faucet-source-databricks 1.0.0

//! Databricks SQL query source over the Statement Execution API.
//!
//! Submits `sql` to `POST /api/2.0/sql/statements`, polls
//! `GET /api/2.0/sql/statements/{id}` until the statement is terminal, then
//! streams the result chunks (INLINE + JSON_ARRAY) as typed JSON rows,
//! following `result.next_chunk_internal_link` across chunks. No SDK — plain
//! `reqwest` over the shared-auth bearer token.

use std::collections::HashMap;
use std::collections::hash_map::DefaultHasher;
use std::hash::{Hash, Hasher};
use std::pin::Pin;
use std::sync::Mutex;
use std::time::Duration;

use async_trait::async_trait;
use faucet_core::replication::{filter_incremental, max_value};
use faucet_core::{AuthSpec, FaucetError, SharedAuthProvider, Source, Stream, StreamPage};
use reqwest::Client;
use serde::Deserialize;
use serde_json::{Value, json};

use crate::config::{DatabricksReplication, DatabricksSourceConfig};
use crate::convert::{ColumnInfo, row_to_json};

/// Databricks SQL query source.
pub struct DatabricksSource {
    config: DatabricksSourceConfig,
    client: Client,
    /// Base URL override (up to but not including `/api/2.0/...`). `None` uses
    /// `config.workspace_url`. Set by tests to point at a mock server.
    endpoint_base: Option<String>,
    /// Shared auth provider; when set, supplies the bearer token (takes
    /// precedence over inline auth).
    auth_provider: Option<SharedAuthProvider>,
    /// Bookmark applied via [`Source::apply_start_bookmark`].
    start_bookmark: Mutex<Option<Value>>,
}

/// The statement lifecycle response (only the fields we consume).
#[derive(Debug, Deserialize)]
struct StatementResponse {
    #[serde(default)]
    statement_id: Option<String>,
    #[serde(default)]
    status: Option<StatusInfo>,
    #[serde(default)]
    manifest: Option<Manifest>,
    #[serde(default)]
    result: Option<ResultChunk>,
}

#[derive(Debug, Deserialize)]
struct StatusInfo {
    #[serde(default)]
    state: String,
    #[serde(default)]
    error: Option<ErrorInfo>,
}

#[derive(Debug, Deserialize)]
struct ErrorInfo {
    #[serde(default)]
    error_code: Option<String>,
    #[serde(default)]
    message: Option<String>,
}

#[derive(Debug, Deserialize)]
struct Manifest {
    #[serde(default)]
    schema: Option<SchemaInfo>,
}

#[derive(Debug, Deserialize)]
struct SchemaInfo {
    #[serde(default)]
    columns: Vec<ColumnInfo>,
}

#[derive(Debug, Deserialize)]
struct ResultChunk {
    #[serde(default)]
    data_array: Option<Vec<Vec<Value>>>,
    #[serde(default)]
    next_chunk_internal_link: Option<String>,
}

/// Client-side incremental filter context.
struct IncrementalCtx {
    column: String,
    start: Value,
}

impl DatabricksSource {
    /// Create a new source. Validates config; does no I/O.
    pub fn new(config: DatabricksSourceConfig) -> Result<Self, FaucetError> {
        config.validate()?;
        Ok(Self {
            config,
            client: Client::new(),
            endpoint_base: None,
            auth_provider: None,
            start_bookmark: Mutex::new(None),
        })
    }

    /// Attach a shared auth provider (yields the bearer token). Takes
    /// precedence over inline auth — lets several connectors share one token.
    pub fn with_auth_provider(mut self, provider: SharedAuthProvider) -> Self {
        self.auth_provider = Some(provider);
        self
    }

    /// Override the base URL (e.g. a wiremock server). Requests go to
    /// `{base}/api/2.0/sql/statements`.
    pub fn with_endpoint_base(mut self, base: impl Into<String>) -> Self {
        self.endpoint_base = Some(base.into());
        self
    }

    fn base_url(&self) -> String {
        match &self.endpoint_base {
            Some(b) => b.trim_end_matches('/').to_owned(),
            None => self.config.workspace_url.trim_end_matches('/').to_owned(),
        }
    }

    fn statements_url(&self) -> String {
        format!("{}/api/2.0/sql/statements", self.base_url())
    }

    /// Resolve the `Authorization` header value: shared provider first, else
    /// inline auth.
    async fn auth_header(&self) -> Result<String, FaucetError> {
        if let Some(p) = &self.auth_provider {
            let cred = p.credential().await?;
            return cred.authorization_value().ok_or_else(|| {
                FaucetError::Auth("databricks: shared provider yielded no bearer credential".into())
            });
        }
        match &self.config.auth {
            AuthSpec::Inline(a) => Ok(a.authorization_value()),
            AuthSpec::Reference(r) => Err(FaucetError::Auth(format!(
                "databricks: auth references provider '{}' but none was supplied",
                r.name
            ))),
        }
    }

    /// The effective incremental start bookmark (persisted bookmark, else the
    /// configured `initial_value`).
    fn incremental_ctx(&self) -> Option<IncrementalCtx> {
        match &self.config.replication {
            DatabricksReplication::Full => None,
            DatabricksReplication::Incremental {
                column,
                initial_value,
            } => {
                let start = self
                    .start_bookmark
                    .lock()
                    .expect("start_bookmark mutex poisoned")
                    .clone()
                    .unwrap_or_else(|| initial_value.clone());
                Some(IncrementalCtx {
                    column: column.clone(),
                    start,
                })
            }
        }
    }

