use crate::transaction::{
    field::{
        GasLimit, GasPrice, Inputs, Maturity, Outputs, ReceiptsRoot, Script as ScriptField, ScriptData, Witnesses,
    },
    metadata::CommonMetadata,
    validity::{check_common_part, FormatValidityChecks},
    Chargeable,
};
use crate::{CheckError, ConsensusParameters, Input, Output, Witness};
use derivative::Derivative;
use fuel_types::bytes::{SizedBytes, WORD_SIZE};
use fuel_types::{bytes, fmt_truncated_hex, Bytes32, Word};

#[cfg(feature = "std")]
use std::io;

#[cfg(feature = "alloc")]
use alloc::vec::Vec;

#[cfg(feature = "std")]
use fuel_types::bytes::SerializableVec;

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub(crate) struct ScriptMetadata {
    pub common: CommonMetadata,
    pub script_data_offset: usize,
}

#[derive(Clone, Derivative)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[derivative(Eq, PartialEq, Hash, Debug)]
pub struct Script {
    pub(crate) gas_price: Word,
    pub(crate) gas_limit: Word,
    pub(crate) maturity: Word,
    #[derivative(Debug(format_with = "fmt_truncated_hex::<16>"))]
    pub(crate) script: Vec<u8>,
    #[derivative(Debug(format_with = "fmt_truncated_hex::<16>"))]
    pub(crate) script_data: Vec<u8>,
    pub(crate) inputs: Vec<Input>,
    pub(crate) outputs: Vec<Output>,
    pub(crate) witnesses: Vec<Witness>,
    pub(crate) receipts_root: Bytes32,
    #[cfg_attr(feature = "serde", serde(skip))]
    #[derivative(PartialEq = "ignore", Hash = "ignore")]
    pub(crate) metadata: Option<ScriptMetadata>,
}

impl Default for Script {
    fn default() -> Self {
        // Create a valid transaction with a single return instruction
        //
        // The Return op is mandatory for the execution of any context
        let script = fuel_asm::op::ret(0x10).to_bytes().to_vec();

        Self {
            gas_price: Default::default(),
            gas_limit: ConsensusParameters::DEFAULT.max_gas_per_tx,
            maturity: Default::default(),
            script,
            script_data: Default::default(),
            inputs: Default::default(),
            outputs: Default::default(),
            witnesses: Default::default(),
            receipts_root: Default::default(),
            metadata: None,
        }
    }
}

#[cfg(feature = "std")]
impl crate::UniqueIdentifier for Script {
    fn id(&self) -> Bytes32 {
        if let Some(ScriptMetadata {
            common: CommonMetadata { id, .. },
            ..
        }) = self.metadata
        {
            return id;
        }

        let mut clone = self.clone();

        // Empties fields that should be zero during the signing.
        *clone.receipts_root_mut() = Default::default();
        clone.inputs_mut().iter_mut().for_each(Input::prepare_sign);
        clone.outputs_mut().iter_mut().for_each(Output::prepare_sign);
        clone.witnesses_mut().clear();

        fuel_crypto::Hasher::hash(clone.to_bytes().as_slice())
    }
}

impl Chargeable for Script {
    fn price(&self) -> Word {
        *GasPrice::gas_price(self)
    }

    fn limit(&self) -> Word {
        *GasLimit::gas_limit(self)
    }

    #[inline(always)]
    fn metered_bytes_size(&self) -> usize {
        // Just use the default serialized size for now until
        // the compressed representation for accounting purposes
        // is defined. Witness data should still be excluded.
        self.witnesses_offset()
    }
}

impl FormatValidityChecks for Script {
    #[cfg(feature = "std")]
    fn check_signatures(&self) -> Result<(), CheckError> {
        use crate::UniqueIdentifier;

        let id = self.id();

        self.inputs()
            .iter()
            .enumerate()
            .try_for_each(|(index, input)| input.check_signature(index, &id, &self.witnesses))?;

        Ok(())
    }

    fn check_without_signatures(&self, block_height: Word, parameters: &ConsensusParameters) -> Result<(), CheckError> {
        check_common_part(self, block_height, parameters)?;

        if self.script.len() > parameters.max_script_length as usize {
            Err(CheckError::TransactionScriptLength)?;
        }

        if self.script_data.len() > parameters.max_script_data_length as usize {
            Err(CheckError::TransactionScriptDataLength)?;
        }

        self.outputs
            .iter()
            .enumerate()
            .try_for_each(|(index, output)| match output {
                Output::ContractCreated { .. } => Err(CheckError::TransactionScriptOutputContractCreated { index }),
                _ => Ok(()),
            })?;

