#!/bin/bash
set -euo pipefail

log() {
  printf '%s\n' "$*" >&2
}

fail() {
  log "ERROR: $*"
  exit 1
}

trim() {
  # Remove leading and trailing ASCII whitespace from a string.
  local value="$1"
  value="${value#"${value%%[![:space:]]*}"}"
  value="${value%"${value##*[![:space:]]}"}"
  printf '%s' "$value"
}

url_encode() {
  # URL-encode a single path or query component using jq's RFC 3986 encoding.
  jq -rn --arg value "$1" '$value|@uri'
}

resolve_token() {
  # Resolve the already-merged token input passed in RUNNER_TOKEN.
  log "Trying token from RUNNER_TOKEN"

  if [[ -n "${RUNNER_TOKEN:-}" ]]; then
    log "Using token from RUNNER_TOKEN"
    printf '%s' "${RUNNER_TOKEN}"
    return 0
  fi

  return 1
}

resolve_keep_count() {
  # Parse KEEP_COUNT and ensure it is a non-negative integer.
  local raw_value="${INPUT_KEEP_COUNT:-2}"

  if [[ -z "${raw_value}" ]]; then
    raw_value="2"
  fi

  if [[ ! "${raw_value}" =~ ^[0-9]+$ ]]; then
    fail "Invalid keep_count: ${raw_value}"
  fi

  printf '%s' "${raw_value}"
}

resolve_package_names() {
  # Normalize PACKAGE_NAMES into a unique, newline-separated list.
  local raw_value="${INPUT_PACKAGE_NAMES:-}"
  local normalized token
  local -A seen=()
  local -a package_names=()

  if [[ -z "$(trim "${raw_value}")" ]]; then
    fail "Missing PACKAGE_NAMES"
  fi

  normalized="${raw_value//$'\n'/,}"
  IFS=',' read -r -a tokens <<< "${normalized}"

  for token in "${tokens[@]}"; do
    token="$(trim "${token}")"
    [[ -n "${token}" ]] || continue

    if [[ -z "${seen["${token}"]+x}" ]]; then
      seen["${token}"]=1
      package_names+=("${token}")
    fi
  done

  if (( ${#package_names[@]} == 0 )); then
    fail "Missing PACKAGE_NAMES"
  fi

  printf '%s\n' "${package_names[@]}"
}

parse_repo_context() {
  # Convert the repository slug into owner/repo parts.
  local repository="$1"
  local owner repo

  repository="$(trim "${repository}")"
  if [[ -z "${repository}" || "${repository}" != */* ]]; then
    fail "Invalid GITEA_REPOSITORY: ${repository:-<empty>}"
  fi

  owner="${repository%%/*}"
  repo="${repository#*/}"

  if [[ -z "${owner}" || -z "${repo}" || "${repo}" == */* ]]; then
    fail "Invalid GITEA_REPOSITORY: ${repository}"
  fi

  printf '%s\t%s\n' "${owner}" "${repo}"
}

api_request() {
  # Perform one HTTP request and return status metadata as TSV.
  # stdout format: http_code<TAB>status_text<TAB>request_id
  local method="$1"
  local path="$2"
  local body_file="$3"
  local headers_file="$4"
  local url http_code status_text request_id status_line

  url="${GITEA_SERVER_URL%/}${path}"

  if ! http_code="$(
    curl -sS \
      -H "Accept: application/json" \
      -H "Authorization: token ${RESOLVED_GITEA_TOKEN}" \
      -X "${method}" \
      -D "${headers_file}" \
      -o "${body_file}" \
      -w '%{http_code}' \
      "${url}"
  )"; then
    fail "Request failed: ${method} ${path}"
  fi

  status_line="$(head -n 1 "${headers_file}" | tr -d '\r')"
  status_text="$(printf '%s' "${status_line}" | cut -d' ' -f2-)"
  request_id="$(
    awk -F': *' 'tolower($1)=="x-gitea-request-id" || tolower($1)=="x-request-id" {value=$2} END {print value}' "${headers_file}" | tr -d '\r'
  )"

