use std::{str::FromStr, time::Instant};

use serde::{Deserialize, Serialize};

use crate::*;
use alloy_primitives::keccak256;
#[cfg(feature = "resolc")]
use alloy_primitives::Address;
#[cfg(feature = "resolc")]
use resolc::test_utils::*;
#[cfg(feature = "resolc")]
use revive_differential::{Evm, EvmLog};

const SPEC_MARKER_BEGIN: &str = "/* runner.json";
const SPEC_MARKER_END: &str = "*/";

/// An action to perform in a contract test
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum SpecsAction {
    /// Instantiate a contract
    Instantiate {
        #[serde(default)]
        origin: TestAddress,
        #[serde(default)]
        value: Balance,
        #[serde(default)]
        gas_limit: Option<Weight>,
        #[serde(default)]
        storage_deposit_limit: Option<Balance>,
        #[serde(default)]
        code: Code,
        #[serde(default, with = "hex::serde")]
        data: Vec<u8>,
        #[serde(default, with = "hex::serde")]
        salt: OptionalHex<[u8; 32]>,
    },
    /// Upload contract code without calling the constructor
    Upload {
        #[serde(default)]
        origin: TestAddress,
        #[serde(default)]
        code: Code,
        #[serde(default)]
        storage_deposit_limit: Option<Balance>,
    },
    /// Call a contract
    Call {
        #[serde(default)]
        origin: TestAddress,
        dest: TestAddress,
        #[serde(default)]
        value: Balance,
        #[serde(default)]
        gas_limit: Option<Weight>,
        #[serde(default)]
        storage_deposit_limit: Option<Balance>,
        #[serde(default, with = "hex::serde")]
        data: Vec<u8>,
    },
    /// Verify the result of the last call, omitting this will simply ensure the last call was successful
    VerifyCall(VerifyCallExpectation),
    /// Verify the balance of an account
    VerifyBalance {
        origin: TestAddress,
        expected: Balance,
    },
    /// Verify the storage of a contract
    VerifyStorage {
        contract: TestAddress,
        #[serde(with = "hex::serde")]
        key: [u8; 32],
        #[serde(default, with = "hex::serde")]
        expected: [u8; 32],
    },
}

#[cfg(feature = "solidity")]
impl SpecsAction {
    /// Derive verification actions from the EVM output log
    pub fn derive_verification(
        log: &EvmLog,
        address_evm: Address,
        account_pvm: TestAddress,
    ) -> Vec<Self> {
        let account = log
            .state_dump
            .accounts
            .get(&address_evm)
            .unwrap_or_else(|| panic!("account {address_evm} not in state dump"));

        let mut actions = vec![
            Self::VerifyCall(VerifyCallExpectation {
                gas_consumed: None,
                success: log.output.run_success(),
                output: log.output.output.to_vec().into(),
            }),
            Self::VerifyBalance {
                origin: account_pvm.clone(),
                expected: account
                    .balance
                    .try_into()
                    .expect("balance should fit into u128"),
            },
        ];

        let Some(storage) = &account.storage else {
            return actions;
        };

        for (key, expected) in storage {
            actions.push(Self::VerifyStorage {
                contract: account_pvm.clone(),
                key: **key,
                expected: **expected,
            });
        }

        actions
    }
}

#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq)]
pub enum TestAddress {
    /// The ALICE account
    #[default]
    Alice,
    /// The BOB account
    Bob,
    /// The CHARLIE account
    Charlie,
    /// AccountID that was created during the nth call in this run.
    Instantiated(usize),
    /// Arbitrary AccountID
    AccountId(H160),
}

impl TestAddress {
    fn to_eth_addr(&self, results: &[CallResult]) -> H160 {
        match self {
            TestAddress::Alice => ALICE,
            TestAddress::Bob => BOB,
            TestAddress::Charlie => CHARLIE,
            TestAddress::AccountId(account_id) => *account_id,
            TestAddress::Instantiated(n) => match results
                .get(*n)
                .expect("should provide valid index into call results")
            {
                CallResult::Exec { .. } => panic!("call #{n} should be an instantiation"),
                CallResult::Instantiate { result, .. } => {
                    result.result.as_ref().expect("call #{n} reverted").addr
                }
            },
        }
    }

