use crate::chain_config::{ChainConfig, ContractConfig, StateConfig};
use crate::database::Database;
use crate::model::coin::{Coin, CoinStatus};
use crate::tx_pool::TxPool;
use fuel_storage::{MerkleStorage, Storage};
use fuel_tx::UtxoId;
use fuel_types::{Bytes32, Color, ContractId, Salt, Word};
use fuel_vm::prelude::Contract;
pub use graph_api::start_server;
#[cfg(feature = "rocksdb")]
use std::io::ErrorKind;
use std::{
    net::{self, Ipv4Addr, SocketAddr},
    panic,
    path::PathBuf,
    sync::Arc,
};
use strum_macros::{Display, EnumString};
use thiserror::Error;
use tokio::task::JoinHandle;

pub mod graph_api;

#[derive(Clone, Debug)]
pub struct Config {
    pub addr: net::SocketAddr,
    pub database_path: PathBuf,
    pub database_type: DbType,
    pub chain_conf: ChainConfig,
}

impl Config {
    pub fn local_node() -> Self {
        Self {
            addr: SocketAddr::new(Ipv4Addr::new(127, 0, 0, 1).into(), 0),
            database_path: Default::default(),
            database_type: DbType::InMemory,
            chain_conf: ChainConfig::local_testnet(),
        }
    }
}

#[derive(Clone, Debug, PartialEq, EnumString, Display)]
pub enum DbType {
    InMemory,
    RocksDb,
}

pub struct FuelService {
    tasks: Vec<JoinHandle<Result<(), Error>>>,
    /// The address bound by the system for serving the API
    pub bound_address: SocketAddr,
}

impl FuelService {
    /// Create a fuel node instance from service config
    pub async fn new_node(config: Config) -> Result<Self, std::io::Error> {
        // initialize database
        let database = match config.database_type {
            #[cfg(feature = "rocksdb")]
            DbType::RocksDb => Database::open(&config.database_path)
                .map_err(|e| std::io::Error::new(ErrorKind::Other, e))?,
            DbType::InMemory => Database::default(),
            #[cfg(not(feature = "rocksdb"))]
            _ => Database::default(),
        };
        // initialize service
        Self::init_service(database, config).await
    }

    #[cfg(any(test, feature = "test-helpers"))]
    /// Used to initialize a service with a pre-existing database
    pub async fn from_database(database: Database, config: Config) -> Result<Self, std::io::Error> {
        Self::init_service(database, config).await
    }

    /// Private inner method for initializing the fuel service
    async fn init_service(database: Database, config: Config) -> Result<Self, std::io::Error> {
        // initialize state
        Self::import_state(&config.chain_conf, &database)?;
        // initialize transaction pool
        let tx_pool = Arc::new(TxPool::new(database.clone()));

        // start background tasks
        let mut tasks = vec![];
        let (bound_address, api_server) =
            graph_api::start_server(config, database, tx_pool).await?;
        tasks.push(api_server);

        Ok(FuelService {
            tasks,
            bound_address,
        })
    }

    /// Loads state from the chain config into database
    fn import_state(config: &ChainConfig, database: &Database) -> Result<(), std::io::Error> {
        // start a db transaction for bulk-writing
        let mut import_tx = database.transaction();
        let database = import_tx.as_mut();

        // check if chain is initialized
        if database.get_chain_name()?.is_none() {
            // initialize the chain id
            database.init_chain_name(config.chain_name.clone())?;

            if let Some(initial_state) = &config.initial_state {
                Self::init_block_height(database, initial_state)?;
                Self::init_coin_state(database, initial_state)?;
                Self::init_contracts(database, initial_state)?;
            }
        }

        // Write transaction to db
        import_tx.commit()?;

        Ok(())
    }

    /// initialize starting block height if set
    fn init_block_height(db: &Database, state: &StateConfig) -> Result<(), std::io::Error> {
        if let Some(height) = state.height {
            db.init_chain_height(height)?;
        }
        Ok(())
    }

    /// initialize coins
    fn init_coin_state(db: &mut Database, state: &StateConfig) -> Result<(), std::io::Error> {
        // TODO: Store merkle sum tree root over coins with unspecified utxo ids.
        let mut generated_output_index = 0;
        if let Some(coins) = &state.coins {
            for coin in coins {
                let utxo_id = UtxoId::new(
                    coin.tx_id.unwrap_or_default(),
                    coin.output_index.map(|i| i as u8).unwrap_or_else(|| {
                        generated_output_index += 1;
                        generated_output_index
                    }),
                );

                let coin = Coin {
                    owner: coin.owner,
                    amount: coin.amount,
                    color: coin.color,
                    maturity: coin.maturity.unwrap_or_default(),
                    status: CoinStatus::Unspent,
                    block_created: coin.block_created.unwrap_or_default(),
                };

