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

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

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

#[derive(Serialize, Deserialize, Debug)]
enum FileState {
    C(file::Checked),
    U(file::Uploading),
}

impl FileState {
    fn start_upload(
        self,
        client: &impl sharry::Client,
        uri: &sharry::Uri,
        alias_id: &str,
        share_id: &str,
    ) -> sharry::Result<file::Uploading> {
        match self {
            FileState::C(checked) => checked.start_upload(client, uri, alias_id, share_id),
            FileState::U(uploading) => Ok(uploading),
        }
    }
}

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

    uri: Uri,
    alias_id: String,
    share_id: String,
    files: VecDeque<FileState>,
}

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,
            files: args.files.clone().into_iter().map(FileState::C).collect(),
        }
    }

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

    pub fn pop_file(&mut self, client: &impl Client) -> Option<file::Uploading> {
        if let Some(state) = self.files.pop_front() {
            // HACK unwrap
            // TODO somehow retry
            Some(
                state
                    .start_upload(client, &self.uri, &self.alias_id, &self.share_id)
                    .unwrap(),
            )
        } else {
            None
        }
    }

    pub fn push_file(&mut self, file: file::Uploading) {
        self.files.push_front(FileState::U(file));
    }

    pub fn requeue_file(&mut self, file: file::Checked) {
        self.files.push_back(FileState::C(file));
    }

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

    pub fn file_patch(&self, client: &impl Client, chunk: &Chunk) -> sharry::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(())
    }
}