    fn to_account_id(&self, results: &[CallResult]) -> AccountId32 {
        AccountId::to_account_id(&self.to_eth_addr(results))
    }
}

impl FromStr for TestAddress {
    type Err = &'static str;

    fn from_str(value: &str) -> Result<Self, Self::Err> {
        value.try_into()
    }
}

impl TryFrom<&str> for TestAddress {
    type Error = &'static str;

    fn try_from(value: &str) -> Result<Self, Self::Error> {
        match value {
            "alice" => Ok(Self::Alice),
            "bob" => Ok(Self::Bob),
            "charlie" => Ok(Self::Charlie),
            value => {
                if let Ok(value) = value.parse() {
                    return Ok(Self::Instantiated(value));
                }

                if let Ok(value) = hex::decode(value) {
                    if value.len() == 20 {
                        return Ok(Self::AccountId(H160(value.try_into().unwrap())));
                    }
                }

                Err("can not parse into test address")
            }
        }
    }
}

/// Specs for a contract test
#[derive(Clone, Debug, Serialize, Deserialize)]
#[serde(default)]
pub struct Specs {
    /// Interpret EVM bytecode and assert output, storage and events
    #[serde(default)]
    pub differential: bool,
    /// List of endowments at genesis
    pub balances: Vec<(H160, Balance)>,
    /// List of actions to perform
    pub actions: Vec<SpecsAction>,
}

impl Default for Specs {
    fn default() -> Self {
        Self {
            differential: false,
            balances: vec![
                (ALICE, 1_000_000_000),
                (BOB, 1_000_000_000),
                (CHARLIE, 1_000_000_000),
            ],
            actions: Default::default(),
        }
    }
}

impl Specs {
    /// Get the list of actions to perform
    /// A default [`SpecAction::VerifyCall`] is injected after each Instantiate or Call action when
    /// missing and not in differential mode
    pub fn actions(&self) -> Vec<SpecsAction> {
        self.actions
            .iter()
            .enumerate()
            .flat_map(|(index, item)| {
                let next_item = self.actions.get(index + 1);
                if matches!(
                    item,
                    SpecsAction::Instantiate { .. } | SpecsAction::Call { .. }
                ) && !matches!(next_item, Some(SpecsAction::VerifyCall { .. }))
                    && !self.differential
                {
                    return vec![
                        item.clone(),
                        SpecsAction::VerifyCall(VerifyCallExpectation::default()),
                    ];
                }
                vec![item.clone()]
            })
            .collect()
    }

    /// Helper to allow not specifying the code bytes or path directly in the runner.json
    /// - Replace `Code::Bytes(bytes)` if `bytes` are empty: read `contract_file`
    /// - Replace `Code::Solidity{ path, ..}` if `path` is not provided: replace `path` with `contract_file`
    #[allow(unused_variables)]
    pub fn replace_empty_code(&mut self, contract_name: &str, contract_path: &str) {
        for action in self.actions.iter_mut() {
            let code = match action {
                SpecsAction::Instantiate { code, .. } | SpecsAction::Upload { code, .. } => code,
                _ => continue,
            };

            match code {
                #[cfg(feature = "resolc")]
                Code::Bytes(bytes) if bytes.is_empty() => {
                    let contract_source = match std::fs::read_to_string(contract_path) {
                        Err(err) => panic!("unable to read {contract_path}: {err}"),
                        Ok(solidity) => solidity,
                    };
                    *bytes = compile_blob(contract_name, &contract_source)
                }
                #[cfg(not(feature = "resolc"))]
                Code::Bytes(_) => panic!("{NO_SOLIDITY_FRONTEND}"),
                #[cfg(feature = "resolc")]
                Code::Solidity { path, .. } if path.is_none() => *path = Some(contract_path.into()),
                _ => continue,
            }
        }
    }

