use std::io::Read;
use std::path::Path;
use std::{fs::File, io::BufReader};

use flate2::{bufread::GzDecoder, Compression};
use index::{Checked, Settings, Unchecked};
use index_scheduler::TaskView;
use meilisearch_auth::Key;
use serde::{Deserialize, Serialize};

use tempfile::TempDir;
use time::OffsetDateTime;
use uuid::Uuid;

use crate::{Result, Version};

// use self::loaders::{v2, v3, v4, v5};

// pub mod error;
// mod compat;
// mod loaders;
// mod v1;
mod v6;

pub fn open(
    dump: impl Read,
) -> Result<
    Box<
        dyn DumpReader<
            Document = serde_json::Map<String, serde_json::Value>,
            Settings = Settings<Checked>,
            Task = TaskView,
            UpdateFile = File,
            Key = Key,
        >,
    >,
> {
    let path = TempDir::new()?;
    let mut dump = BufReader::new(dump);
    let gz = GzDecoder::new(&mut dump);
    let mut archive = tar::Archive::new(gz);
    archive.unpack(path.path())?;

    #[derive(Deserialize)]
    #[serde(rename_all = "camelCase")]
    struct MetadataVersion {
        pub dump_version: Version,
    }
    let mut meta_file = File::open(path.path().join("metadata.json"))?;
    let MetadataVersion { dump_version } = serde_json::from_reader(&mut meta_file)?;

    match dump_version {
        // Version::V1 => Ok(Box::new(v1::Reader::open(path)?)),
        Version::V1 => todo!(),
        Version::V2 => todo!(),
        Version::V3 => todo!(),
        Version::V4 => todo!(),
        Version::V5 => todo!(),
        Version::V6 => {
            let dump_reader = Box::new(v6::V6Reader::open(path)?)
                as Box<
                    dyn DumpReader<
                        Document = serde_json::Map<String, serde_json::Value>,
                        Settings = Settings<Checked>,
                        Task = TaskView,
                        UpdateFile = File,
                        Key = Key,
                    >,
                >;

            Ok(dump_reader)
        }
    }
}

pub trait DumpReader {
    type Document;
    type Settings;

    type Task;
    type UpdateFile;

    type Key;

    /// Return the version of the dump.
    fn version(&self) -> Version;

    /// Return at which date the dump was created if there was one.
    fn date(&self) -> Option<OffsetDateTime>;

    /// Return the instance-uid if there was one.
    fn instance_uid(&self) -> Result<Option<Uuid>>;

    /// Return an iterator over each indexes.
    fn indexes(
        &self,
    ) -> Result<
        Box<
            dyn Iterator<
                Item = Result<
                    Box<dyn IndexReader<Document = Self::Document, Settings = Self::Settings>>,
                >,
            >,
        >,
    >;

    /// Return all the tasks in the dump with a possible update file.
    fn tasks(
        &mut self,
    ) -> Box<dyn Iterator<Item = Result<(Self::Task, Option<Self::UpdateFile>)>> + '_>;

    /// Return all the keys.
    fn keys(&mut self) -> Box<dyn Iterator<Item = Result<Self::Key>> + '_>;
}

pub trait IndexReader {
    type Document;
    type Settings;

    fn name(&self) -> &str;
    fn documents(&mut self) -> Result<Box<dyn Iterator<Item = Result<Self::Document>> + '_>>;
    fn settings(&mut self) -> Result<Self::Settings>;
}