{ backupFile ? "" }:
with import <nixpkgs> { };

pkgs.mkShell {
  name = "Solid Scribe Env";

  buildInputs = [
    nodejs
    nodemon
    pnpm
    pm2
    mariadb
    openssl

    # Schema migrations and DB scaffolding only -- the running server never
    # imports Prisma. The nixpkgs wrapper is self-configuring: it exports
    # PRISMA_SCHEMA_ENGINE_BINARY pointing at a nix-built prisma-engines and
    # execs the bundled CLI, so there is no engine download and none of the
    # usual NixOS prebuilt-binary trouble.
    #
    # Pinned to prisma_7 deliberately, NOT the `prisma` alias: Prisma 8 has no
    # MariaDB support yet, so if nixpkgs moves that alias to v8 this project's
    # database would stop being supported underneath us.
    prisma_7
  ];

  shellHook = ''
    echo "Welcome to Solid Scribe"
    alias npm=pnpm

    MYSQL_DATADIR="$PWD/.mysql/data"
    MYSQL_SOCKET="$PWD/.mysql/mysql.sock"
    MYSQL_PIDFILE="$PWD/.mysql/mysql.pid"

    #
    # Work out what database situation we are in BEFORE touching anything.
    # This shell is used on the production server too, where a system MariaDB
    # is already running -- we must not initialise a datadir, start a second
    # server on port 3306, or inject dev credentials over the real ones.
    #
    #   ours     - the project-local server is already up (another nix-shell)
    #   existing - some other server is listening; not ours to manage
    #   start    - nothing is running; this is a dev box, bring one up
    #
    SS_DB_MODE="start"

    if mysqladmin --socket="$MYSQL_SOCKET" ping &>/dev/null 2>&1; then
      SS_DB_MODE="ours"
    elif (echo >/dev/tcp/127.0.0.1/3306) &>/dev/null \
      || [ -S /run/mysqld/mysqld.sock ] \
      || [ -S /var/run/mysqld/mysqld.sock ] \
      || [ -S /tmp/mysql.sock ]; then
      SS_DB_MODE="existing"
    fi

    if [ "$SS_DB_MODE" = "existing" ]; then
      echo "Existing database detected -- not starting the project one."
      echo "Leaving DB_* and JSON_KEY alone so the server's own config wins."
    fi

    STARTED_MYSQL=0

    if [ "$SS_DB_MODE" = "start" ]; then

      mkdir -p "$MYSQL_DATADIR"

      # Initialize data directory on first run
      if [ ! -d "$MYSQL_DATADIR/mysql" ]; then
        echo "Initializing MySQL data directory (first run)..."
        mysql_install_db \
          --datadir="$MYSQL_DATADIR" \
          --skip-test-db \
          --auth-root-authentication-method=normal \
          2>/dev/null
        echo "Initialization complete."
      fi

      STARTED_MYSQL=1
      echo "Starting MySQL..."
      mysqld --no-defaults \
        --datadir="$MYSQL_DATADIR" \
        --socket="$MYSQL_SOCKET" \
        --pid-file="$MYSQL_PIDFILE" \
        --port=3306 \
        --bind-address=127.0.0.1 \
        --log-error="$PWD/.mysql/error.log" &

      until mysqladmin --socket="$MYSQL_SOCKET" ping &>/dev/null 2>&1; do
        sleep 0.5
      done
      echo "MySQL ready."

      #
      # Collation is explicit because the server default here is
      # utf8mb4_unicode_ci while every application table is
      # utf8mb4_general_ci. Without this, a table created later without an
      # explicit COLLATE would silently inherit the wrong one, changing string
      # comparison and FULLTEXT ranking. Prisma does not model collation and
      # `prisma migrate diff` does not report the difference.
      #
      # Existing databases need a one-time, non-destructive fix:
      #   ALTER DATABASE application
      #     CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;
      #
      mysql -u root --socket="$MYSQL_SOCKET" \
        -e "CREATE DATABASE IF NOT EXISTS application \
              CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;" 2>/dev/null
    fi