    /// Run a contract test
    /// The test takes a [`Specs`] and executes the actions in order
    pub fn run(self) -> Vec<CallResult> {
        if self.differential {
            #[cfg(not(feature = "solidity"))]
            panic!("{NO_SOLIDITY_FRONTEND}");
            #[cfg(feature = "solidity")]
            self.run_on_evm()
        } else {
            self
        }
        .run_on_pallet()
    }

    #[cfg(feature = "solidity")]
    fn run_on_evm(self) -> Self {
        let mut derived_specs = Self {
            actions: vec![],
            ..self
        };

        let mut evm = Evm::default();
        let mut deployed_accounts = vec![];

        for action in self.actions {
            derived_specs.actions.push(action.clone());

            use specs::SpecsAction::*;
            match action {
                Instantiate {
                    origin,
                    value,
                    gas_limit,
                    code,
                    data,
                    salt,
                    ..
                } => {
                    let Code::Solidity {
                        path: Some(path),
                        solc_optimizer,
                        contract,
                    } = code
                    else {
                        panic!("the differential runner requires Code::Solidity source");
                    };
                    assert!(
                        salt.0.is_none(),
                        "salt is not supported in differential mode"
                    );
                    assert_eq!(
                        origin,
                        TestAddress::default(),
                        "configuring the origin is not supported in differential mode"
                    );

                    let deploy_code = match std::fs::read_to_string(&path) {
                        Ok(solidity_source) => hex::encode(compile_evm_deploy_code(
                            &contract,
                            &solidity_source,
                            solc_optimizer.unwrap_or(true),
                        )),
                        Err(err) => panic!(
                            "failed to read solidity source\n .  path: '{}'\n .   error: {:?}",
                            path.display(),
                            err
                        ),
                    };
                    let mut vm = evm
                        .code_blob(deploy_code.as_bytes().to_vec())
                        .sender(origin.to_eth_addr(&[]).0.into())
                        .deploy(true);
                    if !data.is_empty() {
                        vm = vm.input(data.into());
                    }
                    if value > 0 {
                        vm = vm.value(value);
                    }
                    if let Some(gas) = gas_limit {
                        vm = vm.gas(gas.ref_time());
                    }
                    let mut log = vm.run();
                    log.output.output = Default::default(); // PVM will not have constructor output
                    let deployed_account = log.account_deployed.expect("no account was created");
                    let account_pvm = TestAddress::Instantiated(deployed_accounts.len());
                    deployed_accounts.push(deployed_account);
                    derived_specs
                        .actions
                        .append(&mut SpecsAction::derive_verification(
                            &log,
                            deployed_account,
                            account_pvm,
                        ));
                    evm = Evm::from_genesis(log.state_dump.into());
                }
                Call {
                    origin,
                    dest,
                    value,
                    gas_limit,
                    data,
                    ..
                } => {
                    assert_eq!(
                        origin,
                        TestAddress::default(),
                        "configuring the origin is not supported in differential mode"
                    );
                    let TestAddress::Instantiated(n) = dest else {
                        panic!("the differential runner requires TestAccountId::Instantiated(n) as dest");
                    };
                    let address = deployed_accounts
                        .get(n)
                        .unwrap_or_else(|| panic!("no account at index {n} "));
                    let mut vm = evm
                        .receiver(*address)
                        .sender(origin.to_eth_addr(&[]).0.into());
                    if !data.is_empty() {
                        vm = vm.input(data.into());
                    }
                    if value > 0 {
                        vm = vm.value(value);
                    }
                    if let Some(gas) = gas_limit {
                        vm = vm.gas(gas.ref_time());
                    }

                    let log = vm.run();
                    derived_specs
                        .actions
                        .append(&mut SpecsAction::derive_verification(&log, *address, dest));
                    evm = Evm::from_genesis(log.state_dump.into());
                }
                Upload { .. } => continue,
                other => derived_specs.actions.push(other),
            }
        }

        derived_specs
    }

    fn run_on_pallet(self) -> Vec<CallResult> {
        let mut results = vec![];

