#!/bin/bash
# ==============================================================================================
# ================================= Failover ===================================================
# ==============================================================================================
# Mutual container failover between two unRAID servers.
# Each server runs this script independently — no direct coordination between servers.
# All decisions based solely on two pings: remote reachable + internet reachable.
#
# ── HOW IT WORKS ──────────────────────────────────────────────────────────────────────────────
# Both servers run this script continuously as a background task via User Scripts.
# Every FAILOVER_CHECK_INTERVAL seconds each server:
#   1. Pings the remote server
#   2. Pings the internet
#   3. Determines its current state
#   4. Takes the appropriate action
#
# No SSH signaling, no shared state files, no coordination — each server acts autonomously
# based only on what it can see from its own network perspective.
#
# ── STATES ────────────────────────────────────────────────────────────────────────────────────
#   NORMAL      — remote up, internet up
#                 Own containers only. DDNS ON. Silent operation.
#
#   FAILOVER    — remote down, internet up
#                 Start remote containers locally — tiered by outage duration.
#                 Remote DDNS started immediately (Tier 1).
#                 Own containers keep running — failover is additive.
#
#   NO_INTERNET — internet down (remote may be up or down)
#                 Stop own DDNS immediately — can't update DNS without internet.
#                 Do not start remote containers — no internet = no point.
#                 Wait for recovery.
#
#   DARK        — remote down AND internet down
#                 Same actions as NO_INTERNET.
#                 Cannot determine if remote is truly down or just unreachable.
#
# ── DDNS RULES — ABSOLUTE ─────────────────────────────────────────────────────────────────────
#   Each server owns its own DDNS — ON when that server has internet.
#   Script controls DDNS exclusively — network state NEVER auto-starts DDNS.
#   DDNS only starts after full handback sequence confirms containers are up.
#   One DDNS per domain active at all times — never two, never zero for long.
#   1 minute TTL + 1 minute check interval = minimal user impact on failover.
#
# ── HANDBACK SEQUENCE ─────────────────────────────────────────────────────────────────────────
#   When remote returns after FAILOVER:
#   1. Strike confirmation     — FAILOVER_HANDBACK_STRIKES consecutive remote-up checks
#                                prevents handing back during a brief network blip
#   2. Pre-flight checks       — remote array started, Docker healthy, rootfs not full
#   3. Stop remote DDNS first  — prevents split brain DNS during rsync
#   4. Stop remote containers  — clean state, no dirty writes during rsync
#   5. Tiered rsync writeback  — skip if outage under threshold (short outages = cleaner to skip)
#                                Tier 1: skip if under HOST1_TIER1_WRITEBACK_DELAY (60min default)
#                                Tier 2: skip if under HOST1_TIER2_DELAY
#                                Tier 3: skip if under HOST1_TIER3_DELAY
#                                Tier 4: skip if under HOST*_TIER4_DELAY — opposing daily sync shares + edge cases
#   6. Start local containers  — confirmed up before DNS cuts over
#   7. Start local DDNS        — DNS cuts back ONLY after containers confirmed up
#   8. Return to NORMAL
#
# ── TIERED FAILOVER ───────────────────────────────────────────────────────────────────────────
#   Tier 1 — Immediate   — vital services + Live TV — can't wait
#   Tier 2 — 2hr default — shared productivity services
#   Tier 3 — 6hr default — secondary services
#   Tier 4 — 18hr default — arrs + downloaders — minimal writeback on handback
#   Delays configurable per host in Master.conf
#
# ── TO STOP THIS SCRIPT ───────────────────────────────────────────────────────────────────────
#   Click Abort beside the script in unRAID's User Scripts plugin page.
#   Do NOT kill the process directly — state file may be left in inconsistent state.
#
# All configuration in Master.conf under Failover section.
# Supports --dry-run (no container changes) and --status (show current state and exit).
# ==============================================================================================

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

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

parse_args "$@"

# ==============================================================================================
# ━━━ $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"
detect_hosts
resolve_remote_ip

[[ "$DRY_RUN" == true ]] && warn "DRY RUN — no container or DDNS changes will be made"

