use std::{
    collections::{hash_map::Entry, HashMap},
    env,
    fs::File,
    io::{prelude::*, BufReader, Error, ErrorKind, Result},
    net::{TcpListener, TcpStream},
    path::{Path, PathBuf},
    sync::{Arc, Mutex},
};

use data_stream::{
    collections::SizeSettings, default_settings::PortableSettings, from_stream, to_stream,
    FromStream, ToStream,
};
use maud::html;
use percent_encoding::percent_decode_str;
use pukram2html::{convert, convert_extended, convert_subheader, Settings};
use threadpool::ThreadPool;

mod request;
use request::Request;

fn main() {
    let Ok(path) = env::current_dir() else {
        eprintln!("Current directory does not exist!");
        return;
    };

    let mut context = Context::default();
    let pool = ThreadPool::new(4);

    let mut args = env::args();
    args.next();
    let address = args.next().unwrap_or("127.0.0.1:8080".to_string());
    let listener = TcpListener::bind(address).expect("Invalid bind address!");
    eprintln!("Strated server!");

    for stream in listener.incoming() {
        eprintln!("New connection!");

        let Ok(stream) = stream else {
            eprintln!("Connection failed!");
            continue;
        };

        context.handle_connection(&path, stream, &pool);
    }
}

fn fail(mut stream: TcpStream) {
    let _ = write!(stream, "HTTP/1.1 404 Not Found\r\n\r\n");
    let _ = writeln!(stream, "Page not found!");
}

#[derive(Clone)]
struct Comment {
    name: Box<str>,
    text: Box<str>,
}

#[derive(Default, Clone)]
struct SiteInfo {
    comments: Vec<Comment>,
    visits: usize,
    up: usize,
    down: usize,
}

impl<S: SizeSettings> ToStream<S> for SiteInfo {
    fn to_stream<W: Write>(&self, stream: &mut W) -> Result<()> {
        S::size_to_stream(self.comments.len(), stream)?;
        for Comment { name, text } in &self.comments {
            let name_bytes = name.as_bytes();
            S::size_to_stream(name_bytes.len(), stream)?;
            stream.write_all(name_bytes)?;

            let text_bytes = text.as_bytes();
            S::size_to_stream(text_bytes.len(), stream)?;
            stream.write_all(text_bytes)?;
        }

        S::size_to_stream(self.visits, stream)?;
        S::size_to_stream(self.up, stream)?;
        S::size_to_stream(self.down, stream)?;

        Ok(())
    }
}

impl<S: SizeSettings> FromStream<S> for SiteInfo {
    fn from_stream<R: Read>(stream: &mut R) -> Result<Self> {
        let size = S::size_from_stream(stream)?;
        let comments = (0..size)
            .map(|_| {
                let name_bytes = <Vec<_> as FromStream<S>>::from_stream(stream)?;
                let name = std::str::from_utf8(&name_bytes)
                    .map_err(|e| Error::new(ErrorKind::InvalidData, e))?
                    .into();

                let text_bytes = <Vec<_> as FromStream<S>>::from_stream(stream)?;
                let text = std::str::from_utf8(&text_bytes)
                    .map_err(|e| Error::new(ErrorKind::InvalidData, e))?
                    .into();

                Ok(Comment { name, text })
            })
            .collect::<Result<Vec<_>>>()?;

        let visits = S::size_from_stream(stream)?;
        let up = S::size_from_stream(stream)?;
        let down = S::size_from_stream(stream)?;

        Ok(SiteInfo {
            comments,
            visits,
            up,
            down,
        })
    }
}

#[derive(Default)]
struct Context {
    infos: HashMap<Box<str>, Arc<Mutex<SiteInfo>>>,
}

impl Context {
    fn handle_connection(&mut self, path: &Path, mut stream: TcpStream, pool: &ThreadPool) {
        let Some(request) = Request::from(&stream) else {
            eprintln!("Invalid request!");
            return;
        };

        eprintln!();
        eprintln!("Request:");
        eprintln!("- Method: {}", request.method);
        eprintln!("- Path: {}", request.path);
        eprintln!("- Version: {}", request.version);
        eprintln!("- Headers:");
        for header in request.headers {
            eprintln!("  - {header}");
        }
        eprintln!("- Body: {}", request.body);
        eprintln!();

        let (mut relative_path, _) = request
            .path
            .split_once('?')
            .unwrap_or((&request.path, Default::default()));

        if relative_path.contains("//") {
            fail(stream);
            return;
        }

        if let Some(path) = relative_path.strip_prefix('/') {
            relative_path = path;
        }

        let mut pk_path = path.to_path_buf();
        let mut data_path = path.to_path_buf();

        let (pki_path, start_level, relative_path) = if relative_path.is_empty() {
            pk_path.push("index.pk");
            data_path.push("index.dat");

