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// Copyright lowRISC contributors (OpenTitan project).
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0

use anyhow::{anyhow, Result};
use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
use serde::{Deserialize, Serialize};
use serde_annotate::Annotate;
use std::cmp::Ordering;
use std::io::{Read, Write};

use crate::crypto::ecdsa::EcdsaRawPublicKey;
use crate::crypto::rsa::RsaRawPublicKey;
use crate::crypto::spx::SpxRawPublicKey;
use crate::crypto::Error;
use crate::util::serde::string_or_struct;
use crate::with_unknown;

with_unknown! {
    pub enum TlvTag: u32 [default = Self::Unknown] {
        Unknown = 0,
        Owner = u32::from_le_bytes(*b"OWNR"),
        ApplicationKey = u32::from_le_bytes(*b"APPK"),
        FlashConfig = u32::from_le_bytes(*b"FLSH"),
        FlashInfoConfig = u32::from_le_bytes(*b"INFO"),
        Rescue = u32::from_le_bytes(*b"RESQ"),
        NotPresent = u32::from_le_bytes(*b"ZZZZ"),
    }

    pub enum OwnershipKeyAlg: u32 [default = Self::Unknown] {
        Unknown = 0,
        Rsa = u32::from_le_bytes(*b"RSA3"),
        EcdsaP256 = u32::from_le_bytes(*b"P256"),
        Spx = u32::from_le_bytes(*b"SPX+"),
        Spxq20 = u32::from_le_bytes(*b"Sq20"),
    }
}

#[derive(Debug, Default, Serialize, Deserialize, Annotate)]
pub struct TlvHeader {
    pub identifier: TlvTag,
    pub length: usize,
}

impl TlvHeader {
    pub const SIZE: usize = 6;
    pub fn new(id: TlvTag, len: usize) -> Self {
        Self {
            identifier: id,
            length: len,
        }
    }

    pub fn read(src: &mut impl Read) -> Result<Self> {
        Ok(Self {
            identifier: TlvTag(src.read_u32::<LittleEndian>()?),
            length: src.read_u32::<LittleEndian>()? as usize,
        })
    }

    pub fn write(&self, dest: &mut impl Write) -> Result<()> {
        dest.write_u32::<LittleEndian>(u32::from(self.identifier))?;
        dest.write_u32::<LittleEndian>(self.length as u32)?;
        Ok(())
    }
    pub fn write_len(&self, dest: &mut impl Write, length: usize) -> Result<()> {
        dest.write_u32::<LittleEndian>(u32::from(self.identifier))?;
        dest.write_u32::<LittleEndian>(length as u32)?;
        Ok(())
    }
}

/// Low-level key material (ie: bit representation).
#[derive(Debug, Serialize, Deserialize)]
pub enum KeyMaterial {
    Unknown(Vec<u8>),
    Ecdsa(#[serde(deserialize_with = "string_or_struct")] EcdsaRawPublicKey),
    Rsa(#[serde(deserialize_with = "string_or_struct")] RsaRawPublicKey),
    Spx(#[serde(deserialize_with = "string_or_struct")] SpxRawPublicKey),
}

impl Default for KeyMaterial {
    fn default() -> Self {
        Self::Unknown(Vec::default())
    }
}

impl KeyMaterial {
    pub fn len(&self) -> usize {
        match self {
            KeyMaterial::Ecdsa(_) => EcdsaRawPublicKey::SIZE,
            KeyMaterial::Rsa(_) => RsaRawPublicKey::SIZE,
            KeyMaterial::Spx(_) => SpxRawPublicKey::SIZE,
            KeyMaterial::Unknown(u) => u.len(),
        }
    }

    pub fn kind(&self) -> OwnershipKeyAlg {
        match self {
            KeyMaterial::Ecdsa(_) => OwnershipKeyAlg::EcdsaP256,
            KeyMaterial::Rsa(_) => OwnershipKeyAlg::Rsa,
            KeyMaterial::Spx(_) => OwnershipKeyAlg::Spx,
            KeyMaterial::Unknown(_) => OwnershipKeyAlg::Unknown,
        }
    }

    pub fn read_length(src: &mut impl Read, kind: OwnershipKeyAlg, buflen: usize) -> Result<Self> {
        let result = match kind {
            OwnershipKeyAlg::Rsa => KeyMaterial::Rsa(RsaRawPublicKey::read(src)?),
            OwnershipKeyAlg::EcdsaP256 => KeyMaterial::Ecdsa(EcdsaRawPublicKey::read(src)?),
            OwnershipKeyAlg::Spx | OwnershipKeyAlg::Spxq20 => {
                KeyMaterial::Spx(SpxRawPublicKey::read(src)?)
            }
            _ => {
                return Err(
                    Error::InvalidPublicKey(anyhow!("Unknown key algorithm {}", kind)).into(),
                );
            }
        };
        let len = result.len();
        if buflen != 0 {
            match len.cmp(&buflen) {
                Ordering::Less => {
                    let mut discard = vec![0; buflen - len];
                    src.read_exact(&mut discard)?;
                }
                Ordering::Greater => {
                    return Err(Error::InvalidPublicKey(anyhow!(
                        "Key type {} does not fit in {} bytes",
                        kind,
                        buflen
                    ))
                    .into());
                }
                Ordering::Equal => {}
            };
        }
        Ok(result)
    }

    pub fn write_length(&self, dest: &mut impl Write, buflen: usize) -> Result<()> {
        match self {
            KeyMaterial::Ecdsa(k) => k.write(dest)?,
            KeyMaterial::Rsa(k) => k.write(dest)?,
            KeyMaterial::Spx(k) => k.write(dest)?,
            _ => {
                return Err(Error::InvalidPublicKey(anyhow!("Unknown key type")).into());
            }
        };

        if buflen != 0 {
            let len = self.len();
            match len.cmp(&buflen) {
                Ordering::Less => {
                    let zero = vec![0; buflen - len];
                    dest.write_all(&zero)?;
                }
                Ordering::Greater => {
                    return Err(Error::InvalidPublicKey(anyhow!(
                        "Key type {} does not fit in {} bytes",
                        self.kind(),
                        buflen
                    ))
                    .into());
                }
                Ordering::Equal => {}
            };
        }
        Ok(())
    }
}