pg-srv 0.3.0

//! Decoding values from the Protocol representation

use crate::{
    protocol::{ErrorCode, ErrorResponse, Format},
    ProtocolError,
};
use byteorder::{BigEndian, ByteOrder};
use std::backtrace::Backtrace;

/// This trait explains how to decode values from the protocol
/// It's used in the Bind message
pub trait FromProtocolValue {
    // Converts native type to raw value in specific format
    fn from_protocol(raw: &[u8], format: Format) -> Result<Self, ProtocolError>
    where
        Self: Sized,
    {
        match format {
            Format::Text => Self::from_text(raw),
            Format::Binary => Self::from_binary(raw),
        }
    }

    /// Decodes raw value to native type in text format
    fn from_text(raw: &[u8]) -> Result<Self, ProtocolError>
    where
        Self: Sized;

    /// Decodes raw value to native type in binary format
    fn from_binary(raw: &[u8]) -> Result<Self, ProtocolError>
    where
        Self: Sized;
}

impl FromProtocolValue for String {
    fn from_text(raw: &[u8]) -> Result<Self, ProtocolError> {
        std::str::from_utf8(raw)
            .map(|s| s.to_string())
            .map_err(|err| ProtocolError::ErrorResponse {
                source: ErrorResponse::error(ErrorCode::ProtocolViolation, err.to_string()),
                backtrace: Backtrace::capture(),
            })
    }

    fn from_binary(raw: &[u8]) -> Result<Self, ProtocolError> {
        std::str::from_utf8(raw)
            .map(|s| s.to_string())
            .map_err(|err| ProtocolError::ErrorResponse {
                source: ErrorResponse::error(ErrorCode::ProtocolViolation, err.to_string()),
                backtrace: Backtrace::capture(),
            })
    }
}

impl FromProtocolValue for i64 {
    fn from_text(raw: &[u8]) -> Result<Self, ProtocolError> {
        let as_str = std::str::from_utf8(raw).map_err(|err| ProtocolError::ErrorResponse {
            source: ErrorResponse::error(ErrorCode::ProtocolViolation, err.to_string()),
            backtrace: Backtrace::capture(),
        })?;

        as_str
            .parse::<i64>()
            .map_err(|err| ProtocolError::ErrorResponse {
                source: ErrorResponse::error(ErrorCode::ProtocolViolation, err.to_string()),
                backtrace: Backtrace::capture(),
            })
    }

    fn from_binary(raw: &[u8]) -> Result<Self, ProtocolError> {
        Ok(BigEndian::read_i64(raw))
    }
}

impl FromProtocolValue for bool {
    fn from_text(raw: &[u8]) -> Result<Self, ProtocolError> {
        match raw[0] {
            b't' => Ok(true),
            b'f' => Ok(false),
            other => Err(ProtocolError::ErrorResponse {
                source: ErrorResponse::error(
                    ErrorCode::ProtocolViolation,
                    format!("Unable to decode bool from text, actual: {}", other),
                ),
                backtrace: Backtrace::capture(),
            }),
        }
    }

    fn from_binary(raw: &[u8]) -> Result<Self, ProtocolError> {
        match raw[0] {
            1 => Ok(true),
            0 => Ok(false),
            other => Err(ProtocolError::ErrorResponse {
                source: ErrorResponse::error(
                    ErrorCode::ProtocolViolation,
                    format!("Unable to decode bool from binary, actual: {}", other),
                ),
                backtrace: Backtrace::capture(),
            }),
        }
    }
}

impl FromProtocolValue for f64 {
    fn from_text(raw: &[u8]) -> Result<Self, ProtocolError> {
        let as_str = std::str::from_utf8(raw).map_err(|err| ProtocolError::ErrorResponse {
            source: ErrorResponse::error(ErrorCode::ProtocolViolation, err.to_string()),
            backtrace: Backtrace::capture(),
        })?;

        as_str
            .parse::<f64>()
            .map_err(|err| ProtocolError::ErrorResponse {
                source: ErrorResponse::error(ErrorCode::ProtocolViolation, err.to_string()),
                backtrace: Backtrace::capture(),
            })
    }

    fn from_binary(raw: &[u8]) -> Result<Self, ProtocolError> {
        Ok(BigEndian::read_f64(raw))
    }
}

