#!/usr/bin/perl

use warnings;

use Test::More skip_all => 'tests to teach me about transactions--done';
use Class::Std::Utils;

my $dbh = DBI->connect( die 'connect info goes here' );

die 'I had code here to ensure I was connected to the test database, not production.';

# CREATE TABLE ( itemnum serial, item varchar(100) );
# CREATE UNIQUE INDEX items_itemnum ON items (itemnum);
# CREATE UNIQUE INDEX items_item ON items (item);

# TESTING BEGINS.

ok( $dbh->{AutoCommit}, 'AutoCommit is on' );

my $item_there;
($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.1'" );

is( $item_there, 0, 'no item in table' );

$dbh->do( "INSERT INTO items (item) VALUES ('test.1')" );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.1'" );

is( $item_there, 1, 'item in table' );

ok( $dbh->begin_work, 'begin_work succeeds' );
ok( !$dbh->{AutoCommit}, 'AutoCommit is off' );

eval {
    $dbh->do( "INSERT INTO items (item) VALUES ('test.1')" );
};
ok( $@, 'duplicate insert fails' );
ok( $@ =~ /duplicate key violates unique constraint/,
    'duplicate insert fails for the expected reason' );

ok( $dbh->rollback, 'rollback succeeds' );

ok( $dbh->{AutoCommit}, 'AutoCommit is on' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.1'" );
is( $item_there, 1, 'item 1 in table' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.2'" );
is( $item_there, 0, 'item 2 not in table' );

ok( $dbh->begin_work, 'begin_work succeeds' );

eval {
    $dbh->do( "INSERT INTO items (item) VALUES ('test.2')" );
    $dbh->do( "INSERT INTO items (item) VALUES ('test.1')" );
};
ok( $@, 'duplicate insert after nondupe fails' );
ok( $@ =~ /duplicate key violates unique constraint/,
    'duplicate insert after nondupe fails for the expected reason' );

# CAN'T SELECT during an aborted transaction.
# ($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.1'" );
# is( $item_there, 1, 'item 1 in table before rollback' );

# ($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.2'" );
# is( $item_there, 0, 'item 2 not in table before rollback' );

ok( $dbh->rollback, 'rollback succeeds' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.1'" );
is( $item_there, 1, 'item 1 in table after rollback' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.2'" );
is( $item_there, 0, 'item 2 not in table after rollback' );

ok( $dbh->begin_work, 'begin_work succeeds' );

eval {
    $dbh->do( "INSERT INTO items (item) VALUES ('test.2')" );
    $dbh->do( "INSERT INTO items (item) VALUES ('test.1')" );
};
ok( $@, 'duplicate insert after nondupe fails' );
ok( $@ =~ /duplicate key violates unique constraint/,
    'duplicate insert after nondupe fails for the expected reason' );

ok( $dbh->commit, 'commit succeeds after aborted transaction' );

# After a transaction aborts, it doesn't matter whether I commit or rollback
# They both succeed, and the transaction does not happen.

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.1'" );
is( $item_there, 1, 'item 1 in table after commit' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.2'" );
is( $item_there, 0, 'item 2 not in table after commit' );

ok( $dbh->begin_work, 'begin_work succeeds' );

eval {
    $dbh->do( "INSERT INTO items (item) VALUES ('test.2')" );
};
ok( !$@, 'no eval error after item 2 insert' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.1'" );
is( $item_there, 1, 'item 1 in table during item 2 transaction' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.2'" );
is( $item_there, 1, 'item 2 in table during item 2 transaction' );

ok( $dbh->rollback, 'rollback succeeds' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.1'" );
is( $item_there, 1, 'item 1 in table after item 2 insert rollback' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.2'" );
is( $item_there, 0, 'item 2 not in table after item 2 insert rollback' );

ok( $dbh->begin_work, 'begin_work succeeds' );

eval {
    $dbh->do( "INSERT INTO items (item) VALUES ('test.2')" );
};
ok( !$@, 'no eval error after item 2 full insert' );
ok( $dbh->commit, 'commit succeeds' );

($item_there) = $dbh->selectrow_array( "SELECT count(*) FROM items WHERE item = 'test.2'" );
is( $item_there, 1, 'item 2 in table after item 2 insert commit' );

####
#### ouchy tests.
####

my $dbh2 = DBI->connect( die 'connect info goes here' );

ok( $dbh2, 'dbh2' );
ok( ident $dbh2 != ident $dbh, 'dbh2 is different from dbh' );

ok( $dbh->begin_work, 'dbh1 begin_work succeeds' );
ok( $dbh2->begin_work, 'dbh2 begin_work succeeds' );

eval {
    $dbh->do( "INSERT INTO items (item) VALUES ('test.3')" );
};
ok( !$@, 'dbh insert succeeds' );
warn $@ if $@;

# The second transaction BLOCKS until the first one commits.
# I guess Pg has to wait and see if it will commit or rollback before it knows
# whether the second one will succeed.

if ( !fork() ) {
    # I am child
    eval {
        $dbh2->do( "INSERT INTO items (item) VALUES ('test.3')" );
    };
#    ok( sleep 1, 'child sleep 1' );
    ok( $@, "child duplicate insert transaction causes error" );
    ok( $dbh2->commit, 'child dbh2 commit succeeds' );
    exit;
}

ok( sleep 2, 'parent slept' );

ok( $dbh->commit, 'parent dbh commit succeeds' );

ok( wait, 'parent waited' );

ok( $dbh2->disconnect(), 'dbh2 disconnect succeeded' );