#!/usr/bin/env bash
set -euo pipefail

# === METADATA ===
SCRIPT_NAME="$(basename "$0")"
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
SKILL_ROOT="$(dirname "$SCRIPT_DIR")"

# === CONFIGURATION ===
: "${NODE_NAME:=node-a}"
: "${BACKUP_LABEL:=manual}"
: "${OUTPUT_DIR:=$SKILL_ROOT/outputs}"
: "${BACKUP_SOURCES:=}"
: "${BACKUP_EXCLUDES:=.git,node_modules,target,dist,outputs}"

# === FUNCTIONS ===
log_plan() { echo "[PLAN]  $(date -Iseconds) $*"; }
die()      { echo "[ERROR] $(date -Iseconds) $*" >&2; exit 1; }

estimate_size() {
    local total=0
    IFS=',' read -r -a sources <<< "$BACKUP_SOURCES"
    IFS=',' read -r -a excludes <<< "$BACKUP_EXCLUDES"

    for src in "${sources[@]}"; do
        src="${src/#\~/$HOME}"
        if [[ -e "$src" ]]; then
            # Build find exclude args
            local find_excludes=()
            for ex in "${excludes[@]}"; do
                find_excludes+=(-name "$ex" -prune -o)
            done

            local size
            size=$(find "$src" "${find_excludes[@]}" -type f -print0 2>/dev/null | \
                   xargs -0 stat -c%s 2>/dev/null | \
                   awk '{sum+=$1} END {print sum+0}')
            total=$((total + size))
        fi
    done
    echo "$total"
}

main() {
    [[ -n "$BACKUP_SOURCES" ]] || die "BACKUP_SOURCES is required (comma-separated paths)."

    local ts run_id run_dir
    ts="$(date -Iseconds | tr ':' '-')"
    run_id="${NODE_NAME}_${BACKUP_LABEL}_${ts}"
    run_dir="$OUTPUT_DIR/runs/$run_id"

    log_plan "=== Backup Plan ==="
    log_plan "Run ID: $run_id"
    log_plan "Run directory: $run_dir"
    log_plan "Archive: $run_dir/archive.tar.gz"
    log_plan "Manifest: $run_dir/manifest.json"
    echo ""

    log_plan "=== Sources ==="
    IFS=',' read -r -a sources <<< "$BACKUP_SOURCES"
    for src in "${sources[@]}"; do
        src="${src/#\~/$HOME}"
        if [[ -e "$src" ]]; then
            log_plan "  [OK] $src"
        else
            log_plan "  [MISSING] $src"
        fi
    done
    echo ""

    log_plan "=== Excludes ==="
    IFS=',' read -r -a excludes <<< "$BACKUP_EXCLUDES"
    for ex in "${excludes[@]}"; do
        log_plan "  - $ex"
    done
    echo ""

    log_plan "=== Size Estimate ==="
    local est_bytes est_mb
    est_bytes=$(estimate_size)
    est_mb=$((est_bytes / 1024 / 1024))
    log_plan "Estimated uncompressed: ${est_mb} MB ($est_bytes bytes)"
    log_plan "Compressed size will be smaller (typically 30-70% of original)"
    echo ""

    log_plan "Next: ./scripts/11_backup_apply.sh (requires DRY_RUN=0)"
}

[[ "${BASH_SOURCE[0]}" == "$0" ]] && main "$@"