/**
 * artifacts-sync preamble block (renamed from gbrain-sync in v1.27.0.0).
 *
 * Emits bash that runs at every skill invocation:
 *   0. Live gbrain-availability hint (per /plan-eng-review): when gbrain is
 *      configured, emit one of two variants (steady-state vs empty-corpus
 *      emergency). Zero context cost when gbrain is not configured.
 *   1. If ~/.gstack-artifacts-remote.txt (or legacy ~/.gstack-brain-remote.txt
 *      during the v1.27.0.0 migration window) exists AND ~/.gstack/.git is
 *      missing, surface a restore-available hint (does NOT auto-run restore).
 *   2. If sync is on, run `gstack-brain-sync --once` (drain + push). The
 *      script keeps its old name; only the config-key + state-file names flip.
 *   3. On first skill of the day (24h cache via .brain-last-pull):
 *      `git fetch` + ff-only merge (JSONL merge driver handles conflicts).
 *   4. Emit an `ARTIFACTS_SYNC:` status line so every skill surfaces health.
 *      In remote-MCP mode, the line reads `ARTIFACTS_SYNC: remote-mode
 *      (managed by brain server <host>)` since this machine doesn't sync
 *      anything locally — the brain admin's server pulls from GitHub/GitLab.
 *
 * Also emits prose instructions for the host LLM to fire a one-time privacy
 * stop-gate via AskUserQuestion when artifacts_sync_mode is unset and gbrain
 * is available on the host.
 *
 * Block emitted across all tiers. Internal bash short-circuits when feature
 * is disabled; cost is <5ms.
 *
 * Skill-end sync is handled by the completion-status generator via a call
 * to `gstack-brain-sync --discover-new` + `--once`.
 */
import type { TemplateContext } from '../types';
import { quoteSafePath } from '../types';

/**
 * Shared jq sub-expression resolving the gbrain MCP registration entry
 * (#2499). Claude Code registers MCP servers at TWO scopes in
 * ~/.claude.json: user scope (.mcpServers.gbrain) and project scope
 * (.projects["/abs/path"].mcpServers.gbrain — what `claude mcp add`
 * WITHOUT --scope user writes). Reading only user scope makes a correctly
 * configured project-scoped brain invisible: brain-aware blocks suppress,
 * remote-mode sync is never recognised, nothing errors.
 *
 * Resolution order: user scope first, then the nearest-ancestor project
 * entry for $PWD that actually carries a gbrain server (longest matching
 * key with a path-boundary check, so nested repos pick their own
 * registration, /a/repo never matches /a/repo2, and a nested project
 * WITHOUT gbrain doesn't shadow its parent's registration). The emitted
 * bash resolves the entry ONCE into _GBRAIN_MCP_ENTRY (compact JSON) and
 * extracts fields from that variable — one jq parse of claude.json per
 * skill start, and the long expression appears once per rendered SKILL.md.
 */
const GBRAIN_MCP_ENTRY_JQ =
  '.mcpServers.gbrain // ((.projects // {}) | to_entries | map(select((.key as $k | $cwd == $k or ($cwd | startswith($k + "/"))) and ((try .value.mcpServers.gbrain catch null) != null))) | sort_by(.key | length) | last | .value.mcpServers.gbrain) // empty';

export function generateBrainSyncBlock(ctx: TemplateContext): string {
  const isBrainHost = ctx.host === 'gbrain' || ctx.host === 'hermes';
  return `## Artifacts Sync (skill start)

\`\`\`bash
_GSTACK_HOME="\${GSTACK_HOME:-$HOME/.gstack}"
# Prefer the v1.27.0.0 artifacts file; fall back to brain file for users
# upgrading mid-stream before the migration script runs.
if [ -f "$HOME/.gstack-artifacts-remote.txt" ]; then
  _BRAIN_REMOTE_FILE="$HOME/.gstack-artifacts-remote.txt"
else
  _BRAIN_REMOTE_FILE="$HOME/.gstack-brain-remote.txt"
fi
_BRAIN_SYNC_BIN="${quoteSafePath(ctx.paths.binDir)}/gstack-brain-sync"
_BRAIN_CONFIG_BIN="${quoteSafePath(ctx.paths.binDir)}/gstack-config"

