#!/usr/bin/perl

# {{{ POD documentation

=head1 NAME

        site-generator - HPR Site Generator

=head1 SYNOPSIS

        site-generator [OPTION]... PAGE|PAGE=<comma separated list of ids>...

        -a, --all           generate all pages defined in configuration file
        -c, --configuration path to configuration file
        -l, --list          print list of configured pages
        -p, --preview       print generated pages to standard out
        -q, --quiet         suppress progress information while generating pages
        -v, --verbose       print extended progress information while generating pages
        --help              print this help message

        Where I<PAGE> is a file name of a web page
        or the special I<ALL> (to generate all pages).

        Examples:

                Generate two specific pages:
                site-generator index about

                Generate the whole site:
                site-generator --all

                Generate pages based on the same template:
                site-generator correspondent=1,3,5..10

                Generate two specific pages with a different configuration:
                site-generator --configuration=site_sqlite.cfg index about


=head1 DESCRIPTION

This is a site generator for the Hacker Public Radio website based upon the
Perl Template Toolkit.

=head1 INSTALLATION

        With SQLite
        * Create the sqlite3 database from the hpr.sql MySQL dump file available on
          hackerpublicradio.org. The default name for the database file is "hpr.db"
          and should be located in the root of the project directory. The name and
          location can be set in the site.cfg file.
        * An "update-hpr.sh" helper script is available in the utils directory. This
          script will download the hpr.sql file, convert it to the SQLite hpr.db file,
          and regenerate the website using the site-generator.
                1. `cd` into the root of the project directory
                2.  Run `./utils/update-hpr.sh`
        * SQLite v3.8.3 or greater is recommended. CTE WITH clauses are used in some template queries.
          Must convert WITH clauses to sub-queries when using earlier versions of SQLite.

        With MySQL
        * Create database hpr_hpr in the MySQL server from HPR dump file.
                - sudo mysql --host=localhost < hpr.sql
        * Create a user that will be used by the site-generator.
                - Suggested username: hpr-generator
                - CREATE USER 'hpr-generator'@'localhost' IDENTIFIED BY '<password>';
        * Limit the user's privileges to EXECUTE and SELECT
                - GRANT SELECT ON hpr_hpr.* TO 'hpr-generator'@'localhost';
                - GRANT EXECUTE ON `hpr_hpr`.* TO 'hpr-generator'@'localhost';

        Install the needed Perl modules using preferred method (distribution packages, CPAN, etc.)
                * GetOpt
                * Pod::Usage
                * Config::Std
                * Template
                * Template::Plugin::File
                * Template::Plugin::DBI
                * Template::Plugin::HTML::Strip
                * DBI
                * Tie::DBI
                * DBD::SQLite or DBD:mysql
                * Date::Calc
                * Text::CSV_XS

=head1 AUTHOR

        Roan Horning <roan.horning@no-spam.gmail.com>

=head1 LICENSE

        site-generator -- a static website generator for HPR
        Copyright (C) 2022 Roan Horning

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.

=cut

# }}}

use 5.012;
use strict;
use warnings;
use open ':encoding(UTF-8)';

use Getopt::Long qw(:config auto_help);
use Pod::Usage;
use Config::Std;
use Text::CSV_XS;
use HTML::Entities qw(encode_entities_numeric);
use Date::Calc;
use DBI;
use DBD::SQLite;
use Tie::DBI;
use Template;
use Template::Plugin::Date;
use Template::Plugin::DBI;
use Template::Plugin::HTML::Strip;

use Data::Dumper;

exit main();

sub main {

    # Argument parsing
    my $all;
    my $configuration_path;
    my $preview;
    my $verbose;
    my $quiet;
    GetOptions(
        'all'             => \$all,
        'configuration=s' => \$configuration_path,
        'list'            => \&print_available_pages,
        'preview'         => \$preview,
        'verbose'         => \$verbose,
        'quiet'           => \$quiet,
    ) or pod2usage(1);
    pod2usage(1) unless @ARGV || $all;
    my (@page_args) = @ARGV;

    if ($quiet) {
        $verbose = 'quiet';
    };

    if (!$configuration_path) {
        $configuration_path = "site.cfg";
    }

    my %config;
    if ( -f $configuration_path ) {
        # Load config file
        read_config $configuration_path => %config;
    }
    else {
        print STDOUT "Could not read configuration file: $configuration_path\n";
        exit 1;
    }

    my $tt = get_template_html($config{DBI}, $config{app_paths});