  if [[ -n "${request_id}" ]]; then
    log "${method} ${path} -> ${status_text} request_id=${request_id}"
  else
    log "${method} ${path} -> ${status_text}"
  fi

  printf '%s\t%s\t%s\n' "${http_code}" "${status_text}" "${request_id}"
}

fetch_package_versions() {
  # Fetch and aggregate all package versions for a single package name.
  # Params:
  #   $1 owner
  #   $2 package_name
  # stdout:
  #   JSON array of version objects.
  local owner="$1"
  local package_name="$2"
  local page=1
  local limit=100
  local aggregate_file page_file headers_file meta http_code status_text request_id page_length path
  local encoded_owner encoded_package_name

  encoded_owner="$(url_encode "${owner}")"
  encoded_package_name="$(url_encode "${package_name}")"

  aggregate_file="$(mktemp)"
  printf '[]' > "${aggregate_file}"

  while :; do
    path="/api/v1/packages/${encoded_owner}/nuget/${encoded_package_name}?page=${page}&limit=${limit}"
    page_file="$(mktemp)"
    headers_file="$(mktemp)"
    meta="$(api_request GET "${path}" "${page_file}" "${headers_file}")"
    IFS=$'\t' read -r http_code status_text request_id <<< "${meta}"
    rm -f "${headers_file}"

    if [[ "${http_code}" == "404" ]]; then
      rm -f "${page_file}" "${aggregate_file}"
      printf '[]'
      return 0
    fi

    if [[ ! "${http_code}" =~ ^2 ]]; then
      rm -f "${page_file}" "${aggregate_file}"
      fail "Unexpected response for package ${package_name}: ${status_text}"
    fi

    page_length="$(jq 'length' "${page_file}")"

    tmp_file="$(mktemp)"
    jq -s '.[0] + .[1]' "${aggregate_file}" "${page_file}" > "${tmp_file}"
    mv "${tmp_file}" "${aggregate_file}"
    rm -f "${page_file}"

    if (( page_length < limit )); then
      break
    fi

    page=$((page + 1))
  done

  cat "${aggregate_file}"
  rm -f "${aggregate_file}"
}

collect_package_candidates() {
  # Build the delete candidate file for the requested package names.
  # Params:
  #   $1 owner
  #   $2 keep_count
  #   $3 candidate_file
  #   $4... package names
  # stdout:
  #   package_count<TAB>total_version_count<TAB>kept_count<TAB>candidate_count
  local owner="$1"
  local keep_count="$2"
  local candidate_file="$3"
  shift 3
  local -a package_names=("$@")
  local package_name versions_json total_versions candidates_json
  local package_count=0
  local total_version_count=0
  local kept_count=0
  local candidate_count=0

  : > "${candidate_file}"

  for package_name in "${package_names[@]}"; do
    versions_json="$(fetch_package_versions "${owner}" "${package_name}")"

    if [[ "$(jq 'length' <<<"${versions_json}")" -eq 0 ]]; then
      log "No versions found for package ${package_name}"
      continue
    fi

    package_count=$((package_count + 1))
    total_versions="$(jq 'length' <<<"${versions_json}")"
    total_version_count=$((total_version_count + total_versions))

    log "Package ${package_name}: total_versions=${total_versions} keep_count=${keep_count}"
    log "Package ${package_name} versions (oldest -> newest):"
    while IFS=$'\t' read -r version created_at; do
      [[ -z "${version}" ]] && continue
      log "  - ${version} (${created_at})"
    done < <(jq -r 'sort_by(.created_at, .version)[] | [.version, .created_at] | @tsv' <<<"${versions_json}")

    if (( total_versions <= keep_count )); then
      log "  keep all ${total_versions} versions"
      kept_count=$((kept_count + total_versions))
      continue
    fi

    kept_count=$((kept_count + keep_count))
    candidates_json="$(
      jq -c --argjson keep "${keep_count}" \
        'sort_by(.created_at, .version) | .[0:(length - $keep)]' <<<"${versions_json}"
    )"

