#!/usr/bin/env bash
set -euox pipefail

IMAGE="$1"
VERSION="$2"

ROOTFS="${GITHUB_WORKSPACE}/images/${IMAGE}/rootfs"
CHANGELOG_DIR="changelogs/${IMAGE}"

mkdir -p "${CHANGELOG_DIR}"

PKG_CUR="${CHANGELOG_DIR}/packages-current.txt"
PKG_PREV="${CHANGELOG_DIR}/packages-latest.txt"
BUILD_ID="$(cat .buildid)"
CHANGELOG_FILE="${CHANGELOG_DIR}/${VERSION}.${BUILD_ID}.json"

# Ensure rpmdb exists
if [[ ! -f "${ROOTFS}/usr/lib/sysimage/rpm/Packages" ]]; then
    echo "WARNING: rpmdb missing in rootfs (${ROOTFS})"
    echo "Skipping changelog generation."
    exit 0
fi

# Extract package list
rpm -qa --root "${ROOTFS}" --qf '%{NAME} %{EVR}\n' | sort > "${PKG_CUR}"

# Prepare safe temp files
CUR_NAMES_FILE="$(mktemp)"
PREV_NAMES_FILE="$(mktemp)"

cut -d' ' -f1 "${PKG_CUR}" | sort > "${CUR_NAMES_FILE}"

if [[ -f "${PKG_PREV}" ]]; then
    cut -d' ' -f1 "${PKG_PREV}" | sort > "${PREV_NAMES_FILE}"
else
    cp "${CUR_NAMES_FILE}" "${PREV_NAMES_FILE}"
fi

# Safe comm operations
ADDED_NAMES="$(comm -13 "${PREV_NAMES_FILE}" "${CUR_NAMES_FILE}" || true)"
REMOVED_NAMES="$(comm -23 "${PREV_NAMES_FILE}" "${CUR_NAMES_FILE}" || true)"
COMMON_NAMES="$(comm -12 "${PREV_NAMES_FILE}" "${CUR_NAMES_FILE}" || true)"

# Helper: get version from file using awk (exact match)
get_ver() {
    local pkg="$1"
    local file="$2"
    awk -v p="$pkg" '$1 == p {print $2}' "$file"
}

# Build lists
ADDED_LIST=()
while read -r name; do
    [[ -z "$name" ]] && continue
    ver="$(get_ver "$name" "$PKG_CUR")"
    ADDED_LIST+=("${name} ${ver}")
done <<< "${ADDED_NAMES}"

REMOVED_LIST=()
while read -r name; do
    [[ -z "$name" ]] && continue
    ver="$(get_ver "$name" "$PKG_PREV")"
    REMOVED_LIST+=("${name} ${ver}")
done <<< "${REMOVED_NAMES}"

UPDATED_LIST=()
while read -r name; do
    [[ -z "$name" ]] && continue
    old_ver="$(get_ver "$name" "$PKG_PREV")"
    new_ver="$(get_ver "$name" "$PKG_CUR")"

    # Skip if either version is missing
    [[ -z "$old_ver" || -z "$new_ver" ]] && continue

    if [[ "$old_ver" != "$new_ver" ]]; then
        UPDATED_LIST+=("${name} ${old_ver} -> ${new_ver}")
    fi
done <<< "${COMMON_NAMES}"

ADDED_COUNT="${#ADDED_LIST[@]}"
REMOVED_COUNT="${#REMOVED_LIST[@]}"
UPDATED_COUNT="${#UPDATED_LIST[@]}"

# Write JSON
{
  echo "{"
  echo "  \"image\": \"${IMAGE}\","
  echo "  \"version\": \"${VERSION}\","
  echo "  \"build_id\": \"${BUILD_ID}\","
  echo "  \"added_count\": ${ADDED_COUNT},"
  echo "  \"removed_count\": ${REMOVED_COUNT},"
  echo "  \"updated_count\": ${UPDATED_COUNT},"
  echo "  \"added\": ["
  for i in "${!ADDED_LIST[@]}"; do
    sep=$([[ $i -lt $((ADDED_COUNT-1)) ]] && echo "," || echo "")
    printf '    "%s"%s\n' "${ADDED_LIST[$i]}" "${sep}"
  done
  echo "  ],"
  echo "  \"removed\": ["
  for i in "${!REMOVED_LIST[@]}"; do
    sep=$([[ $i -lt $((REMOVED_COUNT-1)) ]] && echo "," || echo "")
    printf '    "%s"%s\n' "${REMOVED_LIST[$i]}" "${sep}"
  done
  echo "  ],"
  echo "  \"updated\": ["
  for i in "${!UPDATED_LIST[@]}"; do
    sep=$([[ $i -lt $((UPDATED_COUNT-1)) ]] && echo "," || echo "")
    printf '    "%s"%s\n' "${UPDATED_LIST[$i]}" "${sep}"
  done
  echo "  ]"
  echo "}"
} > "${CHANGELOG_FILE}"

mv "${PKG_CUR}" "${PKG_PREV}"

echo "Changelog written to ${CHANGELOG_FILE}"