// Written in 2020 by the rust-miniscript developers
// SPDX-License-Identifier: CC0-1.0

//! # Segwit Output Descriptors
//!
//! Implementation of Segwit Descriptors. Contains the implementation
//! of wsh, wpkh and sortedmulti inside wsh.

use core::fmt;
use std::fmt::Write;
use std::str::FromStr;

use elements::{self, secp256k1_zkp, Address, Script};

use super::checksum::verify_checksum;
use super::{SortedMultiVec, ELMTS_STR};
use crate::descriptor::checksum;
use crate::expression::{self, FromTree};
use crate::miniscript::context::{ScriptContext, ScriptContextError};
use crate::policy::{semantic, Liftable};
use crate::util::varint_len;
use crate::{
    elementssig_to_rawsig, Error, ForEachKey, Miniscript, MiniscriptKey, Satisfier, Segwitv0,
    ToPublicKey, TranslatePk, Translator,
};
/// A Segwitv0 wsh descriptor
#[derive(Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub struct Wsh<Pk: MiniscriptKey> {
    /// underlying miniscript
    inner: WshInner<Pk>,
}

impl<Pk: MiniscriptKey> Wsh<Pk> {
    /// Get the Inner
    pub fn into_inner(self) -> WshInner<Pk> {
        self.inner
    }

    /// Get a reference to inner
    pub fn as_inner(&self) -> &WshInner<Pk> {
        &self.inner
    }

    /// Create a new wsh descriptor
    pub fn new(ms: Miniscript<Pk, Segwitv0>) -> Result<Self, Error> {
        // do the top-level checks
        Segwitv0::top_level_checks(&ms)?;
        Ok(Self {
            inner: WshInner::Ms(ms),
        })
    }

    /// Create a new sortedmulti wsh descriptor
    pub fn new_sortedmulti(k: usize, pks: Vec<Pk>) -> Result<Self, Error> {
        // The context checks will be carried out inside new function for
        // sortedMultiVec
        Ok(Self {
            inner: WshInner::SortedMulti(SortedMultiVec::new(k, pks)?),
        })
    }

    /// Get the descriptor without the checksum and the el prefix
    pub fn to_string_no_el_pref(&self, f: &mut checksum::Formatter) -> fmt::Result {
        match self.inner {
            WshInner::SortedMulti(ref smv) => write!(f, "wsh({})", smv),
            WshInner::Ms(ref ms) => write!(f, "wsh({})", ms),
        }
    }

    /// Checks whether the descriptor is safe.
    pub fn sanity_check(&self) -> Result<(), Error> {
        match self.inner {
            WshInner::SortedMulti(ref smv) => smv.sanity_check()?,
            WshInner::Ms(ref ms) => ms.sanity_check()?,
        }
        Ok(())
    }

    /// Computes an upper bound on the difference between a non-satisfied
    /// `TxIn`'s `segwit_weight` and a satisfied `TxIn`'s `segwit_weight`
    ///
    /// Assumes all ECDSA signatures are 73 bytes, including push opcode and
    /// sighash suffix.
    ///
    /// # Errors
    /// When the descriptor is impossible to safisfy (ex: sh(OP_FALSE)).
    pub fn max_weight_to_satisfy(&self) -> Result<usize, Error> {
        let (redeem_script_size, max_sat_elems, max_sat_size) = match self.inner {
            WshInner::SortedMulti(ref smv) => (
                smv.script_size(),
                smv.max_satisfaction_witness_elements(),
                smv.max_satisfaction_size(),
            ),
            WshInner::Ms(ref ms) => (
                ms.script_size(),
                ms.max_satisfaction_witness_elements()?,
                ms.max_satisfaction_size()?,
            ),
        };
        // stack size varint difference between non-satisfied (0) and satisfied
        // `max_sat_elems` is inclusive of the "witness script" (redeem script)
        let stack_varint_diff = varint_len(max_sat_elems) - varint_len(0);

        Ok(stack_varint_diff + varint_len(redeem_script_size) + redeem_script_size + max_sat_size)
    }

