// Copyright 2020 MaidSafe.net limited.
//
// This SAFE Network Software is licensed to you under the MIT license <LICENSE-MIT
// https://opensource.org/licenses/MIT> or the Modified BSD license <LICENSE-BSD
// https://opensource.org/licenses/BSD-3-Clause>, at your option. This file may not be copied,
// modified, or distributed except according to those terms. Please review the Licences for the
// specific language governing permissions and limitations relating to use of the SAFE Network
// Software.

mod metadata;
mod seq_crdt;

use crate::{Error, PublicKey, Result, XorName};
pub use metadata::{
    Action, Address, Entries, Entry, Index, Indices, Kind, Owner, Perm, Permissions,
    PrivPermissions, PrivUserPermissions, PubPermissions, PubUserPermissions, User,
    UserPermissions,
};
use seq_crdt::{Op, SequenceCrdt};
use serde::{Deserialize, Serialize};
use std::{
    collections::BTreeMap,
    fmt::{self, Debug, Formatter},
    hash::Hash,
};

// Type of data used for the 'Actor' in CRDT vector clocks
type ActorType = PublicKey;

/// Public Sequence.
pub type PubSeqData = SequenceCrdt<ActorType, PubPermissions>;
/// Private Sequence.
pub type PrivSeqData = SequenceCrdt<ActorType, PrivPermissions>;

impl Debug for PubSeqData {
    fn fmt(&self, formatter: &mut Formatter) -> fmt::Result {
        write!(formatter, "PubSequence {:?}", self.address().name())
    }
}

impl Debug for PrivSeqData {
    fn fmt(&self, formatter: &mut Formatter) -> fmt::Result {
        write!(formatter, "PrivSequence {:?}", self.address().name())
    }
}

/// Mutation operation to apply to Sequence.
/// This is used for all kind of CRDT operationsmade on the Sequence,
/// i.e. not only on the data but also on the permissions and owner info.
#[derive(Clone, Serialize, Deserialize, PartialEq, PartialOrd, Eq, Hash)]
pub struct MutationOperation<T> {
    /// Address of a Sequence object on the network.
    pub address: Address,
    /// The operation to apply.
    pub crdt_op: Op<T, ActorType>,
}

/// Object storing a Sequence variant.
#[derive(Clone, Eq, PartialEq, PartialOrd, Hash, Serialize, Deserialize, Debug)]
pub enum Data {
    /// Public Sequence Data.
    Public(PubSeqData),
    /// Private Sequence Data.
    Private(PrivSeqData),
}

impl Data {
    /// Constructs a new Public Sequence Data.
    pub fn new_pub(actor: PublicKey, name: XorName, tag: u64) -> Self {
        Self::Public(PubSeqData::new(actor, Address::Public { name, tag }))
    }

    /// Constructs a new Private Sequence Data.
    pub fn new_priv(actor: PublicKey, name: XorName, tag: u64) -> Self {
        Self::Private(PrivSeqData::new(actor, Address::Private { name, tag }))
    }

    /// Returns the address.
    pub fn address(&self) -> &Address {
        match self {
            Data::Public(data) => data.address(),
            Data::Private(data) => data.address(),
        }
    }

    /// Returns the kind.
    pub fn kind(&self) -> Kind {
        self.address().kind()
    }

    /// Returns the name.
    pub fn name(&self) -> &XorName {
        self.address().name()
    }

    /// Returns the tag.
    pub fn tag(&self) -> u64 {
        self.address().tag()
    }

    /// Returns `true` if public.
    pub fn is_pub(&self) -> bool {
        self.kind().is_pub()
    }

    /// Returns `true` if private.
    pub fn is_priv(&self) -> bool {
        self.kind().is_priv()
    }

    /// Checks permissions for given `action` for the provided user.
    ///
    /// Returns:
    /// `Ok(())` if the permissions are valid,
    /// `Err::InvalidOwners` if the last owner is invalid,
    /// `Err::AccessDenied` if the action is not allowed.
    pub fn check_permission(&self, action: Action, requester: PublicKey) -> Result<()> {
        macro_rules! check_perm {
            ($data: ident, $requester: ident, $action: ident) => {
                $data.check_is_last_owner($requester).or_else(|_| {
                    $data
                        .permissions(Index::FromEnd(1))
                        .ok_or(Error::AccessDenied)?
                        .is_action_allowed($requester, $action)
                })
            };
        }

        match self {
            Data::Public(data) => {
                if action == Action::Read {
                    return Ok(());
                }
                check_perm!(data, requester, action)
            }
            Data::Private(data) => check_perm!(data, requester, action),
        }
    }