#[cfg(test)]
mod tests {
    use crate::*;

    use crate::protocol::Format;
    use crate::values::timestamp::TimestampValue;
    use bytes::BytesMut;
    #[cfg(feature = "with-chrono")]
    use chrono::NaiveDate;

    fn assert_test_decode<T: ToProtocolValue + FromProtocolValue + std::cmp::PartialEq>(
        value: T,
        format: Format,
    ) -> Result<(), ProtocolError> {
        let mut buf = BytesMut::new();
        value.to_protocol(&mut buf, format)?;

        // skip length
        let mut encoded = Vec::with_capacity(buf.len() - 4);
        encoded.extend_from_slice(&buf.as_ref()[4..]);

        assert_eq!(value, T::from_protocol(&encoded, format)?);

        Ok(())
    }

    #[test]
    fn test_text_decoders() -> Result<(), ProtocolError> {
        assert_test_decode("test".to_string(), Format::Text)?;
        assert_test_decode(true, Format::Text)?;
        assert_test_decode(false, Format::Text)?;
        assert_test_decode(1_i64, Format::Text)?;
        assert_test_decode(100_i64, Format::Text)?;
        assert_test_decode(std::f64::consts::PI, Format::Text)?;
        assert_test_decode(-std::f64::consts::E, Format::Text)?;
        assert_test_decode(0.0_f64, Format::Text)?;
        assert_test_decode(TimestampValue::new(1650890322000000000, None), Format::Text)?;
        assert_test_decode(TimestampValue::new(0, None), Format::Text)?;
        assert_test_decode(TimestampValue::new(1234567890123456000, None), Format::Text)?;

        #[cfg(feature = "with-chrono")]
        {
            assert_test_decode(NaiveDate::from_ymd_opt(2025, 8, 8).unwrap(), Format::Text)?;
            assert_test_decode(NaiveDate::from_ymd_opt(2000, 1, 1).unwrap(), Format::Text)?;
            assert_test_decode(NaiveDate::from_ymd_opt(1999, 12, 31).unwrap(), Format::Text)?;
        }

        Ok(())
    }

    #[test]
    fn test_binary_decoders() -> Result<(), ProtocolError> {
        assert_test_decode("test".to_string(), Format::Binary)?;
        assert_test_decode(true, Format::Binary)?;
        assert_test_decode(false, Format::Binary)?;
        assert_test_decode(1_i64, Format::Binary)?;
        assert_test_decode(100_i64, Format::Binary)?;
        assert_test_decode(std::f64::consts::PI, Format::Binary)?;
        assert_test_decode(-std::f64::consts::E, Format::Binary)?;
        assert_test_decode(0.0_f64, Format::Binary)?;
        assert_test_decode(
            TimestampValue::new(1650890322000000000, None),
            Format::Binary,
        )?;
        assert_test_decode(TimestampValue::new(0, None), Format::Binary)?;
        assert_test_decode(
            TimestampValue::new(1234567890123456000, None),
            Format::Binary,
        )?;

        #[cfg(feature = "with-chrono")]
        {
            assert_test_decode(NaiveDate::from_ymd_opt(2025, 8, 8).unwrap(), Format::Binary)?;
            assert_test_decode(NaiveDate::from_ymd_opt(2000, 1, 1).unwrap(), Format::Binary)?;
            assert_test_decode(
                NaiveDate::from_ymd_opt(1999, 12, 31).unwrap(),
                Format::Binary,
            )?;
        }

        Ok(())
    }
}