use std::{
    cell::{RefCell, RefMut},
    collections::{HashMap, hash_map::Entry},
};

use crate::{
    Error, Result,
    file::{self, FileTrait},
    sharry::{AliasID, Client, FileID, ShareID, Uri, json},
};

use super::mock_ids::CheckID;

#[derive(Debug)]
pub struct MockClient {
    shares: RefCell<HashMap<String, MockShare>>,
}

#[derive(Debug, Default)]
struct MockShare {
    files: HashMap<String, MockFile>,
}

#[derive(Debug)]
struct MockFile {
    name: String,
    size: u64,
    offset: u64,
}

impl MockClient {
    fn insert_share(&self, share_id: &ShareID) -> Result<()> {
        let mut shares = self.shares.borrow_mut();

        let Entry::Vacant(entry) = shares.entry(share_id.to_string()) else {
            return Err(Error::response(format_args!(
                "Can't create share {share_id:?}!"
            )));
        };

        entry.insert(MockShare::default());

        Ok(())
    }

    fn insert_file(
        &self,
        share_id: &ShareID,
        file_id: &FileID,
        name: String,
        size: u64,
    ) -> Result<()> {
        let mut share = self.get_share_mut(share_id)?;

        let Entry::Vacant(entry) = share.files.entry(file_id.to_string()) else {
            return Err(Error::response(format_args!(
                "Can't create file {file_id:?}!"
            )));
        };

        entry.insert(MockFile {
            name,
            size,
            offset: 0,
        });

        Ok(())
    }

    fn get_share_mut<'t>(&'t self, share_id: &ShareID) -> Result<RefMut<'t, MockShare>> {
        let share_id = &share_id.to_string();
        let shares = self.shares.borrow_mut();

        shares
            .get(share_id)
            .ok_or_else(|| Error::response(format_args!("Can't find share {share_id:?}!")))?;

        // share exists
        Ok(RefMut::map(shares, |shares| {
            shares.get_mut(share_id).expect("checked but None!")
        }))
    }

    fn get_file_mut<'t>(
        &'t self,
        share_id: &ShareID,
        file_id: &FileID,
    ) -> Result<RefMut<'t, MockFile>> {
        let file_id = &file_id.to_string();
        let share = self.get_share_mut(share_id)?;

        share
            .files
            .get(file_id)
            .ok_or_else(|| Error::response(format_args!("Can't find file {file_id:?}!")))?;

        // file exists
        Ok(RefMut::map(share, move |share| {
            share.files.get_mut(file_id).expect("checked but None!")
        }))
    }
}

impl Client for MockClient {
    fn share_create(
        &self,
        uri: &Uri,
        alias_id: &AliasID,
        _: json::NewShareRequest,
    ) -> Result<ShareID> {
        (uri, alias_id).check()?;

        let share_id = true.into();
        self.insert_share(&share_id)?;

        Ok(share_id)
    }

    fn share_notify(&self, uri: &Uri, alias_id: &AliasID, share_id: &ShareID) -> crate::Result<()> {
        (uri, alias_id).check()?;
        share_id.check()?;

        Ok(())
    }

    fn file_create(
        &self,
        uri: &Uri,
        alias_id: &AliasID,
        share_id: &ShareID,
        file: &file::Checked,
    ) -> Result<FileID> {
        (uri, alias_id).check()?;
        share_id.check()?;

        let file_id = true.into();
        self.insert_file(
            share_id,
            &file_id,
            file.get_name().to_string(),
            file.get_size(),
        )?;

        Ok(file_id)
    }

    fn file_patch(
        &self,
        uri: &Uri,
        alias_id: &AliasID,
        share_id: &ShareID,
        chunk: &file::Chunk,
    ) -> Result<()> {
        (uri, alias_id).check()?;
        (share_id, chunk.get_file_id()).check()?;

        // TODO: `chunk` must align to a full MiB
        let file = self.get_file_mut(share_id, chunk.get_file_id())?;

        todo!()

        // Ok(())
    }
}