use crate::{
    vector::vector_types::{Vector, VectorType},
    LimboError, Result,
};

pub fn vector_to_text(vector: &Vector) -> String {
    match vector.vector_type {
        VectorType::Float32Dense => format_text(vector.as_f32_slice().iter()),
        VectorType::Float64Dense => format_text(vector.as_f64_slice().iter()),
        VectorType::Float32Sparse => {
            let mut dense = vec![0.0f32; vector.dims];
            let sparse = vector.as_f32_sparse();
            tracing::info!("{:?}", sparse);
            for (&idx, &value) in sparse.idx.iter().zip(sparse.values.iter()) {
                dense[idx as usize] = value;
            }
            format_text(dense.iter())
        }
    }
}

fn format_text<T: std::string::ToString>(values: impl Iterator<Item = T>) -> String {
    let mut text = String::new();
    text.push('[');
    let mut first = true;
    for value in values {
        if !first {
            text.push(',');
        }
        first = false;
        text.push_str(&value.to_string());
    }
    text.push(']');
    text
}

/// Parse a vector in text representation into a Vector.
///
/// The format of a vector in text representation looks as follows:
///
/// ```console
/// [1.0, 2.0, 3.0]
/// ```
pub fn vector_from_text(vector_type: VectorType, text: &str) -> Result<Vector> {
    let text = text.trim();
    let mut chars = text.chars();
    if chars.next() != Some('[') || chars.last() != Some(']') {
        return Err(LimboError::ConversionError(
            "Invalid vector value".to_string(),
        ));
    }
    let text = &text[1..text.len() - 1];
    if text.trim().is_empty() {
        return Ok(match vector_type {
            VectorType::Float32Dense | VectorType::Float64Dense | VectorType::Float32Sparse => {
                Vector {
                    vector_type,
                    dims: 0,
                    data: Vec::new(),
                }
            }
        });
    }
    let tokens = text.split(',').map(|x| x.trim());
    match vector_type {
        VectorType::Float32Dense => vector32_from_text(tokens),
        VectorType::Float64Dense => vector64_from_text(tokens),
        VectorType::Float32Sparse => vector32_sparse_from_text(tokens),
    }
}

fn vector32_from_text<'a>(tokens: impl Iterator<Item = &'a str>) -> Result<Vector> {
    let mut data = Vec::new();
    for token in tokens {
        let value = token
            .parse::<f32>()
            .map_err(|_| LimboError::ConversionError("Invalid vector value".to_string()))?;
        if !value.is_finite() {
            return Err(LimboError::ConversionError(
                "Invalid vector value".to_string(),
            ));
        }
        data.extend_from_slice(&value.to_le_bytes());
    }
    Ok(Vector {
        vector_type: VectorType::Float32Dense,
        dims: data.len() / 4,
        data,
    })
}

fn vector64_from_text<'a>(tokens: impl Iterator<Item = &'a str>) -> Result<Vector> {
    let mut data = Vec::new();
    for token in tokens {
        let value = token
            .parse::<f64>()
            .map_err(|_| LimboError::ConversionError("Invalid vector value".to_string()))?;
        if !value.is_finite() {
            return Err(LimboError::ConversionError(
                "Invalid vector value".to_string(),
            ));
        }
        data.extend_from_slice(&value.to_le_bytes());
    }
    Ok(Vector {
        vector_type: VectorType::Float64Dense,
        dims: data.len() / 8,
        data,
    })
}

fn vector32_sparse_from_text<'a>(tokens: impl Iterator<Item = &'a str>) -> Result<Vector> {
    let mut idx = Vec::new();
    let mut values = Vec::new();
    let mut dims = 0u32;
    for token in tokens {
        let value = token
            .parse::<f32>()
            .map_err(|_| LimboError::ConversionError("Invalid vector value".to_string()))?;
        if !value.is_finite() {
            return Err(LimboError::ConversionError(
                "Invalid vector value".to_string(),
            ));
        }

        dims += 1;
        if value == 0.0 {
            continue;
        }
        idx.extend_from_slice(&(dims - 1).to_le_bytes());
        values.extend_from_slice(&value.to_le_bytes());
    }

    values.extend_from_slice(&idx);
    Ok(Vector {
        vector_type: VectorType::Float32Sparse,
        dims: dims as usize,
        data: values,
    })
}