    /// Returns the last entry index.
    pub fn entries_index(&self) -> u64 {
        match self {
            Data::Public(data) => data.entries_index(),
            Data::Private(data) => data.entries_index(),
        }
    }

    /// Returns the last permissions index.
    pub fn permissions_index(&self) -> u64 {
        match self {
            Data::Public(data) => data.permissions_index(),
            Data::Private(data) => data.permissions_index(),
        }
    }

    /// Returns the last owners index.
    pub fn owners_index(&self) -> u64 {
        match self {
            Data::Public(data) => data.owners_index(),
            Data::Private(data) => data.owners_index(),
        }
    }

    /// Gets a list of keys and values with the given indices.
    pub fn in_range(&self, start: Index, end: Index) -> Option<Entries> {
        match self {
            Data::Public(data) => data.in_range(start, end),
            Data::Private(data) => data.in_range(start, end),
        }
    }

    /// Returns a value at 'index', if present.
    pub fn get(&self, index: Index) -> Option<&Vec<u8>> {
        match self {
            Data::Public(data) => data.get(index),
            Data::Private(data) => data.get(index),
        }
    }

    /// Returns the last entry, if present.
    pub fn last_entry(&self) -> Option<&Entry> {
        match self {
            Data::Public(data) => data.last_entry(),
            Data::Private(data) => data.last_entry(),
        }
    }

    /// Fetches owner at index.
    pub fn owner(&self, owners_index: impl Into<Index>) -> Option<&Owner> {
        match self {
            Data::Public(data) => data.owner(owners_index),
            Data::Private(data) => data.owner(owners_index),
        }
    }

    /// Appends new entry.
    pub fn append(&mut self, entry: Entry) -> MutationOperation<Entry> {
        let crdt_op = match self {
            Data::Public(data) => data.append(entry),
            Data::Private(data) => data.append(entry),
        };

        MutationOperation {
            address: *self.address(),
            crdt_op,
        }
    }

    /// Apply CRDT operation.
    pub fn apply_crdt_op(&mut self, op: Op<Entry, ActorType>) {
        match self {
            Data::Public(data) => data.apply_crdt_op(op),
            Data::Private(data) => data.apply_crdt_op(op),
        };
    }

    /// Adds a new permissions entry for Public Sequence.
    pub fn set_pub_permissions(
        &mut self,
        permissions: BTreeMap<User, PubUserPermissions>,
    ) -> Result<MutationOperation<PubPermissions>> {
        let address = *self.address();
        match self {
            Data::Public(data) => {
                let crdt_op = data.append_permissions(PubPermissions {
                    entries_index: data.entries_index(),
                    owners_index: data.owners_index(),
                    permissions,
                });
                Ok(MutationOperation { address, crdt_op })
            }
            Data::Private(_) => Err(Error::InvalidOperation),
        }
    }

    /// Adds a new permissions entry for Private Sequence.
    pub fn set_priv_permissions(
        &mut self,
        permissions: BTreeMap<PublicKey, PrivUserPermissions>,
    ) -> Result<MutationOperation<PrivPermissions>> {
        let address = *self.address();
        match self {
            Data::Private(data) => {
                let crdt_op = data.append_permissions(PrivPermissions {
                    entries_index: data.entries_index(),
                    owners_index: data.owners_index(),
                    permissions,
                });
                Ok(MutationOperation { address, crdt_op })
            }
            Data::Public(_) => Err(Error::InvalidOperation),
        }
    }

    /// Apply Public Permissions CRDT operation.
    pub fn apply_crdt_pub_perms_op(&mut self, op: Op<PubPermissions, ActorType>) -> Result<()> {
        match (self, &op) {
            (Data::Public(data), Op::Insert { .. }) => {
                data.apply_crdt_perms_op(op);
                Ok(())
            }
            _ => Err(Error::InvalidOperation),
        }
    }

