#!/bin/bash
# -----------------------------------------------------------------------------------------------
# --------------------------------- Transcode Cleanup ------------------------------------------
# -----------------------------------------------------------------------------------------------
# Removes old inactive transcode files from both ramdisk and SSD fallback locations.
# Never deletes files belonging to active sessions or files being actively written.
# After cleanup checks if ramdisk usage dropped enough to flip symlink back to ramdisk.
#
# Safety rules — a file is eligible for deletion only if ALL conditions are true:
#   1. Older than TRANSCODE_MAX_AGE minutes (mtime)
#   2. Not currently open by any process (lsof check)
#   3. Not in an orphan grace period shorter than TRANSCODE_ORPHAN_AGE minutes
#
# Run every 5 minutes via cron/User Scripts plugin.
# All configuration in Master.conf under Transcode Manager section.
# Supports --dry-run to preview what would be deleted without making changes.
# -----------------------------------------------------------------------------------------------

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

source "$SCRIPT_DIR/../Master.conf"
source "$SCRIPT_DIR/../common.sh"

parse_args "$@"

STATE_FILE="/tmp/transcode_state.db"

# -----------------------------------------------------------------------------------------------
# ━━━ $ICON_GEAR Setup ━━━
# -----------------------------------------------------------------------------------------------
echo ""
echo "━━━ $ICON_GEAR Setup ━━━"

if [[ "$EUID" -ne 0 ]]; then
    error "Must be run as root"
    exit 1
fi

success "Running as root"

if ! command -v lsof >/dev/null 2>&1; then
    warn "lsof not available — active file check will be skipped"
    LSOF_AVAILABLE=false
else
    LSOF_AVAILABLE=true
fi

# -----------------------------------------------------------------------------------------------
# ━━━ $ICON_SUMMARY Status ━━━
# -----------------------------------------------------------------------------------------------
if [[ "$SHOW_STATUS" == true ]]; then
    echo ""
    echo "━━━━━ $ICON_SUMMARY STATUS ━━━━━"
    echo "$ICON_RAM   Ramdisk:      $RAMDISK_PATH"
    echo "$ICON_DISK  SSD fallback: $TRANSCODE_SSD"
    echo "$ICON_TRASH Max age:      ${TRANSCODE_MAX_AGE} minutes"
    echo "$ICON_TRASH Orphan age:   ${TRANSCODE_ORPHAN_AGE} minutes"
    echo "$ICON_GEAR  lsof check:   $LSOF_AVAILABLE"
    echo "$ICON_GEAR  Dry Run:      $DRY_RUN"
    echo "━━━━━━━━━━━━━━━━━━━━━━━"
    exit 0
fi

[[ "$DRY_RUN" == true ]] && warn "DRY RUN — no files will be deleted"

# -----------------------------------------------------------------------------------------------
# FILE SAFETY CHECK
# Returns 0 (safe to delete) if file is old enough and not actively open.
# Returns 1 (keep) if file should be preserved.
# -----------------------------------------------------------------------------------------------
is_safe_to_delete() {
    local file="$1" max_age="$2"

    # Check age using find — if find returns the file it's old enough
    if ! find "$file" -maxdepth 0 -mmin +"$max_age" 2>/dev/null | grep -q .; then
        return 1  # Too recent
    fi

    # Check if file is actively open by any process
    if [[ "$LSOF_AVAILABLE" == true ]]; then
        if lsof "$file" >/dev/null 2>&1; then
            return 1  # File is open — being written or read
        fi
    fi

    return 0  # Safe to delete
}

# -----------------------------------------------------------------------------------------------
# CLEANUP FUNCTION
# Scans a directory and removes eligible files.
# Returns bytes freed.
# -----------------------------------------------------------------------------------------------
cleanup_location() {
    local location="$1" label="$2" max_age="$3"
    local files_removed=0
    local bytes_freed=0
    local files_skipped=0

    if [[ ! -d "$location" ]]; then
        warn "$label does not exist — skipping"
        return
    fi

    local file_count
    file_count=$(find "$location" -type f 2>/dev/null | wc -l)
    info "$ICON_TRASH $label: $file_count files to scan (age threshold: ${max_age}min)"

    while IFS= read -r file; do
        [[ -z "$file" ]] && continue

        if is_safe_to_delete "$file" "$max_age"; then
            local file_size
            file_size=$(stat -c%s "$file" 2>/dev/null || echo 0)

            if [[ "$DRY_RUN" == true ]]; then
                warn "DRY RUN — would delete: $file"
                ((files_skipped++))
            else
                if rm -f "$file" 2>/dev/null; then
                    ((files_removed++))
                    bytes_freed=$((bytes_freed + file_size))
                    log "Deleted: $file"
                else
                    warn "Could not delete: $file"
                    ((files_skipped++))
                fi
            fi
        else
            ((files_skipped++))
            log "Keeping: $file (active or too recent)"
        fi
    done < <(find "$location" -type f 2>/dev/null)

