use std::fs::File;
use std::io::Read;
use std::net::SocketAddr;
use std::path::{Path, PathBuf};
use std::{env, fs};

use actix_files::NamedFile;
use actix_web::error::ErrorInternalServerError;
use actix_web::{error, get, http, middleware, web, App, Error, HttpResponse, HttpServer};
use chrono::{DateTime, Local};
use clap::{App as ClapApp, Arg};
use log::info;
use percent_encoding::utf8_percent_encode;
use pulldown_cmark::{html, Options, Parser};
use regex::{Captures, Regex};
use tera::{Context, Tera};

#[derive(Clone)]
struct State {
    garden_dir: PathBuf,
    index_file: Option<String>,
    title: Option<String>,
    tera: Tera,
}

const VERSION: &str = env!("CARGO_PKG_VERSION");

fn main() -> anyhow::Result<()> {
    let env = env_logger::Env::default().filter_or(env_logger::DEFAULT_FILTER_ENV, "info");
    env_logger::init_from_env(env);

    let app = ClapApp::new("gardenserver")
        .version(VERSION)
        .author("Tomáš Mládek <t@mldk.cz>")
        .arg(Arg::with_name("DIRECTORY").required(true).index(1))
        .arg(
            Arg::with_name("BIND")
                .long("bind")
                .default_value("127.0.0.1:8642")
                .help("address and port to bind the Web interface on")
                .required(true),
        )
        .arg(
            Arg::with_name("INDEX_FILE")
                .takes_value(true)
                .short("i")
                .long("index")
                .help("File to be served at the root."),
        )
        .arg(
            Arg::with_name("TITLE")
                .takes_value(true)
                .short("t")
                .long("title")
                .help("Title of this digital garden."),
        );

    let matches = app.get_matches();

    let directory = Path::new(matches.value_of("DIRECTORY").unwrap());

    info!(
        "Starting GardenServer {} of {}...",
        VERSION,
        directory.display()
    );

    let tera = Tera::new("templates/**/*.html")?;

    let sys = actix::System::new("gardenserver");

    let bind: SocketAddr = matches
        .value_of("BIND")
        .unwrap()
        .parse()
        .expect("Incorrect bind format.");
    info!("Starting server at: {}", &bind);

    let state = State {
        garden_dir: directory.to_path_buf(),
        index_file: matches.value_of("INDEX_FILE").map(|s| s.to_string()),
        title: matches.value_of("TITLE").map(|s| s.to_string()),
        tera,
    };

    // Start HTTP server
    HttpServer::new(move || {
        App::new()
            .wrap(middleware::Logger::default())
            .data(state.clone())
            .service(render)
    })
    .bind(&bind)?
    .run();

    Ok(sys.run()?)
}

#[get("{path:.*}")]
async fn render(
    request: web::HttpRequest,
    state: web::Data<State>,
    path: web::Path<String>,
) -> Result<HttpResponse, Error> {
    let mut files: Vec<PathBuf> = fs::read_dir(&state.garden_dir)?
        .filter_map(|entry| {
            if let Ok(entry) = entry {
                let path = entry.path();
                if path.is_file() {
                    return Some(path.strip_prefix(&state.garden_dir).unwrap().to_path_buf());
                }
            }
            None
        })
        .collect();
    files.sort();

    if files.is_empty() {
        return Err(error::ErrorNotFound("Garden is empty."));
    }

    if path.is_empty() {
        let location = match state.index_file.as_ref() {
            Some(index_file) => index_file.clone(),
            None => files.get(0).unwrap().display().to_string(),
        };

        return Ok(HttpResponse::Found()
            .header(http::header::LOCATION, location.as_str())
            .finish());
    }

    let full_path = state.garden_dir.join(path.as_str());
    match (full_path.exists(), full_path.extension()) {
        (false, None) => {
            return Ok(HttpResponse::Found()
                .header(http::header::LOCATION, format!("{}.md", path.to_string()))
                .finish());
        }
        (false, Some(_)) => return Err(error::ErrorNotFound("File not found.")),
        _ => {}
    }

    if !path.ends_with(".md") {
        Ok(NamedFile::open(full_path)?.into_response(&request)?)
    } else {
        let mut file = File::open(full_path.clone())?;
        let mut file_string = String::new();
        file.read_to_string(&mut file_string)?;
        let markdown_source = preprocess(file_string);
        let parser = Parser::new_ext(markdown_source.as_str(), Options::all());
        let mut html_output = String::new();
        html::push_html(&mut html_output, parser);

        // TODO!
        let h1_regex = Regex::new(r"<h1>([^>]+)</h1>").unwrap();
        let page_title = match h1_regex.captures(&html_output) {
            Some(h1_match) => h1_match.get(1).unwrap().as_str(),
            _ => full_path
                .components()
                .last()
                .unwrap()
                .as_os_str()
                .to_str()
                .unwrap_or("???"),
        };

        let mtime: Option<DateTime<Local>> = match file.metadata() {
            Ok(metadata) => metadata.modified().ok().map(|mtime| mtime.into()),
            _ => None,
        };

        let mut context = Context::new();
        context.insert(
            "garden_title",
            state
                .title
                .as_ref()
                .unwrap_or(&"Digital Garden".to_string()),
        );
        context.insert("page_title", page_title);
        context.insert("files", &files);
        context.insert("content", &html_output);
        context.insert(
            "mtime",
            &mtime.map_or("???".to_string(), |t| t.format("%c").to_string()),
        );

        Ok(HttpResponse::Ok().body(
            state
                .tera
                .render("main.html", &context)
                .map_err(ErrorInternalServerError)?,
        ))
    }
}

fn preprocess(string: String) -> String {
    let double_brackets = Regex::new(r"\[\[(?P<inner>[\w .]+)\]\]").unwrap();

    double_brackets
        .replace_all(string.as_str(), |caps: &Captures| {
            format!(
                "[{}]({})",
                &caps[1],
                utf8_percent_encode(&caps[1], percent_encoding::NON_ALPHANUMERIC)
            )
        })
        .to_string()
}