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.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 BlogBuilder {
    private final Git git;
    private final Path workingDirectory;

    private Site site;
    private TemplateRenderer template;

    private Path templateDirectory;
    private Path outputDirectory;
    private boolean renderDrafts = false;

    public BlogBuilder(Git git) {
        this.git = git;

        this.workingDirectory = git.getRepository().getDirectory().toPath().getParent();
        this.templateDirectory = workingDirectory.resolve("template");
        this.outputDirectory =  workingDirectory.resolve("generated_out");
    }

    public static BlogBuilder fromPath(Path workingDirectory) throws IOException {
        var repository = new RepositoryBuilder()
                .setGitDir(workingDirectory.resolve(".git").toFile())
                .build();
        var git = new Git(repository);

        //

        return new BlogBuilder(git);
    }

    public BlogBuilder templateDirectory(Path templateDirectory) {
        this.templateDirectory = templateDirectory;
        return this;
    }

    public BlogBuilder outputDirectory(Path outputDirectory) {
        this.outputDirectory = outputDirectory;
        return this;
    }

    public BlogBuilder renderDrafts(boolean renderDrafts) {
        this.renderDrafts = renderDrafts;
        return this;
    }

    public void mkdirs(boolean force) throws IOException {
        if (outputDirectory.toFile().exists()) {
            if (force) {
                PathUtils.deleteDirectory(outputDirectory);
            } else {
                throw new FileAlreadyExistsException(outputDirectory.toString(), null, "Output directory already exists. --force?");
            }
        }

        Files.createDirectory(outputDirectory);
    }

    public void build() throws IOException {
        if (site == null)
            this.site = Site.fromConfig(workingDirectory.resolve("site-config.json"));

        if (template == null)
            this.template = new TemplateRenderer(templateDirectory);

        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);

                if (post.draft() && !renderDrafts) {
                    System.out.println("Post " + path.getFileName() + ": draft, ignoring");
                    continue;
                }

                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));
    }


    /* Internal functions */

    private 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 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");
        }
    }
}