#!/bin/bash
# ==============================================================================================
# ================================= Docker Update ==============================================
# ==============================================================================================
#
# PURPOSE
# ─────────────────────────────────────────────────────────────────────────────
# Pulls the latest images for configured containers. Three modes:
#
# Normal mode — called by daily_sync_maintenance.sh before docker_daily_restart.sh.
# Containers stay running during the pull — no extra downtime beyond what the
# nightly restart already causes.
#
# Weekly mode — called by weekly_sync_maintenance.sh via WEEKLY_MAINTENANCE_SCRIPTS
# before docker_weekly_restart.sh. Pulls WEEKLY_RESTART_CONTAINERS so the
# subsequent restart lands on the fresh image.
#
# Remainder mode — called by monthly_maintenance.sh. Catches everything not
# already owned by daily or weekly — derived from docker ps, nothing to configure.
#
# ==============================================================================================
# OPERATIONAL MODEL
# ==============================================================================================
#
# Normal mode (daily):
#   Targets DAILY_RESTART_CONTAINERS — same list used by docker_daily_restart.sh.
#   Pull → compare old vs new image ID → mark updated or already current.
#   docker_daily_restart.sh runs after — containers restart onto the fresh image.
#
# Weekly mode:
#   Targets WEEKLY_RESTART_CONTAINERS — same list used by docker_weekly_restart.sh.
#   Pull → compare → rebuild if changed.
#   docker_weekly_restart.sh runs after — containers restart onto the fresh image.
#
# Remainder mode (monthly):
#   Targets all currently running containers NOT in:
#     DAILY_RESTART_CONTAINERS       — already updated daily
#     WEEKLY_RESTART_CONTAINERS      — already updated weekly
#     emby + critical-data profiles  — updated inline by the weekly sync window
#     FALLBACK_*_TIER*               — owned by the remote server's update cycle
#   Pull → compare → prune dangling images.
#
# ==============================================================================================
# DESIGN PRINCIPLES
# ==============================================================================================
#
# Single List
#   Normal mode reuses DAILY_RESTART_CONTAINERS rather than maintaining a
#   separate update list. Adding or removing a container from the restart list
#   automatically updates the image pull list — one change, both places.
#
# Version Ownership
#   Fallback containers are excluded from remainder mode. This server only runs
#   them during a fallback. The remote server owns their version — if remainder
#   updates them independently and a handback occurs, the remote's older image
#   may not handle data written by the newer version.
#
# State Respect
#   Stopped containers are never targeted. Pulling while stopped adds no value
#   and a stopped container was likely halted intentionally.
#
# ==============================================================================================
# OPERATIONAL SAFEGUARDS
# ==============================================================================================
#
# Lock Acquisition
#   Prevents concurrent execution via acquire_lock(). Safe to call from
#   maintenance scripts without risk of overlap.
#
# Host Detection
#   detect_hosts() identifies which server is running the script and aliases
#   HOST*_DAILY_RESTART_CONTAINERS to the correct host's values.
#
# Root Enforcement
#   Docker operations require root privileges.
#
# Docker Presence Check
#   Verifies the docker binary exists before execution.
#
# Docker Daemon Check
#   Verifies the daemon is responsive before container discovery. Remainder mode
#   derives its entire target list from docker ps — against a hung daemon that
#   returns empty and the run silently reports "no containers to update".
