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

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

use super::{
    cli::Cli,
    sharry::{Alias, FileChecked, FileUploading, Share},
};

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

    alias: Alias,
    share: Share,
    files: Vec<FileState>,
}

#[derive(Serialize, Deserialize, Debug)]
enum FileState {
    C(FileChecked),
    U(FileUploading),
}

impl AppState {
    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
    }

    fn load(file_name: impl AsRef<Path>) -> io::Result<Self> {
        let content = fs::read_to_string(file_name)?;
        serde_json::from_str(&content).map_err(io::Error::other)
    }

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

        Self::load(&file_name)
            .inspect_err(|e| debug!("could not resume from {}: {e}", file_name.display()))
            .map(|state| {
                debug!("successfully loaded AppState");

                Self {
                    file_name,
                    alias: state.alias,
                    share: state.share,
                    files: state.files,
                }
            })
            .ok()
    }

    pub fn from_args(args: &Cli, agent: &ureq::Agent) -> Option<Self> {
        let file_name = Self::cache_file(args);
        let alias = args.get_alias();

        let share = Share::create(agent, &alias, args.get_share_request())
            .inspect_err(|e| error!("could not create Share: {e}"))
            .ok()?;

        let files: Vec<_> = args.files.clone().into_iter().map(FileState::C).collect();

        Some(Self {
            file_name,
            alias,
            share,
            files,
        })
    }

    pub fn save(&self) -> io::Result<()> {
        fs::create_dir_all(Self::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!("successfully saved AppState");
        Ok(())
    }

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

        trace!("successfully cleared AppState");
        Ok(())
    }
}