use std::{
    fs::{read_to_string, File},
    io::{BufRead, BufReader, Write},
    path::PathBuf,
};

use clap::{Parser, Subcommand};
use laby::{html, internal::Buffer, iter, li, raw, ul, Render};
use markdown::{Block, Span};

#[derive(Parser)]
struct Args {
    #[clap(short, long)]
    output: Option<String>,
    #[clap(subcommand)]
    action: ArgAction,
}

#[derive(Subcommand)]
enum ArgAction {
    RenderArticle { input: String },
    RenderIndex { root: String },
}

fn main() {
    let args = Args::parse();
    match args.action {
        ArgAction::RenderArticle { input } => {
            let md_source = read_to_string(input).unwrap();
            let mut out = Buffer::new();
            article(md_source).render(&mut out);
            write_output(&args.output, out.into_string());
        }
        ArgAction::RenderIndex { root } => {
            let mut out = Buffer::new();
            index(root).render(&mut out);
            write_output(&args.output, out.into_string());
        }
    }
}

fn write_output(t: &Option<String>, o: String) {
    if let Some(f) = t {
        let mut f = File::create(f).unwrap();
        f.write_fmt(format_args!("{o}")).unwrap()
    } else {
        println!("{o}")
    }
}

fn scaffold(title: String, body: impl Render) -> impl Render {
    html!(
        head!(title!(title)),
        body!(
            nav!(h2!("metamuffin's blog"), a!(href = "./index.html", "index")),
            article!(body)
        )
    )
}

fn index(root: String) -> impl Render {
    scaffold(
        "index".to_string(),
        ul!(iter!(std::fs::read_dir(root)
            .unwrap()
            .map(|e| e.unwrap())
            .map(|e| (
                e.file_name().to_str().unwrap().to_string(),
                article_title(e.path())
            ))
            .map(|(path, title)| li!(
                path.as_str()[0..10].to_string(),
                ": ",
                a!(href = format!("./{}", path.replace(".md", ".html")), title)
            )))),
    )
}

fn article_title(path: PathBuf) -> String {
    let f = File::open(path).unwrap();
    let mut f = BufReader::new(f);
    let mut buf = String::new();
    f.read_line(&mut buf).unwrap(); // assume the 1st line has the title
    String::from(&buf[2..])
}

fn article(md_source: String) -> impl Render {
    scaffold(
        "blub".to_string(),
        raw!(blocks_to_html(markdown::tokenize(&md_source))),
    )
}

fn span_to_html(ss: Vec<Span>) -> String {
    let mut out = String::new();
    for s in ss {
        out += match s {
            Span::Break => format!("<br/>"),
            Span::Text(t) => escape(&t),
            Span::Code(c) => format!("<pre><code>{}</code></pre>", escape(&c)),
            Span::Link(text, url, _) => {
                format!("<a href=\"{}\">{}</a>", escape(&url), escape(&text))
            }
            Span::Image(_, _, _) => todo!(),
            Span::Emphasis(c) => format!("<i>{}</i>", span_to_html(c)),
            Span::Strong(c) => format!("<b>{}</b>", span_to_html(c)),
        }
        .as_str()
    }
    out
}
fn blocks_to_html(blocks: Vec<Block>) -> String {
    let mut out = String::new();
    for e in blocks {
        out += match e {
            markdown::Block::Header(text, level) => {
                format!("<h{level}>{}</h{level}>", span_to_html(text))
            }
            markdown::Block::Paragraph(p) => span_to_html(p),
            markdown::Block::Blockquote(q) => format!("<quote>{}</quote>", blocks_to_html(q)),
            markdown::Block::CodeBlock(_syntax, content) => {
                format!("<pre><code>{}</code></pre>", escape(&content)) // TODO syntax highlighting
            }
            markdown::Block::OrderedList(_, _) => todo!(),
            markdown::Block::UnorderedList(_) => todo!(),
            markdown::Block::Raw(r) => r,
            markdown::Block::Hr => format!("<hr/>"),
        }
        .as_str();
    }
    out
}

fn escape(text: &str) -> String {
    text.replace("&", "&amp;")
        .replace("<", "&lt;")
        .replace(">", "&gt;")
        .replace("'", "&#8217;")
        .replace("\"", "&quot;")
}