using Invercargill;
using Invercargill.DataStructures;

/**
 * `usm update [-y|--yes] [<packages>]` — bring installed packages up to
 * the newest version their repositories offer.
 *
 * Without package names every installed package with a newer repository
 * version becomes a resolution root; with names exactly those packages
 * do (already-current names are skipped with a note). Either way there
 * is one resolution, one {@link Usm.TransactionSummary}, one confirm —
 * and the downloads happen only once the plan is accepted.
 *
 * Dependencies already installed at the resolved version are left alone;
 * an installed package moving to a different version is removed
 * (RemoveType.UPGRADE) and the new version installed in its place. The
 * old version's state directory is kept, which is what makes `usm
 * downgrade` possible.
 */
private int update_main(string[] args) {

    var assume_yes = false;
    var package_names = new Vector<string>();
    for(int i = 2; i < args.length; i++) {
        var argument = args[i];
        if(argument == "-y" || argument == "--yes") {
            assume_yes = true;
        }
        else if(argument.has_prefix("-")) {
            printerr(@"Unknown option \"$argument\"\n");
            return update_usage();
        }
        else {
            package_names.add(argument);
        }
    }

    var progress = new Usm.Cli.ProgressBar();

    Usm.SystemState state = null;
    try {
        state = new Usm.SystemState(paths);
    }
    catch(Error e) {
        printerr(@"This system is not managed by usm: $(e.message)\n");
        return 245;
    }

    try {
        printerr("Refreshing repositories...\n");
        var resolver = new Usm.Resolver(new Usm.ResourceFinder());
        foreach(var repo in state.get_repositories()) {
            state.refresh_list(repo, (f, c, t) => printerr(@"Refreshing list for $(repo.name): downloading $f $c/$t bytes\r"));
            var listing = state.get_latest_list(repo);
            if(listing != null) {
                resolver.load_listing(repo, listing);
            }
            printerr("\n");
        }

        // Cached packages can satisfy dependencies, including the old
        // versions kept behind by earlier updates
        resolver.load_cache(paths);

        var installed_by_name = new Dictionary<string, Usm.CachedPackage>();
        var installed_versions = new Dictionary<string, Usm.Version>();
        foreach(var installed in state.get_installed_packages()) {
            var manifest = installed.get_manifest();
            Usm.Version seen;
            if(installed_versions.try_get(manifest.name, out seen) && !manifest.version.greater_than(seen)) {
                continue;
            }
            installed_by_name.set(manifest.name, state.resolve_installed(installed));
            installed_versions.set(manifest.name, manifest.version);
        }

        var roots = new Vector<Usm.AbstractPackage>();
        if(package_names.length > 0) {
            foreach(var package_name in package_names) {
                Usm.CachedPackage installed;
                if(!installed_by_name.try_get(package_name, out installed)) {
                    printerr(@"No installed package named \"$package_name\"\n");
                    return 254;
                }
                var target = resolver.find_package(package_name);
                if(target == null) {
                    printerr(@"No package named \"$package_name\" found in any repository or the cache\n");
                    return 254;
                }
                Usm.Version installed_version;
                installed_versions.try_get(package_name, out installed_version);
                if(!target.manifest.version.greater_than(installed_version)) {
                    print(@"\"$package_name\" is already up to date.\n");
                    continue;
                }
                roots.add(target);
            }
            if(roots.length == 0) {
                return 0;
            }
        }
        else {
            foreach(var pair in installed_by_name) {
                var target = resolver.find_package(pair.key);
                if(target != null && target.manifest.version.greater_than(installed_versions[pair.key])) {
                    roots.add(target);
                }
            }
            if(roots.length == 0) {
                print("All installed packages are up to date.\n");
                return 0;
            }
        }

        var spm = new Usm.SystemPackageManager(state.config);
        Usm.ResolutionResult resolution;
        try {
            resolution = resolver.resolve(roots, spm);
        }
        catch(Usm.ResolverError e) {
            printerr("%s\n".printf(e.message));
            return 240;
        }