# ==============================================================================================
# STATE FILE HELPERS
# State file format — key=value, one per line, persists on /boot/
# Tracks: state, failover_start, handback_strikes, tier2_started, tier3_started, tier4_started
# ==============================================================================================

state_get() {
    grep "^${1}=" "$FAILOVER_STATE_FILE" 2>/dev/null | cut -d= -f2
}

state_set() {
    local key="$1" value="$2"
    if grep -q "^${key}=" "$FAILOVER_STATE_FILE" 2>/dev/null; then
        sed -i "s|^${key}=.*|${key}=${value}|" "$FAILOVER_STATE_FILE"
    else
        echo "${key}=${value}" >> "$FAILOVER_STATE_FILE"
    fi
}

state_init() {
    mkdir -p "$(dirname "$FAILOVER_STATE_FILE")"
    [[ ! -f "$FAILOVER_STATE_FILE" ]] && touch "$FAILOVER_STATE_FILE"
    [[ -z "$(state_get state)" ]] && state_set state "NORMAL"
    [[ -z "$(state_get failover_start)" ]] && state_set failover_start "0"
    [[ -z "$(state_get handback_strikes)" ]] && state_set handback_strikes "0"
    [[ -z "$(state_get tier2_started)" ]] && state_set tier2_started "false"
    [[ -z "$(state_get tier3_started)" ]] && state_set tier3_started "false"
    [[ -z "$(state_get tier4_started)" ]] && state_set tier4_started "false"
}

# ==============================================================================================
# CONTAINER HELPERS
# ==============================================================================================

# Start a container locally
local_start() {
    local container="$1"
    [[ -z "$container" ]] && return
    local status
    status=$(docker inspect -f '{{.State.Running}}' "$container" 2>/dev/null)
    if [[ "$status" == "true" ]]; then
        log "$container already running locally"
        return 0
    fi
    info "$ICON_START Starting $container locally..."
    if [[ "$DRY_RUN" == false ]]; then
        docker start "$container" >/dev/null 2>&1 && \
            success "$ICON_STARTED $container started" || \
            error "Failed to start $container locally"
    else
        warn "DRY RUN — would start $container locally"
    fi
}

# Stop a container locally
local_stop() {
    local container="$1"
    [[ -z "$container" ]] && return
    local status
    status=$(docker inspect -f '{{.State.Running}}' "$container" 2>/dev/null)
    if [[ "$status" != "true" ]]; then
        log "$container already stopped locally"
        return 0
    fi
    info "$ICON_STOP Stopping $container locally..."
    if [[ "$DRY_RUN" == false ]]; then
        docker stop "$container" >/dev/null 2>&1 && \
            success "$ICON_STOPPED $container stopped" || \
            error "Failed to stop $container locally"
    else
        warn "DRY RUN — would stop $container locally"
    fi
}

# Start a container on remote via SSH
remote_start() {
    local container="$1"
    [[ -z "$container" ]] && return
    local status
    status=$(ssh -i "$SSH_KEY" -o ConnectTimeout=10 root@"$REMOTE_SERVER" \
        "docker inspect -f '{{.State.Running}}' $container 2>/dev/null" 2>/dev/null)
    if [[ "$status" == "true" ]]; then
        log "$container already running on $REMOTE_SERVER_NAME"
        return 0
    fi
    info "$ICON_START Starting $container on $REMOTE_SERVER_NAME..."
    if [[ "$DRY_RUN" == false ]]; then
        ssh -i "$SSH_KEY" -o ConnectTimeout=10 root@"$REMOTE_SERVER" \
            "docker start $container" >/dev/null 2>&1 && \
            success "$ICON_STARTED $container started on $REMOTE_SERVER_NAME" || \
            error "Failed to start $container on $REMOTE_SERVER_NAME"
    else
        warn "DRY RUN — would start $container on $REMOTE_SERVER_NAME"
    fi
}

# Stop a container on remote via SSH
remote_stop() {
    local container="$1"
    [[ -z "$container" ]] && return
    local status
    status=$(ssh -i "$SSH_KEY" -o ConnectTimeout=10 root@"$REMOTE_SERVER" \
        "docker inspect -f '{{.State.Running}}' $container 2>/dev/null" 2>/dev/null)
    if [[ "$status" != "true" ]]; then
        log "$container already stopped on $REMOTE_SERVER_NAME"
        return 0
    fi
    info "$ICON_STOP Stopping $container on $REMOTE_SERVER_NAME..."
    if [[ "$DRY_RUN" == false ]]; then
        ssh -i "$SSH_KEY" -o ConnectTimeout=10 root@"$REMOTE_SERVER" \
            "docker stop $container" >/dev/null 2>&1 && \
            success "$ICON_STOPPED $container stopped on $REMOTE_SERVER_NAME" || \
            error "Failed to stop $container on $REMOTE_SERVER_NAME"
    else
        warn "DRY RUN — would stop $container on $REMOTE_SERVER_NAME"
    fi
}

