# note: place this as the last step of the job, so the new cache is saved by "Post ccache" right after the old one is cleared
name: "ccache-clear"
description: "Delete GitHub Actions caches matching a key prefix, oldest first"
inputs:
  key:
    description: "Cache key prefix to match and delete"
    required: true
  older:
    description: "Only delete caches created more than this long ago (e.g. 90m, 1h, 1d). By default all matching caches are deleted"
    required: false
    default: ""
  min:
    description: "Stop deleting if fewer than this many caches would remain (e.g. 1). By default there is no minimum"
    required: false
    default: "0"
  dry-run:
    description: "Only print the caches that would be deleted, without deleting them"
    required: false
    default: "false"

runs:
  using: "composite"
  steps:
    - name: Clear caches
      shell: bash
      env:
        CLEAR_KEY: ${{ inputs.key }}
        CLEAR_OLDER: ${{ inputs.older }}
        CLEAR_MIN: ${{ inputs.min }}
        CLEAR_DRY_RUN: ${{ inputs.dry-run }}
      run: |
        # Convert a duration (e.g. 90m, 1h, 1d, plain seconds) to seconds
        to_seconds() {
          local val="$1"
          [[ "$val" =~ ^[0-9]+$ ]] && { echo "$val"; return 0; }
          local num="${val%?}" unit="${val: -1}" mult
          [[ "$num" =~ ^[0-9]+$ ]] || return 1
          case "$unit" in
            s) mult=1 ;;
            m) mult=60 ;;
            h) mult=3600 ;;
            d) mult=86400 ;;
            *) return 1 ;;
          esac
          echo $((num * mult))
        }

        [[ "$CLEAR_MIN" =~ ^[0-9]+$ ]] || { echo "Invalid min value: $CLEAR_MIN" >&2; exit 1; }
        [[ "$CLEAR_DRY_RUN" =~ ^(true|false)$ ]] || { echo "Invalid dry-run value: $CLEAR_DRY_RUN" >&2; exit 1; }

        CACHES=$(gh cache list --key "ccache-$CLEAR_KEY" --json id,key,createdAt --jq '.[] | [.createdAt, .id, .key] | @tsv' 2>/dev/null | LC_ALL=C sort)
        if [ -z "$CACHES" ]; then
          echo "No caches found with key prefix: $CLEAR_KEY"
          exit 0
        fi

        TOTAL=$(( $(wc -l <<< "$CACHES") ))

        echo "Found $TOTAL cache(s) with key prefix: $CLEAR_KEY (oldest first):"
        while IFS=$'\t' read -r CREATED ID KEY; do
          printf '  %s  %s  %s\n' "$CREATED" "$ID" "$KEY"
        done <<< "$CACHES"

        CUTOFF=""
        if [ -n "$CLEAR_OLDER" ]; then
          OLDER_SECONDS=$(to_seconds "$CLEAR_OLDER") || { echo "Invalid older value: $CLEAR_OLDER (expected e.g. 90m, 1h, 1d)" >&2; exit 1; }
          CUTOFF=$(( $(date +%s) - OLDER_SECONDS ))
        fi

        # Caches are sorted oldest first
        DELETED=0
        while IFS=$'\t' read -r CREATED ID KEY; do
          if [ -n "$CUTOFF" ] && [ "$(date -d "$CREATED" +%s)" -ge "$CUTOFF" ]; then
            echo "Rest are not older than $CLEAR_OLDER, stopping"
            break
          fi
          if [ $((TOTAL - DELETED - 1)) -lt "$CLEAR_MIN" ]; then
            echo "Keeping at least $CLEAR_MIN cache(s), stopping"
            break
          fi
          if [ "$CLEAR_DRY_RUN" = "true" ]; then
            echo "Would delete cache: $ID ($KEY)"
          else
            echo "Deleting cache: $ID ($KEY)"
            gh cache delete "$ID"
          fi
          DELETED=$((DELETED + 1))
        done <<< "$CACHES"