    /// Apply Private Permissions CRDT operation.
    pub fn apply_crdt_priv_perms_op(&mut self, op: Op<PrivPermissions, ActorType>) -> Result<()> {
        match self {
            Data::Private(data) => {
                data.apply_crdt_perms_op(op);
                Ok(())
            }
            _ => Err(Error::InvalidOperation),
        }
    }

    /// Adds a new owner entry.
    pub fn set_owner(&mut self, owner: PublicKey) -> MutationOperation<Owner> {
        let address = *self.address();
        let crdt_op = match self {
            Data::Public(data) => data.append_owner(owner),
            Data::Private(data) => data.append_owner(owner),
        };

        MutationOperation { address, crdt_op }
    }

    /// Apply Owner CRDT operation.
    pub fn apply_crdt_owner_op(&mut self, op: Op<Owner, ActorType>) {
        match self {
            Data::Public(data) => data.apply_crdt_owner_op(op),
            Data::Private(data) => data.apply_crdt_owner_op(op),
        };
    }

    /// Checks if the requester is the last owner.
    ///
    /// Returns:
    /// `Ok(())` if the requester is the owner,
    /// `Err::InvalidOwners` if the last owner is invalid,
    /// `Err::AccessDenied` if the requester is not the owner.
    pub fn check_is_last_owner(&self, requester: PublicKey) -> Result<()> {
        match self {
            Data::Public(data) => data.check_is_last_owner(requester),
            Data::Private(data) => data.check_is_last_owner(requester),
        }
    }

    /// Returns user permissions, if applicable.
    pub fn user_permissions(&self, user: User, index: impl Into<Index>) -> Result<UserPermissions> {
        let user_perm = match self {
            Data::Public(data) => data
                .permissions(index)
                .ok_or(Error::NoSuchEntry)?
                .user_permissions(user)
                .ok_or(Error::NoSuchEntry)?,
            Data::Private(data) => data
                .permissions(index)
                .ok_or(Error::NoSuchEntry)?
                .user_permissions(user)
                .ok_or(Error::NoSuchEntry)?,
        };

        Ok(user_perm)
    }

    /// Returns public permissions, if applicable.
    pub fn pub_permissions(&self, index: impl Into<Index>) -> Result<&PubPermissions> {
        let perms = match self {
            Data::Public(data) => data.permissions(index),
            Data::Private(_) => return Err(Error::InvalidOperation),
        };
        perms.ok_or(Error::NoSuchEntry)
    }

    /// Returns private permissions, if applicable.
    pub fn priv_permissions(&self, index: impl Into<Index>) -> Result<&PrivPermissions> {
        let perms = match self {
            Data::Private(data) => data.permissions(index),
            Data::Public(_) => return Err(Error::InvalidOperation),
        };
        perms.ok_or(Error::NoSuchEntry)
    }
}

impl From<PubSeqData> for Data {
    fn from(data: PubSeqData) -> Self {
        Data::Public(data)
    }
}

impl From<PrivSeqData> for Data {
    fn from(data: PrivSeqData) -> Self {
        Data::Private(data)
    }
}

#[cfg(test)]
mod tests {
    use crate::{
        Error, PublicKey, Result, SData, SDataAddress, SDataIndex, SDataKind,
        SDataPrivUserPermissions, SDataPubUserPermissions, SDataUser, SDataUserPermissions,
        XorName,
    };
    use std::collections::BTreeMap;
    use threshold_crypto::SecretKey;

    fn gen_public_key() -> PublicKey {
        PublicKey::Bls(SecretKey::random().public_key())
    }

    #[test]
    fn sequence_create_public() {
        let actor = gen_public_key();
        let sdata_name: XorName = rand::random();
        let sdata_tag = 43_000;
        let sdata = SData::new_pub(actor, sdata_name, sdata_tag);
        assert_eq!(sdata.kind(), SDataKind::Public);
        assert_eq!(*sdata.name(), sdata_name);
        assert_eq!(sdata.tag(), sdata_tag);
        assert!(sdata.is_pub());
        assert!(!sdata.is_priv());

        let sdata_address = SDataAddress::from_kind(SDataKind::Public, sdata_name, sdata_tag);
        assert_eq!(*sdata.address(), sdata_address);
    }