# /sync-gbrain context-load: teach the agent to use gbrain when it's available.
# Per-worktree pin: post-spike redesign uses kubectl-style \`.gbrain-source\` in the
# git toplevel to scope queries. Look for the pin in the worktree (not a global
# state file) so that opening worktree B without a pin doesn't claim "indexed"
# just because worktree A was synced. Empty string when gbrain is not
# configured (zero context cost for non-gbrain users).
_GBRAIN_CONFIG="$HOME/.gbrain/config.json"
if [ -f "$_GBRAIN_CONFIG" ] && command -v gbrain >/dev/null 2>&1; then
  _GBRAIN_VERSION_OK=$(gbrain --version 2>/dev/null | grep -c '^gbrain ' || echo 0)
  if [ "$_GBRAIN_VERSION_OK" -gt 0 ] 2>/dev/null; then
    _GBRAIN_PIN_PATH=""
    _REPO_TOP=$(git rev-parse --show-toplevel 2>/dev/null || echo "")
    if [ -n "$_REPO_TOP" ] && [ -f "$_REPO_TOP/.gbrain-source" ]; then
      _GBRAIN_PIN_PATH="$_REPO_TOP/.gbrain-source"
    fi
    if [ -n "$_GBRAIN_PIN_PATH" ]; then
      echo "GBrain configured. Prefer \\\`gbrain search\\\`/\\\`gbrain query\\\` over Grep for"
      echo "semantic questions; use \\\`gbrain code-def\\\`/\\\`code-refs\\\`/\\\`code-callers\\\` for"
      echo "symbol-aware code lookup. See \\"## GBrain Search Guidance\\" in CLAUDE.md."
      echo "Run /sync-gbrain to refresh."
    else
      echo "GBrain configured but this worktree isn't pinned yet. Run \\\`/sync-gbrain --full\\\`"
      echo "before relying on \\\`gbrain search\\\` for code questions in this worktree."
      echo "Falls back to Grep until pinned."
    fi
  fi
fi

_BRAIN_SYNC_MODE=$("$_BRAIN_CONFIG_BIN" get artifacts_sync_mode 2>/dev/null || echo off)

# Detect remote-MCP mode (Path 4 of /setup-gbrain). Local artifacts sync is
# a no-op in remote mode; the brain server pulls from GitHub/GitLab on its
# own cadence. Read claude.json directly to keep this preamble fast (no
# subprocess to claude CLI on every skill start). Both registration scopes
# are read (#2499): user scope, then the nearest-ancestor project scope.
_GBRAIN_MCP_MODE="none"
_GBRAIN_MCP_ENTRY=""
if command -v jq >/dev/null 2>&1 && [ -f "$HOME/.claude.json" ]; then
  _GBRAIN_MCP_ENTRY=$(jq -c --arg cwd "$PWD" '${GBRAIN_MCP_ENTRY_JQ}' "$HOME/.claude.json" 2>/dev/null)
  _GBRAIN_MCP_TYPE=$(printf '%s' "$_GBRAIN_MCP_ENTRY" | jq -r '.type // .transport // empty' 2>/dev/null)
  case "$_GBRAIN_MCP_TYPE" in
    url|http|sse) _GBRAIN_MCP_MODE="remote-http" ;;
    stdio) _GBRAIN_MCP_MODE="local-stdio" ;;
  esac
fi

if [ -f "$_BRAIN_REMOTE_FILE" ] && [ ! -d "$_GSTACK_HOME/.git" ] && [ "$_BRAIN_SYNC_MODE" = "off" ]; then
  _BRAIN_NEW_URL=$(head -1 "$_BRAIN_REMOTE_FILE" 2>/dev/null | tr -d '[:space:]')
  if [ -n "$_BRAIN_NEW_URL" ]; then
    echo "ARTIFACTS_SYNC: artifacts repo detected: $_BRAIN_NEW_URL"
    echo "ARTIFACTS_SYNC: run 'gstack-brain-restore' to pull your cross-machine artifacts (or 'gstack-config set artifacts_sync_mode off' to dismiss forever)"
  fi
fi