    #
    # Define a TT² vmethod called 'csv_parse', it takes a scalar value and
    # returns an arrayref. Also define a filter called 'xml_entity' which
    # numerically encodes non-ASCII characters.
    #
    $tt->context->define_vmethod( 'scalar', 'csv_parse', \&parse_csv );
    $tt->context->define_filter( 'xml_entity', \&xml_entity );

    # If command line option all is set, parse configuration file
    # for all pages
    if ($all) {
        @page_args = keys %config;

        # Remove non page sections of the configuration file
        # from the generated list of pages.
        @page_args= grep { $_ ne 'DBI' } @page_args;
        @page_args= grep { $_ ne 'root_template' } @page_args;
        @page_args= grep { $_ ne 'app_paths' } @page_args;

    };
    foreach my $page_arg (@page_args) {
        my %parsed_arg = parse_page_arg($page_arg);
        if (exists($config{$parsed_arg{'page'}})) {
            my $page_config = $config{$parsed_arg{'page'}};
            $page_config->{'page'} = $parsed_arg{'page'};

            # Set page's root_template to the default root_template if the
            # page root_template property is not set in the configuration file.
            if (exists $page_config->{'root_template'} == 0) {
                $page_config->{'root_template'} = $config{root_template}{content};
            }

            # Set all config root_template properties as default page config properties
            # except the previously set root_template content property
            my @root_args = grep { $_ ne 'content' } keys %{$config{root_template}};
            foreach my $root_arg (@root_args) {
                if (exists $page_config->{$root_arg} == 0) {
                    $page_config->{$root_arg} = $config{root_template}{$root_arg};
                }
            }

            if ($page_config->{'multipage'} && $page_config->{'multipage'} eq 'true') {
                if (scalar @{$parsed_arg{'ids'}} == 0) {
                    @{$parsed_arg{'ids'}} = get_ids_from_db($tt, \$page_config);
                }
                foreach my $id (@{$parsed_arg{'ids'}}) {
                    $page_config->{'id'} = $id;
                    verbose ($verbose, "Generating page: $page_config->{'page'} with id: $id");
                    generate_page($tt, \$page_config, $preview);
                }
            }
            else {
                verbose ($verbose, "Generating page: $page_config->{'page'}");
                generate_page($tt, \$page_config, $preview);
            }
        }
        else {
            verbose (1, "\nWarning: Page $parsed_arg{'page'} is not defined in the configuration file.");
        }
    }
    verbose (1, "\nFinished processing the files.");
    return 0;
}

sub get_template_html {
    # For an HTML based Template file, define the
    # template start and end tags to also function as
    # HTML comments to make the template file valid HTML.
    #
    return Template->new(
        {   INCLUDE_PATH => $_[1]{templates_path},
            OUTPUT_PATH  => $_[1]{output_path},
            EVAL_PERL    => 1,
            START_TAG    => '<!--%',
            END_TAG      => '%-->',
            PRE_CHOMP    => 1,
            POST_CHOMP   => 1,
            CONSTANTS    => {
                database => $_[0]{database},
                driver   => $_[0]{driver},
                user     => $_[0]{user},
                password => $_[0]{password},
            }
        }
    ) || die $Template::ERROR, "\n";

}

sub generate_page {
    my ( $tt, $config, $preview ) = @_;
    my $html;
    if ( !$preview ) {
        $html = get_filename($$config);
    }
    $tt->process( $$config->{root_template},
        $$config, $html
    )
        || die $tt->error(), "\n";

}

sub verbose {
        my ($verbose, $message) = @_;
        if ($verbose) {
                if ($verbose ne 'quiet') {
                        print STDOUT "$message\n";
                }
        }
        else {
                STDOUT->autoflush(1);
                print STDOUT ".";
        };
}

sub parse_page_arg {
    my ($page_arg) =  @_;
    # Split page name from page ids if available.
    my ($page, $ids) = split(/=/, $page_arg);
    my @ids;