#
# Timeout Protection
#   Inspect, discovery and image-query commands are wrapped in a timeout so a
#   hung daemon cannot stall the maintenance window. docker pull is deliberately
#   NOT wrapped — a large image legitimately takes longer than any sane timeout,
#   and killing it mid-layer wastes the transfer.
#
# Empty List Guards
#   Each mode exits cleanly with a pointer to the relevant conf key when its
#   container list is unconfigured for this host.
#
# Rebuild Failure Fallback
#   A container that fails to rebuild is excluded from the rebuilt-list handoff
#   file, so the follow-up restart script still gives it a normal restart pass.
#
# DAILY_CONTAINER_UPDATES / WEEKLY_CONTAINER_UPDATES Toggles
#   Each mode exits cleanly when disabled. Restart scripts run regardless —
#   update and restart are independent operations.
#
# Fallback Exclusion
#   Remainder mode excludes containers owned by the remote server's update cycle
#   to prevent version divergence across the fallback boundary.
#
# Running-Only Filter
#   Stopped containers excluded from remainder mode — intentionally down.
#
# Image ID Comparison
#   Containers not restarted unless their image actually changed. Pulls that
#   result in "already up to date" produce no restart.
#
# ==============================================================================================
# CONFIGURATION
# ==============================================================================================
#
# master.conf
#
#   DAILY_CONTAINER_UPDATES
#       Enable or disable normal mode. docker_daily_restart.sh runs regardless.
#       (default: true)
#
#   WEEKLY_CONTAINER_UPDATES
#       Enable or disable weekly mode. docker_weekly_restart.sh runs regardless.
#       (default: true)
#
#   MONTHLY_REMAINING_UPDATES
#       Enable or disable remainder mode. (default: true)
#
#   DOCKER_UPDATE_REBUILT_DAILY_FILE / DOCKER_UPDATE_REBUILT_WEEKLY_FILE
#       Written after each normal/weekly run with the containers actually rebuilt
#       this pass — read by docker_daily_restart.sh / docker_weekly_restart.sh so
#       they skip restarting a container a second time right after this script
#       already rebuilt it onto the new image. Not written in remainder mode
#       (no follow-up restart script exists for it).
#
#   PROFILE_CRITICAL_CONTAINER_NAMES[emby|critical-data]
#       Container names for emby and critical-data profiles — excluded from
#       remainder mode (already updated by the weekly sync window)
#
# host*.conf
#
#   HOST*_DAILY_RESTART_CONTAINERS
#       Containers updated in normal mode. Aliased by detect_hosts() →
#       DAILY_RESTART_CONTAINERS
#
#   HOST*_WEEKLY_RESTART_CONTAINERS
#       Containers updated in weekly mode. Aliased by detect_hosts() →
#       WEEKLY_RESTART_CONTAINERS
#
# ==============================================================================================
# RUNTIME MODES
# ==============================================================================================
#
# docker_update.sh
#     Normal mode — pull latest images for DAILY_RESTART_CONTAINERS
#     Called by daily_sync_maintenance.sh before docker_daily_restart.sh
#
# docker_update.sh --weekly
#     Weekly mode — pull latest images for WEEKLY_RESTART_CONTAINERS
#     Called by weekly_sync_maintenance.sh (WEEKLY_MAINTENANCE_SCRIPTS) before docker_weekly_restart.sh
#
# docker_update.sh --remainder
#     Remainder mode — pull all running containers not in managed lists,
#     restart those that received updates, prune dangling images
#     Called by monthly_maintenance.sh
#
# docker_update.sh --dry-run
#     Preview which containers would be pulled without making changes
#
# docker_update.sh --status
#     Show configuration and container list for current mode
#
# docker_update.sh --log
#     Verbose per-container pull and comparison output
#
# ==============================================================================================