# ==============================================================================================
# DDNS HELPERS
# DDNS is managed exclusively by this script — never by network state
# ==============================================================================================

# Stop local DDNS — called on internet loss
local_ddns_stop() {
    info "$ICON_NET Stopping local DDNS — internet lost"
    for container in "${LOCAL_DDNS_CONTAINERS[@]}"; do
        local_stop "$container"
    done
}

# Start local DDNS — called at end of handback ONLY after containers confirmed up
local_ddns_start() {
    info "$ICON_NET Starting local DDNS — containers confirmed up"
    for container in "${LOCAL_DDNS_CONTAINERS[@]}"; do
        local_start "$container"
    done
}

# Stop remote DDNS — FIRST step of handback sequence, prevents split brain
remote_ddns_stop() {
    info "$ICON_NET Stopping remote DDNS on $REMOTE_SERVER_NAME — handback starting"
    for container in "${REMOTE_DDNS_CONTAINERS[@]}"; do
        remote_stop "$container"
    done
}

# ==============================================================================================
# TIERED FAILOVER HELPERS
# Containers selected based on which server is local and which arrays to use
# ==============================================================================================

# Get the correct tier arrays based on local host
# HOST2 runs for HOST1, HOST1 runs for HOST2
get_tier_containers() {
    local tier="$1"
    if [[ "$LOCAL_SERVER_NAME" == "$HOST2" ]]; then
        # HOST2 is running — covers HOST1
        case "$tier" in
            1) echo "${FAILOVER_HOST2_RUNS_FOR_HOST1_IMMEDIATE[@]}" ;;
            2) echo "${FAILOVER_HOST2_RUNS_FOR_HOST1_2HR[@]}" ;;
            3) echo "${FAILOVER_HOST2_RUNS_FOR_HOST1_6HR[@]}" ;;
            4) echo "${FAILOVER_HOST2_RUNS_FOR_HOST1_18HR[@]}" ;;
        esac
    else
        # HOST1 is running — covers HOST2
        case "$tier" in
            1) echo "${FAILOVER_HOST1_RUNS_FOR_HOST2_IMMEDIATE[@]}" ;;
            2) echo "${FAILOVER_HOST1_RUNS_FOR_HOST2_2HR[@]}" ;;
            3) echo "${FAILOVER_HOST1_RUNS_FOR_HOST2_6HR[@]}" ;;
            4) echo "${FAILOVER_HOST1_RUNS_FOR_HOST2_18HR[@]}" ;;
        esac
    fi
}

get_tier2_delay() {
    [[ "$LOCAL_SERVER_NAME" == "$HOST2" ]] && \
        echo "$HOST1_TIER2_DELAY" || echo "$HOST2_TIER2_DELAY"
}

get_tier3_delay() {
    [[ "$LOCAL_SERVER_NAME" == "$HOST2" ]] && \
        echo "$HOST1_TIER3_DELAY" || echo "$HOST2_TIER3_DELAY"
}

get_tier4_delay() {
    [[ "$LOCAL_SERVER_NAME" == "$HOST2" ]] && \
        echo "$HOST1_TIER4_DELAY" || echo "$HOST2_TIER4_DELAY"
}

get_tier1_writeback_delay() {
    [[ "$LOCAL_SERVER_NAME" == "$HOST2" ]] && \
        echo "$HOST1_TIER1_WRITEBACK_DELAY" || echo "$HOST2_TIER1_WRITEBACK_DELAY"
}

