#!/usr/bin/env perl
# SPDX-FileCopyrightText: 2026 GPForum Contributors
# SPDX-License-Identifier: BSD-3-Clause

package main;

use v5.40;
use Carp    qw(croak);
use English qw(-no_match_vars);

our $VERSION = '0.001';

exit _run();

# Keep pg_dump's SQL, including grants, comments and function bodies. Only
# version banners, the random psql restriction key and rolling month
# partitions vary independently of the migrations. Pin the dump client to
# major 18: different clients serialize an identical schema differently.
sub _run {
    my $check;
    if ( @ARGV && $ARGV[0] eq '--check' ) {
        shift @ARGV;
        $check = shift @ARGV // croak '--check needs a snapshot file';
    }
    if ( !@ARGV || $ARGV[0] eq '--help' ) {
        say 'Usage: script/schema-snapshot [--check FILE] [psql options] DBNAME'
          or croak $OS_ERROR;
        say
'Uses PGHOST, PGPORT, PGUSER, PGPASSWORD; GPFORUM_PG_DUMP selects pg_dump 18.'
          or croak $OS_ERROR;
        exit 0;
    }
    my $sql = _snapshot();
    if ( defined $check ) {
        return _check_snapshot( $sql, $check );
    }
    print $sql or croak "cannot print schema: $OS_ERROR";
    return 0;
}

sub _check_snapshot ( $sql, $check ) {
    open my $handle, '<', $check or croak "cannot read $check: $OS_ERROR";
    my $expected = do { local $INPUT_RECORD_SEPARATOR = undef; <$handle> };
    close $handle or croak "cannot close $check: $OS_ERROR";
    if ( $sql eq $expected ) {
        return 0;
    }
    print $sql or croak "cannot print schema: $OS_ERROR";
    warn "schema differs from $check; regenerate and review its SQL diff\n";
    return 1;
}

sub _snapshot {
    my $dump    = $ENV{GPFORUM_PG_DUMP} // 'pg_dump';
    my $version = _capture( $dump, '--version' );
    croak 'schema snapshots require the PostgreSQL 18 pg_dump client'
      if $version !~ /PostgreSQL[)] [ ] 18[.]/msx;

    my $partitions = _capture(
        $ENV{PSQL} // 'psql',
        '-X',
        '-At',
        '-v',
        'ON_ERROR_STOP=1',
        @ARGV,
        '-c',
        join q{ },
        q{SELECT format('%I.%I', n.nspname, c.relname)},
        q{FROM pg_catalog.pg_class c},
        q{JOIN pg_catalog.pg_namespace n ON n.oid=c.relnamespace},
        q{WHERE c.relispartition AND n.nspname='public'},
        q{AND pg_catalog.pg_get_expr(c.relpartbound, c.oid) <> 'DEFAULT'},
        q{ORDER BY 1},
    );

    # The migrations' ALTER DEFAULT PRIVILEGES names the role that ran them,
    # which owns the api schema; the role dumping may be another (a
    # superuser on a developer host), so the dump user is no witness.
    my $owner = _capture(
        $ENV{PSQL} // 'psql',
        '-X',
        '-At',
        '-v',
        'ON_ERROR_STOP=1',
        @ARGV,
        '-c',
        join q{ },
        q{SELECT quote_ident(COALESCE(},
        q{(SELECT pg_catalog.pg_get_userbyid(nspowner)},
        q{FROM pg_catalog.pg_namespace WHERE nspname = 'api'),},
        q{current_user))},
    );
    chomp $owner;
    my @excluded = map { "--exclude-table=$_" } split /\n/msx, $partitions;
    my $sql =
      _capture( $dump, '--schema-only', '--no-owner',
        '--exclude-extension=pg_stat_statements',
        @excluded, @ARGV, );
    $sql =~ s/^--[ ]Dumped[ ]from[ ]database[ ]version[^\n]*\n//gmsx;
    $sql =~ s/^--[ ]Dumped[ ]by[ ]pg_dump[ ]version[^\n]*\n//gmsx;
    $sql =~ s/^\\(?:un)?restrict[^\n]*\n//gmsx;
    $sql =~ s/^(--[ ]Name:[^\n]*;[ ]Owner:)[^\n]*/$1 -/gmsx;
    $sql =~
s/^ALTER[ ]DEFAULT[ ]PRIVILEGES[ ]FOR[ ]ROLE[ ]\Q$owner\E[ ]/ALTER DEFAULT PRIVILEGES FOR ROLE CURRENT_USER /gmsx;
    $sql =~ s/\A\n+//msx;
    $sql =~ s/\n+\z/\n/msx;

    return $sql;
}

sub _capture (@command) {
    open my $handle, q{-|}, @command
      or croak "cannot run $command[0]: $OS_ERROR";
    my $output = do { local $INPUT_RECORD_SEPARATOR = undef; <$handle> };
    close $handle or croak "$command[0] failed (status $CHILD_ERROR)";
    return $output // q{};
}