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

source "$SCRIPT_DIR/../load_config.sh"

# Pre-parse mode flags before parse_args (unknown args pass through to PARSED_ARGS)
REMAINDER_MODE=false
WEEKLY_MODE=false
_filtered_args=()
for _arg in "$@"; do
    case "$_arg" in
        --remainder) REMAINDER_MODE=true ;;
        --weekly)    WEEKLY_MODE=true ;;
        *)           _filtered_args+=("$_arg") ;;
    esac
done
unset _arg

parse_args "${_filtered_args[@]}"
unset _filtered_args

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

acquire_lock

if ! command -v docker &>/dev/null; then
    error "Docker command not found"
    exit 1
fi

detect_hosts

# Remainder mode builds its whole target list from docker ps — a hung daemon returns
# empty and the run would report "no containers to update" instead of failing.
if ! timeout "$DOCKER_TIMEOUT" docker info >/dev/null 2>&1; then
    error "Docker daemon not responding — skipping image updates"
    notify "Docker update skipped on $(hostname) — Docker daemon not responding" "Docker Update" "warning"
    exit 1
fi

# ==============================================================================================
# ━━━ Container Discovery ━━━
# ==============================================================================================
if [[ "$REMAINDER_MODE" == true ]]; then
    if [[ "${MONTHLY_REMAINING_UPDATES:-true}" != "true" ]]; then
        echo "MONTHLY_REMAINING_UPDATES=false — skipping remainder container updates"
        exit 0
    fi

    declare -A _exclude=()

    # Daily containers — updated by docker_update.sh normal mode
    for _c in "${DAILY_RESTART_CONTAINERS[@]}"; do
        [[ -n "$_c" ]] && _exclude["$_c"]=1
    done

    # Weekly containers — updated by docker_update.sh --weekly
    for _c in "${WEEKLY_RESTART_CONTAINERS[@]}"; do
        [[ -n "$_c" ]] && _exclude["$_c"]=1
    done

    # Weekly sync-window containers (emby + critical-data) — updated inline by weekly_sync_maintenance.sh
    _weekly_str="${PROFILE_CRITICAL_CONTAINER_NAMES[emby]:-} ${PROFILE_CRITICAL_CONTAINER_NAMES[critical-data]:-}"
    read -r -a _weekly_arr <<< "$_weekly_str"
    for _c in "${_weekly_arr[@]}"; do
        [[ -n "$_c" ]] && _exclude["$_c"]=1
    done
    unset _weekly_str _weekly_arr

    # Fallback coverage containers — owned by the remote server's update cycle.
    # This server runs them during fallback but should never update them independently.
    # Updating them here risks version divergence: if remote's writeback after handback
    # encounters data written by a newer version, it may not handle it correctly.
    for _tier in 1 2 3 4; do
        _tier_var="FALLBACK_${REMOTE_ID}_TIER${_tier}"
        eval "_tier_arr=(\"\${${_tier_var}[@]:-}\")" 2>/dev/null
        for _c in "${_tier_arr[@]}"; do
            [[ -n "$_c" ]] && _exclude["$_c"]=1
        done
    done
    unset _tier _tier_var _tier_arr _c

    mapfile -t _all_running < <(timeout "$DOCKER_TIMEOUT" docker ps --format '{{.Names}}' | sort)
    TARGET_CONTAINERS=()
    for _c in "${_all_running[@]}"; do
        [[ -z "${_exclude[$_c]+x}" ]] && TARGET_CONTAINERS+=("$_c")
    done
    unset _all_running _exclude _c
elif [[ "$WEEKLY_MODE" == true ]]; then
    if [[ "${WEEKLY_CONTAINER_UPDATES:-true}" != "true" ]]; then
        echo "WEEKLY_CONTAINER_UPDATES=false — skipping weekly container updates"
        exit 0
    fi

    if [[ ${#WEEKLY_RESTART_CONTAINERS[@]} -eq 0 ]]; then
        warn "WEEKLY_RESTART_CONTAINERS is empty for $MY_ID — nothing to update"
        warn "Check HOST${MY_ID#HOST}_WEEKLY_RESTART_CONTAINERS in host*.conf"
        exit 0
    fi

    TARGET_CONTAINERS=("${WEEKLY_RESTART_CONTAINERS[@]}")
else
    if [[ "${DAILY_CONTAINER_UPDATES:-true}" != "true" ]]; then
        echo "DAILY_CONTAINER_UPDATES=false — skipping container updates"
        exit 0
    fi

    if [[ ${#DAILY_RESTART_CONTAINERS[@]} -eq 0 ]]; then
        warn "DAILY_RESTART_CONTAINERS is empty for $MY_ID — nothing to update"
        warn "Check HOST${MY_ID#HOST}_DAILY_RESTART_CONTAINERS in host*.conf"
        exit 0
    fi