get_writeback_jobs_for_tier() {
    local tier="$1"
    if [[ "$LOCAL_SERVER_NAME" == "$HOST2" ]]; then
        # HOST2 is covering HOST1 — write back HOST1's data
        case "$tier" in
            1) echo "${FAILOVER_HOST1_WRITEBACK_TIER1[@]}" ;;
            2) echo "${FAILOVER_HOST1_WRITEBACK_TIER2[@]}" ;;
            3) echo "${FAILOVER_HOST1_WRITEBACK_TIER3[@]}" ;;
            4)
                # Tier 4 — push HOST1's daily sync shares back (opposing orch list)
                # These are HOST1's source-of-truth shares that HOST2's arrs managed during outage
                # Plus any edge case paths defined in FAILOVER_HOST1_WRITEBACK_TIER4
                echo "${HOST1_DAILY_SYNC_SHARES[@]}"
                echo "${FAILOVER_HOST1_WRITEBACK_TIER4[@]}"
                ;;
        esac
    else
        # HOST1 is covering HOST2 — write back HOST2's data
        case "$tier" in
            1) echo "${FAILOVER_HOST2_WRITEBACK_TIER1[@]}" ;;
            2) echo "${FAILOVER_HOST2_WRITEBACK_TIER2[@]}" ;;
            3) echo "${FAILOVER_HOST2_WRITEBACK_TIER3[@]}" ;;
            4)
                # Tier 4 — push HOST2's daily sync shares back (opposing orch list)
                # These are HOST2's source-of-truth shares that HOST1's arrs managed during outage
                # Plus any edge case paths defined in FAILOVER_HOST2_WRITEBACK_TIER4
                echo "${HOST2_DAILY_SYNC_SHARES[@]}"
                echo "${FAILOVER_HOST2_WRITEBACK_TIER4[@]}"
                ;;
        esac
    fi
}

# Select correct DDNS arrays based on local host
set_ddns_arrays() {
    if [[ "$LOCAL_SERVER_NAME" == "$HOST1" ]]; then
        LOCAL_DDNS_CONTAINERS=("${HOST1_DDNS_CONTAINERS[@]}")
        REMOTE_DDNS_CONTAINERS=("${HOST2_DDNS_CONTAINERS[@]}")
    else
        LOCAL_DDNS_CONTAINERS=("${HOST2_DDNS_CONTAINERS[@]}")
        REMOTE_DDNS_CONTAINERS=("${HOST1_DDNS_CONTAINERS[@]}")
    fi
}

# ==============================================================================================
# STATUS DISPLAY
# ==============================================================================================
if [[ "$SHOW_STATUS" == true ]]; then
    state_init
    set_ddns_arrays
    CURRENT_STATE=$(state_get state)
    FAILOVER_START=$(state_get failover_start)
    TIER2=$(state_get tier2_started)
    TIER3=$(state_get tier3_started)
    TIER4=$(state_get tier4_started)
    STRIKES=$(state_get handback_strikes)

    echo ""
    echo "━━━━━ $ICON_SUMMARY FAILOVER STATUS ━━━━━"
    echo "$ICON_HOST    Local:      $LOCAL_SERVER_NAME"
    echo "$ICON_HOST    Remote:     $REMOTE_SERVER_NAME ($REMOTE_SERVER)"
    echo "$ICON_FAILOVER State:     $CURRENT_STATE"
    echo "$ICON_NET     Local DDNS: ${LOCAL_DDNS_CONTAINERS[*]}"
    echo "$ICON_NET     Remote DDNS: ${REMOTE_DDNS_CONTAINERS[*]}"
    echo "$ICON_TIME    Interval:   ${FAILOVER_CHECK_INTERVAL}s"
    echo "$ICON_FAILOVER Strikes:   $STRIKES / $FAILOVER_HANDBACK_STRIKES"

    if [[ "$CURRENT_STATE" == "FAILOVER" && "$FAILOVER_START" -gt 0 ]]; then
        ELAPSED=$(( ($(date +%s) - FAILOVER_START) / 60 ))
        echo "$ICON_TIME    Outage:     ${ELAPSED}min"
        echo "$ICON_FAILOVER Tier 2:    $TIER2 (delay: $(get_tier2_delay)min)"
        echo "$ICON_FAILOVER Tier 3:    $TIER3 (delay: $(get_tier3_delay)min)"
        echo "$ICON_FAILOVER Tier 4:    $TIER4 (delay: $(get_tier4_delay)min)"
    fi

    echo "$ICON_GEAR    Dry Run:    $DRY_RUN"
    echo "━━━━━━━━━━━━━━━━━━━━━━━"
    exit 0
fi

# ==============================================================================================
# HANDBACK SEQUENCE
# Called when remote returns after FAILOVER state
# Critical sequencing — do not reorder without understanding the consequences
# ==============================================================================================
run_handback() {
    echo ""
    echo "━━━ $ICON_FAILOVER Handback Sequence — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
    info "Remote $REMOTE_SERVER_NAME has returned — beginning handback"

