CURI.pm6

use nqp;

# perl6 -Ilib -e '                                                           \
#   use CURI;                                                                \
#   my $spec = CompUnit::DependencySpecification.new(:short-name("zef"));    \
#   my $dist = CompUnit::Repository::Installation::Distribution.new(:$spec); \
#   say $dist.content("lib/Zef.pm6").open.slurp-rest'

# Just some way for a CURI to set the prefix of various items in a Distribution. Maybe share this with CURI
role CUR::Prefixes {
    method prefix        { "/home/nickl/.rakudobrew/moar-2016.07/install/share/perl6/site/".IO }
    method dist-dir      { $.prefix.child('dist')      }
    method resources-dir { $.prefix.child('resources') }
    method sources-dir   { $.prefix.child('sources')   }
}

# The $version bit is just toying with the idea of handling repo-version translation in Distribution; ignore
role CompUnit::Repository::Installation::Distribution[$version where *.Int == 2 = 2] does CUR::Prefixes {
    also does Distribution;
    has $!meta;
    has $!spec;

    # CU::DependencySpecification would be nicer if it .Str gave the same id
    submethod BUILD(CompUnit::DependencySpecification :$!spec!) {
        #my $id  = nqp::sha1($!spec.str); # couldn't get $!spec id to match installed id, but you get the idea
        my $id   = '9FC151204D7B2313A9A9F7E39603BED7DC60259A'; # Known installation on my machine; see above comment
        my $path = self.dist-dir.child($id);
        $!meta   = Rakudo::Internals::JSON.from-json($path.slurp)
    }

    method meta { $!meta }

    method content($name-path) {
        my $path = do given $name-path {
            when /^resources\// { self.resources-dir ~ '/' ~ self.meta<files>{parse-value($_)}    }
            when /^bin\//       { self.resources-dir ~ '/' ~ self.meta<files>{parse-value($_)}    }
            when /^lib\//       {
                my $lib-meta = self.meta<provides>.values.first({ $name-path eq parse-value($_) });
                self.sources-dir ~ '/' ~ $lib-meta{$_}<file>;
            }
        }
        my $handle = IO::Handle.new: path => $path.IO;
        $handle // $handle.throw;
    }

    # For meta<files> and meta<provides>
    # We want a key/value, where the key is what can be passed to .content and the value is the mangled name path
    # A name-path is just a relative path part that gets rooted against some authority/prefix
    # Meant to be extended such that if the .value is a Pair we know the .key of the pair is the value we want
    # "bin/zef"                                       [Typical pre-installation format. Translate to "bin/zef" => "bin/zef"]
    # "bin/zef" => "10923801928309d90182d"            [Typical installation format]
    # "bin/zef" => { "10923801928309d90182d" => ... } [Extended value, such as additional metadata (modified times, etc)
    #                                                  without denormalization. Take the .value.key as the .value and'
    #                                                  ignore the .value.value.] (Not actually used yet, but the same
    #                                                  thing is used for meta<provides> and IS used for storing the
    #                                                  mangled name so it can be uninstalled)
    # Or for meta<provides>:
    # "Zef" => "lib/Zef.pm6"                                                         [Typical pre-installation]
    # "Zef" => { "lib/Zef.pm6" => { "file" => "f32f9023jf0923f", modified => "..."}} [Typical post installation]
    my sub parse-value($str-or-kv) {
        do given $str-or-kv {
            when Str  { $_ }
            when Hash { $_.keys[0] }
            when Pair { $_.key     }
        }
    }
}