#!/usr/bin/env bash
# gstack-learnings-log — append a learning to the project learnings file
# Usage: gstack-learnings-log '{"skill":"review","type":"pitfall","key":"n-plus-one","insight":"...","confidence":8,"source":"observed"}'
#
# Append-only storage. Duplicates (same key+type) are resolved at read time
# by gstack-learnings-search ("latest winner" per key+type).
set -euo pipefail
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
eval "$("$SCRIPT_DIR/gstack-slug" 2>/dev/null)"
GSTACK_HOME="${GSTACK_HOME:-$HOME/.gstack}"
mkdir -p "$GSTACK_HOME/projects/$SLUG"

INPUT="$1"

# Validate and sanitize input
VALIDATED=$(printf '%s' "$INPUT" | bun -e "
const raw = await Bun.stdin.text();
let j;
try { j = JSON.parse(raw); } catch { process.stderr.write('gstack-learnings-log: invalid JSON, skipping\n'); process.exit(1); }

// Field validation: type must be from allowed list
const ALLOWED_TYPES = ['pattern', 'pitfall', 'preference', 'architecture', 'tool', 'operational'];
if (!j.type || !ALLOWED_TYPES.includes(j.type)) {
  process.stderr.write('gstack-learnings-log: invalid type \"' + (j.type || '') + '\", must be one of: ' + ALLOWED_TYPES.join(', ') + '\n');
  process.exit(1);
}

// Field validation: key must be alphanumeric, hyphens, underscores (no injection surface)
if (!j.key || !/^[a-zA-Z0-9_-]+$/.test(j.key)) {
  process.stderr.write('gstack-learnings-log: invalid key, must be alphanumeric with hyphens/underscores only\n');
  process.exit(1);
}

// Field validation: confidence must be 1-10
const conf = Number(j.confidence);
if (!Number.isInteger(conf) || conf < 1 || conf > 10) {
  process.stderr.write('gstack-learnings-log: confidence must be integer 1-10\n');
  process.exit(1);
}
j.confidence = conf;

// Field validation: source must be from allowed list
const ALLOWED_SOURCES = ['observed', 'user-stated', 'inferred', 'cross-model'];
if (j.source && !ALLOWED_SOURCES.includes(j.source)) {
  process.stderr.write('gstack-learnings-log: invalid source, must be one of: ' + ALLOWED_SOURCES.join(', ') + '\n');
  process.exit(1);
}

// Content sanitization: strip instruction-like patterns from insight field
// These patterns could be used for prompt injection when learnings are loaded into agent context
if (j.insight) {
  const INJECTION_PATTERNS = [
    /ignore\s+(all\s+)?previous\s+(instructions|context|rules)/i,
    /you\s+are\s+now\s+/i,
    /always\s+output\s+no\s+findings/i,
    /skip\s+(all\s+)?(security|review|checks)/i,
    /override[:\s]/i,
    /\bsystem\s*:/i,
    /\bassistant\s*:/i,
    /\buser\s*:/i,
    /do\s+not\s+(report|flag|mention)/i,
    /approve\s+(all|every|this)/i,
  ];
  for (const pat of INJECTION_PATTERNS) {
    if (pat.test(j.insight)) {
      process.stderr.write('gstack-learnings-log: insight contains suspicious instruction-like content, rejected\n');
      process.exit(1);
    }
  }
}

// Inject timestamp if not present
if (!j.ts) j.ts = new Date().toISOString();

// Mark trust level based on source
// user-stated = user explicitly told the agent this. All others are AI-generated.
j.trusted = j.source === 'user-stated';

console.log(JSON.stringify(j));
" 2>/dev/null)

if [ $? -ne 0 ] || [ -z "$VALIDATED" ]; then
  exit 1
fi

echo "$VALIDATED" >> "$GSTACK_HOME/projects/$SLUG/learnings.jsonl"