    # ── Step 1: Pre-flight checks ────────────────────────────────────────────────────────────
    echo ""
    echo "━━━ $ICON_SHIELD Pre-flight ━━━"

    if ! check_remote_array; then
        warn "Remote array not ready — aborting handback, will retry next cycle"
        state_set handback_strikes 0
        return 1
    fi

    if ! check_remote_docker; then
        warn "Remote Docker not ready — aborting handback, will retry next cycle"
        state_set handback_strikes 0
        return 1
    fi

    success "Pre-flight checks passed"

    # ── Step 2: Stop remote DDNS FIRST ──────────────────────────────────────────────────────
    # CRITICAL — prevents split brain DNS during rsync window
    # Remote DDNS must be OFF before any data moves
    echo ""
    echo "━━━ $ICON_NET DDNS Handoff ━━━"
    remote_ddns_stop
    info "Remote DDNS stopped — DNS will not update during rsync"
    sleep 5  # brief pause to ensure DDNS stop propagates

    # ── Step 3: Stop remote containers ──────────────────────────────────────────────────────
    # Clean state before rsync — no dirty writes during transfer
    # Containers are only down during the rsync window — minimise this time
    echo ""
    echo "━━━ $ICON_STOP Stop Remote Containers ━━━"

    # Stop all tiers that were started — in reverse order
    local ALL_FAILOVER_CONTAINERS=()

    if [[ "$(state_get tier4_started)" == "true" ]]; then
        read -r -a t4 <<< "$(get_tier_containers 4)"
        ALL_FAILOVER_CONTAINERS+=("${t4[@]}")
    fi
    if [[ "$(state_get tier3_started)" == "true" ]]; then
        read -r -a t3 <<< "$(get_tier_containers 3)"
        ALL_FAILOVER_CONTAINERS+=("${t3[@]}")
    fi
    if [[ "$(state_get tier2_started)" == "true" ]]; then
        read -r -a t2 <<< "$(get_tier_containers 2)"
        ALL_FAILOVER_CONTAINERS+=("${t2[@]}")
    fi

    # Tier 1 always started — stop last (DDNS already stopped above)
    read -r -a t1 <<< "$(get_tier_containers 1)"
    # Remove DDNS containers from tier 1 list — already handled
    for container in "${t1[@]}"; do
        local is_ddns=false
        for ddns in "${REMOTE_DDNS_CONTAINERS[@]}"; do
            [[ "$container" == "$ddns" ]] && is_ddns=true && break
        done
        [[ "$is_ddns" == false ]] && ALL_FAILOVER_CONTAINERS+=("$container")
    done

    for container in "${ALL_FAILOVER_CONTAINERS[@]}"; do
        [[ -z "$container" ]] && continue
        local_stop "$container"
    done

    success "All failover containers stopped locally"

    # ── Step 4: Rsync writeback ──────────────────────────────────────────────────────────────
    # Tiered writeback with skip window — short outages do not benefit from writeback.
    # Emby syncs every 30min dirty (live container). Clean sync runs nightly at 2:30am.
    # After a short outage HOST1's clean nightly state is more reliable than HOST2's
    # dirty sync accumulation — skip writeback entirely for short outages.
    #
    # Tier 1 — skip if under HOST1_TIER1_WRITEBACK_DELAY (default 60min)
    # Tier 2 — skip if under HOST1_TIER2_DELAY (reused — if Tier 2 never started, skip)
    # Tier 3 — skip if under HOST1_TIER3_DELAY (reused — same logic)
    # Tier 4 — always writeback — 18hr+ means meaningful delta accumulated
    echo ""
    echo "━━━ $ICON_SYNC Rsync Writeback ━━━"

    local outage_minutes=$(( ($(date +%s) - $(state_get failover_start)) / 60 ))
    local tier1_wb_delay
    tier1_wb_delay=$(get_tier1_writeback_delay)

    info "Outage duration: ${outage_minutes}min"

    run_writeback_tier() {
        local tier="$1"
        local threshold="$2"
        local label="$3"
        local jobs
        read -r -a jobs <<< "$(get_writeback_jobs_for_tier "$tier")"
        [[ ${#jobs[@]} -eq 0 ]] && return

        if [[ "$outage_minutes" -ge "$threshold" ]]; then
            info "Tier $tier writeback ($label) — outage ${outage_minutes}min >= ${threshold}min"
            for job in "${jobs[@]}"; do
                [[ -z "$job" ]] && continue
                info "Syncing: $job"
                if [[ "$DRY_RUN" == false ]]; then
                    bash "$SCRIPT_DIR/../Rsync/rsync.sh" "$job"
                else
                    warn "DRY RUN — would rsync: $job"
                fi
            done
        else
            info "Tier $tier writeback skipped — outage ${outage_minutes}min < ${threshold}min threshold"
            info "Primary has cleaner state — no writeback needed"
        fi
    }

    run_writeback_tier 1 "$tier1_wb_delay"        "Emby + auth stack"
    run_writeback_tier 2 "$HOST1_TIER2_DELAY"     "NextCloud + Immich"
    run_writeback_tier 3 "$HOST1_TIER3_DELAY"     "secondary services"
    run_writeback_tier 4 "$(get_tier4_delay)"     "media shares + edge cases"

    success "Writeback complete"