        // Build the transaction set WITHOUT downloading: dependencies
        // already installed at the resolved version stay as-is (so an
        // update plan names only what actually moves), and repository
        // packages join as their cache directories carrying the listing
        // manifest — the plan is confirmed before a single byte moves
        var current_names = new HashSet<string>();
        foreach(var package in resolution.install_order) {
            Usm.Version installed_version;
            if(installed_versions.try_get(package.manifest.name, out installed_version)
                    && installed_version.compare(package.manifest.version) == 0) {
                current_names.add(package.manifest.name);
            }
        }

        var cached_packages = new HashSet<Usm.CachedPackage>();
        uint download_count = 0;
        int64 download_bytes = 0;
        var download_sizes_known = true;
        foreach(var package in resolution.install_order) {
            if(current_names.contains(package.manifest.name)) {
                continue;
            }
            if(package.repository == null) {
                if(package.package_path != null) {
                    cached_packages.add(new Usm.CachedPackage(Path.get_dirname((!)package.package_path)));
                }
                continue;
            }
            var path = state.generate_cache_path(package.manifest);
            cached_packages.add(new Usm.CachedPackage(path) {
                known_manifest = package.manifest
            });
            if(File.new_for_path(Path.build_filename(path, "package.usmc")).query_exists()) {
                continue;
            }
            download_count++;
            var size = install_package_download_size(package.repository, package.repository_entry);
            if(size == null) {
                download_sizes_known = false;
            }
            else {
                download_bytes += size;
            }
        }

        // The installed versions being replaced by a different version
        var to_remove = new HashSet<Usm.CachedPackage>();
        foreach(var package in resolution.install_order) {
            Usm.CachedPackage installed;
            Usm.Version installed_version;
            if(!installed_by_name.try_get(package.manifest.name, out installed)) {
                continue;
            }
            if(installed_versions.try_get(package.manifest.name, out installed_version)
                    && installed_version.compare(package.manifest.version) != 0) {
                to_remove.add(installed);
            }
        }

        var install_order = new Vector<string>();
        foreach(var package in resolution.install_order) {
            install_order.add(package.manifest.name);
        }

        // The exact reverse: dependents are removed before their providers
        var remove_order = new Vector<string>();
        foreach(var package in resolution.removal_order) {
            remove_order.add(package.manifest.name);
        }

        var transaction = new Usm.Transaction() {
            paths = paths,
            resource_finder = new Usm.ResourceFinder(paths),
            to_remove = to_remove,
            to_install = cached_packages,
            install_order = install_order,
            remove_order = remove_order,
            state = state
        };

        // Planning before the prompt populates the rebuildDependants
        // entries so the summary shows the whole transaction
        try {
            transaction.strategise();
        }
        catch(Usm.TransactionError e) {
            printerr(@"$(e.message)\n");
            return 240;
        }

        var summary = new Usm.TransactionSummary() {
            to_install = cached_packages.to_vector(),
            to_remove = to_remove.to_vector(),
            to_rebuild = transaction.rebuilds,
            download_count = download_count,
            download_bytes = download_sizes_known ? download_bytes : -1
        };
        if(!Usm.Cli.confirm_transaction(summary, assume_yes)) {
            print("Aborted.\n");
            return 1;
        }

        // Only now that the plan is confirmed do the packages transfer
        install_download_packages(state, resolution, current_names);

        if(resolution.system_packages.any()) {
            if(!install_system_packages(spm, resolution.system_packages)) {
                return 239;
            }
        }

        printerr("\nRunning transaction...\n");
        transaction.progress_updated.connect(progress.on_transaction_progress);
        transaction.run();
        progress.finish();
    }
    catch(Error e) {
        progress.fail();
        printerr(@"Error: $(e.message)\n");
        return 238;
    }

    return 0;
}

private int update_usage() {
    printerr("USAGE:\n\tusm update [-y|--yes] [<packages>]\n");
    return 255;
}