#!/usr/bin/env bash
# Nightly logical dump of platform.db + messenger.db from black.
# Stored as zstd-compressed .sql.zst in $BACKUP_DIR.
# Pruned to keep last 14 daily + last 8 weekly (Sundays) + last 6 monthly (1st).
#
# Run on BLACK (where the authoritative DBs live).
# Typical schedule: daily @ 03:00 via systemd timer.

set -euo pipefail

BACKUP_DIR="${BACKUP_DIR:-/mnt/bigdisk/atlilith-backups/pg}"
DATE="$(date +%Y%m%d_%H%M%S)"

mkdir -p "$BACKUP_DIR"

dump_db() {
    local name="$1"
    local port="$2"
    local out="$BACKUP_DIR/${name}_${DATE}.sql.zst"

    echo "==> dumping ${name} on :${port} → ${out}"
    pg_dump \
        --host=localhost \
        --port="$port" \
        --username=platform \
        --no-owner --no-acl \
        --format=plain \
        "$name" \
    | zstd -3 -T0 -o "$out"

    echo "    size: $(du -h "$out" | cut -f1)"
}

dump_db "platform"  "25440"
dump_db "messenger" "25441"

# Retention: keep last 14 dailies. Older dailies get pruned unless they
# fall on a Sunday (weekly) or the 1st of the month (monthly).
echo "==> pruning old backups (keep 14d/8w/6m)"
find "$BACKUP_DIR" -name "*.sql.zst" -mtime +14 -print | while read -r f; do
    fname=$(basename "$f")
    date_part="${fname#*_}"; date_part="${date_part%_*}"
    if [[ -n "$date_part" ]]; then
        day_of_week=$(date -d "${date_part:0:4}-${date_part:4:2}-${date_part:6:2}" +%u 2>/dev/null || echo 0)
        day_of_month="${date_part:6:2}"
        if [[ "$day_of_week" == "7" ]] && [[ $(date -d "${date_part:0:4}-${date_part:4:2}-${date_part:6:2}" +%s 2>/dev/null) -gt $(date -d "8 weeks ago" +%s) ]]; then
            echo "    [keep weekly] $fname"; continue
        fi
        if [[ "$day_of_month" == "01" ]] && [[ $(date -d "${date_part:0:4}-${date_part:4:2}-${date_part:6:2}" +%s 2>/dev/null) -gt $(date -d "6 months ago" +%s) ]]; then
            echo "    [keep monthly] $fname"; continue
        fi
    fi
    echo "    [prune] $fname"
    rm -f "$f"
done

echo "done."