                let _ = Storage::<UtxoId, Coin>::insert(db, &utxo_id, &coin)?;
            }
        }
        Ok(())
    }

    fn init_contracts(db: &mut Database, state: &StateConfig) -> Result<(), std::io::Error> {
        // initialize contract state
        if let Some(contracts) = &state.contracts {
            for contract_config in contracts {
                let contract = Contract::from(contract_config.code.as_slice());
                let salt = contract_config.salt;
                let root = contract.root();
                let contract_id = contract.id(&salt, &root);
                // insert contract code
                let _ = Storage::<ContractId, Contract>::insert(db, &contract_id, &contract)?;
                // insert contract root
                let _ = Storage::<ContractId, (Salt, Bytes32)>::insert(
                    db,
                    &contract_id,
                    &(salt, root),
                )?;
                Self::init_contract_state(db, &contract_id, contract_config)?;
                Self::init_contract_balance(db, &contract_id, contract_config)?;
            }
        }
        Ok(())
    }

    fn init_contract_state(
        db: &mut Database,
        contract_id: &ContractId,
        contract: &ContractConfig,
    ) -> Result<(), std::io::Error> {
        // insert state related to contract
        if let Some(contract_state) = &contract.state {
            for (key, value) in contract_state {
                MerkleStorage::<ContractId, Bytes32, Bytes32>::insert(db, contract_id, key, value)?;
            }
        }
        Ok(())
    }

    fn init_contract_balance(
        db: &mut Database,
        contract_id: &ContractId,
        contract: &ContractConfig,
    ) -> Result<(), std::io::Error> {
        // insert balances related to contract
        if let Some(balances) = &contract.balances {
            for (key, value) in balances {
                MerkleStorage::<ContractId, Color, Word>::insert(db, contract_id, key, value)?;
            }
        }
        Ok(())
    }

    /// Awaits for the completion of any server background tasks
    pub async fn run(self) {
        for task in self.tasks {
            match task.await {
                Err(err) => {
                    if err.is_panic() {
                        // Resume the panic on the main task
                        panic::resume_unwind(err.into_panic());
                    }
                }
                Ok(Err(e)) => {
                    eprintln!("server error: {:?}", e);
                }
                Ok(Ok(_)) => {}
            }
        }
    }

    /// Shutdown background tasks
    pub fn stop(&self) {
        for task in &self.tasks {
            task.abort();
        }
    }
}

#[derive(Debug, Error)]
pub enum Error {
    #[error("An api server error occurred {0}")]
    ApiServer(#[from] hyper::Error),
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::chain_config::{CoinConfig, ContractConfig, StateConfig};
    use crate::model::fuel_block::BlockHeight;
    use fuel_asm::Opcode;
    use fuel_types::{Address, Color, Word};
    use itertools::Itertools;
    use rand::rngs::StdRng;
    use rand::{Rng, RngCore, SeedableRng};

    #[tokio::test]
    async fn config_initializes_chain_name() {
        let test_name = "test_net_123".to_string();
        let service_config = Config {
            chain_conf: ChainConfig {
                chain_name: test_name.clone(),
                ..ChainConfig::local_testnet()
            },
            ..Config::local_node()
        };

        let db = Database::default();
        FuelService::from_database(db.clone(), service_config)
            .await
            .unwrap();

        assert_eq!(
            test_name,
            db.get_chain_name()
                .unwrap()
                .expect("Expected a chain name to be set")
        )
    }

    #[tokio::test]
    async fn config_initializes_block_height() {
        let test_height = BlockHeight::from(99u32);
        let service_config = Config {
            chain_conf: ChainConfig {
                initial_state: Some(StateConfig {
                    height: Some(test_height),
                    ..Default::default()
                }),
                ..ChainConfig::local_testnet()
            },
            ..Config::local_node()
        };

        let db = Database::default();
        FuelService::from_database(db.clone(), service_config)
            .await
            .unwrap();

        assert_eq!(
            test_height,
            db.get_block_height()
                .unwrap()
                .expect("Expected a block height to be set")
        )
    }

    #[tokio::test]
    async fn config_state_initializes_multiple_coins_with_different_owners_and_colors() {
        let mut rng = StdRng::seed_from_u64(10);

        // a coin with all options set
        let alice: Address = rng.gen();
        let color_alice: Color = rng.gen();
        let alice_value = rng.gen();
        let alice_maturity = Some(rng.next_u32().into());
        let alice_block_created = Some(rng.next_u32().into());
        let alice_tx_id = Some(rng.gen());
        let alice_output_index = Some(rng.gen());
        let alice_utxo_id = UtxoId::new(alice_tx_id.unwrap(), alice_output_index.unwrap());