    /// Computes an upper bound on the weight of a satisfying witness to the
    /// transaction.
    ///
    /// Assumes all ec-signatures are 73 bytes, including push opcode and
    /// sighash suffix. Includes the weight of the VarInts encoding the
    /// scriptSig and witness stack length.
    ///
    /// # Errors
    /// When the descriptor is impossible to safisfy (ex: sh(OP_FALSE)).
    #[deprecated(note = "use max_weight_to_satisfy instead")]
    pub fn max_satisfaction_weight(&self) -> Result<usize, Error> {
        let (script_size, max_sat_elems, max_sat_size) = match self.inner {
            WshInner::SortedMulti(ref smv) => (
                smv.script_size(),
                smv.max_satisfaction_witness_elements(),
                smv.max_satisfaction_size(),
            ),
            WshInner::Ms(ref ms) => (
                ms.script_size(),
                ms.max_satisfaction_witness_elements()?,
                ms.max_satisfaction_size()?,
            ),
        };
        Ok(4 +  // scriptSig length byte
            varint_len(script_size) +
            script_size +
            varint_len(max_sat_elems) +
            max_sat_size)
    }
}

#[rustfmt::skip]
impl_block_str!(
    Wsh<Pk>,
    // Constructor for creating inner wsh for the sh fragment
    pub(super) fn from_inner_tree(top: &expression::Tree<'_>, ) -> Result<Self, Error>
    {
        if top.name == "wsh" && top.args.len() == 1 {
            let top = &top.args[0];
            if top.name == "sortedmulti" {
                return Ok(Wsh {
                    inner: WshInner::SortedMulti(SortedMultiVec::from_tree(top)?),
                });
            }
            let sub = Miniscript::from_tree(top)?;
            Segwitv0::top_level_checks(&sub)?;
            Ok(Wsh {
                inner: WshInner::Ms(sub),
            })
        } else {
            Err(Error::Unexpected(format!(
                "{}({} args) while parsing wsh descriptor",
                top.name,
                top.args.len(),
            )))
        }
    }
);

impl<Pk: MiniscriptKey + ToPublicKey> Wsh<Pk> {
    /// Obtains the corresponding script pubkey for this descriptor.
    pub fn script_pubkey(&self) -> Script {
        self.inner_script().to_v0_p2wsh()
    }

    /// Obtains the corresponding script pubkey for this descriptor.
    pub fn address(
        &self,
        blinder: Option<secp256k1_zkp::PublicKey>,
        params: &'static elements::AddressParams,
    ) -> elements::Address {
        match self.inner {
            WshInner::SortedMulti(ref smv) => {
                elements::Address::p2wsh(&smv.encode(), blinder, params)
            }
            WshInner::Ms(ref ms) => elements::Address::p2wsh(&ms.encode(), blinder, params),
        }
    }

    /// Obtains the underlying miniscript for this descriptor.
    pub fn inner_script(&self) -> Script {
        match self.inner {
            WshInner::SortedMulti(ref smv) => smv.encode(),
            WshInner::Ms(ref ms) => ms.encode(),
        }
    }

    /// Obtains the pre bip-340 signature script code for this descriptor.
    pub fn ecdsa_sighash_script_code(&self) -> Script {
        self.inner_script()
    }

    /// Returns satisfying non-malleable witness and scriptSig with minimum
    /// weight to spend an output controlled by the given descriptor if it is
    /// possible to construct one using the `satisfier`.
    pub fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
    where
        S: Satisfier<Pk>,
    {
        let mut witness = match self.inner {
            WshInner::SortedMulti(ref smv) => smv.satisfy(satisfier)?,
            WshInner::Ms(ref ms) => ms.satisfy(satisfier)?,
        };
        let witness_script = self.inner_script();
        witness.push(witness_script.into_bytes());
        let script_sig = Script::new();
        Ok((witness, script_sig))
    }