    # ── Step 5: Start remote containers ─────────────────────────────────────────────────────
    # Start in dependency order — databases before apps
    echo ""
    echo "━━━ $ICON_START Start Remote Containers ━━━"

    # Start tier 1 on remote (excluding DDNS — handled separately)
    for container in "${t1[@]}"; do
        [[ -z "$container" ]] && continue
        local is_ddns=false
        for ddns in "${REMOTE_DDNS_CONTAINERS[@]}"; do
            [[ "$container" == "$ddns" ]] && is_ddns=true && break
        done
        [[ "$is_ddns" == false ]] && remote_start "$container"
    done

    # Brief pause — give databases time to initialise before apps
    sleep 10

    if [[ "$(state_get tier2_started)" == "true" ]]; then
        for container in "${t2[@]}"; do
            [[ -n "$container" ]] && remote_start "$container"
        done
    fi

    if [[ "$(state_get tier3_started)" == "true" ]]; then
        for container in "${t3[@]}"; do
            [[ -n "$container" ]] && remote_start "$container"
        done
    fi

    if [[ "$(state_get tier4_started)" == "true" ]]; then
        for container in "${t4[@]}"; do
            [[ -n "$container" ]] && remote_start "$container"
        done
    fi

    success "Remote containers started"

    # ── Step 6: Start remote DDNS LAST ──────────────────────────────────────────────────────
    # DNS cuts over ONLY after containers confirmed up
    # This is the final step — after this users hit remote
    echo ""
    echo "━━━ $ICON_NET DNS Cutover ━━━"
    sleep 5  # brief pause to ensure containers are accepting connections
    for container in "${REMOTE_DDNS_CONTAINERS[@]}"; do
        remote_start "$container"
    done
    success "Remote DDNS started — DNS now points at $REMOTE_SERVER_NAME"

    # ── Step 7: Return to NORMAL ─────────────────────────────────────────────────────────────
    echo ""
    state_set state "NORMAL"
    state_set failover_start "0"
    state_set handback_strikes "0"
    state_set tier2_started "false"
    state_set tier3_started "false"
    state_set tier4_started "false"

    success "$ICON_DONE Handback complete — returned to NORMAL"
    notify "Failover handback complete on $(hostname) — $REMOTE_SERVER_NAME is back, all containers returned" "Failover" "normal"
}

# ==============================================================================================
# MAIN STATE MACHINE
# ==============================================================================================
state_init
set_ddns_arrays

echo ""
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
echo "  $ICON_FAILOVER FAILOVER — $(date '+%Y-%m-%d %H:%M:%S')"
echo "  $ICON_HOST $LOCAL_SERVER_NAME → monitoring $REMOTE_SERVER_NAME"
echo "  $ICON_NET  Remote: $REMOTE_SERVER"
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"

while true; do
    NOW=$(date +%s)
    CURRENT_STATE=$(state_get state)

    # ── Connectivity checks ──────────────────────────────────────────────────────────────────
    REMOTE_UP=false
    INTERNET_UP=false

    ping_remote  && REMOTE_UP=true
    ping_internet && INTERNET_UP=true

    log "Remote: $REMOTE_UP | Internet: $INTERNET_UP | State: $CURRENT_STATE"

    # ── State machine ────────────────────────────────────────────────────────────────────────

    # ════════════════════════════════════════════════════════════════
    # NORMAL STATE
    # ════════════════════════════════════════════════════════════════
    if [[ "$CURRENT_STATE" == "NORMAL" ]]; then

        if [[ "$REMOTE_UP" == true && "$INTERNET_UP" == true ]]; then
            # All good — silent operation
            log "$ICON_SUCCESS NORMAL — all systems up"

        elif [[ "$REMOTE_UP" == false && "$INTERNET_UP" == true ]]; then
            # Remote is down — enter FAILOVER
            echo ""
            echo "━━━ $ICON_FAILOVER Entering FAILOVER — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
            warn "$REMOTE_SERVER_NAME is unreachable — internet is up — starting failover"

            state_set state "FAILOVER"
            state_set failover_start "$NOW"
            state_set handback_strikes "0"
            state_set tier2_started "false"
            state_set tier3_started "false"
            state_set tier4_started "false"

