// Copyright 2021-2022 IOTA Stiftung
// SPDX-License-Identifier: Apache-2.0

use alloc::vec::Vec;

use packable::Packable;

use crate::{
    address::Address,
    output::{
        feature::{verify_allowed_features, Feature, FeatureFlags, Features},
        unlock_condition::{verify_allowed_unlock_conditions, UnlockCondition, UnlockConditionFlags, UnlockConditions},
        NativeToken, NativeTokens, Output, OutputAmount, OutputBuilderAmount, OutputId, Rent, RentStructure,
    },
    semantic::{ConflictReason, ValidationContext},
    unlock::Unlock,
    Error,
};

///
#[derive(Clone)]
#[must_use]
pub struct BasicOutputBuilder {
    amount: OutputBuilderAmount,
    native_tokens: Vec<NativeToken>,
    unlock_conditions: Vec<UnlockCondition>,
    features: Vec<Feature>,
}

impl BasicOutputBuilder {
    /// Creates a [`BasicOutputBuilder`] with a provided amount.
    #[inline(always)]
    pub fn new_with_amount(amount: u64) -> Result<Self, Error> {
        Self::new(OutputBuilderAmount::Amount(
            amount.try_into().map_err(Error::InvalidOutputAmount)?,
        ))
    }

    /// Creates an [`BasicOutputBuilder`] with a provided rent structure.
    /// The amount will be set to the minimum storage deposit.
    #[inline(always)]
    pub fn new_with_minimum_storage_deposit(rent_structure: RentStructure) -> Result<Self, Error> {
        Self::new(OutputBuilderAmount::MinimumStorageDeposit(rent_structure))
    }

    fn new(amount: OutputBuilderAmount) -> Result<Self, Error> {
        Ok(Self {
            amount,
            native_tokens: Vec::new(),
            unlock_conditions: Vec::new(),
            features: Vec::new(),
        })
    }

    /// Sets the amount to the provided value.
    #[inline(always)]
    pub fn with_amount(mut self, amount: u64) -> Result<Self, Error> {
        self.amount = OutputBuilderAmount::Amount(amount.try_into().map_err(Error::InvalidOutputAmount)?);
        Ok(self)
    }

    /// Sets the amount to the minimum storage deposit.
    #[inline(always)]
    pub fn with_minimum_storage_deposit(mut self, rent_structure: RentStructure) -> Self {
        self.amount = OutputBuilderAmount::MinimumStorageDeposit(rent_structure);
        self
    }

    ///
    #[inline(always)]
    pub fn add_native_token(mut self, native_token: NativeToken) -> Self {
        self.native_tokens.push(native_token);
        self
    }

    ///
    #[inline(always)]
    pub fn with_native_tokens(mut self, native_tokens: impl IntoIterator<Item = NativeToken>) -> Self {
        self.native_tokens = native_tokens.into_iter().collect();
        self
    }

    ///
    #[inline(always)]
    pub fn add_unlock_condition(mut self, unlock_condition: UnlockCondition) -> Self {
        self.unlock_conditions.push(unlock_condition);
        self
    }

    ///
    #[inline(always)]
    pub fn with_unlock_conditions(mut self, unlock_conditions: impl IntoIterator<Item = UnlockCondition>) -> Self {
        self.unlock_conditions = unlock_conditions.into_iter().collect();
        self
    }

    ///
    pub fn replace_unlock_condition(mut self, unlock_condition: UnlockCondition) -> Result<Self, Error> {
        match self
            .unlock_conditions
            .iter_mut()
            .find(|u| u.kind() == unlock_condition.kind())
        {
            Some(u) => *u = unlock_condition,
            None => return Err(Error::CannotReplaceMissingField),
        }
        Ok(self)
    }

    ///
    #[inline(always)]
    pub fn add_feature(mut self, feature: Feature) -> Self {
        self.features.push(feature);
        self
    }

    ///
    #[inline(always)]
    pub fn with_features(mut self, features: impl IntoIterator<Item = Feature>) -> Self {
        self.features = features.into_iter().collect();
        self
    }

    ///
    pub fn replace_feature(mut self, feature: Feature) -> Result<Self, Error> {
        match self.features.iter_mut().find(|f| f.kind() == feature.kind()) {
            Some(f) => *f = feature,
            None => return Err(Error::CannotReplaceMissingField),
        }
        Ok(self)
    }

    ///
    pub fn finish(self) -> Result<BasicOutput, Error> {
        let unlock_conditions = UnlockConditions::new(self.unlock_conditions)?;

        verify_unlock_conditions::<true>(&unlock_conditions)?;

        let features = Features::new(self.features)?;

        verify_features::<true>(&features)?;

        let mut output = BasicOutput {
            amount: 1u64.try_into().map_err(Error::InvalidOutputAmount)?,
            native_tokens: NativeTokens::new(self.native_tokens)?,
            unlock_conditions,
            features,
        };

        output.amount = match self.amount {
            OutputBuilderAmount::Amount(amount) => amount,
            OutputBuilderAmount::MinimumStorageDeposit(rent_structure) => Output::Basic(output.clone())
                .rent_cost(&rent_structure)
                .try_into()
                .map_err(Error::InvalidOutputAmount)?,
        };

