//! PostgreSQL source configuration.

use faucet_core::DEFAULT_BATCH_SIZE;
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
use serde_json::Value;

/// Configuration for the PostgreSQL query source.
#[derive(Clone, Serialize, Deserialize, JsonSchema)]
pub struct PostgresSourceConfig {
    /// PostgreSQL connection URL (e.g. `postgres://user:pass@host/db`).
    pub connection_url: String,
    /// SQL query to execute.
    pub query: String,
    /// Bind parameters for the query. Defaults to empty.
    #[serde(default)]
    pub params: Vec<Value>,
    /// Maximum number of connections in the pool. Defaults to 10.
    #[serde(default = "default_max_connections")]
    pub max_connections: u32,
    /// Records per emitted [`StreamPage`](faucet_core::StreamPage). Rows are
    /// drained from the sqlx cursor and yielded whenever the buffer reaches
    /// this size. Defaults to [`DEFAULT_BATCH_SIZE`].
    ///
    /// `batch_size = 0` is the "no batching" sentinel: the cursor is fully
    /// drained and the entire result set is emitted in a single page. Useful
    /// for small lookup tables or for sinks (e.g. SQL `COPY`, BigQuery load
    /// jobs) that prefer one large request to many small ones.
    #[serde(default = "default_batch_size")]
    pub batch_size: usize,
}

fn default_max_connections() -> u32 {
    10
}

fn default_batch_size() -> usize {
    DEFAULT_BATCH_SIZE
}

impl std::fmt::Debug for PostgresSourceConfig {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("PostgresSourceConfig")
            .field("connection_url", &"***")
            .field("query", &self.query)
            .field("params", &self.params)
            .field("max_connections", &self.max_connections)
            .field("batch_size", &self.batch_size)
            .finish()
    }
}

impl PostgresSourceConfig {
    /// Create a new config with the required connection URL and query.
    pub fn new(connection_url: impl Into<String>, query: impl Into<String>) -> Self {
        Self {
            connection_url: connection_url.into(),
            query: query.into(),
            params: Vec::new(),
            max_connections: 10,
            batch_size: DEFAULT_BATCH_SIZE,
        }
    }

    /// Set bind parameters for the query.
    pub fn params(mut self, params: Vec<Value>) -> Self {
        self.params = params;
        self
    }

    /// Set the maximum number of connections in the pool.
    pub fn with_max_connections(mut self, max_connections: u32) -> Self {
        self.max_connections = max_connections;
        self
    }

    /// Set the per-page row count for [`Source::stream_pages`](faucet_core::Source::stream_pages).
    ///
    /// Pass `0` to opt out of batching — the entire result set is emitted in
    /// a single [`StreamPage`](faucet_core::StreamPage).
    pub fn with_batch_size(mut self, batch_size: usize) -> Self {
        self.batch_size = batch_size;
        self
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    #[test]
    fn default_config() {
        let config = PostgresSourceConfig::new("postgres://localhost/test", "SELECT * FROM events");
        assert_eq!(config.query, "SELECT * FROM events");
        assert!(config.params.is_empty());
    }

    #[test]
    fn builder_with_params() {
        let config = PostgresSourceConfig::new(
            "postgres://localhost/test",
            "SELECT * FROM events WHERE id = $1",
        )
        .params(vec![json!(42)]);
        assert_eq!(config.params.len(), 1);
        assert_eq!(config.params[0], json!(42));
    }

    #[test]
    fn debug_masks_connection_url() {
        let config = PostgresSourceConfig::new("postgres://secret:pass@host/db", "SELECT 1");
        let debug = format!("{config:?}");
        assert!(debug.contains("***"));
        assert!(!debug.contains("secret"));
        assert!(!debug.contains("pass"));
    }

    #[test]
    fn batch_size_defaults_to_default_batch_size() {
        let config = PostgresSourceConfig::new("postgres://localhost/test", "SELECT 1");
        assert_eq!(config.batch_size, faucet_core::DEFAULT_BATCH_SIZE);
    }

    #[test]
    fn with_batch_size_overrides_default() {
        let config =
            PostgresSourceConfig::new("postgres://localhost/test", "SELECT 1").with_batch_size(500);
        assert_eq!(config.batch_size, 500);
    }

    #[test]
    fn batch_size_zero_is_accepted_as_no_batching_sentinel() {
        let config =
            PostgresSourceConfig::new("postgres://localhost/test", "SELECT 1").with_batch_size(0);
        assert_eq!(config.batch_size, 0);
        assert!(faucet_core::validate_batch_size(config.batch_size).is_ok());
    }

    #[test]
    fn batch_size_above_max_is_rejected_by_validate_batch_size() {
        let config = PostgresSourceConfig::new("postgres://localhost/test", "SELECT 1")
            .with_batch_size(faucet_core::MAX_BATCH_SIZE + 1);
        assert!(faucet_core::validate_batch_size(config.batch_size).is_err());
    }

    #[test]
    fn batch_size_deserializes_from_json() {
        let json = r#"{
            "connection_url": "postgres://localhost/test",
            "query": "SELECT 1",
            "batch_size": 250
        }"#;
        let config: PostgresSourceConfig = serde_json::from_str(json).unwrap();
        assert_eq!(config.batch_size, 250);
    }
}