        ExtBuilder::default()
            .balance_genesis_config(self.balances.clone())
            .build()
            .execute_with(|| {
                use specs::SpecsAction::*;

                for action in self.actions() {
                    match action {
                        Instantiate {
                            origin,
                            value,
                            gas_limit,
                            storage_deposit_limit,
                            code,
                            data,
                            salt,
                        } => {
                            let code: pallet_revive::Code = code.into();
                            let code_hash = match code.clone() {
                                pallet_revive::Code::Existing(code_hash) => code_hash,
                                pallet_revive::Code::Upload(bytes) => {
                                    H256::from_slice(keccak256(&bytes).as_slice())
                                }
                            };
                            let origin = RuntimeOrigin::signed(origin.to_account_id(&results));
                            let time_start = Instant::now();
                            let result = Contracts::bare_instantiate(
                                origin,
                                value,
                                gas_limit.unwrap_or(GAS_LIMIT),
                                storage_deposit_limit.unwrap_or(DEPOSIT_LIMIT).into(),
                                code,
                                data,
                                salt.0,
                            );
                            results.push(CallResult::Instantiate {
                                result,
                                wall_time: time_start.elapsed(),
                                code_hash,
                            })
                        }
                        Upload {
                            origin,
                            code,
                            storage_deposit_limit,
                        } => Contracts::upload_code(
                            RuntimeOrigin::signed(origin.to_account_id(&results)),
                            match pallet_revive::Code::from(code) {
                                pallet_revive::Code::Existing(_) => continue,
                                pallet_revive::Code::Upload(bytes) => bytes,
                            },
                            storage_deposit_limit.unwrap_or(DEPOSIT_LIMIT),
                        )
                        .unwrap_or_else(|error| panic!("code upload failed: {error:?}")),
                        Call {
                            origin,
                            dest,
                            value,
                            gas_limit,
                            storage_deposit_limit,
                            data,
                        } => {
                            let time_start = Instant::now();
                            let result = Contracts::bare_call(
                                RuntimeOrigin::signed(origin.to_account_id(&results)),
                                dest.to_eth_addr(&results),
                                value,
                                gas_limit.unwrap_or(GAS_LIMIT),
                                storage_deposit_limit.unwrap_or(DEPOSIT_LIMIT).into(),
                                data,
                            );
                            results.push(CallResult::Exec {
                                result,
                                wall_time: time_start.elapsed(),
                            });
                        }
                        VerifyCall(expectation) => {
                            expectation.verify(results.last().expect("No call to verify"));
                        }
                        VerifyBalance { origin, expected } => {
                            let balance = Balances::usable_balance(origin.to_account_id(&results));
                            assert_eq!(balance, expected);
                        }
                        VerifyStorage {
                            contract,
                            key,
                            expected,
                        } => {
                            let address = contract.to_eth_addr(&results);
                            let Ok(value) = Contracts::get_storage(address, key) else {
                                panic!("error reading storage for address {address}");
                            };
                            let Some(value) = value else {
                                panic!("no value at {address} key 0x{}", hex::encode(key));
                            };
                            assert_eq!(value, expected, "at key 0x{}", hex::encode(key));
                        }
                    }
                }
            });

        results
    }

    pub fn from_comment(contract_name: &str, path: &str) -> Vec<Self> {
        let solidity = match std::fs::read_to_string(path) {
            Err(err) => panic!("unable to read {path}: {err}"),
            Ok(solidity) => solidity,
        };
        let mut json_string = String::with_capacity(solidity.len());
        let mut is_reading = false;
        let mut specs = Vec::new();

        for line in solidity.lines() {
            if line.starts_with(SPEC_MARKER_BEGIN) {
                is_reading = true;
                continue;
            }

            if is_reading {
                if line.starts_with(SPEC_MARKER_END) {
                    match serde_json::from_str::<Specs>(&json_string) {
                        Ok(mut spec) => {
                            spec.replace_empty_code(contract_name, path);
                            specs.push(spec);
                        }
                        Err(e) => panic!("invalid spec JSON: {e}"),
                    }
                    is_reading = false;
                    json_string.clear();
                    continue;
                }

                json_string.push_str(line)
            }
        }

        assert!(!specs.is_empty(), "source does not contain any test spec");

        specs
    }
}