            # Start Tier 1 immediately — DDNS first, then vital services
            echo ""
            echo "━━━ $ICON_START Tier 1 — Immediate ━━━"
            read -r -a tier1 <<< "$(get_tier_containers 1)"
            for container in "${tier1[@]}"; do
                [[ -n "$container" ]] && local_start "$container"
            done

            notify "FAILOVER started on $(hostname) — $REMOTE_SERVER_NAME is down — Tier 1 containers started" "Failover" "warning"

        elif [[ "$INTERNET_UP" == false ]]; then
            # Lost internet — enter NO_INTERNET
            echo ""
            echo "━━━ $ICON_NET Entering NO_INTERNET — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
            warn "Internet connectivity lost — stopping local DDNS"

            state_set state "NO_INTERNET"
            local_ddns_stop

            # Stop any containers configured to stop without internet
            if [[ "$LOCAL_SERVER_NAME" == "$HOST1" ]]; then
                for container in "${FAILOVER_HOST1_STOP_ON_NO_NET[@]}"; do
                    [[ -n "$container" ]] && local_stop "$container"
                done
            else
                for container in "${FAILOVER_HOST2_STOP_ON_NO_NET[@]}"; do
                    [[ -n "$container" ]] && local_stop "$container"
                done
            fi

            notify "NO_INTERNET on $(hostname) — DDNS stopped, waiting for recovery" "Failover" "warning"
        fi

    # ════════════════════════════════════════════════════════════════
    # FAILOVER STATE
    # ════════════════════════════════════════════════════════════════
    elif [[ "$CURRENT_STATE" == "FAILOVER" ]]; then

        FAILOVER_START=$(state_get failover_start)
        ELAPSED_MIN=$(( (NOW - FAILOVER_START) / 60 ))

        if [[ "$REMOTE_UP" == true && "$INTERNET_UP" == true ]]; then
            # Remote returned — increment handback strikes
            STRIKES=$(state_get handback_strikes)
            STRIKES=$(( STRIKES + 1 ))
            state_set handback_strikes "$STRIKES"

            info "$ICON_FAILOVER $REMOTE_SERVER_NAME is back — handback strike $STRIKES/$FAILOVER_HANDBACK_STRIKES"

            if [[ "$STRIKES" -ge "$FAILOVER_HANDBACK_STRIKES" ]]; then
                run_handback
            fi

        elif [[ "$INTERNET_UP" == false ]]; then
            # Lost internet during failover — enter DARK
            echo ""
            echo "━━━ $ICON_NET Entering DARK — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
            warn "Lost internet during failover — entering DARK state"
            state_set state "DARK"
            local_ddns_stop
            notify "DARK state on $(hostname) — lost internet during failover" "Failover" "warning"

        else
            # Still in failover — check tier escalation
            state_set handback_strikes "0"  # reset strikes — remote still down

            # Tier 2
            TIER2_DELAY=$(get_tier2_delay)
            if [[ "$(state_get tier2_started)" == "false" && \
                  "$ELAPSED_MIN" -ge "$TIER2_DELAY" ]]; then
                echo ""
                echo "━━━ $ICON_START Tier 2 — ${ELAPSED_MIN}min outage ━━━"
                read -r -a tier2 <<< "$(get_tier_containers 2)"
                for container in "${tier2[@]}"; do
                    [[ -n "$container" ]] && local_start "$container"
                done
                state_set tier2_started "true"
                notify "Failover Tier 2 started on $(hostname) — ${ELAPSED_MIN}min outage" "Failover" "warning"
            fi

            # Tier 3
            TIER3_DELAY=$(get_tier3_delay)
            if [[ "$(state_get tier3_started)" == "false" && \
                  "$ELAPSED_MIN" -ge "$TIER3_DELAY" ]]; then
                echo ""
                echo "━━━ $ICON_START Tier 3 — ${ELAPSED_MIN}min outage ━━━"
                read -r -a tier3 <<< "$(get_tier_containers 3)"
                for container in "${tier3[@]}"; do
                    [[ -n "$container" ]] && local_start "$container"
                done
                state_set tier3_started "true"
                notify "Failover Tier 3 started on $(hostname) — ${ELAPSED_MIN}min outage" "Failover" "warning"
            fi