            (None, 0, String::new())
        } else {
            let mut pki_path = path.to_path_buf();

            let path = percent_decode_str(relative_path).decode_utf8_lossy();
            if path.contains('_') {
                let path = path.replace('_', " ");
                let _ = write!(stream, "HTTP/1.1 308 Permanent Redirect\r\n");
                let _ = write!(stream, "Location: /{path}\r\n\r\n");
                return;
            }

            pk_path.push(format!("{path}.pk"));
            pki_path.push(format!("{path}.pki"));
            data_path.push(format!("{path}.dat"));

            (Some(pki_path), 1, path.to_string())
        };

        if relative_path.split('/').any(|name| name == "Images") {
            let path = path.to_path_buf();
            pool.execute(move || reply_image(stream, &relative_path, path));
            return;
        }

        if !Path::is_file(&pk_path) {
            fail(stream);
            return;
        }

        if let Some(pki_path) = &pki_path {
            if !Path::is_file(pki_path) {
                fail(stream);
                return;
            }
        }

        use Entry::*;
        let info = match self.infos.entry(relative_path.clone().into_boxed_str()) {
            Occupied(o) => o.get().clone(),
            Vacant(v) => v
                .insert(Arc::new(Mutex::new(
                    File::open(&data_path)
                        .map(|mut file| {
                            from_stream::<PortableSettings, _, _>(&mut file).unwrap_or_default()
                        })
                        .unwrap_or_default(),
                )))
                .clone(),
        };

        let path = path.to_path_buf();
        pool.execute(move || {
            handle_relative_connection(
                info,
                stream,
                &request.body,
                &relative_path,
                &path,
                &pk_path,
                pki_path.as_ref().map(|path| path.as_ref()),
                &data_path,
                start_level,
            )
        });
    }
}

fn reply_image(mut stream: TcpStream, relative_path: &str, mut path: PathBuf) {
    let Some((_, ending)) = relative_path.rsplit_once('.') else {
        fail(stream);
        return;
    };

    let ending = ending.to_lowercase();

    let image_type = match ending.as_ref() {
        "jpg" => "jpeg",
        "png" | "tiff" | "gif" | "jpeg" => &ending,
        _ => {
            fail(stream);
            return;
        }
    };

    path.push(relative_path);
    let Ok(mut file) = File::open(path) else {
        fail(stream);
        return;
    };

    let _ = write!(stream, "HTTP/1.1 200 OK\r\n");
    let _ = write!(stream, "Content-Type: image/{image_type}\r\n");
    let _ = write!(stream, "\r\n");

    let mut buf = [0; 0x400];

    while let Ok(len) = file.read(&mut buf) {
        if len == 0 {
            break;
        }
        let _ = stream.write_all(&buf[0..len]);
    }
}

fn handle_relative_connection(
    info: Arc<Mutex<SiteInfo>>,
    mut stream: TcpStream,
    body: &str,
    relative_path: &str,
    path: &Path,
    pk_path: &Path,
    pki_path: Option<&Path>,
    data_path: &Path,
    start_level: usize,
) {
    let mut name = None;
    let mut text = None;

    let mut up = false;
    let mut down = false;

    for entry in body.split('&') {
        let Some((key, input)) = entry.split_once('=') else {
            continue;
        };

        match key {
            "name" => {
                let name_value = input.replace('+', " ");
                let decoded_name = percent_decode_str(&name_value).decode_utf8_lossy();
                eprintln!("Received comment by \"{decoded_name}\":");
                name = Some(
                    decoded_name
                        .replace('&', "&amp;")
                        .replace('<', "&lt;")
                        .replace('>', "&gt;")
                        .into(),
                );
            }
            "text" => {
                let text_value = input.replace('+', " ");
                let decoded_text = percent_decode_str(&text_value).decode_utf8_lossy();
                for line in decoded_text.lines() {
                    eprintln!("  {line}");
                }
                eprintln!();
                let mut text_buf = Vec::new();
                convert(decoded_text.lines(), &mut text_buf);
                text = Some(
                    std::str::from_utf8(text_buf.as_slice())
                        .unwrap_or_default()
                        .into(),
                );
            }
            "up" => up = true,
            "down" => down = true,
            _ => (),
        }
    }

