package DBIx::Custom::QueryBuilder;

use strict;

use warnings;

use base 'Object::Simple';

use Carp 'croak';

use DBIx::Custom::Query;

use DBIx::Custom::Util '_subname';

# Carp trust relationship

push @DBIx::Custom::CARP_NOT, __PACKAGE__;

push @DBIx::Custom::Where::CARP_NOT, __PACKAGE__;

# Parameter regex

our $PARAM_RE = qr/(^|[^\.\w]):([\.\w]+)([^\.\w]|$)/sm;

sub build_query {

    my ($self, $source) = @_;

    my $query;

    # Parse tag. tag is DEPRECATED!

    if ($source =~ /\{/ && $source =~ /\}/) {

        $query = $self->_parse_tag($source);

        my $tag_count = delete $query->{tag_count};

        warn qq/Tag system such as {? name} is DEPRECATED! This will be removed after 2017/ .

             qq/use parameter system :name instead/

          if $tag_count;

        my $query2 = $self->_parse_parameter($query->sql);

        $query->sql($query2->sql);

        for (my $i =0; $i < @{$query->columns}; $i++) {

            my $column = $query->columns->[$i];

            if ($column eq 'RESERVED_PARAMETER') {

                my $column2 = shift @{$query2->columns};

                croak ":name syntax is wrong"

                  unless defined $column2;

                $query->columns->[$i] = $column2;

            }

        }

    }

    # Parse parameter

    else {

        $query = $self->_parse_parameter($source);

    }

    my $sql = $query->sql;

    $sql .= ';' unless $source =~ /;$/;

    $query->sql($sql);

    # Check placeholder count

    croak qq{Placeholder count in "$sql" must be same as column count}

        . _subname

      unless $self->_placeholder_count($sql) eq @{$query->columns};

    return $query;

}

sub _placeholder_count {

    my ($self, $sql) = @_;

    # Count

    $sql ||= '';

    my $count = 0;

    my $pos   = -1;

    while (($pos = index($sql, '?', $pos + 1)) != -1) {

        $count++;

    }

    return $count;

}

sub _parse_parameter {

    my ($self, $source) = @_;

    # Get and replace parameters

    my $sql = $source || '';

    my $columns = [];

    while ($source =~ /$PARAM_RE/g) {

        push @$columns, $2;

    }

    $sql =~ s/$PARAM_RE/$1?$3/g;

    # Create query

    my $query = DBIx::Custom::Query->new(

        sql => $sql,

        columns => $columns

    );

    return $query;

}

# DEPRECATED!

__PACKAGE__->attr('tags' => sub { {} });

# DEPRECATED!

sub register_tag {

    my $self = shift;

    # Merge tag

    my $tags = ref $_[0] eq 'HASH' ? $_[0] : {@_};

    $self->tags({%{$self->tags}, %$tags});

    return $self;

}

# DEPRECATED!

sub _parse_tag {

    my ($self, $source) = @_;

    # Source

    $source ||= '';

    # Tree

    my @tree;

    # Value

    my $value = '';

    # State

    my $state = 'text';

    # Before charactor

    my $before = '';

    # Position

    my $pos = 0;

    # Parse

    my $original = $source;

    my $tag_count = 0;

    while (defined(my $c = substr($source, $pos, 1))) {

        # Last

        last unless length $c;

        # Parameter

        if ($c eq ':' && (substr($source, $pos + 1, 1) || '') =~ /\w/) {

            push @tree, {type => 'param'};;

        }

        # State is text

        if ($state eq 'text') {

            # Tag start charactor

            if ($c eq '{') {

                # Escaped charactor

                if ($before eq "\\") {

                    substr($value, -1, 1, '');

                    $value .= $c;

                }

                # Tag start

                else {

                    # Change state

                    $state = 'tag';

                    # Add text

                    push @tree, {type => 'text', value => $value}

                      if $value;

                    # Clear

                    $value = '';

                }

            }

            # Tag end charactor

            elsif ($c eq '}') {

                # Escaped charactor

                if ($before eq "\\") {

                    substr($value, -1, 1, '');

                    $value .= $c;

