package eu.m724.blog;

import eu.m724.blog.data.Feed;
import eu.m724.blog.data.Post;
import eu.m724.blog.data.Site;
import org.apache.commons.cli.*;
import org.apache.commons.io.file.PathUtils;
import org.eclipse.jgit.api.Git;
import org.eclipse.jgit.lib.RepositoryBuilder;

import java.io.IOException;
import java.nio.file.FileAlreadyExistsException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) throws IOException {
        System.out.println("Hello world!");

        var options = new Options()
                .addOption("h", "help", false, "Show help")
                .addOption("f", "force", false, "Overwrite current build")
                .addOption("dir", "working-dir", true, "Working directory. Default: current directory")
                .addOption("t", "template-dir", true, "Template directory. Default: working directory/template")
                .addOption("o", "output-dir", true, "Output directory. Default: working directory/generated_out")
                .addOption("s", "server", false, "Run webserver. Default: no");

        CommandLine commandLine;
        try {
            commandLine = new DefaultParser().parse(options, args);
            if (commandLine.hasOption("help"))
                throw new ParseException("Showing help");
        } catch (ParseException e) {
            System.out.println(e.getMessage());
            new HelpFormatter().printHelp("blog-software-java", options);

            System.exit(1);
            return;
        }


        var workingDirectory = Path.of(commandLine.getOptionValue("working-dir", "."));
        var templateDirectory = Path.of(commandLine.getOptionValue("output-dir", workingDirectory.resolve("template").toString()));
        var outputDirectory = Path.of(commandLine.getOptionValue("output-dir", workingDirectory.resolve("generated_out").toString()));
        var force = commandLine.hasOption("force");

        var server = commandLine.hasOption("server");
        var openBrowser = true;

        //

        var start = System.nanoTime();

        var repository = new RepositoryBuilder()
                .setGitDir(workingDirectory.resolve(".git").toFile())
                .build();
        var git = new Git(repository);

        //

        if (outputDirectory.toFile().exists()) {
            if (force) {
                PathUtils.deleteDirectory(outputDirectory);
            } else {
                throw new FileAlreadyExistsException(outputDirectory.toString(), null, "Output directory already exists");
            }
        }

        var site = Site.fromConfig(git);
        var template = new TemplateRenderer(templateDirectory);

        Files.createDirectory(outputDirectory);

        copyIfExists(workingDirectory.resolve("assets"), outputDirectory.resolve("assets"));
        copyIfExists(templateDirectory.resolve("static"), outputDirectory.resolve("static"));

        Files.createDirectory(outputDirectory.resolve("post"));
        var postDirectory = workingDirectory.resolve("posts");
        var posts = new ArrayList<Post>();

        try (var stream = Files.walk(postDirectory)) {
            for (var path : stream.collect(Collectors.toSet())) {
                if (!Files.isRegularFile(path))
                    continue; // directory is created below

                if (!path.toString().endsWith(".html")) {
                    System.out.println("Post " + path.getFileName() + ": unsupported file type");
                    continue;
                }

                path = postDirectory.relativize(path);
                var post = Post.fromFile(git, path);

                var render = template.renderPost(site, post);
                var outFile = outputDirectory.resolve("post").resolve(path);

                try {
                    Files.createDirectory(outFile.getParent());
                } catch (FileAlreadyExistsException ignored) { }

                Files.writeString(outFile, render);
                posts.add(post);
            }
        }

        posts.sort(Comparator.comparing(Post::createdAt).reversed());
        Files.writeString(outputDirectory.resolve("index.html"), template.renderIndex(site, posts));

        Files.writeString(outputDirectory.resolve("posts.rss"), Feed.generateRss(site, posts));


        var end = System.nanoTime();
        System.out.printf("Exported to %s (%.2f ms)\n", outputDirectory, (end - start) / 1000000.0);

        if (server) {
            var listenAddress = new Server(outputDirectory).start();
            if (openBrowser) {
                try {
                    var process = Runtime.getRuntime().exec(new String[] { "xdg-open", "http://" + listenAddress.getHostString() + ":" + listenAddress.getPort() });
                    var code = process.waitFor();
                    if (code != 0) {
                        throw new Exception("Exit code " + code);
                    }
                    System.out.println("Opened browser");
                } catch (Exception e) {
                    System.out.println("Failed to open browser: " + e);
                }
            }
        }
    }

    private static boolean copyTree(Path srcDir, Path destDir) throws IOException {
        if (!Files.isDirectory(srcDir)) {
            return false;
        }

        try (var walk = Files.walk(srcDir)) {
            for (var src : walk.collect(Collectors.toSet())) {
                var rel = srcDir.relativize(src);
                var dest = destDir.resolve(rel);

                if (Files.isRegularFile(src)) {
                    var parent = dest.getParent();

                    if (!Files.isDirectory(parent)) {
                        Files.createDirectories(parent);
                    }

                    Files.copy(src, dest);
                }
            }
        }

        return true;
    }


    private static void copyIfExists(Path srcDir, Path destDir) throws IOException {
        System.out.print(srcDir);

        if (copyTree(srcDir, destDir)) {
            System.out.println(" copied");
        } else {
            System.out.println(" doesn't exist, not copying");
        }
    }
}