    TARGET_CONTAINERS=("${DAILY_RESTART_CONTAINERS[@]}")
fi

# ==============================================================================================
# ━━━ Status ━━━
# ==============================================================================================
if [[ "$SHOW_STATUS" == true ]]; then
    echo ""
    echo "━━━━━ $ICON_SUMMARY STATUS ━━━━━"
    echo "$ICON_HOST       Identity:   $MY_ID ($LOCAL_SERVER_NAME)"
    if [[ "$REMAINDER_MODE" == true ]]; then
        echo "$ICON_GEAR       Mode:       remainder (monthly)"
        echo "$ICON_CONTAINERS Containers: ${#TARGET_CONTAINERS[@]} running (excluding daily, weekly, sync-window, fallback)"
        for _c in "${TARGET_CONTAINERS[@]}"; do echo "  $_c"; done
    elif [[ "$WEEKLY_MODE" == true ]]; then
        echo "$ICON_GEAR       Mode:       weekly"
        echo "$ICON_CONTAINERS Containers: ${TARGET_CONTAINERS[*]}"
        echo "$ICON_GEAR       Enabled:    ${WEEKLY_CONTAINER_UPDATES:-true}"
    else
        echo "$ICON_GEAR       Mode:       normal (daily)"
        echo "$ICON_CONTAINERS Containers: ${TARGET_CONTAINERS[*]}"
        echo "$ICON_GEAR       Enabled:    ${DAILY_CONTAINER_UPDATES:-true}"
    fi
    echo "$ICON_GEAR       Dry Run:    $DRY_RUN"
    echo "━━━━━━━━━━━━━━━━━━━━━━━"
    exit 0
fi

[[ "$DRY_RUN" == true ]] && warn "DRY RUN — no images will be pulled"

if [[ ${#TARGET_CONTAINERS[@]} -eq 0 ]]; then
    echo "No containers to update"
    exit 0
fi

# ==============================================================================================
# ━━━ Pull Updates ━━━
# ==============================================================================================
echo ""
if [[ "$REMAINDER_MODE" == true ]]; then
    echo "━━━ $ICON_CONTAINERS Docker Update (remainder) — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
    echo "$ICON_CONTAINERS Updating ${#TARGET_CONTAINERS[@]} container(s) (not in daily, weekly, or sync window)"
    log "$ICON_CONTAINERS Remainder targets: ${TARGET_CONTAINERS[*]}"
elif [[ "$WEEKLY_MODE" == true ]]; then
    echo "━━━ $ICON_CONTAINERS Docker Update (weekly) — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
    log "$ICON_CONTAINERS Containers: ${TARGET_CONTAINERS[*]}"
else
    echo "━━━ $ICON_CONTAINERS Docker Update — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
    log "$ICON_CONTAINERS Containers: ${TARGET_CONTAINERS[*]}"
fi
echo ""

START=$(date +%s)
UPDATED=()
UP_TO_DATE=()
FAILED=()
OLD_IMAGE_IDS=()   # old image IDs to explicitly remove after rebuilds
SKIPPED=()

for container in "${TARGET_CONTAINERS[@]}"; do
    [[ -z "$container" ]] && continue
    log "━━━ $ICON_CONTAINERS $container ━━━"

    if ! timeout "$DOCKER_TIMEOUT" docker inspect "$container" &>/dev/null; then
        warn "$container — not found, skipping"
        SKIPPED+=("$container")
        continue
    fi

    IMAGE=$(timeout "$DOCKER_TIMEOUT" docker inspect --format='{{.Config.Image}}' "$container" 2>/dev/null)
    if [[ -z "$IMAGE" ]]; then
        warn "$container — could not determine image, skipping"
        SKIPPED+=("$container")
        continue
    fi

    log "$container — image: $IMAGE"

    if [[ "$DRY_RUN" == true ]]; then
        warn "DRY RUN — would pull: $IMAGE"
        UPDATED+=("$container")
        continue
    fi