    # Remove empty directories left behind
    if [[ "$DRY_RUN" == false ]]; then
        find "$location" -mindepth 1 -type d -empty -delete 2>/dev/null
    fi

    local freed_human
    if (( bytes_freed > 1073741824 )); then
        freed_human=$(awk "BEGIN {printf \"%.1fGB\", $bytes_freed / 1073741824}")
    elif (( bytes_freed > 1048576 )); then
        freed_human=$(awk "BEGIN {printf \"%.1fMB\", $bytes_freed / 1048576}")
    else
        freed_human="${bytes_freed}B"
    fi

    if [[ "$DRY_RUN" == true ]]; then
        info "$label — dry run complete ($files_skipped files scanned)"
    else
        success "$label — removed $files_removed files, freed $freed_human, skipped $files_skipped"
    fi

    # Export for summary
    LOCATION_REMOVED=$files_removed
    LOCATION_FREED=$freed_human
    LOCATION_SKIPPED=$files_skipped
}

# -----------------------------------------------------------------------------------------------
# ━━━ $ICON_TRASH Transcode Cleanup ━━━
# -----------------------------------------------------------------------------------------------
echo ""
echo "━━━ $ICON_TRASH Transcode Cleanup — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
echo ""

START=$(date +%s)
TOTAL_REMOVED=0
TOTAL_SKIPPED=0

# Cleanup ramdisk
if mountpoint -q "$RAMDISK_PATH" 2>/dev/null; then
    echo "━━━ $ICON_RAM Ramdisk ━━━"
    RAMDISK_BEFORE=$(df "$RAMDISK_PATH" | awk 'NR==2 {print $3}')
    cleanup_location "$RAMDISK_PATH" "Ramdisk" "$TRANSCODE_MAX_AGE"
    TOTAL_REMOVED=$((TOTAL_REMOVED + LOCATION_REMOVED))
    TOTAL_SKIPPED=$((TOTAL_SKIPPED + LOCATION_SKIPPED))
    RAMDISK_FREED=$LOCATION_FREED
    echo ""
else
    warn "$ICON_RAM Ramdisk not mounted — skipping ramdisk cleanup"
    RAMDISK_FREED="0B"
fi

# Cleanup SSD fallback
if [[ -d "$TRANSCODE_SSD" ]]; then
    echo "━━━ $ICON_DISK SSD Fallback ━━━"
    cleanup_location "$TRANSCODE_SSD" "SSD fallback" "$TRANSCODE_MAX_AGE"
    TOTAL_REMOVED=$((TOTAL_REMOVED + LOCATION_REMOVED))
    TOTAL_SKIPPED=$((TOTAL_SKIPPED + LOCATION_SKIPPED))
    SSD_FREED=$LOCATION_FREED
    echo ""
else
    info "$ICON_DISK SSD fallback not found — skipping"
    SSD_FREED="0B"
fi

# -----------------------------------------------------------------------------------------------
# Post-cleanup symlink check
# If ramdisk had space freed, check if manager should flip symlink back
# -----------------------------------------------------------------------------------------------
if [[ "$DRY_RUN" == false ]] && mountpoint -q "$RAMDISK_PATH" 2>/dev/null; then
    RAMDISK_USED_KB=$(df "$RAMDISK_PATH" | awk 'NR==2 {print $3}')
    LOW_THRESHOLD=$(awk "BEGIN {print $RAMDISK_LOW_GB * 1024 * 1024}")

    if (( RAMDISK_USED_KB < LOW_THRESHOLD )); then
        CURRENT_TARGET=$(grep "^current_target=" "$STATE_FILE" 2>/dev/null | cut -d'=' -f2)
        if [[ "$CURRENT_TARGET" == "$TRANSCODE_SSD" ]]; then
            info "$ICON_RAM Ramdisk has space after cleanup — triggering manager to flip back"
            bash "$SCRIPT_DIR/transcode_manager.sh" --no-log
        fi
    fi
fi

END=$(date +%s)

# -----------------------------------------------------------------------------------------------
# ━━━ $ICON_SUMMARY Summary ━━━
# -----------------------------------------------------------------------------------------------
echo "━━━━━ $ICON_SUMMARY TRANSCODE CLEANUP SUMMARY ━━━━━"
echo "$ICON_RAM   Ramdisk freed:  $RAMDISK_FREED"
echo "$ICON_DISK  SSD freed:      $SSD_FREED"
echo "$ICON_TRASH Removed:        $TOTAL_REMOVED files"
echo "$ICON_TRASH Skipped:        $TOTAL_SKIPPED files (active or recent)"
echo "$ICON_TIME  Duration:       $(format_duration $((END - START)))"
if [[ "$DRY_RUN" == true ]]; then
    echo "$ICON_WARN  Status:         DRY RUN — no files deleted"
else
    echo "$ICON_DONE  Status:         $ICON_SUCCESS DONE"
    if [[ "$TOTAL_REMOVED" -gt 0 ]]; then
        notify "Transcode cleanup on $(hostname) — removed $TOTAL_REMOVED files (RAM: $RAMDISK_FREED SSD: $SSD_FREED)" "Transcode Cleanup" "normal"
    fi
fi
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"