                }

                # Unexpected

                else {

                    croak qq{Parsing error. unexpected "\}". }

                        . qq{pos $pos of "$original" } . _subname

                }

            }

            # Normal charactor

            else { $value .= $c }

        }

        # State is tags

        else {

            # Tag start charactor

            if ($c eq '{') {

                # Escaped charactor

                if ($before eq "\\") {

                    substr($value, -1, 1, '');

                    $value .= $c;

                }

                # Unexpected

                else {

                    croak qq{Parsing error. unexpected "\{". }

                        . qq{pos $pos of "$original" } . _subname

                }

            }

            # Tag end charactor

            elsif ($c eq '}') {

                # Escaped charactor

                if ($before eq "\\") {

                    substr($value, -1, 1, '');

                    $value .= $c;

                }

                # Tag end

                else {

                    # Change state

                    $state = 'text';

                    # Add tag

                    my ($tag_name, @tag_args) = split /\s+/, $value;

                    push @tree, {type => 'tag', tag_name => $tag_name, 

                                 tag_args => \@tag_args};

                    # Clear

                    $value = '';

                    # Countup

                    $tag_count++;

                }

            }

            # Normal charactor

            else { $value .= $c }

        }

        # Save before charactor

        $before = $c;

        # increment position

        $pos++;

    }

    # Tag not finished

    croak qq{Tag not finished. "$original" } . _subname

      if $state eq 'tag';

    # Not contains tag

    return DBIx::Custom::Query->new(sql => $source, tag_count => $tag_count)

      if $tag_count == 0;

    # Add rest text

    push @tree, {type => 'text', value => $value}

      if $value;

    # SQL

    my $sql = '';

    # All Columns

    my $all_columns = [];

    # Tables

    my $tables = [];

    # Build SQL 

    foreach my $node (@tree) {

        # Text

        if ($node->{type} eq 'text') { $sql .= $node->{value} }

        # Parameter

        elsif ($node->{type} eq 'param') {

            push @$all_columns, 'RESERVED_PARAMETER';

        }

        # Tag

        else {

            # Tag name

            my $tag_name = $node->{tag_name};

            # Tag arguments

            my $tag_args = $node->{tag_args};

            # Table

            if ($tag_name eq 'table') {

                my $table = $tag_args->[0];

                push @$tables, $table;

                $sql .= $table;

                next;

            }

            # Get tag

            my $tag = $self->tag_processors->{$tag_name}

                             || $self->tags->{$tag_name};

            # Tag is not registered

            croak qq{Tag "$tag_name" is not registered } . _subname

              unless $tag;

            # Tag not sub reference

            croak qq{Tag "$tag_name" must be sub reference } . _subname

              unless ref $tag eq 'CODE';

            # Execute tag

            my $r = $tag->(@$tag_args);

            # Check tag return value

            croak qq{Tag "$tag_name" must return [STRING, ARRAY_REFERENCE] }

                . _subname

              unless ref $r eq 'ARRAY' && defined $r->[0] && ref $r->[1] eq 'ARRAY';

            # Part of SQL statement and colum names

            my ($part, $columns) = @$r;

            # Add columns

            push @$all_columns, @$columns;

            # Join part tag to SQL

            $sql .= $part;

        }

    }

    # Query

    my $query = DBIx::Custom::Query->new(

        sql => $sql,

        columns => $all_columns,

        tables => $tables,

        tag_count => $tag_count

    );

    return $query;

}

# DEPRECATED!

__PACKAGE__->attr('tag_processors' => sub { {} });

# DEPRECATED!

sub register_tag_processor {

    my $self = shift;

    warn "register_tag_processor is DEPRECATED! use register_tag instead";

    # Merge tag

    my $tag_processors = ref $_[0] eq 'HASH' ? $_[0] : {@_};

    $self->tag_processors({%{$self->tag_processors}, %{$tag_processors}});

    return $self;

}

1;

=head1 NAME

DBIx::Custom::QueryBuilder - Query builder

=head1 SYNOPSIS

    my $builder = DBIx::Custom::QueryBuilder->new;

    my $query = $builder->build_query(

        "select from table title = :title and author = :author"

    );

=head1 METHODS

L<DBIx::Custom::QueryBuilder> inherits all methods from L<Object::Simple>

and implements the following new ones.

=head2 C<build_query>

    my $query = $builder->build_query($source);

Create a new L<DBIx::Custom::Query> object from SQL source.

=cut