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

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

# Always absolute path
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"

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

if [[ -f "${PKG_PREV}" ]]; then
    # Extract names only
    CUR_NAMES="$(cut -d' ' -f1 "${PKG_CUR}" | sort)"
    PREV_NAMES="$(cut -d' ' -f1 "${PKG_PREV}" | sort)"

    # Safe comm calls (|| true prevents exit 1)
    ADDED_NAMES="$(comm -13 <(echo "${PREV_NAMES}") <(echo "${CUR_NAMES}") || true)"
    REMOVED_NAMES="$(comm -23 <(echo "${PREV_NAMES}") <(echo "${CUR_NAMES}") || true)"
    COMMON_NAMES="$(comm -12 <(echo "${PREV_NAMES}") <(echo "${CUR_NAMES}") || true)"

    ADDED_LIST=()
    while read -r name; do
        [[ -z "$name" ]] && continue
        ver="$(grep -E "^${name} " "${PKG_CUR}" | awk '{print $2}')"
        ADDED_LIST+=("${name} ${ver}")
    done <<< "${ADDED_NAMES}"

    REMOVED_LIST=()
    while read -r name; do
        [[ -z "$name" ]] && continue
        ver="$(grep -E "^${name} " "${PKG_PREV}" | awk '{print $2}')"
        REMOVED_LIST+=("${name} ${ver}")
    done <<< "${REMOVED_NAMES}"

    UPDATED_LIST=()
    while read -r name; do
        [[ -z "$name" ]] && continue
        old_ver="$(grep -E "^${name} " "${PKG_PREV}" | awk '{print $2}')"
        new_ver="$(grep -E "^${name} " "${PKG_CUR}" | awk '{print $2}')"
        if [[ "${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[@]}"

    {
      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}"

else
    # First build: everything is added
    ADDED_LIST=()
    while read -r name ver; do
        ADDED_LIST+=("${name} ${ver}")
    done < "${PKG_CUR}"

    ADDED_COUNT="${#ADDED_LIST[@]}"

    {
      echo "{"
      echo "  \"image\": \"${IMAGE}\","
      echo "  \"version\": \"${VERSION}\","
      echo "  \"build_id\": \"${BUILD_ID}\","
      echo "  \"added_count\": ${ADDED_COUNT},"
      echo "  \"removed_count\": 0,"
      echo "  \"updated_count\": 0,"
      echo "  \"added\": ["
      for i in "${!ADDED_LIST[@]}"; do
        sep=$([[ $i -lt $((ADDED_COUNT-1)) ]] && echo "," || echo "")
        printf '    "%s"%s\n' "${ADDED_LIST[$i]}" "${sep}"
      done
      echo "  ],"
      echo "  \"removed\": [],"
      echo "  \"updated\": []"
      echo "}"
    } > "${CHANGELOG_FILE}"
fi

# Update latest snapshot
mv "${PKG_CUR}" "${PKG_PREV}"

echo "Changelog written to ${CHANGELOG_FILE}"