package Code::TidyAll::CacheModel;

use strict;
use warnings;

use Digest::SHA qw(sha1_hex);
use Path::Tiny ();
use Specio::Declare;
use Specio::Library::Builtins;
use Specio::Library::Path::Tiny;
use Specio::Library::String;

use Moo;

our $VERSION = '0.70';

has base_sig => (
    is      => 'ro',
    isa     => t('Str'),
    default => q{},
);

has cache_engine => (
    is  => 'ro',
    isa => object_can_type(
        methods => [qw( get set remove )],
    ),
    predicate => '_has_cache_engine',
);

has cache_key => (
    is      => 'lazy',
    isa     => t('NonEmptyStr'),
    clearer => 1,
);

has cache_value => (
    is      => 'lazy',
    isa     => t('NonEmptyStr'),
    clearer => 1,
);

has file_contents => (
    is      => 'rw',
    isa     => t('Str'),
    lazy    => 1,
    builder => 1,
    trigger => 1,
    clearer => 1,
);

has full_path => (
    is       => 'ro',
    isa      => t('Path'),
    required => 1,
);

has is_cached => (
    is      => 'rw',
    isa     => t('Bool'),
    lazy    => 1,
    builder => 1,
    clearer => 1,
);

has path => (
    is       => 'ro',
    isa      => t('Path'),
    required => 1,
);

sub _build_file_contents {
    my ($self) = @_;
    return Path::Tiny::path( $self->full_path )->slurp;
}

sub _trigger_file_contents {
    my $self = shift;
    $self->clear_cache_key;
    $self->clear_is_cached;
    $self->clear_cache_value;
    return;
}

sub _build_cache_key {
    my ($self) = @_;
    return 'sig/' . $self->path;
}

sub _build_cache_value {
    my ($self) = @_;

    # this stat isn't ideal, but it'll do
    my $last_mod = ( stat( $self->full_path ) )[9];
    return $self->_sig( [ $self->base_sig, $last_mod, $self->file_contents ] );
}

sub _build_is_cached {
    my ($self) = @_;

    return unless $self->_has_cache_engine;
    my $cached_value = $self->cache_engine->get( $self->cache_key );
    return defined $cached_value && $cached_value eq $self->cache_value;
}

sub update {
    my ($self) = @_;

    return unless $self->_has_cache_engine;
    $self->cache_engine->set( $self->cache_key, $self->cache_value );
    $self->is_cached(1);
    return;
}

sub remove {
    my ($self) = @_;

    return unless $self->_has_cache_engine;
    $self->cache_engine->remove( $self->cache_key );
    return;
}

sub _sig {
    my ( $self, $data ) = @_;
    return sha1_hex( join( ',', @$data ) );
}

1;

# ABSTRACT: Caching model for Code::TidyAll

__END__

=pod

=encoding UTF-8

=head1 NAME

Code::TidyAll::CacheModel - Caching model for Code::TidyAll

=head1 VERSION

version 0.70

=head1 SYNOPSIS

  my $cache_model = Cody::TidyAll::CacheModel->new(
      cache_engine => Code::TidyAll::Cache->new(...),
      path         => '/path/to/file/to/cache',
  );

  # check cache
  print 'Yes!' if $cache_model->is_cached;

  # update cache
  $cache_model->clear_file_contents;
  $cache_model->update;

  # update the cache when you know the file contents
  $cache_model->file_contents($new_content);
  $cache_model->update;

  # force removal from cache
  $cache_model->remove;

=head1 DESCRIPTION

A cache model for Code::TidyAll. Different subclasses can employ different
caching techniques.

The basic model implemented here is simple; It stores a hash key of the file
contents keyed by a hash key of the file's path.

=head1 METHODS

This class has the following methods:

=head2 Code::TidyAll::CacheModel->new(%params)

The constructor accepts the following attributes:

=over 4

=item * full_path

The full path to the cache file on disk. This is required.

=item * path

The local path to the file (i.e. what the cache system will consider the
canonical name of the file).

=item * cache_engine

A C<Code::TidyAll::Cache> compatible instance. This can be omitted if no
caching is actually being done.

=item * base_sig

A base signature. This defaults to an empty string.

=item * file_contents

The contents of the file being cached. This can be omitted, in which case it
will be loaded as needed.

=item * is_cached

A boolean indicating if this file is cached. By default this is computed by
checking that the cache key and cache value match what is in the cache.

=back

=head2 $model->full_path

The value passed to the constructor.

=head2 $model->path

The value passed to the constructor.

=head2 $model->cache_engine

The value passed to the constructor.

=head2 $model->base_sig

The value passed to the constructor or the default value, an empty string.

=head2 $model->file_contents

The file contents, which will be loaded from the file system if needed.

=head2 $model->is_cached

A boolean indicating whether the path is currently in the cache.

=head2 $model->cache_key

The computed cache key for the file.

=head2 $model->cache_value

The computed cache value for the file.

=head2 $model->update

Updates the cache.

=head2 $model->remove

Attempts to remove the value from the cache.

=head1 SUPPORT

Bugs may be submitted at
L<https://github.com/houseabsolute/perl-code-tidyall/issues>.

I am also usually active on IRC as 'autarch' on C<irc://irc.perl.org>.

=head1 SOURCE

The source code repository for Code-TidyAll can be found at
L<https://github.com/houseabsolute/perl-code-tidyall>.

=head1 AUTHORS

=over 4

=item *

Jonathan Swartz <swartz@pobox.com>

=item *

Dave Rolsky <autarch@urth.org>

=back

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2011 - 2018 by Jonathan Swartz.

This is free software; you can redistribute it and/or modify it under the same
terms as the Perl 5 programming language system itself.

The full text of the license can be found in the F<LICENSE> file included with
this distribution.

=cut