use std::{
    fs::{self, create_dir_all},
    mem::ManuallyDrop,
    ops::{Deref, DerefMut},
    path::PathBuf,
    sync::{Arc, LazyLock, RwLockReadGuard, RwLockWriteGuard},
};

use chrono::Utc;
use log::{debug, error, info, warn};
use rustbreak::{DeSerError, DeSerializer, PathDatabase, RustbreakError};
use serde::{Serialize, de::DeserializeOwned};
use url::Url;

use crate::DB;

use super::models::data::Database;

#[cfg(not(debug_assertions))]
static DATA_ROOT_PREFIX: &'static str = "drop";
#[cfg(debug_assertions)]
static DATA_ROOT_PREFIX: &str = "drop-debug";

pub static DATA_ROOT_DIR: LazyLock<Arc<PathBuf>> = LazyLock::new(|| {
    Arc::new(
        dirs::data_dir()
            .expect("Failed to get data dir")
            .join(DATA_ROOT_PREFIX),
    )
});

// Custom JSON serializer to support everything we need
#[derive(Debug, Default, Clone)]
pub struct DropDatabaseSerializer;

impl<T: native_model::Model + Serialize + DeserializeOwned> DeSerializer<T>
    for DropDatabaseSerializer
{
    fn serialize(&self, val: &T) -> rustbreak::error::DeSerResult<Vec<u8>> {
        native_model::encode(val)
            .map_err(|e| DeSerError::Internal(e.to_string()))
    }

    fn deserialize<R: std::io::Read>(&self, mut s: R) -> rustbreak::error::DeSerResult<T> {
        let mut buf = Vec::new();
        s.read_to_end(&mut buf)
            .map_err(|e| rustbreak::error::DeSerError::Other(e.into()))?;
        let (val, _version) = native_model::decode(buf)
            .map_err(|e| DeSerError::Internal(e.to_string()))?;
        Ok(val)
    }
}

pub type DatabaseInterface =
    rustbreak::Database<Database, rustbreak::backend::PathBackend, DropDatabaseSerializer>;

pub trait DatabaseImpls {
    fn set_up_database() -> DatabaseInterface;
    fn database_is_set_up(&self) -> bool;
    fn fetch_base_url(&self) -> Url;
}
impl DatabaseImpls for DatabaseInterface {
    fn set_up_database() -> DatabaseInterface {
        let db_path = DATA_ROOT_DIR.join("drop.db");
        let games_base_dir = DATA_ROOT_DIR.join("games");
        let logs_root_dir = DATA_ROOT_DIR.join("logs");
        let cache_dir = DATA_ROOT_DIR.join("cache");
        let pfx_dir = DATA_ROOT_DIR.join("pfx");

        debug!("creating data directory at {DATA_ROOT_DIR:?}");
        create_dir_all(DATA_ROOT_DIR.as_path()).unwrap_or_else(|e| {
            panic!(
                "Failed to create directory {} with error {}",
                DATA_ROOT_DIR.display(),
                e
            )
        });
        create_dir_all(&games_base_dir).unwrap_or_else(|e| {
            panic!(
                "Failed to create directory {} with error {}",
                games_base_dir.display(),
                e
            )
        });
        create_dir_all(&logs_root_dir).unwrap_or_else(|e| {
            panic!(
                "Failed to create directory {} with error {}",
                logs_root_dir.display(),
                e
            )
        });
        create_dir_all(&cache_dir).unwrap_or_else(|e| {
            panic!(
                "Failed to create directory {} with error {}",
                cache_dir.display(),
                e
            )
        });
        create_dir_all(&pfx_dir).unwrap_or_else(|e| {
            panic!(
                "Failed to create directory {} with error {}",
                pfx_dir.display(),
                e
            )
        });

        let exists = fs::exists(db_path.clone()).unwrap_or_else(|e| {
            panic!(
                "Failed to find if {} exists with error {}",
                db_path.display(),
                e
            )
        });

        if exists {
            match PathDatabase::load_from_path(db_path.clone()) {
                Ok(db) => db,
                Err(e) => handle_invalid_database(e, db_path, games_base_dir, cache_dir),
            }
        } else {
            let default = Database::new(games_base_dir, None, cache_dir);
            debug!("Creating database at path {}", db_path.display());
            PathDatabase::create_at_path(db_path, default).expect("Database could not be created")
        }
    }

    fn database_is_set_up(&self) -> bool {
        !borrow_db_checked().base_url.is_empty()
    }

    fn fetch_base_url(&self) -> Url {
        let handle = borrow_db_checked();
        Url::parse(&handle.base_url)
            .unwrap_or_else(|_| panic!("Failed to parse base url {}", handle.base_url))
    }
}

// TODO: Make the error relelvant rather than just assume that it's a Deserialize error
fn handle_invalid_database(
    _e: RustbreakError,
    db_path: PathBuf,
    games_base_dir: PathBuf,
    cache_dir: PathBuf,
) -> rustbreak::Database<Database, rustbreak::backend::PathBackend, DropDatabaseSerializer> {
    warn!("{_e}");
    let new_path = {
        let time = Utc::now().timestamp();
        let mut base = db_path.clone();
        base.set_file_name(format!("drop.db.backup-{time}"));
        base
    };
    info!("old database stored at: {}", new_path.to_string_lossy());
    fs::rename(&db_path, &new_path).unwrap_or_else(|e| {
        panic!(
            "Could not rename database {} to {} with error {}",
            db_path.display(),
            new_path.display(),
            e
        )
    });

    let db = Database::new(games_base_dir, Some(new_path), cache_dir);

    PathDatabase::create_at_path(db_path, db).expect("Database could not be created")
}

// To automatically save the database upon drop
pub struct DBRead<'a>(RwLockReadGuard<'a, Database>);
pub struct DBWrite<'a>(ManuallyDrop<RwLockWriteGuard<'a, Database>>);
impl<'a> Deref for DBWrite<'a> {
    type Target = Database;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl<'a> DerefMut for DBWrite<'a> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}
impl<'a> Deref for DBRead<'a> {
    type Target = Database;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl Drop for DBWrite<'_> {
    fn drop(&mut self) {
        unsafe {
            ManuallyDrop::drop(&mut self.0);
        }

        match DB.save() {
            Ok(()) => {}
            Err(e) => {
                error!("database failed to save with error {e}");
                panic!("database failed to save with error {e}")
            }
        }
    }
}

pub fn borrow_db_checked<'a>() -> DBRead<'a> {
    match DB.borrow_data() {
        Ok(data) => DBRead(data),
        Err(e) => {
            error!("database borrow failed with error {e}");
            panic!("database borrow failed with error {e}");
        }
    }
}

pub fn borrow_db_mut_checked<'a>() -> DBWrite<'a> {
    match DB.borrow_data_mut() {
        Ok(data) => DBWrite(ManuallyDrop::new(data)),
        Err(e) => {
            error!("database borrow mut failed with error {e}");
            panic!("database borrow mut failed with error {e}");
        }
    }
}