package Dakkar::TweetArchive::Store;
use 5.024;
use Moo;
use experimental 'signatures';
use DBI;
use Types::Standard qw(Str InstanceOf);
use DateTime::Format::Strptime;
use DateTime::Format::Pg;
use JSON::MaybeXS;
use namespace::clean;

has [qw(dsn user pass)] => (
    is => 'ro',
    required => 1,
    isa => Str,
);

has dbh => (
    is => 'lazy',
    isa => InstanceOf['DBI::db'],
);

sub _build_dbh($self) {
    return DBI->connect(
        $self->dsn, $self->user, $self->pass,
        {
            PrintError => 0,
            AutoCommit => 1,
            RaiseError => 1,
        },
    );
}

sub BUILD($self,@) {
    $self->_ensure_schema;
}

my $dt_parser = DateTime::Format::Strptime->new(pattern => '%a %b %d %T %z %Y');
my $dt_printer = DateTime::Format::Pg->new();

my $json_printer = JSON::MaybeXS->new(
    ascii => 1,
    pretty => 0,
    allow_nonref => 1,
    allow_unknown => 1,
    allow_blessed => 1,
    convert_blessed => 1,
);

sub latest_tweet_id($self) {
    return $self->dbh->selectall_arrayref(
        q{SELECT MAX(id) FROM tweets},
    )->[0][0];
}

sub store_tweet($self,$tweet) {
    # yes, the source most probably decoded this from a string, we
    # have to serialise it again, so that PostgreSQL can parse it
    # *again*
    my $tweet_str = $json_printer->encode($tweet);
    my $created_at = $dt_parser->parse_datetime($tweet->{created_at});

    $self->dbh->do(<<'SQL', {},
INSERT INTO tweets(id,created_at,data) VALUES(?,?,?)
 ON CONFLICT (id) DO UPDATE SET
   created_at = EXCLUDED.created_at,
   data = EXCLUDED.data
SQL
                   $tweet->{id_str},
                   $dt_printer->format_datetime($created_at),
                   $tweet_str,
               );
}

sub _store_people($self,$people) {
    my @ids;
    for my $person ($people->@*) {
        my $person_str = $json_printer->encode($person);
        push @ids,
            $self->dbh->selectall_arrayref(<<'SQL',{},$person_str)->[0][0];
INSERT INTO people(data) VALUES (?)
ON CONFLICT (people_details(data)) DO UPDATE
 SET data=EXCLUDED.data
RETURNING id
SQL
    }

    return \@ids;
}


sub store_friends($self,$friends) {
    my $ids = $self->_store_people($friends);

    $self->dbh->do(<<"SQL", {}, $json_printer->encode($ids));
INSERT INTO friends(users) VALUES(?)
SQL
}

sub store_followers($self,$followers) {
    my $ids = $self->_store_people($followers);

    $self->dbh->do(<<"SQL", {}, $json_printer->encode($ids));
INSERT INTO followers(users) VALUES(?)
SQL
}

sub _schema_deploy($self,$next_version) {
    my $method_name = "_schema_deploy_${next_version}";
    if (my $method = $self->can($method_name)) {
        $self->dbh->begin_work;
        $self->$method();
        $self->dbh->do(<<'SQL', {}, $next_version);
INSERT INTO meta(version) VALUES (?)
SQL
        $self->dbh->commit;
        return 1;
    }
    else {
        return 0;
    }
}

sub _ensure_schema($self) {
    my $dbh = $self->dbh;
    # simple-minded schema version management
    {
        # silence the 'NOTICE:  relation "meta" already exists, skipping'
        local $dbh->{PrintWarn} = 0;
        $dbh->do(<<'SQL');
CREATE TABLE IF NOT EXISTS meta (
  version INTEGER PRIMARY KEY,
  created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP
)
SQL
    }
    my $current_version = $dbh->selectall_arrayref(
        q{SELECT max(version) FROM meta}
    )->[0][0];
    $current_version //= 0;

    my $next_version = $current_version + 1;
    while ($self->_schema_deploy($next_version)) {
        ++$next_version;
    }
}

sub _schema_deploy_1($self) {
    $self->dbh->do(<<'SQL');
CREATE TABLE tweets (
  id VARCHAR(255) PRIMARY KEY,
  created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
  data JSONB NOT NULL
)
SQL
}

sub _schema_deploy_2($self) {
    $self->dbh->do(<<'SQL');
CREATE TABLE followers (
  taken_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP PRIMARY KEY,
  users JSONB NOT NULL
)
SQL
    $self->dbh->do(<<'SQL');
CREATE TABLE friends (
  taken_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP PRIMARY KEY,
  users JSONB NOT NULL
)
SQL
}

sub _schema_deploy_3($self) {
    $self->dbh->do(<<'SQL');
CREATE TABLE people (
  id SERIAL PRIMARY KEY,
  data JSONB NOT NULL
)
SQL
    $self->dbh->do(<<'SQL');
CREATE FUNCTION people_details(data jsonb) RETURNS text[] AS $$
 SELECT array[
   (data->>'id_str'),
   (data->>'url'),
   (data->>'name'),
   (data->>'location'),
   (data->>'description'),
   (data->>'screen_name'),
   (data->>'profile_image_url'),
   (data->>'profile_background_image_url')
  ];
$$ LANGUAGE SQL IMMUTABLE RETURNS NULL ON NULL INPUT
SQL
    $self->dbh->do(<<'SQL');
CREATE UNIQUE INDEX idx_people ON people (people_details(data))
SQL

    my $json_parser = JSON::MaybeXS->new();

    my $migrate = sub($table) {
        $self->dbh->do(<<"SQL");
DECLARE migrate_crs CURSOR FOR SELECT taken_at,users FROM $table
SQL
        my $fetch = $self->dbh->prepare(q{FETCH 1 FROM migrate_crs});
        my $update = $self->dbh->prepare(<<"SQL");
UPDATE $table
   SET users = ?
 WHERE taken_at = ?
SQL
        $fetch->execute;
        while (my @row = $fetch->fetchrow_array) {
            my $friends = $json_parser->decode($row[1]);
            my $ids = $self->_store_people($friends);
            $update->execute($json_printer->encode($ids),$row[0]);
            $fetch->execute;
        }
    };

    $migrate->('friends');
    $migrate->('followers');
}

1;