    while IFS=$'\t' read -r package version created_at; do
      [[ -z "${package}" ]] && continue
      log "Candidate to delete: package ${package} version ${version} (created: ${created_at})"
      printf '%s\t%s\t%s\n' "${package}" "${version}" "${created_at}" >> "${candidate_file}"
      candidate_count=$((candidate_count + 1))
    done < <(jq -r '.[] | [.name, .version, .created_at] | @tsv' <<<"${candidates_json}")
  done

  printf '%s\t%s\t%s\t%s\n' "${package_count}" "${total_version_count}" "${kept_count}" "${candidate_count}"
}

process_candidates() {
  # Delete each queued version and summarize the result.
  # Params:
  #   $1 owner
  #   $2 candidate_file
  #   $3 package_count
  #   $4 total_version_count
  #   $5 kept_count
  #   $6 candidate_count
  local owner="$1"
  local candidate_file="$2"
  local package_count="$3"
  local total_version_count="$4"
  local kept_count="$5"
  local candidate_count="$6"
  local deleted_count=0
  local error_count=0
  local package_name version _created_at
  local body_file headers_file meta http_code status_text request_id

  if [[ ! -s "${candidate_file}" ]]; then
    log "No delete candidates found"
    log "Summary: packages=${package_count} versions=${total_version_count} kept=${kept_count} candidates=0 deleted=0 errors=0"
    return 0
  fi

  while IFS=$'\t' read -r package_name version _created_at; do
    [[ -z "${package_name}" ]] && continue

    body_file="$(mktemp)"
    headers_file="$(mktemp)"
    meta="$(api_request DELETE "/api/v1/packages/$(url_encode "${owner}")/nuget/$(url_encode "${package_name}")/$(url_encode "${version}")" "${body_file}" "${headers_file}")"
    IFS=$'\t' read -r http_code status_text request_id <<< "${meta}"
    rm -f "${body_file}" "${headers_file}"

    if [[ "${http_code}" =~ ^2 ]]; then
      log "Deleted package ${package_name} version ${version} -> ${status_text}"
      deleted_count=$((deleted_count + 1))
    else
      if [[ -n "${request_id}" ]]; then
        log "ERROR: DELETE package ${package_name} version ${version} -> ${status_text} request_id=${request_id}"
      else
        log "ERROR: DELETE package ${package_name} version ${version} -> ${status_text}"
      fi
      error_count=$((error_count + 1))
    fi
  done < "${candidate_file}"

  log "Summary: packages=${package_count} versions=${total_version_count} kept=${kept_count} candidates=${candidate_count} deleted=${deleted_count} errors=${error_count}"
}

main() {
  # Entry point for the Docker container. Resolves inputs, builds candidates,
  # and applies deletes for the selected NuGet packages.
  local token keep_count repository owner _repo package_names_csv
  local -a package_names
  local candidate_file summary package_count total_version_count kept_count candidate_count

  log "Gitea Server Url: ${GITEA_SERVER_URL:-}"
  log "Gitea Repository: ${GITEA_REPOSITORY:-}"

  if ! token="$(resolve_token)"; then
    fail "No Gitea token available, exiting"
  fi

  export RESOLVED_GITEA_TOKEN="$token"

  repository="${GITEA_REPOSITORY:-}"
  IFS=$'\t' read -r owner _repo <<< "$(parse_repo_context "${repository}")"
  keep_count="$(resolve_keep_count)"

  mapfile -t package_names < <(resolve_package_names)
  package_names_csv="$(IFS=,; echo "${package_names[*]}")"

  log "keep_count=${keep_count}"
  log "package_names=${package_names_csv}"
  log "Token source resolved successfully"

  candidate_file="$(mktemp)"
  trap "rm -f -- '${candidate_file}'" EXIT

  summary="$(collect_package_candidates "${owner}" "${keep_count}" "${candidate_file}" "${package_names[@]}")"
  IFS=$'\t' read -r package_count total_version_count kept_count candidate_count <<< "${summary}"

  if (( package_count == 0 )); then
    log "No matching packages found for requested package_names"
  fi

  process_candidates "${owner}" "${candidate_file}" "${package_count}" "${total_version_count}" "${kept_count}" "${candidate_count}"
  log "Stage 4 complete"
}

if [[ "${BASH_SOURCE[0]}" == "$0" ]]; then
  main "$@"
fi