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},
    thread,
    time::Duration,
};

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 args = env::args();
    args.next();
    let address = args.next().unwrap_or_else(|| "127.0.0.1:8080".to_string());
    let password = args.next();
    let partial_password = args.next();
    start_server(path, &address, password, partial_password);
}

fn start_server(
    path: PathBuf,
    address: &str,
    password: Option<String>,
    partial_password: Option<String>,
) {
    let listener = TcpListener::bind(address).expect("Invalid bind address!");
    eprintln!("Strated server!");

    let context: Arc<Mutex<Context>> = Arc::default();
    let mut pool = ThreadPool::new(4);

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

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

        if pool.active_count() == pool.max_count() {
            thread::sleep(Duration::from_secs(1));
            if pool.active_count() == pool.max_count() {
                pool = ThreadPool::new(pool.max_count())
            }
        }

        let context = context.clone();
        let path = path.clone();
        let password = password.clone();
        let hidden_password = partial_password.clone();
        pool.execute(move || {
            handle_connection(
                context,
                path,
                stream,
                password.as_deref(),
                hidden_password.as_deref(),
            )
        });
    }
}

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>>>,
}

fn handle_connection(
    context: Arc<Mutex<Context>>,
    path: PathBuf,
    mut stream: TcpStream,
    password: Option<&str>,
    partial_password: Option<&str>,
) {
    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!();

    #[derive(PartialEq, Eq)]
    enum Access {
        None,
        Partial,
        Full,
    }

    let mut access = Access::None;

    let mut cookie = None;

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

            if key == "password" {
                if input == password {
                    access = Access::Full;
                    cookie = Some(password);
                } else if Some(input) == partial_password {
                    access = Access::Partial;
                    cookie = partial_password;
                }
                break;
            }
        }

        if access == Access::None {
            for header in request.headers {
                let Some((key, values)) = header.split_once(':') else {
                    continue;
                };
                let key = key.trim();

                if key.to_lowercase() != "cookie" {
                    continue;
                }

                for cookie in values.split(',') {
                    let cookie = cookie.trim();
                    let Some((name, state)) = cookie.split_once('=') else {
                        continue;
                    };
                    if name != "password" {
                        continue;
                    }

                    if state == password {
                        access = Access::Full;
                        break;
                    } else if Some(state) == partial_password {
                        access = Access::Partial;
                        break;
                    }
                }
            }
        }

        if access == Access::None {
            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 html = html! {
                h1 { "Authentification required" }
                form method="POST" {
                    input type="password" name="password" placeholder="Password";
                    br;
                    input type="submit" value="Authenticate!";
                }
            };

            let _ = stream.write_all(html.into_string().as_bytes());

            return;
        }
    } else {
        access = Access::Full;
    }

    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, audio_path, start_level, relative_path, partial) = if relative_path.is_empty() {
        if access == Access::Full {
            pk_path.push("index.pk");
            data_path.push("index.dat");
        } else {
            pk_path.push("partial.pk");
            data_path.push("partial.dat");
        }

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

        let (path, num) = if let Some((path, num)) = path.rsplit_once('=') {
            (path, num.parse::<usize>().ok())
        } else {
            (path.as_ref(), None)
        };

        pk_path.push(format!("{path}.pk"));
        if access == Access::Full {
            pki_path.push(format!("{path}.pki"));
        } else {
            pki_path.push(format!("{path}.pkc"));
        }
        audio_path.push(format!("{path}.mp3"));
        data_path.push(format!("{path}.dat"));

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

    let file_paths = DocumentPaths {
        pk: &pk_path,
        pki: pki_path.as_ref().map(|path| path.as_ref()),
        audio: audio_path.as_ref().map(|path| path.as_ref()),
        data: &data_path,
    };

    if let Some((_, ending)) = relative_path.rsplit_once('.') {
        let path = path.to_path_buf();
        let ending = ending.to_lowercase();
        match ending.as_ref() {
            "jpg" => reply_binary(stream, &relative_path, "image", "jpeg", path),
            "png" | "tiff" | "gif" | "jpeg" => {
                reply_binary(stream, &relative_path, "image", &ending, path)
            }
            "mp3" | "wav" => reply_binary(stream, &relative_path, "audio", &ending, path),
            _ => fail(stream),
        };
        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;
        }
    }

    let info = if let Ok(mut context) = context.lock() {
        use Entry::*;
        match context.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(),
        }
    } else {
        return;
    };

    let path = path.to_path_buf();

    handle_relative_connection(
        info,
        stream,
        &request.body,
        &relative_path,
        &path,
        file_paths,
        partial,
        start_level,
        cookie,
        access != Access::Full,
    )
}

fn reply_binary(
    mut stream: TcpStream,
    relative_path: &str,
    data_type: &str,
    file_type: &str,
    mut path: PathBuf,
) {
    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: {data_type}/{file_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]);
    }
}

