use std::{
    collections::VecDeque,
    fs,
    io::{self, Write},
    path::PathBuf,
};

use log::trace;
use serde::{Deserialize, Serialize};

use crate::{
    cli::Cli,
    error,
    file::{self, Chunk},
    sharry::{Client, Uri},
};

#[derive(Serialize, Deserialize, Debug)]
pub struct CacheFile {
    #[serde(skip)]
    file_name: PathBuf,

    uri: Uri,
    alias_id: String,
    share_id: String,

    uploading: Option<file::Uploading>,
    files: VecDeque<file::Checked>,
}

impl CacheFile {
    fn cache_dir() -> PathBuf {
        let dir_name = dirs_next::cache_dir()
            .expect("could not determine cache directory")
            .join("shrupl");

        trace!("cachedir: {:?}", dir_name.display());
        dir_name
    }

    fn cache_file(args: &Cli) -> PathBuf {
        let file_name = Self::cache_dir().join(format!("{}.json", args.get_hash()));

        trace!("cachefile: {:?}", file_name.display());
        file_name
    }

    pub fn try_resume(args: &Cli) -> io::Result<Self> {
        let file_name = Self::cache_file(args);

        let state: Self = {
            let file = fs::File::open(&file_name)?;
            let reader = io::BufReader::new(file);
            serde_json::from_reader(reader).map_err(io::Error::other)?
        };

        Ok(Self { file_name, ..state })
    }

    pub fn from_args(args: &Cli, share_id: String) -> Self {
        Self {
            file_name: Self::cache_file(args),
            uri: args.get_uri(),
            alias_id: args.alias.clone(),
            share_id,
            uploading: None,
            files: args.files.clone().into(),
        }
    }

    pub fn queue_empty(&self) -> bool {
        self.files.is_empty()
    }

    pub fn get_uploading(
        &mut self,
        client: &impl Client,
    ) -> error::Result<Option<&mut file::Uploading>> {
        if self.uploading.is_some() {
            Ok(self.uploading.as_mut())
        } else if let Some(chk) = self.files.pop_front() {
            let upl = chk.start_upload(client, &self.uri, &self.alias_id, &self.share_id)?;
            self.uploading.replace(upl);

            Ok(self.uploading.as_mut())
        } else {
            Ok(None)
        }
    }

    pub fn expect_uploading(&mut self) -> &mut file::Uploading {
        self.uploading
            .as_mut()
            .expect("expect_uploading called while not uploading")
    }

    pub fn peek_uploading(&self) -> Option<&file::Uploading> {
        self.uploading.as_ref()
    }

    pub fn check_eof(&mut self) -> Option<PathBuf> {
        if let Some(upl) = self.uploading.take() {
            match upl.check_eof() {
                Ok(upl) => self.uploading = Some(upl),
                Err(p) => return Some(p),
            }
        }

        None
    }

    pub fn rewind_chunk(mut self) -> Option<Self> {
        self.uploading = Some(
            self.uploading
                .take()
                .expect("rewind_chunk called while not uploading")
                .rewind()?,
        );

        Some(self)
    }

    pub fn abort_upload(&mut self) {
        self.files.push_front(
            self.uploading
                .take()
                .expect("abort_upload called while not uploading")
                .abort(),
        );
    }

    pub fn share_notify(&self, client: &impl Client) -> error::Result<()> {
        client.share_notify(&self.uri, &self.alias_id, &self.share_id)
    }

    pub fn file_patch(&self, client: &impl Client, chunk: &Chunk) -> error::Result<()> {
        client.file_patch(&self.uri, &self.alias_id, &self.share_id, chunk)
    }

    pub fn save(&self) -> io::Result<()> {
        let cache_dir = self.file_name.parent().ok_or_else(|| {
            io::Error::other(format!("orphan file {:?}", self.file_name.display()))
        })?;
        fs::create_dir_all(cache_dir)?;

        let json = serde_json::to_string_pretty(self).map_err(io::Error::other)?;
        let mut file = fs::File::create(&self.file_name)?;
        file.write_all(json.as_bytes())?;

        trace!("updated {:?}", self.file_name.display());
        Ok(())
    }

    pub fn clear(self) -> io::Result<()> {
        fs::remove_file(&self.file_name)?;

        trace!("removed {:?}", self.file_name.display());
        Ok(())
    }
}