        Ok(())
    }
}

#[cfg(feature = "std")]
impl crate::Cacheable for Script {
    fn is_computed(&self) -> bool {
        self.metadata.is_some()
    }

    fn precompute(&mut self) {
        self.metadata = None;
        self.metadata = Some(ScriptMetadata {
            common: CommonMetadata::compute(self),
            script_data_offset: self.script_data_offset(),
        });
    }
}

impl SizedBytes for Script {
    fn serialized_size(&self) -> usize {
        self.witnesses_offset() + self.witnesses().iter().map(|w| w.serialized_size()).sum::<usize>()
    }
}

mod field {
    use super::*;

    impl GasPrice for Script {
        #[inline(always)]
        fn gas_price(&self) -> &Word {
            &self.gas_price
        }

        #[inline(always)]
        fn gas_price_mut(&mut self) -> &mut Word {
            &mut self.gas_price
        }

        #[inline(always)]
        fn gas_price_offset_static() -> usize {
            WORD_SIZE /* `Transaction` enum discriminant */
        }
    }

    impl GasLimit for Script {
        #[inline(always)]
        fn gas_limit(&self) -> &Word {
            &self.gas_limit
        }

        #[inline(always)]
        fn gas_limit_mut(&mut self) -> &mut Word {
            &mut self.gas_limit
        }

        #[inline(always)]
        fn gas_limit_offset_static() -> usize {
            Self::gas_price_offset_static() + WORD_SIZE
        }
    }

    impl Maturity for Script {
        #[inline(always)]
        fn maturity(&self) -> &Word {
            &self.maturity
        }

        #[inline(always)]
        fn maturity_mut(&mut self) -> &mut Word {
            &mut self.maturity
        }

        #[inline(always)]
        fn maturity_offset_static() -> usize {
            Self::gas_limit_offset_static() + WORD_SIZE
        }
    }

    impl ReceiptsRoot for Script {
        #[inline(always)]
        fn receipts_root(&self) -> &Bytes32 {
            &self.receipts_root
        }

        #[inline(always)]
        fn receipts_root_mut(&mut self) -> &mut Bytes32 {
            &mut self.receipts_root
        }

        #[inline(always)]
        fn receipts_root_offset_static() -> usize {
            Self::maturity_offset_static() + WORD_SIZE
                + WORD_SIZE // Script size
                + WORD_SIZE // Script data size
                + WORD_SIZE // Inputs size
                + WORD_SIZE // Outputs size
                + WORD_SIZE // Witnesses size
        }
    }

    impl ScriptField for Script {
        #[inline(always)]
        fn script(&self) -> &Vec<u8> {
            &self.script
        }

        #[inline(always)]
        fn script_mut(&mut self) -> &mut Vec<u8> {
            &mut self.script
        }

        #[inline(always)]
        fn script_offset_static() -> usize {
            Self::receipts_root_offset_static() + Bytes32::LEN // Receipts root
        }
    }

    impl ScriptData for Script {
        #[inline(always)]
        fn script_data(&self) -> &Vec<u8> {
            &self.script_data
        }

        #[inline(always)]
        fn script_data_mut(&mut self) -> &mut Vec<u8> {
            &mut self.script_data
        }

        #[inline(always)]
        fn script_data_offset(&self) -> usize {
            if let Some(ScriptMetadata { script_data_offset, .. }) = &self.metadata {
                return *script_data_offset;
            }

            self.script_offset() + bytes::padded_len(self.script.as_slice())
        }
    }

    impl Inputs for Script {
        #[inline(always)]
        fn inputs(&self) -> &Vec<Input> {
            &self.inputs
        }

        #[inline(always)]
        fn inputs_mut(&mut self) -> &mut Vec<Input> {
            &mut self.inputs
        }

        #[inline(always)]
        fn inputs_offset(&self) -> usize {
            if let Some(ScriptMetadata {
                common: CommonMetadata { inputs_offset, .. },
                ..
            }) = &self.metadata
            {
                return *inputs_offset;
            }

            self.script_data_offset() + bytes::padded_len(self.script_data.as_slice())
        }

