#!/bin/sh
set -eu

# Run this on the Unraid host. It creates verified git bundles for every bare
# Gitea repository so a Gitea outage does not make repo bootstrap depend on the
# Gitea application database.
#
# Bundles and their sha256 sidecars are written 0644 on purpose, so the
# Nearline-Pull-Workflow (docs/H_DRIVE_NEARLINE_PULL.md) kann sie ueber den
# SMB-Read-Share holen. Bundle-Inhalt = Git-Historie ohne Secrets (durch
# .gitignore abgedeckt) und nicht sensibler als die uebrigen Dumps unter
# /mnt/user/backups/borg/dumps/latest/, die ebenfalls 0644 sind.

SOURCE_ROOT="${SOURCE_ROOT:-/mnt/user/services/gitea/data/git/repositories}"
BUNDLE_ROOT="${BUNDLE_ROOT:-/mnt/user/backups/git-bundles/gitea}"
TMP_ROOT="${TMP_ROOT:-/mnt/cache/tmp/gitea-bundle-mirror}"
REPORT_PATH="${REPORT_PATH:-$BUNDLE_ROOT/latest-report.md}"
MANIFEST_PATH="${MANIFEST_PATH:-$BUNDLE_ROOT/manifest.tsv}"
RUN_ID="$(date -u '+%Y-%m-%dT%H:%M:%SZ')"

log() {
  printf '%s %s\n' "[gitea-bundles]" "$*"
}

warn() {
  printf '%s %s\n' "[gitea-bundles][warn]" "$*" >&2
}

need_cmd() {
  if ! command -v "$1" >/dev/null 2>&1; then
    warn "Required command missing: $1"
    exit 1
  fi
}

bundle_target_for_repo() {
  repo="$1"
  rel="${repo#$SOURCE_ROOT/}"
  rel="${rel%.git}.bundle"
  printf '%s/%s\n' "$BUNDLE_ROOT" "$rel"
}

cleanup() {
  rm -rf "$TMP_ROOT/run.$$"
}
trap cleanup EXIT

main() {
  need_cmd git
  need_cmd find
  need_cmd sha256sum

  if [ ! -d "$SOURCE_ROOT" ]; then
    warn "Source root missing: $SOURCE_ROOT"
    exit 1
  fi

  run_tmp="$TMP_ROOT/run.$$"
  mkdir -p "$run_tmp" "$(dirname "$REPORT_PATH")" "$(dirname "$MANIFEST_PATH")"

  manifest_tmp="$run_tmp/manifest.tsv"
  report_tmp="$run_tmp/latest-report.md"
  : > "$manifest_tmp"

  total=0
  bundled=0
  skipped=0
  failed=0
  details="$run_tmp/details.txt"
  : > "$details"

  repo_list="$run_tmp/repos.txt"
  find "$SOURCE_ROOT" -type d -name '*.git' | sort > "$repo_list"

  while IFS= read -r repo; do
    total=$((total + 1))

    if [ "$(git --git-dir="$repo" rev-parse --is-bare-repository 2>/dev/null || true)" != "true" ]; then
      skipped=$((skipped + 1))
      printf 'SKIP\t%s\tnot a bare repository\n' "$repo" >> "$details"
      printf '%s\t%s\t%s\t%s\n' "$total" "$bundled" "$skipped" "$failed" > "$run_tmp/counts"
      continue
    fi

    target="$(bundle_target_for_repo "$repo")"
    target_dir="$(dirname "$target")"
    tmp="$run_tmp/$(basename "$target").tmp"
    target_tmp="$target_dir/.$(basename "$target").tmp"
    mkdir -p "$target_dir"

    rel="${repo#$SOURCE_ROOT/}"
    log "Bundling $rel"

    if git --git-dir="$repo" bundle create "$tmp" --all >/dev/null 2>&1 &&
      git --git-dir="$repo" bundle verify "$tmp" >/dev/null 2>&1; then
      chmod 644 "$tmp"
      rm -f "$target_tmp"
      cp "$tmp" "$target_tmp"
      chmod 644 "$target_tmp"
      mv "$target_tmp" "$target"
      rm -f "$tmp"
      git --git-dir="$repo" bundle verify "$target" >/dev/null 2>&1
      (
        cd "$target_dir"
        sha256sum "$(basename "$target")" > "$(basename "$target").sha256.tmp"
      )
      chmod 644 "$target.sha256.tmp"
      mv "$target.sha256.tmp" "$target.sha256"
      size_bytes="$(wc -c < "$target" | tr -d ' ')"
      printf '%s\t%s\t%s\t%s\n' "$RUN_ID" "$rel" "${target#$BUNDLE_ROOT/}" "$size_bytes" >> "$manifest_tmp"
      printf 'OK\t%s\t%s bytes\n' "$rel" "$size_bytes" >> "$details"
      bundled=$((bundled + 1))
    else
      failed=$((failed + 1))
      rm -f "$tmp"
      printf 'FAIL\t%s\tbundle create or verify failed\n' "$rel" >> "$details"
    fi

    printf '%s\t%s\t%s\t%s\n' "$total" "$bundled" "$skipped" "$failed" > "$run_tmp/counts"
  done < "$repo_list"

  if [ -f "$run_tmp/counts" ]; then
    IFS="$(printf '\t')" read -r total bundled skipped failed < "$run_tmp/counts"
  fi

  {
    printf '# Gitea Bundle Mirror Report\n\n'
    printf 'Timestamp: %s\n' "$RUN_ID"
    printf 'Source: `%s`\n' "$SOURCE_ROOT"
    printf 'Target: `%s`\n' "$BUNDLE_ROOT"
    printf 'Total repositories: %s\n' "$total"
    printf 'Bundled: %s\n' "$bundled"
    printf 'Skipped: %s\n' "$skipped"
    printf 'Failed: %s\n\n' "$failed"
    printf '## Details\n\n'
    if [ -s "$details" ]; then
      while IFS="$(printf '\t')" read -r status name message; do
        printf -- '- `%s` %s: %s\n' "$status" "$name" "$message"
      done < "$details"
    else
      printf -- '- No repositories found.\n'
    fi
  } > "$report_tmp"

  chmod 644 "$report_tmp" "$manifest_tmp"
  mv "$report_tmp" "$REPORT_PATH"
  mv "$manifest_tmp" "$MANIFEST_PATH"

  log "Report written to $REPORT_PATH"
  [ "$failed" -eq 0 ]
}

main "$@"