#!/usr/bin/env bash
# gstack-timeline-read — read and format project timeline
# Usage: gstack-timeline-read [--since "7 days ago"|7d|YYYY-MM-DD] [--limit N] [--branch NAME]
#
# Session timeline: local-only, never sent anywhere.
# Reads ~/.gstack/projects/$SLUG/timeline.jsonl, filters, formats.
# Exit 0 silently if no timeline file exists or nothing matches. Missing bun
# exits 127 and a failed read exits non-zero with its stderr (#2790). A missing
# or non-positive-integer --limit, a missing or unparseable --since, a missing
# --branch, or an unknown argument exits 2 before any read (#1723); --help
# prints the usage line and exits 0.
set -euo pipefail
USAGE='Usage: gstack-timeline-read [--since "7 days ago"|7d|YYYY-MM-DD] [--limit N] [--branch NAME]'
SINCE_FORMS='accepted: "<N> minute|hour|day|week|month[s] ago", "<N>h|d|w", or an ISO date YYYY-MM-DD or YYYY-MM-DDTHH:MM:SSZ'
SCRIPT_DIR="$(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"

SINCE_MS=0
LIMIT=20
BRANCH=""

missing_value() { # remaining-arg-count next-arg -> why the flag has no usable value, or nothing
  if [[ $1 -lt 2 ]]; then echo "got no value"
  elif [[ -z "$2" ]]; then echo "got an empty value"
  elif [[ "$2" == --* ]]; then echo "got flag '$2'"
  fi
  return 0
}

days_from_civil() { # year month day (UTC) -> days since 1970-01-01
  local y=$((10#$1)) m=$((10#$2)) d=$((10#$3))
  [[ $m -le 2 ]] && y=$((y - 1))
  local era=$((y / 400)) yoe doy mp
  yoe=$((y - era * 400)); mp=$(((m + 9) % 12)); doy=$(((153 * mp + 2) / 5 + d - 1))
  echo $((era * 146097 + yoe * 365 + yoe / 4 - yoe / 100 + doy - 719468))
}

since_cutoff_ms() { # one --since value -> cutoff epoch ms, or nothing when unparseable
  local now n unit seconds lower
  now=$(date -u +%s)
  lower=$(printf '%s' "$1" | tr '[:upper:]' '[:lower:]')
  if [[ "$lower" =~ ^([1-9][0-9]{0,5})[[:space:]]*(minute|hour|day|week|month)s?[[:space:]]+ago$ ]]; then
    n=${BASH_REMATCH[1]}; unit=${BASH_REMATCH[2]}
  elif [[ "$lower" =~ ^([1-9][0-9]{0,5})([hdw])$ ]]; then
    n=${BASH_REMATCH[1]}
    case ${BASH_REMATCH[2]} in h) unit=hour ;; d) unit=day ;; w) unit=week ;; esac
  elif [[ "$1" =~ ^([0-9]{4})-(0[1-9]|1[0-2])-(0[1-9]|[12][0-9]|3[01])(T([01][0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9])Z)?$ ]]; then
    seconds=$(( $(days_from_civil "${BASH_REMATCH[1]}" "${BASH_REMATCH[2]}" "${BASH_REMATCH[3]}") * 86400 ))
    [[ -n "${BASH_REMATCH[4]}" ]] && seconds=$((seconds + 10#${BASH_REMATCH[5]} * 3600 + 10#${BASH_REMATCH[6]} * 60 + 10#${BASH_REMATCH[7]}))
    echo $((seconds * 1000)); return 0
  else
    return 0
  fi
  case $unit in minute) seconds=60 ;; hour) seconds=3600 ;; day) seconds=86400 ;; week) seconds=604800 ;; month) seconds=2592000 ;; esac
  echo $(((now - n * seconds) * 1000))
}

while [[ $# -gt 0 ]]; do
  case "$1" in
    --help|-h) echo "$USAGE"; exit 0 ;;
    --since)
      problem=$(missing_value $# "${2-}")
      if [[ -n "$problem" ]]; then
        echo "gstack-timeline-read: --since must be a relative time like \"7 days ago\" ($problem); $SINCE_FORMS" >&2
        exit 2
      fi
      SINCE_MS=$(since_cutoff_ms "$2")
      if [[ -z "$SINCE_MS" ]]; then
        echo "gstack-timeline-read: --since must be a relative time like \"7 days ago\" (got '$2'); $SINCE_FORMS" >&2
        exit 2
      fi
      shift 2 ;;
    --limit)
      if [[ $# -lt 2 ]]; then
        echo "gstack-timeline-read: --limit must be a positive integer (got no value); example: --limit 20" >&2
        exit 2
      fi
      if [[ ! "$2" =~ ^[1-9][0-9]*$ ]]; then
        echo "gstack-timeline-read: --limit must be a positive integer (got '$2'); example: --limit 20" >&2
        exit 2
      fi
      LIMIT="$2"; shift 2 ;;
    --branch)
      problem=$(missing_value $# "${2-}")
      if [[ -n "$problem" ]]; then
        echo "gstack-timeline-read: --branch must be a branch name ($problem)" >&2
        exit 2
      fi
      BRANCH="$2"; shift 2 ;;
    *)
      echo "gstack-timeline-read: unknown argument '$1'" >&2
      echo "$USAGE" >&2
      exit 2 ;;
  esac
done

TIMELINE_FILE="$GSTACK_HOME/projects/$SLUG/timeline.jsonl"

if [ ! -f "$TIMELINE_FILE" ]; then
  exit 0
fi

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

cat "$TIMELINE_FILE" | GSTACK_TIMELINE_SINCE_MS="$SINCE_MS" GSTACK_TIMELINE_BRANCH="$BRANCH" GSTACK_TIMELINE_LIMIT="$LIMIT" bun -e "
const lines = (await Bun.stdin.text()).trim().split('\n').filter(Boolean);
const branch = process.env.GSTACK_TIMELINE_BRANCH || '';
const limit = Number(process.env.GSTACK_TIMELINE_LIMIT);
const sinceMs = Number(process.env.GSTACK_TIMELINE_SINCE_MS);

const entries = [];
for (const line of lines) {
  try {
    const e = JSON.parse(line);
    if (sinceMs && new Date(e.ts).getTime() < sinceMs) continue;
    if (branch && e.branch !== branch) continue;
    entries.push(e);
  } catch {}
}

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

// Take last N entries
const recent = entries.slice(-limit);

// Skill counts (completed events only)
const counts = {};
const branches = new Set();
for (const e of entries) {
  if (e.event === 'completed') {
    counts[e.skill] = (counts[e.skill] || 0) + 1;
  }
  if (e.branch) branches.add(e.branch);
}

// Output summary
const countStr = Object.entries(counts)
  .sort((a, b) => b[1] - a[1])
  .map(([s, n]) => n + ' /' + s)
  .join(', ');

if (countStr) {
  console.log('TIMELINE: ' + countStr + ' across ' + branches.size + ' branch' + (branches.size !== 1 ? 'es' : ''));
}

// Output recent events
console.log('');
console.log('## Recent Events');
for (const e of recent) {
  const ts = (e.ts || '').replace('T', ' ').replace(/\.\d+Z$/, 'Z');
  const dur = e.duration_s ? ' (' + e.duration_s + 's)' : '';
  const outcome = e.outcome ? ' [' + e.outcome + ']' : '';
  console.log('- ' + ts + ' /' + e.skill + ' ' + e.event + outcome + dur + (e.branch ? ' on ' + e.branch : ''));
}
"