    #[test]
    fn sequence_create_private() {
        let actor = gen_public_key();
        let sdata_name: XorName = rand::random();
        let sdata_tag = 43_000;
        let sdata = SData::new_priv(actor, sdata_name, sdata_tag);
        assert_eq!(sdata.kind(), SDataKind::Private);
        assert_eq!(*sdata.name(), sdata_name);
        assert_eq!(sdata.tag(), sdata_tag);
        assert!(!sdata.is_pub());
        assert!(sdata.is_priv());

        let sdata_address = SDataAddress::from_kind(SDataKind::Private, sdata_name, sdata_tag);
        assert_eq!(*sdata.address(), sdata_address);
    }

    #[test]
    fn sequence_append_entry_and_apply() {
        let actor = gen_public_key();
        let sdata_name: XorName = rand::random();
        let sdata_tag = 43_000;
        let mut replica1 = SData::new_pub(actor, sdata_name, sdata_tag);
        let mut replica2 = SData::new_pub(actor, sdata_name, sdata_tag);

        let entry1 = b"value0".to_vec();
        let entry2 = b"value1".to_vec();

        let op1 = replica1.append(entry1.clone());
        let op2 = replica1.append(entry2.clone());

        // we apply the operations in different order, to verify that doesn't affect the result
        replica2.apply_crdt_op(op2.crdt_op);
        replica2.apply_crdt_op(op1.crdt_op);

        assert_eq!(replica1.entries_index(), 2);
        assert_eq!(replica2.entries_index(), 2);

        let index_0 = SDataIndex::FromStart(0);
        let first_entry = replica1.get(index_0);
        assert_eq!(first_entry, Some(&entry1));
        assert_eq!(first_entry, replica2.get(index_0));

        let index_1 = SDataIndex::FromStart(1);
        let second_entry = replica1.get(index_1);
        assert_eq!(second_entry, Some(&entry2));
        assert_eq!(second_entry, replica2.get(index_1));

        let last_entry = replica1.last_entry();
        assert_eq!(last_entry, Some(&entry2));
        assert_eq!(last_entry, replica2.last_entry());
    }

    #[test]
    fn sequence_public_append_perms_and_apply() -> Result<()> {
        let actor = gen_public_key();
        let sdata_name: XorName = rand::random();
        let sdata_tag = 43_000;
        let mut replica1 = SData::new_pub(actor, sdata_name, sdata_tag);
        let mut replica2 = SData::new_pub(actor, sdata_name, sdata_tag);

        let mut perms1 = BTreeMap::default();
        let user_perms1 = SDataPubUserPermissions::new(true, false);
        let _ = perms1.insert(SDataUser::Anyone, user_perms1);

        let mut perms2 = BTreeMap::default();
        let user_perms2 = SDataPubUserPermissions::new(false, true);
        let _ = perms2.insert(SDataUser::Key(actor), user_perms2);

        let op1 = replica1.set_pub_permissions(perms1.clone())?;
        let op2 = replica1.set_pub_permissions(perms2.clone())?;

        // we apply the operations in different order, to verify that doesn't affect the result
        replica2.apply_crdt_pub_perms_op(op2.crdt_op)?;
        replica2.apply_crdt_pub_perms_op(op1.crdt_op)?;

        assert_eq!(replica1.permissions_index(), 2);
        assert_eq!(replica2.permissions_index(), 2);

        let index_0 = SDataIndex::FromStart(0);
        let first_entry = replica1.pub_permissions(index_0)?;
        assert_eq!(first_entry.permissions, perms1);
        assert_eq!(first_entry.entries_index, 0);
        assert_eq!(first_entry.owners_index, 0);
        assert_eq!(first_entry, replica2.pub_permissions(index_0)?);
        assert_eq!(
            SDataUserPermissions::Pub(user_perms1),
            replica1.user_permissions(SDataUser::Anyone, index_0)?
        );

        let index_1 = SDataIndex::FromStart(1);
        let second_entry = replica1.pub_permissions(index_1)?;
        assert_eq!(second_entry.permissions, perms2);
        assert_eq!(second_entry.entries_index, 0);
        assert_eq!(second_entry.owners_index, 0);
        assert_eq!(second_entry, replica2.pub_permissions(index_1)?);
        assert_eq!(
            SDataUserPermissions::Pub(user_perms2),
            replica1.user_permissions(SDataUser::Key(actor), index_1)?
        );