    if(!$ids) {
        $ids = "";
    }
    else {
        # Parse the page ids and push them onto @ids array
        my @ids_by_comma = split(/\,/, $ids);
        foreach my $id_by_comma (@ids_by_comma) {
            my @ids_for_range = split(/\.\./, $id_by_comma);
            if ((scalar @ids_for_range) == 2) {
                push @ids, $ids_for_range[0]..$ids_for_range[1];
            }
            elsif ((scalar @ids_for_range) == 1) {
                push @ids, $ids_for_range[0];
            }
            else {
                verbose (1, "\nWarning: Page $page id range $id_by_comma could not be parsed.");
            }
        }
    }
    return ('page' => $page, 'ids' => [@ids]);
}

sub get_ids_from_db {
        # Use a template to generate a string of page identifiers.
        # The template should return the string in the form of
        # <comma><identifier><comma><identifier>...
        #
        my ($tt, $config)  = @_;
        my $selected_ids = "";
        my $id_template = "ids-$$config->{'page'}.tpl.html";

        $tt->process($id_template, $$config, \$selected_ids)
        || die $tt->error(), "\n";

        # Starts with a newline and comma
        return split(/,/, substr($selected_ids, 2));
}

sub get_filename {
        my ($config) = @_;
        my $filename = "output.html";
        my $base_path = "";

        if ($$config{'filename'}) {
                if (substr($$config{'filename'}, -1) eq '/') {
                        $base_path = $$config{'filename'};
                }
                else {
                        $filename = $$config{'filename'};
                        my $padded_index = "";
                        if (exists $$config{'id'} && $$config{'id'} ne "") {
                                $padded_index = sprintf("%04d", $$config{'id'});
                        }
                        $filename =~ s/\[id\]/$padded_index/;
                    return $filename;
                }
        }
        # Default naming if full filename configuration is not supplied.
        if ($$config{'multipage'} && $$config{'multipage'} eq 'true') {
                my $padded_index = sprintf("%04d", $$config{'id'});
                $filename = "$base_path$$config{'page'}${padded_index}.html";
        }
        else {
                $filename = "$base_path$$config{'page'}.html";
        }
        return $filename;
}

sub print_available_pages {
    # Load config file
    read_config "site.cfg" => my %config;

    my @page_args = sort ( keys %config );

    # Remove non page sections of the configuration file
    # from the generated list of pages.
    @page_args = grep { $_ ne 'DBI' } @page_args;
    @page_args = grep { $_ ne 'root_template' } @page_args;

    foreach my $page_arg (@page_args) {
        print "$page_arg\n";
    }
    exit;
}

#===  FUNCTION  ================================================================
#         NAME: parse_csv
#      PURPOSE: Parses a simple string containing CSV data
#   PARAMETERS: $csv_in         CSV string
#      RETURNS: An arrayref containing the parsed CSV elements
#  DESCRIPTION: The Text::CSV_XS module instance is created with the option
#               'allow_whitespace' to be forgiving of any spaces around the
#               CSV elements and to strip them. Also, 'allow_loose_quotes' is
#               forgiving of really messed up CSV. The 'binary' option
#               permits any characters in the tags (expecting Unicode).
#               The fields parsed from the tag string is checked for the
#               existence of utf8 characters and encoded to ensure any found
#               are properly stored.
#       THROWS: No exceptions
#     COMMENTS: None
#     SEE ALSO: N/A
#===============================================================================
sub parse_csv {
    my ($csv_in) = @_;

    my $csv = Text::CSV_XS->new(
        {   binary             => 1,
            auto_diag          => 1,
            allow_whitespace   => 1,
            allow_loose_quotes => 1
        }
    );
    my $status = $csv->parse($csv_in);
    unless ( $status ) {
        warn "Failed to parse CSV '$csv_in'\n" ;
        return;
    }
    my @fields = $csv->fields();

    @fields = map {utf8::encode($_) if utf8::is_utf8($_); $_} @fields;

    return \@fields;
}

#===  FUNCTION  ================================================================
#         NAME: xml_entity
#      PURPOSE: Static filter to encode Unicode for XML
#   PARAMETERS: $text           String to be processed
#      RETURNS: Processed text
#  DESCRIPTION:
#       THROWS: No exceptions
#     COMMENTS: None
#     SEE ALSO: N/A
#===============================================================================
sub xml_entity {
    my ($text) = @_;

    encode_entities_numeric( $text );

    return $text;
}

# vim: syntax=perl:ts=8:sw=4:et:ai:tw=78:fo=tcrqn21:fdm=marker