            # Tier 4
            TIER4_DELAY=$(get_tier4_delay)
            if [[ "$(state_get tier4_started)" == "false" && \
                  "$ELAPSED_MIN" -ge "$TIER4_DELAY" ]]; then
                echo ""
                echo "━━━ $ICON_START Tier 4 — ${ELAPSED_MIN}min outage — full workflow ━━━"
                read -r -a tier4 <<< "$(get_tier_containers 4)"
                for container in "${tier4[@]}"; do
                    [[ -n "$container" ]] && local_start "$container"
                done
                state_set tier4_started "true"
                notify "Failover Tier 4 started on $(hostname) — ${ELAPSED_MIN}min outage — full workflow active" "Failover" "warning"
            fi

            log "$ICON_FAILOVER FAILOVER active — ${ELAPSED_MIN}min — T2:$(state_get tier2_started) T3:$(state_get tier3_started) T4:$(state_get tier4_started)"
        fi

    # ════════════════════════════════════════════════════════════════
    # NO_INTERNET STATE
    # ════════════════════════════════════════════════════════════════
    elif [[ "$CURRENT_STATE" == "NO_INTERNET" ]]; then

        if [[ "$INTERNET_UP" == true ]]; then
            # Internet recovered
            echo ""
            echo "━━━ $ICON_NET Internet Recovered — $(date '+%Y-%m-%d %H:%M:%S') ━━━"

            if [[ "$REMOTE_UP" == true ]]; then
                # Remote up, internet up — return to NORMAL
                info "Remote is up — returning to NORMAL"
                state_set state "NORMAL"
                # DDNS does NOT auto-start here — it only starts via handback sequence
                # or explicit NORMAL state management
                # If local DDNS should be running in NORMAL — start it now
                local_ddns_start
                notify "Internet recovered on $(hostname) — returning to NORMAL" "Failover" "normal"
            else
                # Internet back but remote still down — enter FAILOVER
                info "Remote still down — entering FAILOVER"
                state_set state "FAILOVER"
                state_set failover_start "$NOW"
                state_set handback_strikes "0"
                state_set tier2_started "false"
                state_set tier3_started "false"
                state_set tier4_started "false"

                echo ""
                echo "━━━ $ICON_START Tier 1 — Immediate ━━━"
                read -r -a tier1 <<< "$(get_tier_containers 1)"
                for container in "${tier1[@]}"; do
                    [[ -n "$container" ]] && local_start "$container"
                done
                notify "Internet recovered on $(hostname) but $REMOTE_SERVER_NAME still down — entering FAILOVER" "Failover" "warning"
            fi
        else
            log "$ICON_NET NO_INTERNET — waiting for connectivity"
        fi

    # ════════════════════════════════════════════════════════════════
    # DARK STATE
    # ════════════════════════════════════════════════════════════════
    elif [[ "$CURRENT_STATE" == "DARK" ]]; then

        if [[ "$INTERNET_UP" == true ]]; then
            echo ""
            echo "━━━ $ICON_NET Emerging from DARK — $(date '+%Y-%m-%d %H:%M:%S') ━━━"

            if [[ "$REMOTE_UP" == true ]]; then
                info "Remote up, internet up — returning to NORMAL"
                # Was in failover before DARK — need to handback
                state_set state "FAILOVER"
                state_set handback_strikes "0"
                # Will trigger handback on next cycle via FAILOVER + remote up logic
            else
                info "Internet back but remote still down — entering FAILOVER"
                state_set state "FAILOVER"
                state_set failover_start "$NOW"
                state_set handback_strikes "0"
                state_set tier2_started "false"
                state_set tier3_started "false"
                state_set tier4_started "false"

                read -r -a tier1 <<< "$(get_tier_containers 1)"
                for container in "${tier1[@]}"; do
                    [[ -n "$container" ]] && local_start "$container"
                done
            fi
            notify "Emerging from DARK state on $(hostname)" "Failover" "warning"
        else
            log "$ICON_FAILOVER DARK — no internet, no remote — waiting"
        fi
    fi

    # ── Sleep until next check ───────────────────────────────────────────────────────────────
    log "Next check in ${FAILOVER_CHECK_INTERVAL}s — $(date '+%H:%M:%S')"
    sleep "$FAILOVER_CHECK_INTERVAL"

done