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

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

use super::{
    cachefile::CacheFile,
    cli::Cli,
    file::{self, FileTrait},
    sharry::{self, Client, ClientError},
};

pub struct AppState {
    progress: RefCell<Option<ProgressBar>>,
    buffer: Vec<u8>,

    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(chunk_size: usize, http: ureq::Agent, inner: CacheFile) -> Self {
        Self {
            progress: None.into(),
            buffer: vec![0; chunk_size * 1024 * 1024],
            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(
            args.chunk_size,
            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().endpoint("alias/upload/new"),
            &args.alias,
            args.get_share_request(),
        )?;

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

    fn get_or_create_progressbar(&self, uploading: &file::Uploading) -> Ref<'_, ProgressBar> {
        let mut slot = self.progress.borrow_mut();
        if slot.is_none() {
            let bar = ProgressBar::new(uploading.get_size())
                .with_style(
                    ProgressStyle::with_template(&format!(
                        concat!(
                            "{{msg:.yellow}}: {{bar:50.cyan/blue}} ",
                            "{{binary_bytes:.magenta}}{}{{binary_total_bytes:.magenta}} ",
                            "({{eta}})",
                        ),
                        style("/").magenta(),
                    ))
                    .expect("style template is not valid"),
                )
                .with_position(uploading.get_offset())
                .with_message(uploading.get_name().to_owned());

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

        Ref::map(self.progress.borrow(), |opt| {
            opt.as_ref().expect("somehow the slot holds None")
        })
    }

    fn finish_progressbar(&self) {
        let mut slot = self.progress.borrow_mut();
        if let Some(bar) = slot.as_ref() {
            bar.finish();
            *slot = None;
        }
    }

    pub fn upload_chunk(&mut self) -> sharry::Result<bool> {
        let Some(mut uploading) = self.inner.pop_file(&self.http) else {
            self.inner
                .share_notify(&self.http)
                .unwrap_or_else(|e| warn!("Failed to notify the share: {e}"));

            return Ok(true);
        };

        debug!("{uploading:?}");

        self.get_or_create_progressbar(&uploading);

        let chunk = uploading
            .read(&mut self.buffer)
            .map_err(ClientError::from)?;

        debug!("{chunk:?}");

        self.http.file_patch(
            chunk.get_patch_uri(),
            self.inner.alias_id(),
            chunk.get_offset(),
            chunk.get_data(),
        )?;

        match uploading.check_eof() {
            Ok(uploading) => {
                let bar = self.get_or_create_progressbar(&uploading);
                bar.set_position(uploading.get_offset());
                // BUG in `indicatif` crate?
                // `set_position` does not force immediate redraw, so we also call `inc_length` here
                bar.inc_length(0);
                drop(bar);

                self.inner.push_file(uploading);
                Ok(false)
            }
            Err(path) => {
                debug!("Finished {:?}!", path.display());
                self.finish_progressbar();

                Ok(self.inner.is_empty())
            }
        }
    }

    pub fn file_names(&self) -> Vec<&str> {
        self.inner.file_names()
    }

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

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