#!/bin/bash
# Co-op Cloud entrypoint wrapper for the discourse/postgres image.
#
# discourse/postgres (https://github.com/discourse/discourse-postgres) is pgvector
# plus a management layer that auto-upgrades an older cluster on boot. It does the
# heavy lifting (apt-installs the old binaries, runs pg_upgrade, writes the new
# cluster to the versioned PGDATA). This wrapper only fills the two gaps it leaves:
#
#   1. Secrets: the image reads DB_PASSWORD / POSTGRES_PASSWORD from the process
#      env (no *_FILE support), so inject them from the docker secret.
#   2. Install user: the image runs `pg_upgrade --username="$POSTGRES_USER"` and
#      initdb's the new cluster with $POSTGRES_USER, but never detects the OLD
#      cluster's real bootstrap superuser (the install user, oid 10). pg_upgrade
#      aborts unless the new cluster's install-user name matches the old one. Real
#      deployments differ: some were bootstrapped with `postgres` as the install
#      user (+ a separate `discourse` app role), others with `discourse` itself.
#      So detect oid 10 from the old cluster and export POSTGRES_USER to match
#      before handing off to the image's run-postgres.sh.
set -e

# --- 1. secret injection -----------------------------------------------------
if [ -f /run/secrets/db_password ]; then
  pw="$(cat /run/secrets/db_password)"
  export DB_PASSWORD="$pw"
  export POSTGRES_PASSWORD="$pw"
fi

# --- 2. install-user detection (only matters on the upgrade path) ------------
NEW_MAJOR="$(postgres --version | sed -rn 's/^[^0-9]*([0-9]+).*/\1/p')"

# Newest existing cluster under the data mount (same search the image uses).
PGVER_FILE="$(find /var/lib/postgresql -maxdepth 3 -type f -name PG_VERSION 2>/dev/null \
  | xargs -I{} sh -c 'printf "%s " "{}"; cat "{}"' \
  | sort -nk2,2 | tail -n1 | awk '{print $1}')"

if [ -n "$PGVER_FILE" ]; then
  OLD_DIR="$(dirname "$PGVER_FILE")"
  OLD_MAJOR="$(cat "$PGVER_FILE")"
  if [ "$OLD_MAJOR" != "$NEW_MAJOR" ]; then
    echo "cc-db-entrypoint: existing pg${OLD_MAJOR} cluster at ${OLD_DIR}, image is pg${NEW_MAJOR} -> detecting install user"
    OLD_BIN="/usr/lib/postgresql/${OLD_MAJOR}/bin"
    if [ ! -x "$OLD_BIN/pg_ctl" ]; then
      echo "cc-db-entrypoint: installing postgresql-${OLD_MAJOR} to read the old cluster"
      apt-get update
      apt-get install -y --no-install-recommends "postgresql-${OLD_MAJOR}" >/dev/null
    fi
    chown -R postgres "$OLD_DIR" 2>/dev/null || true

    # Briefly start the old cluster on a local socket only, ask it for oid 10.
    gosu postgres "$OLD_BIN/pg_ctl" -D "$OLD_DIR" -w \
      -o "-c listen_addresses= -c unix_socket_directories=/tmp" start >/dev/null 2>&1 || true
    detected=""
    for login_role in discourse postgres; do
      detected="$(gosu postgres psql -h /tmp -U "$login_role" -d postgres -tAc \
        'select rolname from pg_roles where oid = 10' 2>/dev/null | tr -d '[:space:]')"
      [ -n "$detected" ] && break
    done
    gosu postgres "$OLD_BIN/pg_ctl" -D "$OLD_DIR" -w stop >/dev/null 2>&1 || true

    if [ -n "$detected" ]; then
      echo "cc-db-entrypoint: old cluster install user is '$detected' -> POSTGRES_USER=$detected"
      export POSTGRES_USER="$detected"
    else
      echo "cc-db-entrypoint: WARNING could not detect old install user; leaving POSTGRES_USER=${POSTGRES_USER:-<image default>}"
    fi

    # pg_upgrade refuses to run if the old and new clusters disagree on data
    # checksums. PostgreSQL 18's initdb enables checksums by default, but the
    # older clusters in this recipe's lineage (pg13-17) were created without
    # them, so initdb the new cluster to match. Default to OFF (the lineage
    # reality) and only enable when the old cluster positively reports them on.
    csum=""
    if [ -x "$OLD_BIN/pg_controldata" ]; then
      csum="$("$OLD_BIN/pg_controldata" "$OLD_DIR" 2>/dev/null \
        | awk -F: '/checksum version/{gsub(/[^0-9]/,"",$2); print $2}')"
    fi
    if [ "$csum" = "1" ]; then
      echo "cc-db-entrypoint: old cluster data checksums ON -> initdb new cluster --data-checksums"
      export POSTGRES_INITDB_ARGS="${POSTGRES_INITDB_ARGS:+$POSTGRES_INITDB_ARGS }--data-checksums"
    else
      echo "cc-db-entrypoint: old cluster data checksums OFF (version='${csum:-unknown}') -> initdb new cluster --no-data-checksums"
      export POSTGRES_INITDB_ARGS="${POSTGRES_INITDB_ARGS:+$POSTGRES_INITDB_ARGS }--no-data-checksums"
    fi
  fi
fi

exec run-postgres.sh postgres