    /// Returns satisfying, possibly malleable, witness and scriptSig with
    /// minimum weight to spend an output controlled by the given descriptor if
    /// it is possible to construct one using the `satisfier`.
    pub fn get_satisfaction_mall<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
    where
        S: Satisfier<Pk>,
    {
        let mut witness = match self.inner {
            WshInner::SortedMulti(ref smv) => smv.satisfy(satisfier)?,
            WshInner::Ms(ref ms) => ms.satisfy_malleable(satisfier)?,
        };
        witness.push(self.inner_script().into_bytes());
        let script_sig = Script::new();
        Ok((witness, script_sig))
    }
}

/// Wsh Inner
#[derive(Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub enum WshInner<Pk: MiniscriptKey> {
    /// Sorted Multi
    SortedMulti(SortedMultiVec<Pk, Segwitv0>),
    /// Wsh Miniscript
    // no extensions in regular wsh or shwsh
    // extensions are only supported in cov descriptors
    Ms(Miniscript<Pk, Segwitv0>),
}

impl<Pk: MiniscriptKey> Liftable<Pk> for Wsh<Pk> {
    fn lift(&self) -> Result<semantic::Policy<Pk>, Error> {
        match self.inner {
            WshInner::SortedMulti(ref smv) => smv.lift(),
            WshInner::Ms(ref ms) => ms.lift(),
        }
    }
}

impl_from_tree!(
    Wsh<Pk>,
    fn from_tree(top: &expression::Tree) -> Result<Self, Error> {
        if top.name == "elwsh" && top.args.len() == 1 {
            let top = &top.args[0];
            if top.name == "sortedmulti" {
                return Ok(Wsh {
                    inner: WshInner::SortedMulti(SortedMultiVec::from_tree(top)?),
                });
            }
            let sub = Miniscript::from_tree(top)?;
            Segwitv0::top_level_checks(&sub)?;
            Ok(Wsh {
                inner: WshInner::Ms(sub),
            })
        } else {
            Err(Error::Unexpected(format!(
                "{}({} args) while parsing wsh descriptor",
                top.name,
                top.args.len(),
            )))
        }
    }
);

impl<Pk: MiniscriptKey> fmt::Debug for Wsh<Pk> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self.inner {
            WshInner::SortedMulti(ref smv) => write!(f, "{}wsh({:?})", ELMTS_STR, smv),
            WshInner::Ms(ref ms) => write!(f, "{}wsh({:?})", ELMTS_STR, ms),
        }
    }
}

impl<Pk: MiniscriptKey> fmt::Display for Wsh<Pk> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let mut wrapped_f = checksum::Formatter::new(f);
        match self.inner {
            WshInner::SortedMulti(ref smv) => write!(wrapped_f, "{}wsh({})", ELMTS_STR, smv)?,
            WshInner::Ms(ref ms) => write!(wrapped_f, "{}wsh({})", ELMTS_STR, ms)?,
        }
        wrapped_f.write_checksum_if_not_alt()
    }
}

impl_from_str!(
    Wsh<Pk>,
    type Err = Error;,
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let desc_str = verify_checksum(s)?;
        let top = expression::Tree::from_str(desc_str)?;
        Wsh::<Pk>::from_tree(&top)
    }
);

impl<Pk: MiniscriptKey> ForEachKey<Pk> for Wsh<Pk> {
    fn for_each_key<'a, F: FnMut(&'a Pk) -> bool>(&'a self, pred: F) -> bool
    where
        Pk: 'a,
    {
        match self.inner {
            WshInner::SortedMulti(ref smv) => smv.for_each_key(pred),
            WshInner::Ms(ref ms) => ms.for_each_key(pred),
        }
    }
}

impl<P: MiniscriptKey, Q: MiniscriptKey> TranslatePk<P, Q> for Wsh<P> {
    type Output = Wsh<Q>;

    fn translate_pk<T, E>(&self, t: &mut T) -> Result<Self::Output, E>
    where
        T: Translator<P, Q, E>,
    {
        let inner = match self.inner {
            WshInner::SortedMulti(ref smv) => WshInner::SortedMulti(smv.translate_pk(t)?),
            WshInner::Ms(ref ms) => WshInner::Ms(ms.translate_pk(t)?),
        };
        Ok(Wsh { inner })
    }
}

