#!/bin/bash
# kanban-gateway: SSH forced-command wrapper for n8n -> Hermes kanban.
#
# Install on the Mac as the user that owns ~/.hermes, e.g. ~/bin/kanban-gateway (chmod 755).
# Wire it up in ~/.ssh/authorized_keys with a forced command (see the line in the chat).
#
# Verbs n8n may call (sent as the SSH command string):
#   create <base64 of path relative to the vault, e.g. raw/clippings/foo.md>
#   list [status]          status in: triage todo ready running blocked review done archived
#   show <task id>         id like t_ab12cd34
#
# Nothing from the SSH command is ever passed through a shell or eval; the path
# travels base64-encoded so spaces/quotes/$()/newlines in filenames are inert.

set -euo pipefail

# ---- EDIT THESE ------------------------------------------------------------
HERMES_BIN="${HERMES_BIN:-$HOME/.local/bin/hermes}"   # absolute path; non-interactive SSH has a minimal PATH
VAULT_ROOT="${VAULT_ROOT:-$HOME/Documents/wiki-llm}"  # absolute path to the vault root
RAW_DIR="raw"                                         # inbox folder inside the vault
LIBRARIAN_PROFILE="${LIBRARIAN_PROFILE:-librarian}"   # assignee profile name
SKILL_NAME="${SKILL_NAME:-llm-wiki}"                  # skill installed on that profile ('' to skip pinning)
# ----------------------------------------------------------------------------

export PATH="/usr/bin:/bin:/usr/sbin:/sbin:/opt/homebrew/bin:/usr/local/bin:$HOME/.local/bin"

fail() { echo "kanban-gateway: $1" >&2; exit "${2:-2}"; }

cmd_line="${SSH_ORIGINAL_COMMAND:-}"
[[ "$cmd_line" != *$'\n'* ]] || fail "newline in command"

# n8n's SSH node prefixes the command with "cd <dir> ; " (or "&&") when its Working Directory
# field is set. The directory is never used or executed here; only that exact prefix shape is
# stripped, and whatever remains must still be one of the allowed verbs below.
cd_re='^cd[[:space:]]+("[^"]*"|'"'"'[^'"'"']*'"'"'|[^[:space:];&|`$()<>\\]+)[[:space:]]*(;|&&)[[:space:]]*'
if [[ "$cmd_line" =~ $cd_re ]]; then
  cmd_line="${cmd_line#"${BASH_REMATCH[0]}"}"
fi
[[ -n "$cmd_line" ]] || fail "no command supplied"

# Split only on spaces; the verb and a single argument.
verb="${cmd_line%% *}"
arg=""
if [[ "$cmd_line" == *" "* ]]; then arg="${cmd_line#* }"; fi

decode_b64() {
  # macOS older = -D, newer/GNU = -d
  printf '%s' "$1" | { base64 -d 2>/dev/null || base64 -D; }
}

case "$verb" in
  create)
    [[ "$arg" =~ ^[A-Za-z0-9+/=]+$ ]] || fail "create expects base64 argument"
    rel="$(decode_b64 "$arg")" || fail "bad base64"
    [[ -n "$rel" ]] || fail "empty path"
    # Reject control characters (incl. newlines), absolute paths, and traversal.
    if printf '%s' "$rel" | LC_ALL=C grep -q '[[:cntrl:]]'; then fail "control characters in path"; fi
    [[ "$rel" != /* ]] || fail "absolute path rejected"
    case "/$rel/" in */../*) fail "path traversal rejected" ;; esac
    [[ "$rel" == "$RAW_DIR"/* ]] || fail "path must be under $RAW_DIR/"

    vault_real="$(cd "$VAULT_ROOT" && pwd -P)" || fail "VAULT_ROOT not found"
    abs="$vault_real/$rel"
    [[ -f "$abs" ]] || fail "file not found: $rel" 3
    # Resolve symlinks in the directory part and confirm it is still inside raw/.
    dir_real="$(cd "$(dirname "$abs")" && pwd -P)" || fail "cannot resolve directory"
    case "$dir_real/" in
      "$vault_real/$RAW_DIR/"*) ;;
      *) fail "resolved path escapes $RAW_DIR/" ;;
    esac

    # Folder-scoped rulesets live IN the vault as AGENTS.md files. Collect every AGENTS.md from the
    # vault root down to the file's folder (shallow -> deep) and name them on the card, so the
    # agent reads them deterministically instead of relying on lazy discovery.
    rules=()
    if [[ -f "$vault_real/AGENTS.md" && ! -L "$vault_real/AGENTS.md" ]]; then rules+=("AGENTS.md"); fi
    cur=""
    IFS='/' read -r -a parts <<< "$(dirname "$rel")"
    for part in "${parts[@]}"; do
      cur="${cur:+$cur/}$part"
      if [[ -f "$vault_real/$cur/AGENTS.md" && ! -L "$vault_real/$cur/AGENTS.md" ]]; then
        rules+=("$cur/AGENTS.md")
      fi
    done
    if (( ${#rules[@]} > 0 )); then
      rules_text="Rulesets for this file's folder. Read ALL of them before doing anything else, in this order (later ones are more specific and take precedence):"
      for r in "${rules[@]}"; do rules_text+=$'\n'"- $r"; done
    else
      rules_text="No AGENTS.md rulesets found for this folder; follow the llm-wiki skill defaults."
    fi

    title="Catalog: $(basename "$rel")"
    body="Catalog this new raw file per the llm-wiki skill.
Relative path: $rel
Absolute path: $abs

$rules_text"

    args=( kanban create "$title"
           --body "$body"
           --assignee "$LIBRARIAN_PROFILE"
           --workspace "dir:$vault_real"
           --idempotency-key "$rel"
           --json )
    if [[ -n "$SKILL_NAME" ]]; then args+=( --skill "$SKILL_NAME" ); fi
    exec "$HERMES_BIN" "${args[@]}"
    ;;

  list)
    if [[ -z "$arg" ]]; then
      exec "$HERMES_BIN" kanban list --json
    fi
    case "$arg" in
      triage|todo|ready|running|blocked|review|done|archived)
        exec "$HERMES_BIN" kanban list --status "$arg" --json ;;
      *) fail "invalid status" ;;
    esac
    ;;

  show)
    [[ "$arg" =~ ^t_[A-Za-z0-9]+$ ]] || fail "invalid task id"
    exec "$HERMES_BIN" kanban show "$arg" --json
    ;;

  *)
    fail "verb not allowed: $verb"
    ;;
esac