#!/usr/bin/env bash
# gstack-learnings-search — read and filter project learnings
# Usage: gstack-learnings-search --help
#
# Reads ~/.gstack/projects/$SLUG/learnings.jsonl, applies confidence decay,
# resolves duplicates (latest winner per key+type), and outputs formatted text.
# Exit 0 silently if no learnings file exists or nothing matches. Missing bun
# exits 127 and a failed read exits non-zero with its stderr (#2790): "could
# not read" must never look like "nothing recorded".
# Heredoc delivery guard: bash 5.2+ pipes heredoc bodies <=64KiB, and on
# macOS a starved 512-byte pipe hangs bodies >=512B at startup. Compat level
# 50 restores the tempfile path (test/heredoc-pipe-deadlock.test.ts).
BASH_COMPAT=50
set -euo pipefail
GSTACK_BUN_CONFIG=/dev/null; case "${OSTYPE:-}" in msys*|cygwin*) if command -v cygpath >/dev/null 2>&1; then GSTACK_BUN_CONFIG=NUL; fi ;; esac

usage() {
  cat <<'EOF'
Usage: gstack-learnings-search [--type TYPE] [--query WORDS] [--limit N=10] [--cross-project]
       gstack-learnings-search --stats
       gstack-learnings-search --help

Prints this project's learnings, latest entry per key+type, grouped by type.
  --type TYPE       only one type: pattern pitfall preference architecture tool operational investigation
  --query WORDS     entries matching any word in key, insight or files, best match first
  --limit N         at most N entries (default 10)
  --cross-project   also read up to 5 other projects' user-stated learnings
  --stats           counts for this project: TOTAL, UNIQUE, RAW_ENTRIES, BY_TYPE, BY_SOURCE,
                    AVG_CONFIDENCE, or NO_LEARNINGS when nothing is recorded
Prints nothing when nothing matches. Record a learning with gstack-learnings-log.
EOF
}

TYPE=""
QUERY=""
LIMIT=10
CROSS_PROJECT=false
STATS=false

usage_error() { echo "gstack-learnings-search: $1" >&2; exit 2; }

while [[ $# -gt 0 ]]; do
  case "$1" in
    --type|--query|--limit) [[ $# -ge 2 ]] || usage_error "$1 needs a value" ;;
  esac
  case "$1" in
    --type) TYPE="$2"; shift 2 ;;
    --query) QUERY="$2"; shift 2 ;;
    --limit) [[ "$2" =~ ^[1-9][0-9]*$ ]] || usage_error "--limit needs a positive integer, got '$2'"; LIMIT="$2"; shift 2 ;;
    --cross-project) CROSS_PROJECT=true; shift ;;
    --stats) STATS=true; shift ;;
    -h|--help) usage; exit 0 ;;
    *) usage_error "unknown argument '$1'; valid: --type --query --limit --cross-project --stats --help" ;;
  esac
done

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
eval "$("$SCRIPT_DIR/gstack-slug" 2>/dev/null)"
. "$(dirname "$0")/gstack-state-root.sh" 2>/dev/null || { echo "$0: cannot resolve the gstack state root: $(dirname "$0")/gstack-state-root.sh is missing. fix: reinstall with ./setup or /gstack-upgrade (docs/state-root.md)" >&2; exit 1; }
gstack_state_root_select
GSTACK_HOME="$_gstack_sr_root"

LEARNINGS_FILE="$GSTACK_HOME/projects/$SLUG/learnings.jsonl"