/// A bare Wpkh descriptor at top level
#[derive(Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub struct Wpkh<Pk: MiniscriptKey> {
    /// underlying publickey
    pk: Pk,
}

impl<Pk: MiniscriptKey> Wpkh<Pk> {
    /// Create a new Wpkh descriptor
    pub fn new(pk: Pk) -> Result<Self, Error> {
        // do the top-level checks
        if pk.is_uncompressed() {
            Err(Error::ContextError(ScriptContextError::CompressedOnly(
                pk.to_string(),
            )))
        } else {
            Ok(Self { pk })
        }
    }

    /// Get the inner key
    pub fn into_inner(self) -> Pk {
        self.pk
    }

    /// Get the inner key
    pub fn as_inner(&self) -> &Pk {
        &self.pk
    }

    /// Get the descriptor without the checksum and no el prefix
    pub fn to_string_no_el_pref(&self, f: &mut checksum::Formatter) -> fmt::Result {
        write!(f, "wpkh({})", self.pk)
    }

    /// Checks whether the descriptor is safe.
    pub fn sanity_check(&self) -> Result<(), Error> {
        if self.pk.is_uncompressed() {
            Err(Error::ContextError(ScriptContextError::CompressedOnly(
                self.pk.to_string(),
            )))
        } else {
            Ok(())
        }
    }

    /// Computes an upper bound on the difference between a non-satisfied
    /// `TxIn`'s `segwit_weight` and a satisfied `TxIn`'s `segwit_weight`
    ///
    /// Assumes all ec-signatures are 73 bytes, including push opcode and
    /// sighash suffix.
    pub fn max_weight_to_satisfy(&self) -> usize {
        // stack items: <varint(sig+sigHash)> <sig(71)+sigHash(1)> <varint(pubkey)> <pubkey>
        let stack_items_size = 73 + Segwitv0::pk_len(&self.pk);
        // stackLen varint difference between non-satisfied (0) and satisfied
        let stack_varint_diff = varint_len(2) - varint_len(0);
        stack_varint_diff + stack_items_size
    }

    /// Computes an upper bound on the weight of a satisfying witness to the
    /// transaction.
    ///
    /// Assumes all ec-signatures are 73 bytes, including push opcode and
    /// sighash suffix. Includes the weight of the VarInts encoding the
    /// scriptSig and witness stack length.
    pub fn max_satisfaction_weight(&self) -> usize {
        4 + 1 + 73 + Segwitv0::pk_len(&self.pk)
    }

    // Parse a bitcoin style wpkh tree. Useful when parsing nested trees
    pub(super) fn from_inner_tree(top: &expression::Tree<'_>) -> Result<Self, Error>
    where
        Pk: FromStr,
        <Pk as FromStr>::Err: ToString,
    {
        if top.name == "wpkh" && top.args.len() == 1 {
            Ok(Wpkh::new(expression::terminal(&top.args[0], |pk| {
                Pk::from_str(pk)
            })?)?)
        } else {
            Err(Error::Unexpected(format!(
                "{}({} args) while parsing wpkh descriptor",
                top.name,
                top.args.len(),
            )))
        }
    }
}

impl<Pk: MiniscriptKey + ToPublicKey> Wpkh<Pk> {
    /// Obtains the corresponding script pubkey for this descriptor.
    pub fn script_pubkey(&self) -> Script {
        let addr = self.address(None, &elements::AddressParams::ELEMENTS);
        addr.script_pubkey()
    }

    /// Obtains the corresponding script pubkey for this descriptor.
    pub fn address(
        &self,
        blinder: Option<secp256k1_zkp::PublicKey>,
        params: &'static elements::AddressParams,
    ) -> elements::Address {
        Address::p2wpkh(&self.pk.to_public_key(), blinder, params)
    }

