#!/bin/bash
# lore-watch — daily check for replies to mfritsche@reauktion.de threads
# across multiple lore.kernel.org public-inboxes. Mails any matches via
# msmtp.
#
# Started 2026-04-29 to track the vb2 dma_resv RFC series.

set -euo pipefail

# List of public-inboxes to watch. Add more by appending here.
INBOXES=(
  linux-media
  dri-devel
  linux-rockchip
)

STATE=$HOME/.local/state/lore-watch
mkdir -p "$STATE"
TMPDIR=$(mktemp -d)
trap 'rm -rf "$TMPDIR"' EXIT

GLOBAL_HITS=0

for INBOX in "${INBOXES[@]}"; do
  REPO=$STATE/$INBOX-pi.git
  STATE_FILE=$STATE/last-seen-$INBOX.sha

  if [ ! -d "$REPO" ]; then
    git clone --bare --depth 200 "https://lore.kernel.org/$INBOX/0" "$REPO" >/dev/null 2>&1 || {
      printf 'lore-watch: clone of %s failed, skipping\n' "$INBOX" >&2
      continue
    }
  fi

  # Seed state on first sight (no compare possible yet)
  if [ ! -s "$STATE_FILE" ]; then
    git -C "$REPO" fetch --depth 200 origin >/dev/null 2>&1 || true
    git -C "$REPO" rev-parse FETCH_HEAD > "$STATE_FILE" 2>/dev/null || \
      git -C "$REPO" rev-parse HEAD > "$STATE_FILE"
    continue
  fi

  LAST=$(cat "$STATE_FILE")
  git -C "$REPO" fetch --depth 200 origin master >/dev/null 2>&1 || \
    git -C "$REPO" fetch --depth 200 origin >/dev/null 2>&1 || {
      printf 'lore-watch: fetch of %s failed, skipping\n' "$INBOX" >&2
      continue
    }
  HEAD=$(git -C "$REPO" rev-parse FETCH_HEAD 2>/dev/null || git -C "$REPO" rev-parse HEAD)

  if [ "$LAST" = "$HEAD" ]; then
    continue
  fi

  HITS_HERE=0
  while read -r SHA; do
    MSG=$(git -C "$REPO" show "$SHA:m" 2>/dev/null) || continue
    HDR=$(printf '%s\n' "$MSG" | sed '/^$/q')
    if printf '%s' "$HDR" | grep -qi "mfritsche@reauktion\.de"; then
      {
        printf 'list:      %s\n' "$INBOX"
        printf 'commit:    %s\n' "$SHA"
        printf '%s\n' "$HDR" | grep -iE '^(From|Subject|Date|Message-Id|In-Reply-To):' | head -10
        printf '\n--- snippet ---\n'
        printf '%s\n' "$MSG" | sed -n '/^$/,${p;}' | head -40
        printf '\n=========================================================\n\n'
      } >> "$TMPDIR/digest.txt"
      HITS_HERE=$((HITS_HERE + 1))
      GLOBAL_HITS=$((GLOBAL_HITS + 1))
    fi
  done < <(git -C "$REPO" log --reverse --format=%H "$LAST..$HEAD")

  echo "$HEAD" > "$STATE_FILE"
done

if [ "$GLOBAL_HITS" -gt 0 ]; then
  {
    printf 'Subject: [lore-watch] %d new lore message(s) referencing your threads\n' "$GLOBAL_HITS"
    printf 'From: lore-watch <mfritsche@reauktion.de>\n'
    printf 'To: mfritsche@reauktion.de\n'
    printf '\n'
    printf 'Daily lore.kernel.org scan (lists: %s) caught %d message(s)\n' \
           "$(IFS=,; printf '%s' "${INBOXES[*]}")" "$GLOBAL_HITS"
    printf 'that reference your address:\n\n'
    cat "$TMPDIR/digest.txt"
    printf '\n-- \n(noether ~/.local/bin/lore-watch.sh, scheduled daily)\n'
  } | /usr/bin/msmtp -t
fi