        Ok(())
    }

    #[test]
    fn sequence_private_append_perms_and_apply() -> Result<()> {
        let actor1 = gen_public_key();
        let actor2 = gen_public_key();
        let sdata_name: XorName = rand::random();
        let sdata_tag = 43_000;
        let mut replica1 = SData::new_priv(actor1, sdata_name, sdata_tag);
        let mut replica2 = SData::new_priv(actor2, sdata_name, sdata_tag);

        let mut perms1 = BTreeMap::default();
        let user_perms1 = SDataPrivUserPermissions::new(true, false, true);
        let _ = perms1.insert(actor1, user_perms1);

        let mut perms2 = BTreeMap::default();
        let user_perms2 = SDataPrivUserPermissions::new(false, true, false);
        let _ = perms2.insert(actor2, user_perms2);

        let op1 = replica1.set_priv_permissions(perms1.clone())?;
        let op2 = replica1.set_priv_permissions(perms2.clone())?;

        // we apply the operations in different order, to verify that doesn't affect the result
        replica2.apply_crdt_priv_perms_op(op2.crdt_op)?;
        replica2.apply_crdt_priv_perms_op(op1.crdt_op)?;

        assert_eq!(replica1.permissions_index(), 2);
        assert_eq!(replica2.permissions_index(), 2);

        let index_0 = SDataIndex::FromStart(0);
        let first_entry = replica1.priv_permissions(index_0)?;
        assert_eq!(first_entry.permissions, perms1);
        assert_eq!(first_entry.entries_index, 0);
        assert_eq!(first_entry.owners_index, 0);
        assert_eq!(first_entry, replica2.priv_permissions(index_0)?);
        assert_eq!(
            SDataUserPermissions::Priv(user_perms1),
            replica1.user_permissions(SDataUser::Key(actor1), index_0)?
        );

        let index_1 = SDataIndex::FromStart(1);
        let second_entry = replica1.priv_permissions(index_1)?;
        assert_eq!(second_entry.permissions, perms2);
        assert_eq!(second_entry.entries_index, 0);
        assert_eq!(second_entry.owners_index, 0);
        assert_eq!(second_entry, replica2.priv_permissions(index_1)?);
        assert_eq!(
            SDataUserPermissions::Priv(user_perms2),
            replica1.user_permissions(SDataUser::Key(actor2), index_1)?
        );

        Ok(())
    }

    #[test]
    fn sequence_append_owner_and_apply() -> Result<()> {
        let actor = gen_public_key();
        let sdata_name: XorName = rand::random();
        let sdata_tag = 43_000;
        let mut replica1 = SData::new_pub(actor, sdata_name, sdata_tag);
        let mut replica2 = SData::new_pub(actor, sdata_name, sdata_tag);

        let owner1 = gen_public_key();
        let owner2 = gen_public_key();
        let op1 = replica1.set_owner(owner1);
        let op2 = replica1.set_owner(owner2);

        // we apply the operations in different order, to verify that doesn't affect the result
        replica2.apply_crdt_owner_op(op2.crdt_op);
        replica2.apply_crdt_owner_op(op1.crdt_op);

        assert_eq!(replica1.owners_index(), 2);
        assert_eq!(replica2.owners_index(), 2);

        let index_0 = SDataIndex::FromStart(0);
        let first_entry = replica1.owner(index_0).ok_or(Error::InvalidOwners)?;
        assert_eq!(first_entry.public_key, owner1);
        assert_eq!(first_entry.entries_index, 0);
        assert_eq!(first_entry.permissions_index, 0);
        assert_eq!(
            first_entry,
            replica2.owner(index_0).ok_or(Error::InvalidOwners)?
        );

        let index_1 = SDataIndex::FromStart(1);
        let second_entry = replica1.owner(index_1).ok_or(Error::InvalidOwners)?;
        assert_eq!(second_entry.public_key, owner2);
        assert_eq!(second_entry.entries_index, 0);
        assert_eq!(second_entry.permissions_index, 0);
        assert_eq!(
            second_entry,
            replica2.owner(index_1).ok_or(Error::InvalidOwners)?
        );

        replica1.check_is_last_owner(owner2)?;
        replica2.check_is_last_owner(owner2)?;

        Ok(())
    }
}