use std::{
    fs::{self, File},
    io::{BufReader, BufWriter, Read, Write},
    path::{Path, PathBuf},
    sync::mpsc::channel,
    thread,
    time::Duration,
};

use anyhow::{anyhow, bail, Context, Result};
use clap::Clap;
use evtclib::{Compression, Encounter, Log};
use log::{debug, error, info, warn};
use notify::{self, DebouncedEvent, RecursiveMode, Watcher};
use regex::Regex;
use serde::Deserialize;
use zip::{CompressionMethod, ZipArchive, ZipWriter};

mod categories;
use categories::Categorizable;
mod config;
use config::Config;
#[cfg(feature = "im-discord")]
mod discord;
#[cfg(any(feature = "im-discord", feature = "im-matrix"))]
mod logbag;
#[cfg(feature = "im-matrix")]
mod matrix;

const DPS_REPORT_API: &str = "https://dps.report/uploadContent";
const WATCH_DELAY_SECONDS: u64 = 2;
const RETRY_DELAY: Duration = Duration::from_secs(5);

#[derive(Clap, Debug, Clone, PartialEq, Eq, Hash)]
#[clap(version = "0.1")]
struct Opts {
    /// The configuration file path.
    #[clap(short, long, default_value = "ezau.toml")]
    config: PathBuf,
    #[clap(subcommand)]
    subcmd: SubCommand,
}

#[derive(Clap, Debug, Clone, PartialEq, Eq, Hash)]
enum SubCommand {
    Watch(Watch),
    Upload(Upload),
}

/// Use the watch mode to automatically handle new logs.
///
/// This watches the given directory for new files and then zips and uploads them.
#[derive(Clap, Debug, Clone, PartialEq, Eq, Hash)]
struct Watch {
    /// The directory to watch.
    dirname: PathBuf,
}

/// Upload a single log, as it would be done by the automatic watcher.
#[derive(Clap, Debug, Clone, PartialEq, Eq, Hash)]
struct Upload {
    /// The log to upload.
    path: PathBuf,
}

fn main() {
    pretty_env_logger::init();

    let opts = Opts::parse();
    if let Err(e) = inner_main(&opts) {
        error!("{}", e);
        e.chain()
            .skip(1)
            .for_each(|cause| error!("... because: {}", cause));
        std::process::exit(1);
    }
}

fn inner_main(opts: &Opts) -> Result<()> {
    let config = config::load(&opts.config).context("Could not load configuration")?;
    sanity_check(&config, opts)?;

    match &opts.subcmd {
        SubCommand::Watch(w) => watch(w, &config)?,
        SubCommand::Upload(u) => {
            let permalink = upload_log(&u.path)?;
            println!("{}", permalink);

            let log = load_log(&u.path)?;
            if let Some(d) = &config.discord {
                discord::post_link(&d.auth_token, d.channel_id, &log, &permalink)
                    .context("Could not post link to Discord")?;
            }

            if let Some(m) = &config.matrix {
                matrix::post_link(m.clone().into(), &m.room_id, &log, &permalink)
                    .context("Could not post link to Matrix")?;
            }
        }
    }
    Ok(())
}

fn watch(watch: &Watch, config: &Config) -> Result<()> {
    let raw_evtc_re = Regex::new(r"\d{8}-\d{6}(\.evtc)?$").unwrap();
    let zip_evtc_re = Regex::new(r"(\.zip|\.zevtc)$").unwrap();

    let (tx, rx) = channel();
    let mut watcher = notify::watcher(tx, Duration::from_secs(WATCH_DELAY_SECONDS))?;
    watcher
        .watch(&watch.dirname, RecursiveMode::Recursive)
        .context("Could not watch the given directory")?;
    info!("Watcher set up, watching {:?}", watch.dirname);
    loop {
        let event = rx.recv()?;
        debug!("Event: {:?}", event);
        if let DebouncedEvent::Create(path) = event {
            let path_str = path.to_str().unwrap();
            // Check if we need to zip it first.
            if config.zip && raw_evtc_re.is_match(path_str) {
                info!("Zipping up {}", path_str);
                zip_file(&path)?;
            } else if zip_evtc_re.is_match(path_str) {
                handle_file(config, &path)?;
            }
        }
    }
}

fn zip_file(filepath: &Path) -> Result<()> {
    let evtc_content = fs::read(filepath)?;

    let filename = filepath
        .file_name()
        .ok_or_else(|| anyhow!("Path does not have a file name"))?
        .to_str()
        .ok_or_else(|| anyhow!("Filename is invalid utf-8"))?;
    let outname = filepath.with_extension("zevtc");
    let outfile = BufWriter::new(File::create(&outname)?);
    let mut zip = ZipWriter::new(outfile);
    let options =
        zip::write::FileOptions::default().compression_method(CompressionMethod::Deflated);

    zip.start_file(filename, options)?;
    zip.write_all(&evtc_content)?;
    zip.finish()?.flush()?;

    if !verify_zip(filepath, &outname)? {
        warn!("ZIP content mismatch, keeping original file");
        return Ok(());
    }

    fs::remove_file(filepath)?;
    Ok(())
}

fn verify_zip(original: &Path, zip_path: &Path) -> Result<bool> {
    let expected_content = fs::read(original)?;
    let mut archive = ZipArchive::new(BufReader::new(File::open(zip_path)?))?;
    let mut inner = archive.by_index(0)?;
    let mut actual_content = Vec::new();
    inner.read_to_end(&mut actual_content)?;