    #
    # Dev credentials, injected ONLY when this shell is providing the database
    # and there is no ~/.env supplying real config.
    #
    # This matters because dotenv does NOT override variables already present in
    # process.env (server/config/database.js loads ~/.env). So anything exported
    # here silently beats the server's real configuration -- including JSON_KEY,
    # which would invalidate every existing user session.
    #
    if [ "$SS_DB_MODE" != "existing" ] && [ ! -f "$HOME/.env" ]; then

      export DB_HOST=127.0.0.1
      export DB_USER=root
      export DB_PASS=

      #
      # Prisma CLI connection string, for migrations and scaffolding.
      #
      # The warning above about shadowing ~/.env does NOT apply here:
      # DATABASE_URL is read only by the Prisma CLI, never by
      # server/config/database.js, so it cannot affect the running server.
      #
      # Deliberately NOT derived from DB_USER/DB_PASS. Prisma needs DDL
      # rights, and in production those variables hold the least-privilege
      # `app` account. Admin credentials are composed by migrateDatabase.sh
      # instead, which is why this export lives only in the dev branch.
      #
      export DATABASE_URL="mysql://root@127.0.0.1:3306/application"

      # Stop the Prisma CLI phoning checkpoint.prisma.io for update checks.
      # Keeps the schema tests network-free and the output uncluttered.
      export CHECKPOINT_DISABLE=1

      # Stable dev JWT key, persisted across shell sessions
      if [ -z "''${JSON_KEY:-}" ]; then
        if [ -s "$PWD/.mysql/jwt_key" ]; then
          export JSON_KEY=$(cat "$PWD/.mysql/jwt_key")
        else
          export JSON_KEY=$(openssl rand -hex 32)
          echo "$JSON_KEY" > "$PWD/.mysql/jwt_key"
          echo "Generated dev JSON_KEY (saved to .mysql/jwt_key)"
        fi
      fi

    elif [ -f "$HOME/.env" ]; then
      echo "~/.env found -- using its DB_* and JSON_KEY, not dev defaults."
    fi

    # Restore a SQL dump — handles both plain .sql and .gz files
    restore-db() {
      local file="''${1:-}"
      if [ -z "$file" ]; then
        echo "Usage: restore-db <backup.sql[.gz]>"
        return 1
      fi

      # Refuse to run against a database this shell does not manage. The dumps
      # are --all-databases: restoring one would overwrite every schema on the
      # server and reset root's password. That is fine for a local dev copy and
      # catastrophic on the production box.
      if [ "$SS_DB_MODE" = "existing" ]; then
        echo "Refusing: this shell is talking to a pre-existing database." >&2
        echo "restore-db only runs against the project-local dev database." >&2
        return 1
      fi
      echo "Restoring database from $file ..."
      if [[ "$file" == *.gz ]]; then
        gunzip -c "$file" | mysql -u root --socket="$MYSQL_SOCKET"
      else
        mysql -u root --socket="$MYSQL_SOCKET" < "$file"
      fi
      # The dump is --all-databases, so it includes the `mysql` schema and
      # overwrites local root with production's credentials. In-memory grants
      # are still the old ones until FLUSH, so fix root now while we can
      # still authenticate.
      mysql -u root --socket="$MYSQL_SOCKET" -e "
        ALTER USER 'root'@'localhost' IDENTIFIED VIA mysql_native_password USING PASSWORD(''');
        GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION;
        FLUSH PRIVILEGES;"

      echo "Restore complete."
    }
    export -f restore-db

    # Auto-restore if --argstr backupFile was passed to nix-shell
    # (restore-db itself refuses when the database is not ours)
    if [ -n "${backupFile}" ]; then
      restore-db "${backupFile}"
    fi

    if [ "$STARTED_MYSQL" = "1" ]; then
      trap "echo 'Stopping MySQL...'; mysqladmin -u root --socket=$MYSQL_SOCKET shutdown 2>/dev/null" EXIT
    else
      echo "MySQL already running (started by another shell) -- leaving it up on exit."
    fi
    
    # Do not start the app here.
    # This same shell.nix is used for hosting the app on dev
    # use the startDevServerAndClient.sh script 
  '';
}