if [ -d "$_GSTACK_HOME/.git" ] && [ "$_BRAIN_SYNC_MODE" != "off" ]; then
  _BRAIN_LAST_PULL_FILE="$_GSTACK_HOME/.brain-last-pull"
  _BRAIN_NOW=$(date +%s)
  _BRAIN_DO_PULL=1
  if [ -f "$_BRAIN_LAST_PULL_FILE" ]; then
    _BRAIN_LAST=$(cat "$_BRAIN_LAST_PULL_FILE" 2>/dev/null || echo 0)
    case "$_BRAIN_LAST" in ''|*[!0-9]*) _BRAIN_LAST=0 ;; esac
    _BRAIN_AGE=$(( _BRAIN_NOW - _BRAIN_LAST ))
    [ "$_BRAIN_AGE" -lt 86400 ] && _BRAIN_DO_PULL=0
  fi
  if [ "$_BRAIN_DO_PULL" = "1" ]; then
    ( cd "$_GSTACK_HOME" && git fetch origin >/dev/null 2>&1 && git merge --ff-only "origin/$(git rev-parse --abbrev-ref HEAD)" >/dev/null 2>&1 ) || true
    echo "$_BRAIN_NOW" > "$_BRAIN_LAST_PULL_FILE"
  fi
  "$_BRAIN_SYNC_BIN" --once 2>/dev/null || true
fi

if [ "$_GBRAIN_MCP_MODE" = "remote-http" ]; then
  # Remote-MCP mode: local artifacts sync is a no-op (brain admin's server
  # pulls from GitHub/GitLab). Show the user this is by design, not broken.
  _GBRAIN_HOST=$(printf '%s' "\${_GBRAIN_MCP_ENTRY:-}" | jq -r '.url // empty' 2>/dev/null | sed -E 's|^https?://([^/:]+).*|\\1|' | head -1 | tr -cd 'A-Za-z0-9._-')
  echo "ARTIFACTS_SYNC: remote-mode (managed by brain server \${_GBRAIN_HOST:-remote})"
elif [ -d "$_GSTACK_HOME/.git" ] && [ "$_BRAIN_SYNC_MODE" != "off" ]; then
  _BRAIN_QUEUE_DEPTH=0
  [ -f "$_GSTACK_HOME/.brain-queue.jsonl" ] && _BRAIN_QUEUE_DEPTH=$(wc -l < "$_GSTACK_HOME/.brain-queue.jsonl" | tr -d ' ')
  _BRAIN_LAST_PUSH="never"
  [ -f "$_GSTACK_HOME/.brain-last-push" ] && _BRAIN_LAST_PUSH=$(cat "$_GSTACK_HOME/.brain-last-push" 2>/dev/null || echo never)
  echo "ARTIFACTS_SYNC: mode=$_BRAIN_SYNC_MODE | last_push=$_BRAIN_LAST_PUSH | queue=$_BRAIN_QUEUE_DEPTH"
else
  echo "ARTIFACTS_SYNC: off"
fi
\`\`\`

${isBrainHost ? `If output shows \`ARTIFACTS_SYNC: artifacts repo detected\`, offer \`gstack-brain-restore\` via AskUserQuestion; otherwise continue.` : ''}

Privacy stop-gate: if output shows \`ARTIFACTS_SYNC: off\`, \`artifacts_sync_mode_prompted\` is \`false\`, and gbrain is on PATH or \`gbrain doctor --fast --json\` works, ask once:

> gstack can publish your artifacts (CEO plans, designs, reports) to a private GitHub repo that GBrain indexes across machines. How much should sync?

Options:
- A) Everything allowlisted (recommended)
- B) Only artifacts
- C) Decline, keep everything local

After answer:

\`\`\`bash
# Chosen mode: full | artifacts-only | off
"$_BRAIN_CONFIG_BIN" set artifacts_sync_mode <choice>
"$_BRAIN_CONFIG_BIN" set artifacts_sync_mode_prompted true
\`\`\`

If A/B and \`~/.gstack/.git\` is missing, ask whether to run \`gstack-artifacts-init\`. Do not block the skill.

At skill END before telemetry:

\`\`\`bash
"${quoteSafePath(ctx.paths.binDir)}/gstack-brain-sync" --discover-new 2>/dev/null || true
"${quoteSafePath(ctx.paths.binDir)}/gstack-brain-sync" --once 2>/dev/null || true
\`\`\`
`;
}