    # Capture the image ID the container is currently running on, and the
    # image ID :latest points to before the pull. After pulling, we rebuild if
    # either a new digest landed OR the container is behind what :latest is now.
    CONTAINER_IMAGE_ID=$(timeout "$DOCKER_TIMEOUT" docker inspect "$container" --format='{{.Image}}' 2>/dev/null || echo "")
    OLD_ID=$(timeout "$DOCKER_TIMEOUT" docker image inspect "$IMAGE" --format='{{.Id}}' 2>/dev/null || echo "")

    log "$ICON_SYNC  Pulling $IMAGE..."
    if [[ "$ENABLE_LOGGING" == "true" ]]; then
        docker pull "$IMAGE" 2>&1 | grep -E "^(Status:|Digest:|Error|error)" | sed 's/^/  /'
        _pull_rc=${PIPESTATUS[0]}
    else
        docker pull "$IMAGE" >/dev/null 2>&1
        _pull_rc=$?
    fi
    NEW_ID=$(timeout "$DOCKER_TIMEOUT" docker image inspect "$IMAGE" --format='{{.Id}}' 2>/dev/null || echo "")

    if [[ $_pull_rc -eq 0 ]]; then
        _pull_new=$(  [[ -n "$OLD_ID" && "$OLD_ID" != "$NEW_ID" ]] && echo true || echo false)
        _container_behind=$([[ -n "$CONTAINER_IMAGE_ID" && -n "$NEW_ID" && "$CONTAINER_IMAGE_ID" != "$NEW_ID" ]] && echo true || echo false)

        if [[ "$_pull_new" == true || "$_container_behind" == true ]]; then
            [[ "$_pull_new" == true ]]       && log "$ICON_DONE  $container — new image (${OLD_ID:7:12} → ${NEW_ID:7:12})"
            [[ "$_container_behind" == true && "$_pull_new" == false ]] && log "$ICON_DONE  $container — image already pulled, container behind (${CONTAINER_IMAGE_ID:7:12} → ${NEW_ID:7:12})"
            UPDATED+=("$container")
            OLD_IMAGE_IDS+=("$CONTAINER_IMAGE_ID")
        else
            log "$container — up to date (${NEW_ID:7:12})"
            UP_TO_DATE+=("$container")
        fi
    else
        warn "$container — pull failed ($IMAGE)"
        FAILED+=("$container")
    fi

done

# ── Recreate containers that received a new image ────────────────────────────
# docker restart uses the image ID baked in at creation time — it never picks
# up the new digest. rebuild_container reads the stored XML template, stops the
# old container, recreates it (new image, same config), then prunes the old image.
REBUILT=()
REBUILD_FAILED=()
if [[ ${#UPDATED[@]} -gt 0 ]]; then
    for container in "${UPDATED[@]}"; do
        [[ -z "$container" ]] && continue
        if [[ "$DRY_RUN" == true ]]; then
            warn "DRY RUN — would rebuild $container from template"
            REBUILT+=("$container")
            continue
        fi
        log "$ICON_SYNC Rebuilding $container from template on new image..."
        if platform_rebuild_container "$container"; then
            echo "$ICON_DONE $container rebuilt ✅"
            REBUILT+=("$container")
        else
            _fallback_msg=$([[ "$WEEKLY_MODE" == true ]] && echo "docker_weekly_restart.sh" || ([[ "$REMAINDER_MODE" == true ]] && echo "no follow-up restart" || echo "docker_daily_restart.sh"))
            error "Failed to rebuild $container — $_fallback_msg"
            unset _fallback_msg
            notify "$container failed to rebuild after image update on $(hostname)" "Docker Update" "warning"
            REBUILD_FAILED+=("$container")
        fi
    done
fi

