#!/usr/bin/env bash
# PreToolUse hook: blocks `git` invocations when the working directory
# is inside a Mercurial (.hg) repository.
#
# Reads tool-call JSON from stdin, exits 0 to allow, exits 2 with a
# message on stderr to block.

set -u

# Fail open if jq is missing — better to allow a command than to silently
# block all bash for a missing dependency.
if ! command -v jq >/dev/null 2>&1; then
    echo "isurus-hg hook: 'jq' not found; allowing command. Install jq to enable git-blocking." >&2
    exit 0
fi

input=$(cat)
cmd=$(jq -r '.tool_input.command // ""' <<<"$input")
cwd=$(jq -r '.cwd // ""' <<<"$input")

# Allow if no command extracted.
if [[ -z "$cmd" ]]; then
    exit 0
fi

# Strip leading whitespace and any leading VAR=value env assignments.
trimmed=$(sed -E 's/^[[:space:]]+//' <<<"$cmd")
while [[ "$trimmed" =~ ^[A-Za-z_][A-Za-z0-9_]*=[^[:space:]]*[[:space:]]+ ]]; do
    trimmed=$(sed -E 's/^[A-Za-z_][A-Za-z0-9_]*=[^[:space:]]*[[:space:]]+//' <<<"$trimmed")
done

# Extract the leading word.
first=$(awk '{print $1}' <<<"$trimmed")
if [[ "$first" != "git" ]]; then
    exit 0
fi

# Find VCS context for cwd: the closest .hg or .git ancestor.
# If there's no usable cwd, allow.
if [[ -z "$cwd" || ! -d "$cwd" || "$cwd" != /* ]]; then
    exit 0
fi

# Bare git repo check: cwd contains HEAD + refs/ + objects/ at the top level
# (the directory itself IS the git metadata; there's no .git subdir).
if [[ -e "$cwd/HEAD" && -d "$cwd/refs" && -d "$cwd/objects" ]]; then
    exit 0
fi

dir=$cwd
hg_root=""
git_root=""
while [[ "$dir" != "/" && -n "$dir" ]]; do
    if [[ -z "$hg_root" && -d "$dir/.hg" ]]; then
        hg_root=$dir
    fi
    if [[ -z "$git_root" && -d "$dir/.git" ]]; then
        git_root=$dir
    fi
    if [[ -n "$hg_root" || -n "$git_root" ]]; then
        break
    fi
    dir=$(dirname "$dir")
done

# If a .git was found anywhere up the walk, allow. The loop breaks at
# the first iteration where either is found, so a non-empty git_root means
# .git is at the same level as .hg or closer — either way, the user is in
# a git context.
if [[ -n "$git_root" ]]; then
    exit 0
fi

# No .hg ancestor => allow (e.g. plain `git --version` outside any repo).
if [[ -z "$hg_root" ]]; then
    exit 0
fi

# We are inside an .hg repo and the command starts with `git`. Block.
# Build a suggestion based on the next word.
sub=$(awk '{print $2}' <<<"$trimmed")
case "$sub" in
    status)        suggest="hg status" ;;
    add)           suggest="hg add" ;;
    commit)        suggest="hg commit -m \"...\" (no -u; identity comes from ~/.hgrc)" ;;
    log)           suggest="hg log" ;;
    diff)          suggest="hg diff" ;;
    branch)        suggest="hg bookmarks  (in this workflow, bookmarks are feature branches)" ;;
    checkout)      suggest="hg update <name>" ;;
    pull)          suggest="hg pull -u" ;;
    push)          suggest="hg push -B <bookmark>" ;;
    blame)         suggest="hg annotate" ;;
    *)             suggest="See the mercurial-basics skill for the full command map." ;;
esac

cat >&2 <<EOF
git command blocked: this is a Mercurial repository (.hg/ found at $hg_root).

You ran:    $trimmed
Use:        $suggest

See the mercurial-basics skill for the full command map.
EOF

exit 2