    Ok(expected_content == actual_content)
}

fn handle_file(config: &Config, filename: &Path) -> Result<()> {
    if !config.upload {
        return Ok(());
    }
    let log = load_log(filename)?;
    info!("Loaded log from category {}", log.category());

    if !should_upload(config, &log) {
        info!("Skipping log, not uploading");
        return Ok(());
    }

    let mut try_counter = 0;
    let permalink = loop {
        let result = upload_log(filename);
        if let Ok(link) = result {
            break link;
        }
        warn!(
            "Upload try {} failed, retrying {} more times. Reason: {}",
            try_counter + 1,
            config.retries - try_counter,
            result.as_ref().unwrap_err(),
        );
        if try_counter == config.retries {
            return Err(result.unwrap_err());
        }
        try_counter += 1;
        thread::sleep(RETRY_DELAY);
    };
    info!("Uploaded log, available at {}", permalink);

    if let Some(d) = &config.discord {
        discord::post_link(&d.auth_token, d.channel_id, &log, &permalink)
            .context("Could not post link to Discord")?;
        info!("Posted link to Discord");
    }

    if let Some(m) = &config.matrix {
        matrix::post_link(m.clone().into(), &m.room_id, &log, &permalink)
            .context("Could not post link to Matrix")?;
        info!("Posted link to Matrix");
    }

    Ok(())
}

fn should_upload(config: &Config, log: &Log) -> bool {
    // Only upload known logs
    if log.encounter().is_none() && !config.upload_unknown {
        return false;
    }
    // Only upload Skorvald if it actually was in 100 CM (and not in in lower-tier or non-CM).
    if log.encounter() == Some(Encounter::Skorvald) && !log.is_cm() {
        return false;
    }
    // Only upload logs that are long enough
    if log.span() < config.minimum_duration {
        return false;
    }
    true
}

fn load_log(path: &Path) -> Result<Log> {
    evtclib::process_file(path, Compression::Zip).map_err(Into::into)
}

fn upload_log(file: &Path) -> Result<String> {
    #[derive(Debug, Deserialize)]
    struct ApiResponse {
        permalink: String,
    }

    let client = reqwest::blocking::Client::new();

    let form = reqwest::blocking::multipart::Form::new().file("file", file)?;
    let resp: ApiResponse = client
        .post(DPS_REPORT_API)
        .query(&[("json", 1)])
        .multipart(form)
        .send()?
        .error_for_status()?
        .json()?;
    Ok(resp.permalink)
}

fn sanity_check(config: &Config, opts: &Opts) -> Result<()> {
    if matches!(opts.subcmd, SubCommand::Watch(_))
        && config.discord.is_none()
        && config.matrix.is_none()
        && config.upload
    {
        warn!(
            "You are uploading logs but not posting them anywhere. \
            Consider setting `upload = false` in your settings."
        );
    }
    if config.discord.is_some() && !cfg!(feature = "im-discord") {
        bail!(
            "Discord is configured but ezau was built without Discord support. \
            Please enable the `im-discord` feature or adjust your configuration \
            to continue."
        );
    }
    if config.matrix.is_some() && !cfg!(feature = "im-matrix") {
        bail!(
            "Matrix is configured but ezau was built without Matrix support. \
            Please enable the `im-matrix` feature or adjust your configuration \
            to continue."
        );
    }
    Ok(())
}

// Dummy modules for when the features are disabled
#[cfg(not(feature = "im-discord"))]
mod discord {
    use super::{Log, Result};
    use anyhow::bail;

    /// Stub, enable the `im-discord` feature to use this function.
    pub fn post_link(_: &str, _: u64, _: &Log, _: &str) -> Result<()> {
        bail!("Discord feature is disabled in this build!")
    }
}

#[cfg(not(feature = "im-matrix"))]
mod matrix {
    use super::{Log, Result};
    use anyhow::bail;
    pub struct MatrixUser;
    impl From<super::config::Matrix> for MatrixUser {
        fn from(_: super::config::Matrix) -> MatrixUser {
            MatrixUser
        }
    }
    /// Stub, enable the `im-matrix` feature to use this function.
    pub fn post_link(_: MatrixUser, _: &str, _: &Log, _: &str) -> Result<()> {
        bail!("Matrix feature is disabled in this build!")
    }
}