# Record successfully-rebuilt containers so the follow-up restart script (daily/weekly only —
# remainder has no follow-up) can skip them instead of restarting an already-fresh container a
# second time. Deliberately excludes REBUILD_FAILED — those still need the restart script's
# normal pass as a fallback, exactly as the error message above promises. Written even when
# REBUILT is empty, so a stale file from a previous run doesn't linger and get misread later.
if [[ "$DRY_RUN" == false && "$REMAINDER_MODE" != true ]]; then
    _rebuilt_file="$DOCKER_UPDATE_REBUILT_DAILY_FILE"
    [[ "$WEEKLY_MODE" == true ]] && _rebuilt_file="$DOCKER_UPDATE_REBUILT_WEEKLY_FILE"
    if [[ -n "$_rebuilt_file" ]]; then
        printf '%s\n' "${REBUILT[@]}" > "$_rebuilt_file" 2>/dev/null
    fi
    unset _rebuilt_file
fi

# ── Remove old images ────────────────────────────────────────────────────────
# Explicitly rmi by the IDs captured before each pull. Tagged images are never
# caught by dangling-only prune, so this is the only reliable cleanup path.
# Fall through to dangling prune to catch any leftovers from other update paths.
if [[ "$DRY_RUN" == true ]]; then
    warn "DRY RUN — would remove ${#OLD_IMAGE_IDS[@]} old image(s) and prune dangling"
    PRUNED_SUMMARY="(dry run)"
else
    for _old_id in "${OLD_IMAGE_IDS[@]}"; do
        timeout "$DOCKER_TIMEOUT" docker rmi "$_old_id" >/dev/null 2>&1 || true
    done
    PRUNED_OUTPUT=$(timeout "$DOCKER_TIMEOUT" docker image prune -f 2>&1)
    [[ "$ENABLE_LOGGING" == "true" ]] && echo "$PRUNED_OUTPUT" | sed 's/^/  /'
    PRUNED_SUMMARY=$(echo "$PRUNED_OUTPUT" | grep -E "^Total reclaimed" || echo "nothing reclaimed")
fi

END=$(date +%s)

# ==============================================================================================
# ━━━ Summary ━━━
# ==============================================================================================
if [[ "$REMAINDER_MODE" == true ]]; then
    echo "━━━━━ $ICON_SUMMARY DOCKER UPDATE (REMAINDER) SUMMARY ━━━━━"
elif [[ "$WEEKLY_MODE" == true ]]; then
    echo "━━━━━ $ICON_SUMMARY DOCKER UPDATE (WEEKLY) SUMMARY ━━━━━"
else
    echo "━━━━━ $ICON_SUMMARY DOCKER UPDATE SUMMARY ━━━━━"
fi
echo "$ICON_HOST       Identity:    $MY_ID ($LOCAL_SERVER_NAME)"
echo "$ICON_TIME       Duration:    $(format_duration $(( END - START )))"
if [[ ${#UPDATED[@]} -gt 0 ]]; then
    echo "$ICON_DONE       Updated:     ${#UPDATED[@]}"
    log "  ${UPDATED[*]}"
fi
[[ ${#REBUILT[@]} -gt 0 ]]       && echo "$ICON_SYNC       Rebuilt:     ${#REBUILT[@]}"
[[ ${#REBUILD_FAILED[@]} -gt 0 ]] && echo "$ICON_ERROR      Rebuild fail:${REBUILD_FAILED[*]}"
[[ ${#UP_TO_DATE[@]} -gt 0 ]]    && log "$ICON_RUNNING    Up to date:  ${UP_TO_DATE[*]}"
[[ ${#SKIPPED[@]} -gt 0 ]]       && log "$ICON_WARN       Skipped:     ${SKIPPED[*]}"
[[ ${#FAILED[@]} -gt 0 ]]        && echo "$ICON_ERROR      Failed:      ${FAILED[*]}"
echo "$ICON_SYNC       Pruned:      ${PRUNED_SUMMARY:-none}"

if [[ "$DRY_RUN" == true ]]; then
    warn "DRY RUN — no images pulled"
elif [[ ${#FAILED[@]} -eq 0 ]]; then
    echo "$ICON_DONE Status: done ✅ — ${#UPDATED[@]} updated, ${#UP_TO_DATE[@]} current"
else
    warn "Status: ${#FAILED[@]} pull(s) failed — restart will proceed with existing images"
fi
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"

# Pull failures are non-fatal — restart proceeds regardless
exit 0