        #[inline(always)]
        fn inputs_offset_at(&self, idx: usize) -> Option<usize> {
            if let Some(ScriptMetadata {
                common: CommonMetadata { inputs_offset_at, .. },
                ..
            }) = &self.metadata
            {
                return inputs_offset_at.get(idx).cloned();
            }

            if idx < self.inputs.len() {
                Some(
                    self.inputs_offset()
                        + self
                            .inputs()
                            .iter()
                            .take(idx)
                            .map(|i| i.serialized_size())
                            .sum::<usize>(),
                )
            } else {
                None
            }
        }

        #[inline(always)]
        fn inputs_predicate_offset_at(&self, idx: usize) -> Option<(usize, usize)> {
            if let Some(ScriptMetadata {
                common:
                    CommonMetadata {
                        inputs_predicate_offset_at,
                        ..
                    },
                ..
            }) = &self.metadata
            {
                return inputs_predicate_offset_at.get(idx).cloned().unwrap_or(None);
            }

            self.inputs().get(idx).and_then(|input| {
                input
                    .predicate_offset()
                    .and_then(|predicate| self.inputs_offset_at(idx).map(|inputs| inputs + predicate))
                    .zip(input.predicate_len().map(bytes::padded_len_usize))
            })
        }
    }

    impl Outputs for Script {
        #[inline(always)]
        fn outputs(&self) -> &Vec<Output> {
            &self.outputs
        }

        #[inline(always)]
        fn outputs_mut(&mut self) -> &mut Vec<Output> {
            &mut self.outputs
        }

        #[inline(always)]
        fn outputs_offset(&self) -> usize {
            if let Some(ScriptMetadata {
                common: CommonMetadata { outputs_offset, .. },
                ..
            }) = &self.metadata
            {
                return *outputs_offset;
            }

            self.inputs_offset() + self.inputs().iter().map(|i| i.serialized_size()).sum::<usize>()
        }

        #[inline(always)]
        fn outputs_offset_at(&self, idx: usize) -> Option<usize> {
            if let Some(ScriptMetadata {
                common: CommonMetadata { outputs_offset_at, .. },
                ..
            }) = &self.metadata
            {
                return outputs_offset_at.get(idx).cloned();
            }

            if idx < self.outputs.len() {
                Some(
                    self.outputs_offset()
                        + self
                            .outputs()
                            .iter()
                            .take(idx)
                            .map(|i| i.serialized_size())
                            .sum::<usize>(),
                )
            } else {
                None
            }
        }
    }

    impl Witnesses for Script {
        #[inline(always)]
        fn witnesses(&self) -> &Vec<Witness> {
            &self.witnesses
        }

        #[inline(always)]
        fn witnesses_mut(&mut self) -> &mut Vec<Witness> {
            &mut self.witnesses
        }

        #[inline(always)]
        fn witnesses_offset(&self) -> usize {
            if let Some(ScriptMetadata {
                common: CommonMetadata { witnesses_offset, .. },
                ..
            }) = &self.metadata
            {
                return *witnesses_offset;
            }

            self.outputs_offset() + self.outputs().iter().map(|i| i.serialized_size()).sum::<usize>()
        }

        #[inline(always)]
        fn witnesses_offset_at(&self, idx: usize) -> Option<usize> {
            if let Some(ScriptMetadata {
                common: CommonMetadata {
                    witnesses_offset_at, ..
                },
                ..
            }) = &self.metadata
            {
                return witnesses_offset_at.get(idx).cloned();
            }

            if idx < self.witnesses.len() {
                Some(
                    self.witnesses_offset()
                        + self
                            .witnesses()
                            .iter()
                            .take(idx)
                            .map(|i| i.serialized_size())
                            .sum::<usize>(),
                )
            } else {
                None
            }
        }
    }
}

