// Copyright 2024 Saorsa Labs Limited
//
// This software is dual-licensed under:
// - GNU Affero General Public License v3.0 or later (AGPL-3.0-or-later)
// - Commercial License
//
// For AGPL-3.0 license, see LICENSE-AGPL-3.0
// For commercial licensing, contact: david@saorsalabs.com
//
// Unless required by applicable law or agreed to in writing, software
// distributed under these licenses is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

//! Distributed Key Generation (DKG) for threshold groups

use super::{Result, ThresholdError};
use crate::quantum_crypto::types::*;
use crate::threshold::frost::KeyGenerationResult;
// use frost_ed25519 as frost; // Temporarily disabled
// Removed unused OsRng import
use std::collections::HashMap;

/// DKG ceremony result
pub struct DkgResult {
    pub group_key: FrostGroupPublicKey,
    pub local_share: FrostKeyShare,
}

/// Run DKG ceremony for threshold group creation
pub async fn run_ceremony(
    threshold: u16,
    participants: Vec<crate::threshold::ParticipantInfo>,
) -> Result<DkgResult> {
    // Validate parameters
    if threshold > participants.len() as u16 {
        return Err(ThresholdError::InvalidParameters(
            "Threshold exceeds participant count".to_string(),
        ));
    }

    // Placeholder implementation (frost disabled)
    let local_share = FrostKeyShare {
        participant_id: ParticipantId(0),
        share: vec![0; 32], // Placeholder
    };

    let group_key = FrostGroupPublicKey(vec![1; 32]); // Placeholder

    Ok(DkgResult {
        group_key,
        local_share,
    })
}

/// DKG coordinator for managing ceremonies
pub struct DkgCoordinator {
    /// Active ceremonies
    ceremonies: HashMap<CeremonyId, Ceremony>,
}

/// Ceremony identifier
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct CeremonyId([u8; 32]);

/// Active DKG ceremony
struct Ceremony {
    _id: CeremonyId,
    _threshold: u16,
    participants: Vec<ParticipantId>,
    commitments: HashMap<ParticipantId, Vec<u8>>,
    _shares: HashMap<ParticipantId, Vec<u8>>,
    state: CeremonyState,
}

/// Ceremony state
#[derive(Debug, Clone, PartialEq)]
#[allow(dead_code)]
enum CeremonyState {
    CollectingCommitments,
    DistributingShares,
    Finalizing,
    Complete,
    Failed(String),
}

impl Default for DkgCoordinator {
    fn default() -> Self {
        Self::new()
    }
}

impl DkgCoordinator {
    /// Create new DKG coordinator
    pub fn new() -> Self {
        Self {
            ceremonies: HashMap::new(),
        }
    }

    /// Start new DKG ceremony
    pub fn start_ceremony(
        &mut self,
        threshold: u16,
        participants: Vec<ParticipantId>,
    ) -> Result<CeremonyId> {
        let ceremony_id = CeremonyId(rand::random());

        let ceremony = Ceremony {
            _id: ceremony_id.clone(),
            _threshold: threshold,
            participants,
            commitments: HashMap::new(),
            _shares: HashMap::new(),
            state: CeremonyState::CollectingCommitments,
        };

        self.ceremonies.insert(ceremony_id.clone(), ceremony);

        Ok(ceremony_id)
    }

    /// Process commitment from participant
    pub fn process_commitment(
        &mut self,
        ceremony_id: &CeremonyId,
        participant_id: ParticipantId,
        commitment: Vec<u8>,
    ) -> Result<()> {
        let ceremony = self
            .ceremonies
            .get_mut(ceremony_id)
            .ok_or_else(|| ThresholdError::DkgFailed("Ceremony not found".to_string()))?;

        if ceremony.state != CeremonyState::CollectingCommitments {
            return Err(ThresholdError::DkgFailed(
                "Not in commitment phase".to_string(),
            ));
        }

        ceremony.commitments.insert(participant_id, commitment);

        // Check if all commitments received
        if ceremony.commitments.len() == ceremony.participants.len() {
            ceremony.state = CeremonyState::DistributingShares;
        }

        Ok(())
    }

    /// Complete ceremony and generate result
    pub fn complete_ceremony(&mut self, ceremony_id: &CeremonyId) -> Result<KeyGenerationResult> {
        let ceremony = self
            .ceremonies
            .get_mut(ceremony_id)
            .ok_or_else(|| ThresholdError::DkgFailed("Ceremony not found".to_string()))?;

        if ceremony.state != CeremonyState::DistributingShares {
            return Err(ThresholdError::DkgFailed(
                "Ceremony not ready for completion".to_string(),
            ));
        }

        // Generate final result (simplified)
        ceremony.state = CeremonyState::Complete;

        // In practice, this would aggregate commitments and generate proper shares
        Ok(KeyGenerationResult {
            group_public_key: FrostGroupPublicKey(vec![0; 32]),
            shares: HashMap::new(),
            commitments: vec![],
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::threshold::ParticipantInfo;

    #[tokio::test]
    async fn test_dkg_ceremony() {
        let participants = vec![
            ParticipantInfo {
                participant_id: ParticipantId(1),
                public_key: vec![1; 32],
                frost_share_commitment: FrostCommitment(vec![1; 32]),
                role: crate::threshold::ParticipantRole::Leader {
                    permissions: crate::threshold::LeaderPermissions::default(),
                },
                status: crate::threshold::ParticipantStatus::Active,
                joined_at: std::time::SystemTime::now(),
                metadata: HashMap::new(),
            },
            ParticipantInfo {
                participant_id: ParticipantId(2),
                public_key: vec![2; 32],
                frost_share_commitment: FrostCommitment(vec![2; 32]),
                role: crate::threshold::ParticipantRole::Member {
                    permissions: crate::threshold::MemberPermissions::default(),
                },
                status: crate::threshold::ParticipantStatus::Active,
                joined_at: std::time::SystemTime::now(),
                metadata: HashMap::new(),
            },
        ];

        let result = run_ceremony(2, participants).await;
        assert!(result.is_ok());
    }

    #[test]
    fn test_dkg_coordinator() {
        let mut coordinator = DkgCoordinator::new();

        let participants = vec![ParticipantId(1), ParticipantId(2), ParticipantId(3)];
        let ceremony_id = coordinator.start_ceremony(2, participants).unwrap();

        // Process commitments
        coordinator
            .process_commitment(&ceremony_id, ParticipantId(1), vec![1; 32])
            .unwrap();

        coordinator
            .process_commitment(&ceremony_id, ParticipantId(2), vec![2; 32])
            .unwrap();

        coordinator
            .process_commitment(&ceremony_id, ParticipantId(3), vec![3; 32])
            .unwrap();

        // Complete ceremony
        let result = coordinator.complete_ceremony(&ceremony_id);
        assert!(result.is_ok());
    }
}
