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

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

use super::mock_ids::CheckID;

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

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

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

impl From<&file::Checked> for MockFile {
    fn from(value: &file::Checked) -> Self {
        Self {
            size: value.get_size(),
            offset: 0,
        }
    }
}

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

        let Entry::Vacant(entry) = shares.entry(share_id.to_string()) else {
            return Err(error_response!("can't insert share {share_id:?}!"));
        };

        entry.insert(share);

        Ok(())
    }

    fn insert_file(&self, share_id: &ShareID, file_id: &FileID, file: MockFile) -> Result<()> {
        let mut share = self.get_share(share_id)?;

        let Entry::Vacant(entry) = share.files.entry(file_id.to_string()) else {
            return Err(error_response!("can't insert file {file_id:?}!"));
        };

        entry.insert(file);

        Ok(())
    }

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

        // check share exists
        shares
            .get(share_id)
            .ok_or_else(|| error_response!("can't find share {share_id:?}!"))?;

        Ok(RefMut::map(shares, |shares| {
            shares.get_mut(share_id).unwrap()
        }))
    }

    fn get_file<'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(share_id)?;

        // check file exists
        share
            .files
            .get(file_id)
            .ok_or_else(|| error_response!("can't find file {file_id:?}!"))?;

        Ok(RefMut::map(share, move |share| {
            share.files.get_mut(file_id).unwrap()
        }))
    }
}

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, MockShare::default())?;

        Ok(share_id)
    }

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

        let _share = self.get_share(share_id)?;

        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.into())?;

        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()?;

        let file = self.get_file(share_id, chunk.get_file_id())?;

        if chunk.get_length() == 0 {
            return Err(error_response!("chunk {chunk:?} empty!"));
        } else if chunk.get_offset() % (1024 * 1024) != 0 {
            return Err(error_response!("chunk {chunk:?} not aligned to a MiB!"));
        } else if chunk.get_offset() != file.offset {
            return Error::mismatch(file.offset, chunk.get_offset());
        } else if file.offset + chunk.get_length() > file.size {
            return Err(error_response!("chunk {chunk:?} too long!"));
        }

        let mut file = file;
        file.offset += chunk.get_length();

        Ok(())
    }
}

// technically redundant, but kept for refactoring purposes
#[cfg(test)]
mod tests {
    use std::collections::HashSet;

    use super::*;

    fn check_tostr_eq<L, R>(left: L, right: R)
    where
        L: ExactSizeIterator,
        L::Item: ToString,
        R: ExactSizeIterator,
        R::Item: ToString,
    {
        assert_eq!(left.len(), right.len());

        let l_strings: HashSet<_> = left.map(|s| s.to_string()).collect();
        let r_strings: HashSet<_> = right.map(|s| s.to_string()).collect();

        assert_eq!(l_strings, r_strings);
    }

    fn add_share(client: &MockClient) -> ShareID {
        let share_id = ShareID::from(true);
        client
            .insert_share(&share_id, MockShare::default())
            .unwrap();

        share_id
    }

    fn add_file(client: &MockClient, share_id: &ShareID) -> FileID {
        let file_id = FileID::from(true);
        client
            .insert_file(share_id, &file_id, MockFile::default())
            .unwrap();

        file_id
    }

    #[test]
    fn insert_share_works() {
        let client = MockClient::default();
        let share_ids: [_; 10] = std::array::from_fn(|_| ShareID::from(true));

        for share_id in share_ids.as_ref() {
            assert!(client.insert_share(share_id, MockShare::default()).is_ok());
        }

        check_tostr_eq(client.shares.borrow().keys(), share_ids.iter());
    }

    #[test]
    fn insert_share_double_errors() {
        let client = MockClient::default();
        let share_ids: [_; 10] = std::array::from_fn(|_| add_share(&client));

        for share_id in share_ids.as_ref() {
            let res = client.insert_share(&share_id, MockShare::default());
            assert!(res.is_err());
            assert!(res.unwrap_err().response_contains("can't insert share"));
        }
    }

    #[test]
    fn get_share_works() {
        let client = MockClient::default();
        let share_ids: [_; 10] = std::array::from_fn(|_| add_share(&client));

        for share_id in share_ids.as_ref() {
            assert!(client.get_share(share_id).is_ok());
        }
    }

    #[test]
    fn get_share_nex_errors() {
        let client = MockClient::default();
        add_share(&client);
        let share_ids_nex: [_; 10] = std::array::from_fn(|_| ShareID::from(true));

        for share_id_nex in share_ids_nex.as_ref() {
            let res = client.get_share(share_id_nex);

            assert!(res.is_err());
            assert!(res.unwrap_err().response_contains("can't find share"));
        }
    }

    #[test]
    fn insert_file_works() {
        let client = MockClient::default();
        let share_id = add_share(&client);
        let file_ids: [_; 10] = std::array::from_fn(|_| FileID::from(true));

        for file_id in file_ids.as_ref() {
            assert!(
                client
                    .insert_file(&share_id, file_id, MockFile::default())
                    .is_ok()
            );
        }

        let shares = client.shares.borrow();
        let share = shares.get(&share_id.to_string()).unwrap();

        check_tostr_eq(share.files.keys(), file_ids.iter());
    }

    #[test]
    fn insert_file_nex_share_errors() {
        let client = MockClient::default();
        add_share(&client);

        let share_id_nex = ShareID::default();
        let res = client.insert_file(&share_id_nex, &FileID::from(true), MockFile::default());
        assert!(res.is_err());
        assert!(res.unwrap_err().response_contains("can't find share"));
    }

    #[test]
    fn insert_file_double_errors() {
        let client = MockClient::default();
        let share_id = add_share(&client);
        let file_ids: [_; 10] = std::array::from_fn(|_| add_file(&client, &share_id));

        for file_id in file_ids.as_ref() {
            let res = client.insert_file(&share_id, &file_id, MockFile::default());
            assert!(res.is_err());
            assert!(res.unwrap_err().response_contains("can't insert file"));
        }
    }

    #[test]
    fn get_file_works() {
        let client = MockClient::default();
        let share_id = add_share(&client);
        let file_ids: [_; 10] = std::array::from_fn(|_| add_file(&client, &share_id));

        for file_id in file_ids.as_ref() {
            assert!(client.get_file(&share_id, file_id).is_ok());
        }
    }

    #[test]
    fn get_file_nex_errors() {
        let client = MockClient::default();
        let share_id = add_share(&client);
        add_file(&client, &share_id);
        let file_ids_nex: [_; 10] = std::array::from_fn(|_| FileID::from(true));

        for file_id_nex in file_ids_nex.as_ref() {
            let share_id_nex = ShareID::from(true);
            let res = client.get_file(&share_id_nex, file_id_nex);

            assert!(res.is_err());
            assert!(res.unwrap_err().response_contains("can't find share"));

            let res = client.get_file(&share_id, file_id_nex);

            assert!(res.is_err());
            assert!(res.unwrap_err().response_contains("can't find file"));
        }
    }
}