    /// Obtains the underlying miniscript for this descriptor.
    pub fn inner_script(&self) -> Script {
        self.script_pubkey()
    }

    /// Obtains the pre bip-340 signature script code for this descriptor.
    pub fn ecdsa_sighash_script_code(&self) -> Script {
        // For SegWit outputs, it is defined by bip-0143 (quoted below) and is different from
        // the previous txo's scriptPubKey.
        // The item 5:
        //     - For P2WPKH witness program, the scriptCode is `0x1976a914{20-byte-pubkey-hash}88ac`.
        let addr = elements::Address::p2pkh(
            &self.pk.to_public_key(),
            None,
            &elements::AddressParams::ELEMENTS,
        );
        // Need this expect in future
        // .expect("wpkh descriptors have compressed keys");
        addr.script_pubkey()
    }

    /// Returns satisfying non-malleable witness and scriptSig with minimum
    /// weight to spend an output controlled by the given descriptor if it is
    /// possible to construct one using the `satisfier`.
    pub fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
    where
        S: Satisfier<Pk>,
    {
        if let Some(sig) = satisfier.lookup_ecdsa_sig(&self.pk) {
            let sig_vec = elementssig_to_rawsig(&sig);
            let script_sig = Script::new();
            let witness = vec![sig_vec, self.pk.to_public_key().to_bytes()];
            Ok((witness, script_sig))
        } else {
            Err(Error::MissingSig(self.pk.to_public_key()))
        }
    }

    /// Returns satisfying, possibly malleable, witness and scriptSig with
    /// minimum weight to spend an output controlled by the given descriptor if
    /// it is possible to construct one using the `satisfier`.
    pub fn get_satisfaction_mall<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
    where
        S: Satisfier<Pk>,
    {
        self.get_satisfaction(satisfier)
    }
}

impl<Pk: MiniscriptKey> fmt::Debug for Wpkh<Pk> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}wpkh({:?})", ELMTS_STR, self.pk)
    }
}

impl<Pk: MiniscriptKey> fmt::Display for Wpkh<Pk> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let mut wrapped_f = checksum::Formatter::new(f);
        write!(wrapped_f, "{}wpkh({})", ELMTS_STR, self.pk)?;
        wrapped_f.write_checksum_if_not_alt()
    }
}

impl<Pk: MiniscriptKey> Liftable<Pk> for Wpkh<Pk> {
    fn lift(&self) -> Result<semantic::Policy<Pk>, Error> {
        Ok(semantic::Policy::Key(self.pk.clone()))
    }
}

impl_from_tree!(
    Wpkh<Pk>,
    fn from_tree(top: &expression::Tree) -> Result<Self, Error> {
        if top.name == "elwpkh" && top.args.len() == 1 {
            Ok(Wpkh::new(expression::terminal(&top.args[0], |pk| {
                Pk::from_str(pk)
            })?)?)
        } else {
            Err(Error::Unexpected(format!(
                "{}({} args) while parsing wpkh descriptor",
                top.name,
                top.args.len(),
            )))
        }
    }
);

impl_from_str!(
    Wpkh<Pk>,
    type Err = Error;,
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let desc_str = verify_checksum(s)?;
        let top = expression::Tree::from_str(desc_str)?;
        Self::from_tree(&top)
    }
);

impl<Pk: MiniscriptKey> ForEachKey<Pk> for Wpkh<Pk> {
    fn for_each_key<'a, F: FnMut(&'a Pk) -> bool>(&'a self, mut pred: F) -> bool
    where
        Pk: 'a,
    {
        pred(&self.pk)
    }
}

impl<P: MiniscriptKey, Q: MiniscriptKey> TranslatePk<P, Q> for Wpkh<P> {
    type Output = Wpkh<Q>;

    fn translate_pk<T, E>(&self, t: &mut T) -> Result<Self::Output, E>
    where
        T: Translator<P, Q, E>,
    {
        Ok(Wpkh::new(t.pk(&self.pk)?).expect("Uncompressed keys in Wpkh"))
    }
}