#!/usr/bin/env bash
# sentinel-health-check: Compare current STATE.md against latest snapshot
# Detects drift in venture stage, section counts, entry counts, and edge counts
# Outputs drift report to room/.intelligence/health-YYYY-MM-DD.md
# Part of Sentinel Intelligence (SENT-01)

set -euo pipefail

# Cross-platform file modification time (epoch seconds)
portable_stat_mtime() {
  local file="$1"
  if [ "$(uname -s)" = "Darwin" ]; then
    stat -f %m "$file" 2>/dev/null || echo 0
  else
    stat -c %Y "$file" 2>/dev/null || echo 0
  fi
}

ROOM_DIR="${1:-./room}"

if [ ! -d "$ROOM_DIR" ]; then
  echo "ERROR: Room directory not found: $ROOM_DIR" >&2
  exit 1
fi

if [ ! -f "$ROOM_DIR/STATE.md" ]; then
  echo "ERROR: No STATE.md found in $ROOM_DIR" >&2
  exit 1
fi

# Ensure .intelligence/ directory exists
INTEL_DIR="$ROOM_DIR/.intelligence"
mkdir -p "$INTEL_DIR"

# Find latest snapshot
SNAPSHOTS_DIR="$ROOM_DIR/.snapshots"
if [ ! -d "$SNAPSHOTS_DIR" ]; then
  echo "NO_SNAPSHOTS: No previous snapshots found. Run sentinel-snapshot first."
  echo "Creating initial snapshot now..."
  SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
  bash "$SCRIPT_DIR/sentinel-snapshot" "$ROOM_DIR"
  echo "HEALTH_CHECK:BASELINE:First snapshot created. Run health check again next week for drift detection."
  exit 0
fi

LATEST_SNAPSHOT=$(find "$SNAPSHOTS_DIR" -name "STATE-*.md" 2>/dev/null | sort -r | head -1)

if [ -z "$LATEST_SNAPSHOT" ]; then
  echo "NO_SNAPSHOTS: No snapshot files found. Run sentinel-snapshot first."
  exit 0
fi

SNAPSHOT_DATE=$(basename "$LATEST_SNAPSHOT" | sed 's/STATE-//' | sed 's/\.md//')
TODAY=$(date -u +"%Y-%m-%d")

# ── Extract key metrics from current STATE.md ──
extract_metric() {
  local file="$1"
  local pattern="$2"
  grep -i "$pattern" "$file" 2>/dev/null | head -1 | sed "s/.*${pattern}[[:space:]]*//" | tr -d '"' | xargs || echo ""
}

extract_count() {
  local file="$1"
  local pattern="$2"
  grep -c "$pattern" "$file" 2>/dev/null || echo "0"
}

CURRENT="$ROOM_DIR/STATE.md"
PREVIOUS="$LATEST_SNAPSHOT"

# Extract venture stage
current_stage=$(extract_metric "$CURRENT" "venture_stage:")
previous_stage=$(extract_metric "$PREVIOUS" "venture_stage:")

# Count sections with entries (lines matching "entries:" or entry count patterns)
current_entry_lines=$(grep -E '^\|.*\|.*[0-9]+.*\|' "$CURRENT" 2>/dev/null | wc -l | tr -d ' ')
previous_entry_lines=$(grep -E '^\|.*\|.*[0-9]+.*\|' "$PREVIOUS" 2>/dev/null | wc -l | tr -d ' ')

# Sanitize a numeric capture to a single-line non-negative integer.
# grep -c prints "0" AND exits 1 on zero matches, so a "|| echo 0" form would
# append a SECOND line ("0\n0") and break the $(( )) deltas under set -euo
# pipefail. Coerce every numeric capture here: strip non-digits, take the first
# line, default empty to 0. Always exits cleanly so set -e never aborts.
sanitize_int() {
  local raw="${1:-}"
  local n
  n=$(printf '%s' "$raw" | head -1 | tr -dc '0-9')
  printf '%s' "${n:-0}"
}