if [ "$STATS" = true ]; then
  if [ ! -f "$LEARNINGS_FILE" ]; then
    echo "NO_LEARNINGS"
    exit 0
  fi
  command -v bun >/dev/null 2>&1 || { echo "gstack-learnings-search: bun not found on PATH, so learnings could not be read. Fix: install Bun (https://bun.sh), then re-run ./setup." >&2; exit 127; }
  echo "TOTAL: $(wc -l < "$LEARNINGS_FILE" | tr -d ' ') entries"
  bun --no-env-file --config="${GSTACK_BUN_CONFIG:-/dev/null}" -e "
const lines = (await Bun.stdin.text()).trim().split('\n').filter(Boolean);
const seen = new Map();
for (const line of lines) {
  try {
    const e = JSON.parse(line);
    const dk = (e.key || '') + '|' + (e.type || '');
    const existing = seen.get(dk);
    if (!existing || new Date(e.ts) > new Date(existing.ts)) seen.set(dk, e);
  } catch {}
}
const byType = Object.create(null);
const bySource = Object.create(null);
let totalConf = 0;
for (const e of seen.values()) {
  byType[e.type] = (byType[e.type] || 0) + 1;
  bySource[e.source] = (bySource[e.source] || 0) + 1;
  totalConf += e.confidence || 0;
}
console.log('UNIQUE: ' + seen.size + ' (after dedup)');
console.log('RAW_ENTRIES: ' + lines.length);
console.log('BY_TYPE: ' + JSON.stringify(byType));
console.log('BY_SOURCE: ' + JSON.stringify(bySource));
console.log('AVG_CONFIDENCE: ' + (seen.size ? (totalConf / seen.size).toFixed(1) : '0.0'));
" < "$LEARNINGS_FILE"
  exit 0
fi

# Collect cross-project JSONL files separately so the trust gate can distinguish
# current-project rows from rows loaded from other projects.
CROSS_FILES=()

if [ "$CROSS_PROJECT" = true ]; then
  # Add other projects' learnings (max 5)
  while IFS= read -r f; do
    CROSS_FILES+=("$f")
    [ ${#CROSS_FILES[@]} -ge 5 ] && break
  done < <(find "$GSTACK_HOME/projects" -name "learnings.jsonl" -not -path "$GSTACK_HOME/projects/$SLUG/*" 2>/dev/null)
fi

if [ ! -f "$LEARNINGS_FILE" ] && [ ${#CROSS_FILES[@]} -eq 0 ]; then
  exit 0
fi

command -v bun >/dev/null 2>&1 || {
  echo "gstack-learnings-search: bun not found on PATH, so learnings could not be read. Fix: install Bun (https://bun.sh), then re-run ./setup." >&2
  exit 127
}

emit_tagged_file() {
  local tag="$1"
  local file="$2"
  local line
  while IFS= read -r line || [ -n "$line" ]; do
    [ -n "$line" ] && printf '%s\t%s\n' "$tag" "$line"
  done < "$file"
}

# Process all files through bun for JSON parsing, decay, dedup, filtering
{
  [ -f "$LEARNINGS_FILE" ] && emit_tagged_file current "$LEARNINGS_FILE"
  if [ ${#CROSS_FILES[@]} -gt 0 ]; then
    for f in "${CROSS_FILES[@]}"; do
      emit_tagged_file cross "$f"
    done
  fi
} | GSTACK_SEARCH_TYPE="$TYPE" GSTACK_SEARCH_QUERY="$QUERY" GSTACK_SEARCH_LIMIT="$LIMIT" GSTACK_SEARCH_CROSS="$CROSS_PROJECT" bun --no-env-file --config="${GSTACK_BUN_CONFIG:-/dev/null}" -e "
const lines = (await Bun.stdin.text()).trim().split('\n').filter(Boolean);
const now = Date.now();
const type = process.env.GSTACK_SEARCH_TYPE || '';
const queryRaw = (process.env.GSTACK_SEARCH_QUERY || '').toLowerCase();
const queryTokens = queryRaw.split(/\s+/).filter(Boolean);
const limit = parseInt(process.env.GSTACK_SEARCH_LIMIT || '10', 10);

const entries = [];
for (const taggedLine of lines) {
  try {
    const tabIndex = taggedLine.indexOf('\t');
    const sourceTag = tabIndex === -1 ? 'current' : taggedLine.slice(0, tabIndex);
    const line = tabIndex === -1 ? taggedLine : taggedLine.slice(tabIndex + 1);
    const e = JSON.parse(line);
    if (!e.key || !e.type) continue;

    // Apply confidence decay: observed/inferred lose 1pt per 30 days
    let conf = e.confidence || 5;
    if (e.source === 'observed' || e.source === 'inferred') {
      const days = Math.floor((now - new Date(e.ts).getTime()) / 86400000);
      conf = Math.max(0, conf - Math.floor(days / 30));
    }
    e._effectiveConfidence = conf;