        // a coin with minimal options set
        let bob: Address = rng.gen();
        let color_bob: Color = rng.gen();
        let bob_value = rng.gen();

        let service_config = Config {
            chain_conf: ChainConfig {
                initial_state: Some(StateConfig {
                    coins: Some(vec![
                        CoinConfig {
                            tx_id: alice_tx_id,
                            output_index: alice_output_index.map(|i| i as u64),
                            block_created: alice_block_created,
                            maturity: alice_maturity,
                            owner: alice,
                            amount: alice_value,
                            color: color_alice,
                        },
                        CoinConfig {
                            tx_id: None,
                            output_index: None,
                            block_created: None,
                            maturity: None,
                            owner: bob,
                            amount: bob_value,
                            color: color_bob,
                        },
                    ]),
                    height: alice_block_created.map(|h| {
                        let mut h: u32 = h.into();
                        // set starting height to something higher than alice's coin
                        h = h.saturating_add(rng.next_u32());
                        h.into()
                    }),
                    ..Default::default()
                }),
                ..ChainConfig::local_testnet()
            },
            ..Config::local_node()
        };

        let db = Database::default();
        FuelService::from_database(db.clone(), service_config)
            .await
            .unwrap();

        let alice_coins = get_coins(&db, alice);
        let bob_coins = get_coins(&db, bob)
            .into_iter()
            .map(|(_, coin)| coin)
            .collect_vec();

        assert!(matches!(
            alice_coins.as_slice(),
            &[(utxo_id, Coin {
                owner,
                amount,
                color,
                block_created,
                maturity,
                ..
            })] if utxo_id == alice_utxo_id
            && owner == alice
            && amount == alice_value
            && color == color_alice
            && block_created == alice_block_created.unwrap()
            && maturity == alice_maturity.unwrap(),
        ));
        assert!(matches!(
            bob_coins.as_slice(),
            &[Coin {
                owner,
                amount,
                color,
                ..
            }] if owner == bob
            && amount == bob_value
            && color == color_bob
        ));
    }

    #[tokio::test]
    async fn config_state_initializes_contract_state() {
        let mut rng = StdRng::seed_from_u64(10);

        let test_key: Bytes32 = rng.gen();
        let test_value: Bytes32 = rng.gen();
        let state = vec![(test_key, test_value)];
        let salt: Salt = rng.gen();
        let contract = Contract::from(Opcode::RET(0x10).to_bytes().to_vec());
        let root = contract.root();
        let id = contract.id(&salt, &root);

        let service_config = Config {
            chain_conf: ChainConfig {
                initial_state: Some(StateConfig {
                    contracts: Some(vec![ContractConfig {
                        code: contract.into(),
                        salt,
                        state: Some(state),
                        balances: None,
                    }]),
                    ..Default::default()
                }),
                ..ChainConfig::local_testnet()
            },
            ..Config::local_node()
        };

        let db = Database::default();
        FuelService::from_database(db.clone(), service_config)
            .await
            .unwrap();

        let ret = MerkleStorage::<ContractId, Bytes32, Bytes32>::get(&db, &id, &test_key)
            .unwrap()
            .expect("Expect a state entry to exist with test_key")
            .into_owned();

        assert_eq!(test_value, ret)
    }

    #[tokio::test]
    async fn config_state_initializes_contract_balance() {
        let mut rng = StdRng::seed_from_u64(10);

        let test_color: Color = rng.gen();
        let test_balance: u64 = rng.next_u64();
        let balances = vec![(test_color, test_balance)];
        let salt: Salt = rng.gen();
        let contract = Contract::from(Opcode::RET(0x10).to_bytes().to_vec());
        let root = contract.root();
        let id = contract.id(&salt, &root);

        let service_config = Config {
            chain_conf: ChainConfig {
                initial_state: Some(StateConfig {
                    contracts: Some(vec![ContractConfig {
                        code: contract.into(),
                        salt,
                        state: None,
                        balances: Some(balances),
                    }]),
                    ..Default::default()
                }),
                ..ChainConfig::local_testnet()
            },
            ..Config::local_node()
        };

        let db = Database::default();
        FuelService::from_database(db.clone(), service_config)
            .await
            .unwrap();

        let ret = MerkleStorage::<ContractId, Color, Word>::get(&db, &id, &test_color)
            .unwrap()
            .expect("Expected a balance to be present")
            .into_owned();

        assert_eq!(test_balance, ret)
    }

    fn get_coins(db: &Database, owner: Address) -> Vec<(UtxoId, Coin)> {
        db.owned_coins(owner, None, None)
            .map(|r| {
                r.and_then(|coin_id| {
                    Storage::<UtxoId, Coin>::get(db, &coin_id)
                        .map_err(Into::into)
                        .map(|v| (coin_id, v.unwrap().into_owned()))
                })
            })
            .try_collect()
            .unwrap()
    }
}