use std::{cell::RefCell, fmt, io, time::Duration};

use console::style;
use indicatif::{ProgressBar, ProgressStyle};
use log::{debug, warn};

use crate::{
    cachefile::CacheFile,
    cli::Cli,
    file::{Chunk, FileTrait},
    sharry::{self, Client},
};

pub struct AppState {
    progress: RefCell<Option<ProgressBar>>,
    http: ureq::Agent,
    inner: CacheFile,
}

impl fmt::Debug for AppState {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("AppState")
            .field("inner", &self.inner)
            .finish_non_exhaustive()
    }
}

fn new_http(timeout: Option<Duration>) -> ureq::Agent {
    ureq::Agent::config_builder()
        .timeout_global(timeout)
        .build()
        .into()
}

impl AppState {
    fn new(http: ureq::Agent, inner: CacheFile) -> Self {
        Self {
            progress: RefCell::new(None),
            http,
            inner,
        }
    }

    pub fn try_resume(args: &Cli) -> Option<Self> {
        let inner = CacheFile::try_resume(args)
            .inspect_err(|e| debug!("could not resume from hash {:?}: {e}", args.get_hash()))
            .ok()?;

        Some(Self::new(new_http(args.get_timeout()), inner))
    }

    pub fn from_args(args: &Cli) -> sharry::Result<Self> {
        let http = new_http(args.get_timeout());

        let share_id = http.share_create(&args.get_uri(), &args.alias, args.get_share_request())?;

        Ok(Self::new(http, CacheFile::from_args(args, share_id)))
    }

    fn with_progressbar(&self, drop_bar: bool, f: impl FnOnce(&ProgressBar)) {
        let Some(upl) = self.inner.peek_uploading() else {
            return;
        };

        let mut slot = self.progress.borrow_mut();
        if slot.is_none() {
            let bar = ProgressBar::no_length()
                .with_style(
                    ProgressStyle::with_template(&format!(
                        concat!(
                            "{{bar:50.cyan/blue}} {{msg:.magenta}}: ",
                            "{{binary_bytes:.yellow}}{}{{binary_total_bytes:.yellow}} ",
                            "({{eta}})",
                        ),
                        style("/").magenta(),
                    ))
                    .expect("style template is not valid"),
                )
                .with_message(upl.get_name().to_owned());

            bar.enable_steady_tick(Duration::from_millis(100));
            *slot = Some(bar);
        }

        let bar = slot.as_ref().expect("somehow the slot holds None");

        bar.set_position(upl.get_offset());
        // BUG in `indicatif` crate?
        // `set_position` does not force an immediate redraw, so we need to call `set_length` after
        bar.set_length(upl.get_size());

        f(bar);

        if drop_bar {
            *slot = None;
        }
    }

    fn touch_progressbar(&self) {
        self.with_progressbar(false, |_| ());
    }

    fn next_chunk<'t>(&mut self, buffer: &'t mut [u8]) -> sharry::Result<Option<Chunk<'t>>> {
        if self.inner.get_uploading(&self.http)?.is_none() {
            return Ok(None);
        }

        self.touch_progressbar();

        let uploading = self
            .inner
            .get_uploading(&self.http)?
            .expect("we just checked!");
        debug!("{uploading:?}");

        let chunk = uploading.read(buffer)?;
        debug!("{chunk:?}");

        Ok(Some(chunk))
    }

    fn is_done(&mut self) -> bool {
        if let Some(path) = self.inner.check_eof() {
            debug!("Finished {:?}!", path.display());
            self.with_progressbar(true, ProgressBar::finish);
        } else if self.inner.peek_uploading().is_some() {
            self.touch_progressbar();

            return false;
        }

        self.inner.queue_empty()
    }

    pub fn upload_chunk(&mut self, buffer: &mut [u8]) -> sharry::Result<bool> {
        let Some(chunk) = self.next_chunk(buffer)? else {
            self.inner
                .share_notify(&self.http)
                .unwrap_or_else(|e| warn!("Failed to notify the share: {e}"));

            return Ok(true);
        };

        self.inner.file_patch(&self.http, &chunk)?;

        Ok(self.is_done())
    }

    pub fn rewind_chunk(mut self) -> Option<Self> {
        self.inner = self.inner.rewind_chunk()?;

        Some(self)
    }

    pub fn abort_upload(&mut self) {
        self.inner.abort_upload();
        self.with_progressbar(true, ProgressBar::abandon);
    }

    pub fn rebuild_share(self, args: &Cli) -> sharry::Result<Self> {
        let share_id =
            self.http
                .share_create(&args.get_uri(), &args.alias, args.get_share_request())?;

        self.with_progressbar(true, ProgressBar::abandon);
        Ok(Self::new(self.http, CacheFile::from_args(args, share_id)))
    }

    pub fn save(&self) -> io::Result<()> {
        self.inner.save()
    }

    pub fn clear(self) -> io::Result<()> {
        self.inner.clear()
    }
}