#!/usr/bin/perl

use strict;
use warnings;

use File::Slurp qw( write_file );
use PPI;

rewrite_doc($_) for grep { -w } @ARGV;

sub rewrite_doc {
    my $file = shift;

    my $doc = PPI::Document->new($file);

    return unless $doc =~ /Test::Exception/;

    print $file, "\n";

    my $pattern = sub {
        my $elt = $_[1];

        return 1
            if $elt->isa('PPI::Statement')
                && $elt->content()
                =~ /^\s*(?:::)?(?:lives_|throws_|dies_)(?:ok|and)/;

        return 0;
    };

    for my $elt ( @{ $doc->find($pattern) || [] } ) {
        transform_statement($elt);
    }

    my $content = $doc->content();
    $content =~ s/Test::Exception/Test::Fatal/g;

    write_file( $file, $content );
}

sub transform_statement {
    my $stmt = shift;

    my @children = $stmt->schildren;

    my $func = shift @children;

    my $colons = $func =~ /^::/ ? '::' : q{};

    my $code;
    if ( $func =~ /lives_/ ) {
        $code = function(
            $colons . 'is',
            $children[0],
            'undef',
            $children[1]
        );
    }
    elsif ( $func =~ /dies_/ ) {
        $code = function(
            $colons . 'isnt',
            $children[0],
            'undef',
            $children[1]
        );
    }
    elsif ( $func =~ /throws_/ ) {

        # $children[2] is always a comma if it exists
        if ( $children[1]->isa('PPI::Token::QuoteLike::Regexp') ) {
            $code = function(
                $colons . 'like',
                $children[0],
                $children[1],
                $children[3]
            );
        }
        else {
            $code = function(
                $colons . 'is',
                $children[0],
                $children[1],
                $children[3]
            );
        }
    }

    $stmt->insert_before($code);
    $stmt->remove;
}

sub function {
    my $func      = shift;
    my $exception = shift;
    my $expect    = shift;
    my $desc      = shift;

    my $exc_func = $func =~ /^::/ ? '::exception' : 'exception';

    my @code;

    push @code,
        PPI::Token::Word->new($func),
        PPI::Token::Structure->new('('),
        PPI::Token::Whitespace->new(q{ }),
        PPI::Token::Word->new($exc_func),
        PPI::Token::Whitespace->new(q{ }),
        $exception->clone,
        PPI::Token::Operator->new(','),
        PPI::Token::Whitespace->new(q{ }),
        ( ref $expect ? $expect->clone : PPI::Token::Word->new($expect) );

    if ( $desc && $desc->isa('PPI::Token::Quote') ) {
        push @code, PPI::Token::Operator->new(','),
            PPI::Token::Whitespace->new(q{ }),
            $desc->clone;
    }

    push @code,
        PPI::Token::Whitespace->new(q{ }),
        PPI::Token::Structure->new(')'),
        PPI::Token::Structure->new(';');

    my $stmt = PPI::Statement->new;
    $stmt->add_element($_) for @code;

    return $stmt;
}