///usr/bin/env jbang "$0" "$@" ; exit $?
//
// This is a JBang script. You need JBang to run this script.
//
// To learn more go to https://www.jbang.dev and install JBang.
//
// Run this script:
// ./ghost2md.java -f <input file> -d <output directory>
//
//DEPS info.picocli:picocli:4.7.7
//DEPS com.jayway.jsonpath:json-path:2.8.0
//DEPS com.fasterxml.jackson.core:jackson-databind:2.19.0
//DEPS io.github.furstenheim:copy_down:1.1
//JAVA 21+

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.jayway.jsonpath.Configuration;
import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.ParseContext;
import com.jayway.jsonpath.TypeRef;
import com.jayway.jsonpath.spi.mapper.JacksonMappingProvider;

import io.github.furstenheim.CopyDown;
import picocli.CommandLine;
import picocli.CommandLine.Command;
import picocli.CommandLine.Option;
import java.io.File;
import java.io.FileWriter;
import java.util.List;
import java.util.concurrent.Callable;

@Command(name = "ghost2md", mixinStandardHelpOptions = true, version = "0.1", description = "Converts a Ghost export file to markdown files")
public class ghost2md implements Callable<Integer> {

    private static final ParseContext JSON = JsonPath.using(Configuration.builder().mappingProvider(new JacksonMappingProvider()).build());
    private static final CopyDown HTML_TO_MD = new CopyDown();

    @Option(names = { "--file", "-f" }, required = true, description = "The exported Ghost JSON file")
    private File exportFile;

    @Option(names = { "--dir", "-d" }, defaultValue = "exported", description = "The destination directory")
    private File destinationDir;

    @Override
    public Integer call() throws Exception {
        if (!exportFile.exists()) {
            System.err.printf("%s does not exist%n", exportFile.getAbsolutePath());
            return 404;
        }

        destinationDir.mkdirs();

        var json = JSON.parse(exportFile);
        var posts = json.read("$.db[*].data.posts[*]", new TypeRef<List<Post>>(){});
        for (var post : posts) {
            var filename = post.slug() + ".md";
            var markdown = HTML_TO_MD.convert(post.html());
            var file = new File(destinationDir, filename);
            var title = "# " + post.title();
            System.out.printf("Writing %s\n", file);
            try (var writer = new FileWriter(file)) {
                writer.write(title);
                writer.write("\n\n");
                writer.write(markdown);
            }
        }
        return 0;
    }

    @JsonIgnoreProperties(ignoreUnknown = true)
    record Post(String slug, String title, String html){}

    public static void main(String[] args) {
        final int exitCode = new CommandLine(new ghost2md()).execute(args);
        System.exit(exitCode);
    }

}