#[derive(Copy, Clone)]
struct DocumentPaths<'a> {
    pk: &'a Path,
    pki: Option<&'a Path>,
    audio: Option<&'a Path>,
    data: &'a Path,
}

fn handle_relative_connection(
    info: Arc<Mutex<SiteInfo>>,
    mut stream: TcpStream,
    body: &str,
    relative_path: &str,
    path: &Path,
    file_paths: DocumentPaths,
    partial: Option<usize>,
    start_level: usize,
    cookie: Option<&str>,
    censored: bool,
) {
    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(file_paths.data) {
        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");
    if let Some(password) = cookie {
        let _ = write!(stream, "Set-Cookie: password={password}\r\n");
    }

    let _ = write!(stream, "\r\n");

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

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

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

    section(&mut stream);

    let title = relative_path
        .rsplit_once('/')
        .map(|(_, title)| title)
        .unwrap_or(relative_path);

    let handle_entry = |mut entry: &str, output: &mut TcpStream, level: usize| {
        let level = level + 1;
        let mut pki_path = path.to_path_buf();
        let mut audio_path = path.to_path_buf();
        if let Some((real_entry, _)) = entry.split_once(':') {
            entry = real_entry
        }
        let pki_extension = if censored { "pkc" } else { "pki" };
        if relative_path.is_empty() {
            pki_path.push(format!("{entry}.{pki_extension}"));
            audio_path.push(format!("{entry}.mp3"));
        } else {
            pki_path.push(format!("{relative_path}/{entry}.{pki_extension}"));
            audio_path.push(format!("{relative_path}/{entry}.mp3"));
        };

        let Ok(file) = File::open(pki_path) else {
            return;
        };

        let _ = writeln!(
            output,
            "<h{level}><a href=\"{relative_path}/{entry}\">{entry}</a></h{level}>"
        );

        if Path::is_file(&audio_path) {
            let _ = writeln!(
                output,
                "<p><audio controls src=\"/{relative_path}/{entry}.mp3\"/></p>"
            );
        }

        convert_subheader(
            BufReader::new(file)
                .lines()
                .map(|line| line.unwrap_or_default()),
            output,
            level,
        );
    };

    if let Ok(pk_file) = File::open(file_paths.pk) {
        let lines = BufReader::new(pk_file).lines();

        if let Some(i) = partial {
            let mut last_empty = true;
            let mut block = 0;
            let lines: Vec<_> = lines.map(|line| line.unwrap_or_default()).collect();
            let mut lines = lines.into_iter();
            if i > 0 {
                for line in lines.by_ref() {
                    let empty = line.trim().is_empty();
                    if empty == last_empty {
                        continue;
                    }
                    if empty {
                        block += 1;
                        if block == i {
                            break;
                        }
                    }
                    last_empty = empty;
                }
            }

            for line in lines.clone() {
                let empty = line.trim().is_empty();
                if empty == last_empty {
                    continue;
                }
                if empty {
                    block += 1;
                }
                last_empty = empty;
            }

            let _ = writeln!(stream, "<h1>{title} ({}/{})</h1>", i + 1, block);

            let _ = writeln!(
                stream,
                "<a href=\"/{relative_path}\">&lt; Stop &gt;</a><br><br>"
            );
            if i > 0 {
                let prev = i - 1;
                let _ = writeln!(stream, "<a href=\"/{relative_path}={prev}\">&lt; Prev</a>");
            } else {
                let _ = writeln!(stream, "<font color=\"gray\">&lt; Prev</font>");
            }

            if i + 1 < block {
                let next = i + 1;
                let _ = writeln!(stream, "<a href=\"/{relative_path}={next}\">Next &gt;</a>");
            } else {
                let _ = writeln!(stream, "<font color=\"gray\">Next &gt;</font>");
            }

            let _ = writeln!(stream, "<br>");

            let mut has_text = false;
            convert_extended(
                lines.take_while(|line| {
                    let empty = line.trim().is_empty();
                    if !empty {
                        has_text = true;
                    }
                    !empty || !has_text
                }),
                &mut stream,
                Settings::default()
                    .with_handler(handle_entry)
                    .with_start_level(start_level)
                    .with_use_textboxes(true),
            );
        } else {
            if !title.is_empty() {
                let _ = writeln!(stream, "<h1>{title}</h1>");
            }
            let _ = writeln!(stream, "<a href=\"/{relative_path}=0\">&lt; Play &gt;</a>");
            convert_extended(
                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!();
    }

    section(&mut stream);

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

            if let Some(audio_path) = &file_paths.audio {
                if Path::is_file(audio_path) {
                    let _ = writeln!(
                        stream,
                        "<p><audio controls src=\"/{relative_path}.mp3\"/></p>"
                    );
                }
            }

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

            section(&mut stream);
        } 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>");
    }

    section(&mut stream);
}