    let info = if let Ok(mut info) = info.lock() {
        if let (Some(name), Some(text)) = (name, text) {
            info.comments.push(Comment { name, text });
        }
        if up {
            info.up += 1;
        }
        if down {
            info.down += 1;
        }

        info.visits += 1;

        info.clone()
    } else {
        return;
    };

    if let Ok(mut file) = File::create(data_path) {
        if to_stream::<PortableSettings, _, _>(&info, &mut file).is_err() {
            eprintln!("Error saving data!");
            eprintln!();
        }
    }

    let _ = write!(stream, "HTTP/1.1 200 OK\r\n");
    let _ = write!(stream, "Content-Type: text/html; charset=\"utf-8\"\r\n");
    let _ = write!(stream, "\r\n");

    let _ = writeln!(
        stream,
        "<p>👁️{} 💖️{} 💔️{}</p>",
        info.visits, info.up, info.down
    );

    let title = relative_path
        .rsplit_once('/')
        .map(|(_, title)| title)
        .unwrap_or(relative_path);
    if !title.is_empty() {
        let _ = writeln!(stream, "<h1>{title}</h1>");
    }

    let handle_entry = |mut entry: &str, output: &mut TcpStream, level: usize| {
        let level = level + 1;
        let mut path = path.to_path_buf();
        if let Some((real_entry, _)) = entry.split_once(':') {
            entry = real_entry
        }
        path.push(if relative_path.is_empty() {
            format!("{entry}.pki")
        } else {
            format!("{relative_path}/{entry}.pki")
        });

        let Ok(file) = File::open(path) else {
                return;
            };
        let _ = writeln!(
            output,
            "<h{level}><a href=\"{relative_path}/{entry}\">{entry}</a></h{level}>"
        );
        convert_subheader(
            BufReader::new(file)
                .lines()
                .map(|line| line.unwrap_or_default()),
            output,
            level,
        );
    };

    if let Ok(pk_file) = File::open(pk_path) {
        convert_extended(
            BufReader::new(pk_file)
                .lines()
                .map(|line| line.unwrap_or_default()),
            &mut stream,
            Settings::default()
                .with_handler(handle_entry)
                .with_start_level(start_level)
                .with_use_textboxes(true),
        );
    } else {
        unreachable!();
    }

    let parent_path = relative_path
        .rsplit_once('/')
        .map(|(path, _)| path)
        .unwrap_or_default();

    let _ = writeln!(stream, "<hr>");
    let _ = writeln!(stream, "<a href=\"/{parent_path}\">&lt;&lt; Back</a>");

    if let Some(pki_path) = pki_path {
        if let Ok(pki_file) = File::open(pki_path) {
            let _ = writeln!(stream, "<h1>Description</h1>");

            convert_subheader(
                BufReader::new(pki_file)
                    .lines()
                    .map(|line| line.unwrap_or_default()),
                &mut stream,
                1,
            );

            let _ = writeln!(stream, "<hr>");
            let _ = writeln!(stream, "<a href=\"/{parent_path}\">&lt;&lt; Back</a>");
        } else {
            unreachable!();
        }
    }

    let html = html! {
        h1 { "Comments" }
        form method="POST" {
            input type="text" name="name" value="anon" placeholder="Name";
            br;
            textarea rows="5" cols="60" name="text" placeholder="Enter comment..." {}
            br;
            input type="submit" value="Send!";
        }
        form method="POST" {
            input type="submit" value="💖️" name="up";
            input type="submit" value="💔️" name="down";
        }
    };
    let _ = stream.write_all(html.into_string().as_bytes());

    for Comment { name, text } in &info.comments {
        let _ = writeln!(stream, "<fieldset><legend>{name}</legend>{text}</fieldset>");
    }

    let _ = writeln!(stream, "<hr>");
    let _ = writeln!(stream, "<a href=\"/{parent_path}\">&lt;&lt; Back</a>");
}