        Ok(output)
    }

    /// Finishes the [`BasicOutputBuilder`] into an [`Output`].
    pub fn finish_output(self) -> Result<Output, Error> {
        Ok(Output::Basic(self.finish()?))
    }
}

impl From<&BasicOutput> for BasicOutputBuilder {
    fn from(output: &BasicOutput) -> Self {
        BasicOutputBuilder {
            amount: OutputBuilderAmount::Amount(output.amount),
            native_tokens: output.native_tokens.to_vec(),
            unlock_conditions: output.unlock_conditions.to_vec(),
            features: output.features.to_vec(),
        }
    }
}

/// Describes a basic output with optional features.
#[derive(Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Packable)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[packable(unpack_error = Error)]
pub struct BasicOutput {
    // Amount of IOTA tokens held by the output.
    #[packable(unpack_error_with = Error::InvalidOutputAmount)]
    amount: OutputAmount,
    // Native tokens held by the output.
    native_tokens: NativeTokens,
    #[packable(verify_with = verify_unlock_conditions)]
    unlock_conditions: UnlockConditions,
    #[packable(verify_with = verify_features)]
    features: Features,
}

impl BasicOutput {
    /// The [`Output`](crate::output::Output) kind of an [`BasicOutput`].
    pub const KIND: u8 = 3;

    /// The set of allowed [`UnlockCondition`]s for an [`BasicOutput`].
    const ALLOWED_UNLOCK_CONDITIONS: UnlockConditionFlags = UnlockConditionFlags::ADDRESS
        .union(UnlockConditionFlags::STORAGE_DEPOSIT_RETURN)
        .union(UnlockConditionFlags::TIMELOCK)
        .union(UnlockConditionFlags::EXPIRATION);
    /// The set of allowed [`Feature`]s for an [`BasicOutput`].
    pub const ALLOWED_FEATURES: FeatureFlags = FeatureFlags::SENDER
        .union(FeatureFlags::METADATA)
        .union(FeatureFlags::TAG);

    /// Creates a new [`BasicOutput`] with a provided amount.
    #[inline(always)]
    pub fn new_with_amount(amount: u64) -> Result<Self, Error> {
        BasicOutputBuilder::new_with_amount(amount)?.finish()
    }

    /// Creates a new [`BasicOutput`] with a provided rent structure.
    /// The amount will be set to the minimum storage deposit.
    #[inline(always)]
    pub fn new_with_minimum_storage_deposit(rent_structure: RentStructure) -> Result<Self, Error> {
        BasicOutputBuilder::new_with_minimum_storage_deposit(rent_structure)?.finish()
    }

    /// Creates a new [`BasicOutputBuilder`] with a provided amount.
    #[inline(always)]
    pub fn build_with_amount(amount: u64) -> Result<BasicOutputBuilder, Error> {
        BasicOutputBuilder::new_with_amount(amount)
    }

    /// Creates a new [`BasicOutputBuilder`] with a provided rent structure.
    /// The amount will be set to the minimum storage deposit.
    #[inline(always)]
    pub fn build_with_minimum_storage_deposit(rent_structure: RentStructure) -> Result<BasicOutputBuilder, Error> {
        BasicOutputBuilder::new_with_minimum_storage_deposit(rent_structure)
    }

    ///
    #[inline(always)]
    pub fn amount(&self) -> u64 {
        self.amount.get()
    }

    ///
    #[inline(always)]
    pub fn native_tokens(&self) -> &NativeTokens {
        &self.native_tokens
    }

    ///
    #[inline(always)]
    pub fn unlock_conditions(&self) -> &UnlockConditions {
        &self.unlock_conditions
    }

    ///
    #[inline(always)]
    pub fn features(&self) -> &Features {
        &self.features
    }

    ///
    #[inline(always)]
    pub fn address(&self) -> &Address {
        // An BasicOutput must have an AddressUnlockCondition.
        self.unlock_conditions
            .address()
            .map(|unlock_condition| unlock_condition.address())
            .unwrap()
    }

    ///
    pub fn unlock(
        &self,
        _output_id: &OutputId,
        unlock: &Unlock,
        inputs: &[(OutputId, &Output)],
        context: &mut ValidationContext,
    ) -> Result<(), ConflictReason> {
        let locked_address = self
            .unlock_conditions()
            .locked_address(self.address(), context.milestone_timestamp);

        locked_address.unlock(unlock, inputs, context)
    }

    /// Returns the address of the unlock conditions if the output is a simple deposit.
    /// Simple deposit outputs are basic outputs with only an address unlock condition, no native tokens and no
    /// features. They are used to return storage deposits.
    pub fn simple_deposit_address(&self) -> Option<&Address> {
        if let [UnlockCondition::Address(address)] = self.unlock_conditions().as_ref() {
            if self.native_tokens.is_empty() && self.features.is_empty() {
                return Some(address.address());
            }
        }

