use std::{
    fs::{create_dir_all, File},
    io::{Read, Write},
    path::PathBuf,
    time::{SystemTime, UNIX_EPOCH},
};

use serde::{Deserialize, Serialize};
use tracing::info;
use uuid::Uuid;

use crate::{
    config::Config,
    error::{Error, Result},
    packages::Package,
    pathinfo::PathInfo,
};

pub type Id = String;

#[derive(Debug, Serialize, Deserialize)]
pub struct Backup {
    pub id: String,
    pub timestamp: u64,
    packages: Vec<Package>,
    pub files: Vec<PathInfo>,
    device: String,
}

impl Backup {
    pub fn create(config: &Config, packages: Vec<Package>) -> Result<Self> {
        let mut files: Vec<PathInfo> = Vec::new();
        for dir in &config.directories {
            files.push(PathInfo::from_path(config, dir)?);
        }
        Ok(Self {
            // TODO: UUID not really needed, maybe a shorter hash
            id: Uuid::new_v4().to_string(),
            timestamp: Self::get_timestamp(),
            packages,
            files,
            device: config.device.clone(),
        })
    }

    pub fn save(&self, config: &Config) -> Result<()> {
        info!("Save Backup {:?}", self.get_location(config));
        self.get_location(config).append_to_root(config)?;

        let backup_root = self.get_location(config).get_absolute_dir(config);
        create_dir_all(&backup_root).unwrap();
        let path = format!("{backup_root}/index.json");
        let mut f = File::create(path).unwrap();
        f.write_all(&serde_json::to_vec(self).unwrap()).unwrap();

        for path in &self.files {
            path.save(&backup_root)?;
        }

        Ok(())
    }

    pub fn get_last(config: &Config) -> Result<Option<Self>> {
        let backup_index_root = format!("{}/index.json", config.root);
        let list: Vec<IndexEntry> = match Self::get_json_content(&backup_index_root) {
            Ok(list) => list,
            Err(err) => {
                if err.to_string() == "io: No such file or directory (os error 2)" {
                    return Ok(None);
                };
                return Err(err);
            }
        };

        Ok(Some(Self::from_index(
            config,
            &list.last().ok_or(Error::BackupNotFound)?.id,
        )?))
    }

    pub fn from_index(config: &Config, id: &Id) -> Result<Self> {
        let backup_index_root = format!("{}/index.json", config.root);
        let list: Vec<IndexEntry> = Self::get_json_content(&backup_index_root)?;
        let index_loc = list
            .iter()
            .find(|bl| &bl.id == id)
            .ok_or(Error::BackupNotFound)?
            .rel_location
            .clone();

        let path = format!("{}/{index_loc}/index.json", config.root);
        let index_file: Self = Self::get_json_content(&path)?;

        Ok(index_file)
    }

    pub fn get_location(&self, config: &Config) -> IndexEntry {
        let rel_location = format!("{}_{}", config.device, self.timestamp);

        IndexEntry {
            id: self.id.to_string(),
            rel_location,
        }
    }

    pub fn get_absolute_file_location(&self, config: &Config, rel_location: &str) -> String {
        let loc = self.get_location(config).get_absolute_dir(config);

        format!("{loc}/{rel_location}")
    }

    fn get_json_content<T: for<'a> Deserialize<'a>>(path: &str) -> Result<T> {
        let mut file = File::open(path)?;
        let mut content = String::new();
        file.read_to_string(&mut content)?;
        Ok(serde_json::from_str(&content)?)
    }

    fn get_timestamp() -> u64 {
        SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_secs()
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct IndexEntry {
    id: Id,
    rel_location: String,
}

impl IndexEntry {
    pub fn get_absolute_dir(&self, config: &Config) -> String {
        format!("{}/{}", config.root, self.rel_location)
    }

    pub fn append_to_root(&self, config: &Config) -> Result<()> {
        let backup_index_root = format!("{}/index.json", config.root);
        let path = PathBuf::from(&backup_index_root);
        if path.exists() {
            let mut f = File::open(&path)?;
            let mut content = String::new();
            f.read_to_string(&mut content)?;
            let mut loc: Vec<IndexEntry> = serde_json::from_str(&content)?;

            let mut f = File::create(path)?;
            loc.push(self.clone());

            f.write_all(&serde_json::to_vec(&loc)?)?;
        } else {
            create_dir_all(&config.root).unwrap();
            let mut f = File::create(backup_index_root)?;
            f.write_all(&serde_json::to_vec(&vec![self])?)?;
        };

        Ok(())
    }
}