#[cfg(feature = "std")]
impl io::Read for Script {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        let n = self.serialized_size();
        if buf.len() < n {
            return Err(bytes::eof());
        }

        let buf = bytes::store_number_unchecked(buf, crate::TransactionRepr::Script as Word);
        let Script {
            gas_price,
            gas_limit,
            maturity,
            receipts_root,
            script,
            script_data,
            inputs,
            outputs,
            witnesses,
            ..
        } = self;

        let mut buf = {
            let buf = bytes::store_number_unchecked(buf, *gas_price);
            let buf = bytes::store_number_unchecked(buf, *gas_limit);
            let buf = bytes::store_number_unchecked(buf, *maturity);
            let buf = bytes::store_number_unchecked(buf, script.len() as Word);
            let buf = bytes::store_number_unchecked(buf, script_data.len() as Word);
            let buf = bytes::store_number_unchecked(buf, inputs.len() as Word);
            let buf = bytes::store_number_unchecked(buf, outputs.len() as Word);
            let buf = bytes::store_number_unchecked(buf, witnesses.len() as Word);
            let buf = bytes::store_array_unchecked(buf, receipts_root);

            let (_, buf) = bytes::store_raw_bytes(buf, script.as_slice())?;
            let (_, buf) = bytes::store_raw_bytes(buf, script_data.as_slice())?;

            buf
        };

        for input in self.inputs.iter_mut() {
            let input_len = input.read(buf)?;
            buf = &mut buf[input_len..];
        }

        for output in self.outputs.iter_mut() {
            let output_len = output.read(buf)?;
            buf = &mut buf[output_len..];
        }

        for witness in self.witnesses.iter_mut() {
            let witness_len = witness.read(buf)?;
            buf = &mut buf[witness_len..];
        }

        Ok(n)
    }
}

#[cfg(feature = "std")]
impl io::Write for Script {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        let mut n = crate::consts::TRANSACTION_SCRIPT_FIXED_SIZE;
        if buf.len() < n {
            return Err(bytes::eof());
        }

        let (identifier, buf): (Word, _) = unsafe { bytes::restore_number_unchecked(buf) };
        let identifier = crate::TransactionRepr::try_from(identifier)?;
        if identifier != crate::TransactionRepr::Script {
            return Err(io::Error::new(
                io::ErrorKind::InvalidData,
                "The provided identifier to the `Script` is invalid!",
            ));
        }

        // Safety: buffer size is checked
        let (gas_price, buf) = unsafe { bytes::restore_number_unchecked(buf) };
        let (gas_limit, buf) = unsafe { bytes::restore_number_unchecked(buf) };
        let (maturity, buf) = unsafe { bytes::restore_number_unchecked(buf) };
        let (script_len, buf) = unsafe { bytes::restore_usize_unchecked(buf) };
        let (script_data_len, buf) = unsafe { bytes::restore_usize_unchecked(buf) };
        let (inputs_len, buf) = unsafe { bytes::restore_usize_unchecked(buf) };
        let (outputs_len, buf) = unsafe { bytes::restore_usize_unchecked(buf) };
        let (witnesses_len, buf) = unsafe { bytes::restore_usize_unchecked(buf) };
        let (receipts_root, buf) = unsafe { bytes::restore_array_unchecked(buf) };

        let receipts_root = receipts_root.into();

        let (size, script, buf) = bytes::restore_raw_bytes(buf, script_len)?;
        n += size;

        let (size, script_data, mut buf) = bytes::restore_raw_bytes(buf, script_data_len)?;
        n += size;

        let mut inputs = vec![Input::default(); inputs_len];
        for input in inputs.iter_mut() {
            let input_len = input.write(buf)?;
            buf = &buf[input_len..];
            n += input_len;
        }

        let mut outputs = vec![Output::default(); outputs_len];
        for output in outputs.iter_mut() {
            let output_len = output.write(buf)?;
            buf = &buf[output_len..];
            n += output_len;
        }

        let mut witnesses = vec![Witness::default(); witnesses_len];
        for witness in witnesses.iter_mut() {
            let witness_len = witness.write(buf)?;
            buf = &buf[witness_len..];
            n += witness_len;
        }

        *self = Script {
            gas_price,
            gas_limit,
            maturity,
            receipts_root,
            script,
            script_data,
            inputs,
            outputs,
            witnesses,
            metadata: None,
        };

        Ok(n)
    }

    fn flush(&mut self) -> io::Result<()> {
        self.inputs.iter_mut().try_for_each(|input| input.flush())?;
        self.outputs.iter_mut().try_for_each(|output| output.flush())?;
        self.witnesses.iter_mut().try_for_each(|witness| witness.flush())?;

        Ok(())
    }
}