        None
    }
}

fn verify_unlock_conditions<const VERIFY: bool>(unlock_conditions: &UnlockConditions) -> Result<(), Error> {
    if VERIFY {
        if unlock_conditions.address().is_none() {
            Err(Error::MissingAddressUnlockCondition)
        } else {
            verify_allowed_unlock_conditions(unlock_conditions, BasicOutput::ALLOWED_UNLOCK_CONDITIONS)
        }
    } else {
        Ok(())
    }
}

fn verify_features<const VERIFY: bool>(blocks: &Features) -> Result<(), Error> {
    if VERIFY {
        verify_allowed_features(blocks, BasicOutput::ALLOWED_FEATURES)
    } else {
        Ok(())
    }
}

#[cfg(feature = "dto")]
#[allow(missing_docs)]
pub mod dto {
    use serde::{Deserialize, Serialize};

    use super::*;
    use crate::{
        error::dto::DtoError,
        output::{
            dto::OutputBuilderAmountDto, feature::dto::FeatureDto, native_token::dto::NativeTokenDto,
            unlock_condition::dto::UnlockConditionDto,
        },
    };

    /// Describes a basic output.
    #[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
    pub struct BasicOutputDto {
        #[serde(rename = "type")]
        pub kind: u8,
        // Amount of IOTA tokens held by the output.
        pub amount: String,
        // Native tokens held by the output.
        #[serde(rename = "nativeTokens", skip_serializing_if = "Vec::is_empty", default)]
        pub native_tokens: Vec<NativeTokenDto>,
        #[serde(rename = "unlockConditions")]
        pub unlock_conditions: Vec<UnlockConditionDto>,
        #[serde(skip_serializing_if = "Vec::is_empty", default)]
        pub features: Vec<FeatureDto>,
    }

    impl From<&BasicOutput> for BasicOutputDto {
        fn from(value: &BasicOutput) -> Self {
            Self {
                kind: BasicOutput::KIND,
                amount: value.amount().to_string(),
                native_tokens: value.native_tokens().iter().map(Into::into).collect::<_>(),
                unlock_conditions: value.unlock_conditions().iter().map(Into::into).collect::<_>(),
                features: value.features().iter().map(Into::into).collect::<_>(),
            }
        }
    }

    impl TryFrom<&BasicOutputDto> for BasicOutput {
        type Error = DtoError;

        fn try_from(value: &BasicOutputDto) -> Result<Self, Self::Error> {
            let mut builder = BasicOutputBuilder::new_with_amount(
                value.amount.parse().map_err(|_| DtoError::InvalidField("amount"))?,
            )?;

            for t in &value.native_tokens {
                builder = builder.add_native_token(t.try_into()?);
            }

            for b in &value.unlock_conditions {
                builder = builder.add_unlock_condition(b.try_into()?);
            }

            for b in &value.features {
                builder = builder.add_feature(b.try_into()?);
            }

            Ok(builder.finish()?)
        }
    }

    impl BasicOutput {
        pub fn from_dtos(
            amount: OutputBuilderAmountDto,
            native_tokens: Option<Vec<NativeTokenDto>>,
            unlock_conditions: Vec<UnlockConditionDto>,
            features: Option<Vec<FeatureDto>>,
        ) -> Result<BasicOutput, DtoError> {
            let mut builder = match amount {
                OutputBuilderAmountDto::Amount(amount) => {
                    BasicOutputBuilder::new_with_amount(amount.parse().map_err(|_| DtoError::InvalidField("amount"))?)?
                }
                OutputBuilderAmountDto::MinimumStorageDeposit(rent_structure) => {
                    BasicOutputBuilder::new_with_minimum_storage_deposit(rent_structure)?
                }
            };

            if let Some(native_tokens) = native_tokens {
                let native_tokens = native_tokens
                    .iter()
                    .map(NativeToken::try_from)
                    .collect::<Result<Vec<NativeToken>, DtoError>>()?;
                builder = builder.with_native_tokens(native_tokens);
            }

            let unlock_conditions = unlock_conditions
                .iter()
                .map(UnlockCondition::try_from)
                .collect::<Result<Vec<UnlockCondition>, DtoError>>()?;
            builder = builder.with_unlock_conditions(unlock_conditions);

            if let Some(features) = features {
                let features = features
                    .iter()
                    .map(Feature::try_from)
                    .collect::<Result<Vec<Feature>, DtoError>>()?;
                builder = builder.with_features(features);
            }

            Ok(builder.finish()?)
        }
    }
}