postrust-core 0.1.0

//! RPC (stored function) call planning.

use crate::api_request::{ApiRequest, Payload, QualifiedIdentifier};
use crate::error::{Error, Result};
use crate::schema_cache::Routine;
use serde::{Deserialize, Serialize};

/// A plan for calling a stored function.
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct CallPlan {
    /// Function identifier
    pub function: QualifiedIdentifier,
    /// Call parameters
    pub params: CallParams,
    /// Whether to return a scalar result
    pub returns_scalar: bool,
    /// Whether the function is set-returning
    pub returns_set: bool,
    /// Function volatility (for transaction handling)
    pub volatility: String,
}

/// How parameters are passed to the function.
#[derive(Clone, Debug, Serialize, Deserialize)]
pub enum CallParams {
    /// Named parameters from URL query or JSON body
    Named(Vec<(String, String)>),
    /// Positional parameters (from JSON array)
    Positional(Vec<String>),
    /// Single JSON object passed as first argument
    SingleObject(bytes::Bytes),
    /// No parameters
    None,
}

impl CallPlan {
    /// Create a call plan from an API request.
    pub fn from_request(request: &ApiRequest, routine: &Routine) -> Result<Self> {
        let qi = routine.qualified_identifier();

        let params = extract_call_params(request, routine)?;

        let returns_scalar = !routine.return_type.is_set_returning()
            && routine.return_type.type_name().map(|t| !t.contains("record")).unwrap_or(true);

        Ok(Self {
            function: qi,
            params,
            returns_scalar,
            returns_set: routine.return_type.is_set_returning(),
            volatility: format!("{:?}", routine.volatility),
        })
    }

    /// Check if this call has parameters.
    pub fn has_params(&self) -> bool {
        !matches!(self.params, CallParams::None)
    }
}

/// Extract call parameters from request.
fn extract_call_params(request: &ApiRequest, _routine: &Routine) -> Result<CallParams> {
    // Check for JSON body first
    if let Some(payload) = &request.payload {
        match payload {
            Payload::ProcessedJson { raw, .. } => {
                // Check if it's an object or array
                let value: serde_json::Value = serde_json::from_slice(raw)
                    .map_err(|e| Error::InvalidBody(e.to_string()))?;

                match value {
                    serde_json::Value::Object(map) => {
                        // Named parameters from JSON object
                        let params: Vec<(String, String)> = map
                            .into_iter()
                            .map(|(k, v)| (k, v.to_string()))
                            .collect();
                        return Ok(CallParams::Named(params));
                    }
                    serde_json::Value::Array(_) => {
                        // Pass entire JSON as single argument
                        return Ok(CallParams::SingleObject(raw.clone()));
                    }
                    _ => {
                        // Scalar value - pass as single argument
                        return Ok(CallParams::SingleObject(raw.clone()));
                    }
                }
            }
            Payload::ProcessedUrlEncoded { data, .. } => {
                // Named parameters from form data
                return Ok(CallParams::Named(data.clone()));
            }
            Payload::RawJson(raw) | Payload::RawPayload(raw) => {
                return Ok(CallParams::SingleObject(raw.clone()));
            }
        }
    }

    // Fall back to query parameters
    if !request.query_params.params.is_empty() {
        return Ok(CallParams::Named(request.query_params.params.clone()));
    }

    // No parameters
    Ok(CallParams::None)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::schema_cache::{FuncVolatility, RetType};

    fn make_routine() -> Routine {
        Routine {
            schema: "public".into(),
            name: "get_users".into(),
            description: None,
            params: vec![],
            return_type: RetType::SetOf("users".into()),
            volatility: FuncVolatility::Stable,
            has_variadic: false,
            isolation_level: None,
            settings: vec![],
            is_procedure: false,
        }
    }

    #[test]
    fn test_call_plan_basic() {
        let request = ApiRequest::default();
        let routine = make_routine();

        let plan = CallPlan::from_request(&request, &routine).unwrap();

        assert_eq!(plan.function.name, "get_users");
        assert!(plan.returns_set);
        assert!(!plan.returns_scalar);
    }

    #[test]
    fn test_call_params_none() {
        let request = ApiRequest::default();
        let routine = make_routine();

        let plan = CallPlan::from_request(&request, &routine).unwrap();
        assert!(!plan.has_params());
    }
}