    // Determine if this is from the current project or cross-project
    // Cross-project entries are tagged for display
    const isCrossProject = sourceTag === 'cross';
    e._crossProject = isCrossProject;

    // Trust gate: cross-project learnings only loaded if trusted (user-stated).
    // This prevents prompt injection from one project's AI-generated learnings
    // silently influencing reviews in another project.
    // #1745: this is an ALLOWLIST, not a denylist. The old equals-false check
    // admitted any row where trusted is missing/undefined (legacy rows written
    // before the field existed, hand-edited rows, rows from other tools).
    // Require trusted to be exactly true. NOTE: this whole block is a
    // double-quoted bun -e string, so bash still does command substitution
    // inside it. Keep backticks and dollar-paren out of these comments.
    if (isCrossProject && e.trusted !== true) continue;

    entries.push(e);
  } catch {}
}

// Dedup: latest winner per key+type
const seen = new Map();
for (const e of entries) {
  const dk = e.key + '|' + e.type;
  const existing = seen.get(dk);
  if (!existing || new Date(e.ts) > new Date(existing.ts)) {
    seen.set(dk, e);
  }
}
let results = Array.from(seen.values());

// Filter by type
if (type) results = results.filter(e => e.type === type);

// Filter by query (token-OR: match if ANY whitespace-split token appears in ANY
// haystack) and count how many distinct tokens each entry matched (#2762). The
// count lives in a local map, never on the entry: a stored field from disk
// must not become a sort key.
const tokenHits = new Map();
if (queryTokens.length > 0) results = results.filter(e => {
  const haystacks = [String(e.key || '').toLowerCase(), String(e.insight || '').toLowerCase(), ...(Array.isArray(e.files) ? e.files : []).map(f => String(f).toLowerCase())];
  const hits = [...new Set(queryTokens)].filter(tok => haystacks.some(h => h.includes(tok))).length;
  tokenHits.set(e, hits);
  return hits > 0;
});

// Sort by matched tokens desc, then effective confidence desc, then recency.
// Ranking on confidence alone let high-confidence single-token matches push an
// entry matching every token past the limit.
results.sort((a, b) => {
  const ah = tokenHits.get(a) || 0, bh = tokenHits.get(b) || 0;
  if (bh !== ah) return bh - ah;
  if (b._effectiveConfidence !== a._effectiveConfidence) return b._effectiveConfidence - a._effectiveConfidence;
  return new Date(b.ts).getTime() - new Date(a.ts).getTime();
});

// Limit, and say when a query matched more than fit.
const totalMatched = results.length;
results = results.slice(0, limit);

if (results.length === 0) process.exit(0);

// Format output. A null-prototype map: a row typed 'constructor' or
// '__proto__' must not find an inherited property and blank the whole run.
const byType = Object.create(null);
for (const e of results) {
  const t = e.type || 'unknown';
  if (!byType[t]) byType[t] = [];
  byType[t].push(e);
}

// Summary line
const counts = Object.entries(byType).map(([t, arr]) => arr.length + ' ' + t + (arr.length > 1 ? 's' : ''));
const moreNotice = queryTokens.length > 0 && totalMatched > results.length
  ? ' -- ' + (totalMatched - results.length) + ' more matched, raise --limit to see them'
  : '';
console.log('LEARNINGS: ' + results.length + ' loaded (' + counts.join(', ') + ')' + moreNotice);
console.log('');

for (const [t, arr] of Object.entries(byType)) {
  console.log('## ' + t.charAt(0).toUpperCase() + t.slice(1) + 's');
  for (const e of arr) {
    const cross = e._crossProject ? ' [cross-project]' : '';
    const files = e.files?.length ? ' (files: ' + e.files.join(', ') + ')' : '';
    console.log('- [' + e.key + '] (confidence: ' + e._effectiveConfidence + '/10, ' + e.source + ', ' + (e.ts || '').split('T')[0] + ')' + cross);
    console.log('  ' + e.insight + files);
  }
  console.log('');
}
"