# Count total entries (sum numbers from entry count patterns)
current_total_raw=$(grep -oE '[0-9]+ entries' "$CURRENT" 2>/dev/null | grep -oE '[0-9]+' | paste -sd+ | bc 2>/dev/null; true)
previous_total_raw=$(grep -oE '[0-9]+ entries' "$PREVIOUS" 2>/dev/null | grep -oE '[0-9]+' | paste -sd+ | bc 2>/dev/null; true)
current_total=$(sanitize_int "$current_total_raw")
previous_total=$(sanitize_int "$previous_total_raw")

# Count edges/relationships mentioned
current_edges_raw=$(grep -ciE 'INFORMS|CONTRADICTS|CONVERGES|ENABLES|INVALIDATES' "$CURRENT" 2>/dev/null; true)
previous_edges_raw=$(grep -ciE 'INFORMS|CONTRADICTS|CONVERGES|ENABLES|INVALIDATES' "$PREVIOUS" 2>/dev/null; true)
current_edges=$(sanitize_int "$current_edges_raw")
previous_edges=$(sanitize_int "$previous_edges_raw")

# ── Build drift report ──
REPORT_FILE="$INTEL_DIR/health-${TODAY}.md"

drift_detected=false

{
  echo "---"
  echo "type: health-check"
  echo "date: ${TODAY}"
  echo "snapshot_compared: ${SNAPSHOT_DATE}"
  echo "---"
  echo ""
  echo "# Room Health Check - ${TODAY}"
  echo ""
  echo "Comparing current STATE.md against snapshot from ${SNAPSHOT_DATE}."
  echo ""
  echo "## Venture Stage"
  echo ""

  if [ "$current_stage" != "$previous_stage" ] && [ -n "$previous_stage" ]; then
    drift_detected=true
    echo "DRIFT: Stage changed from **${previous_stage}** to **${current_stage}**"
  else
    echo "Stable: ${current_stage:-Unknown}"
  fi

  echo ""
  echo "## Entry Counts"
  echo ""

  entry_delta=$((current_total - previous_total))
  if [ "$entry_delta" -gt 0 ]; then
    echo "Growth: +${entry_delta} entries since last snapshot (${previous_total} -> ${current_total})"
  elif [ "$entry_delta" -lt 0 ]; then
    drift_detected=true
    echo "DRIFT: Entry count decreased by ${entry_delta#-} (${previous_total} -> ${current_total})"
  else
    echo "No change: ${current_total} entries"
  fi

  echo ""
  echo "## Edge Counts"
  echo ""

  edge_delta=$((current_edges - previous_edges))
  if [ "$edge_delta" -gt 0 ]; then
    echo "Growth: +${edge_delta} edges since last snapshot"
  elif [ "$edge_delta" -lt 0 ]; then
    drift_detected=true
    echo "DRIFT: Edge count decreased by ${edge_delta#-}"
  else
    echo "No change: ${current_edges} edges"
  fi

  echo ""
  echo "## Staleness Check"
  echo ""

  # Check if STATE.md was modified recently
  state_mod=$(portable_stat_mtime "$CURRENT")
  now_epoch=$(date +%s)
  days_since_mod=$(( (now_epoch - state_mod) / 86400 ))

  if [ "$days_since_mod" -gt 14 ]; then
    drift_detected=true
    echo "WARNING: STATE.md not updated in ${days_since_mod} days -- room may be stale"
  elif [ "$days_since_mod" -gt 7 ]; then
    echo "NOTE: STATE.md last updated ${days_since_mod} days ago"
  else
    echo "Fresh: STATE.md updated within the last week"
  fi

  echo ""
  echo "## Summary"
  echo ""

  if $drift_detected; then
    echo "HEALTH_STATUS: DRIFT_DETECTED"
    echo ""
    echo "Action recommended: Review the changes above and determine if they are intentional."
  else
    echo "HEALTH_STATUS: HEALTHY"
    echo ""
    echo "Room is stable since last snapshot on ${SNAPSHOT_DATE}."
  fi
} > "$REPORT_FILE"

# Output summary to stdout
if $drift_detected; then
  echo "HEALTH_CHECK:DRIFT:${TODAY}:Changes detected since ${SNAPSHOT_DATE}"
else
  echo "HEALTH_CHECK:HEALTHY:${TODAY}:No significant drift since ${SNAPSHOT_DATE}"
fi

echo "REPORT:${REPORT_FILE}"