1
  fi
done

exit $FAIL