    /// Build the request body: the SQL (with `${bookmark}` and `{ctx}` tokens
    /// rewritten to named params) plus the `parameters` array.
    fn build_body(&self, context: &HashMap<String, Value>, incr: Option<&IncrementalCtx>) -> Value {
        let mut sql = self.config.sql.clone();
        // Named parameters: start with the user's static ones.
        let mut params: Vec<Value> = self
            .config
            .parameters
            .iter()
            .map(|p| {
                json!({
                    "name": p.name,
                    "value": value_to_param_string(&p.value),
                    "type": p.param_type.clone().unwrap_or_else(|| "STRING".into()),
                })
            })
            .collect();

        // Parent-context `{key}` tokens → `:_faucet_ctN` named params.
        if !context.is_empty() {
            let (rewritten, ctx_values) =
                faucet_core::util::substitute_context_bind_params(&sql, context, 0, |i| {
                    format!(":_faucet_ct{i}")
                });
            sql = rewritten;
            for (i, v) in ctx_values.into_iter().enumerate() {
                params.push(json!({
                    "name": format!("_faucet_ct{i}"),
                    "value": value_to_param_string(&v),
                }));
            }
        }

        // Incremental `${bookmark}` token → `:_faucet_bookmark` named param.
        if let Some(ctx) = incr
            && sql.contains("${bookmark}")
        {
            sql = sql.replace("${bookmark}", ":_faucet_bookmark");
            params.push(json!({
                "name": "_faucet_bookmark",
                "value": value_to_param_string(&ctx.start),
            }));
        }

        let mut body = json!({
            "statement": sql,
            "warehouse_id": self.config.warehouse_id,
            "wait_timeout": format!("{}s", self.config.wait_timeout_secs),
            "on_wait_timeout": "CONTINUE",
            "disposition": "INLINE",
            "format": "JSON_ARRAY",
        });
        if let Some(c) = &self.config.catalog {
            body["catalog"] = json!(c);
        }
        if let Some(s) = &self.config.schema {
            body["schema"] = json!(s);
        }
        if !params.is_empty() {
            body["parameters"] = Value::Array(params);
        }
        body
    }

    /// Submit the statement and poll until it reaches a terminal state.
    async fn run_statement(
        &self,
        context: &HashMap<String, Value>,
        incr: Option<&IncrementalCtx>,
    ) -> Result<StatementResponse, FaucetError> {
        let auth = self.auth_header().await?;
        let body = self.build_body(context, incr);
        let resp = self
            .client
            .post(self.statements_url())
            .header("Authorization", &auth)
            .header("Content-Type", "application/json")
            .json(&body)
            .send()
            .await
            .map_err(|e| FaucetError::Source(format!("databricks: submit request failed: {e}")))?;
        let parsed = parse_http(resp).await?;
        self.poll_until_terminal(parsed, &auth).await
    }

    /// Poll `GET /statements/{id}` until the state is terminal (or the initial
    /// response already is), returning the terminal response.
    async fn poll_until_terminal(
        &self,
        first: StatementResponse,
        auth: &str,
    ) -> Result<StatementResponse, FaucetError> {
        let mut current = first;
        loop {
            let state = current
                .status
                .as_ref()
                .map(|s| s.state.as_str())
                .unwrap_or("");
            match state {
                "SUCCEEDED" => return Ok(current),
                "FAILED" | "CANCELED" | "CLOSED" => {
                    return Err(statement_error(state, current.status.as_ref()));
                }
                "PENDING" | "RUNNING" => {
                    let id = current.statement_id.clone().ok_or_else(|| {
                        FaucetError::Source(
                            "databricks: pending statement without a statement_id to poll".into(),
                        )
                    })?;
                    tokio::time::sleep(Duration::from_secs(self.config.poll_interval_secs.max(1)))
                        .await;
                    let url = format!("{}/{}", self.statements_url(), id);
                    let resp = self
                        .client
                        .get(&url)
                        .header("Authorization", auth)
                        .send()
                        .await
                        .map_err(|e| {
                            FaucetError::Source(format!("databricks: poll request failed: {e}"))
                        })?;
                    current = parse_http(resp).await?;
                }
                other => {
                    return Err(FaucetError::Source(format!(
                        "databricks: unexpected statement state '{other}'"
                    )));
                }
            }
        }
    }

    /// Fetch a follow-up chunk by its `next_chunk_internal_link` (a full API path).
    async fn fetch_chunk(&self, link: &str, auth: &str) -> Result<ResultChunk, FaucetError> {
        let url = format!("{}{}", self.base_url(), link);
        let resp = self
            .client
            .get(&url)
            .header("Authorization", auth)
            .send()
            .await
            .map_err(|e| FaucetError::Source(format!("databricks: chunk request failed: {e}")))?;
        let parsed = parse_http::<ResultChunk>(resp).await?;
        Ok(parsed)
    }
}

/// Derive a stable state key from the workspace, warehouse, and query.
fn default_state_key(config: &DatabricksSourceConfig) -> String {
    let mut h = DefaultHasher::new();
    config.workspace_url.hash(&mut h);
    config.warehouse_id.hash(&mut h);
    config.sql.hash(&mut h);
    format!("databricks:{:016x}", h.finish())
}

/// Stringify a JSON value for a Databricks named parameter (`value` is a
/// string or null in the API).
fn value_to_param_string(v: &Value) -> Value {
    match v {
        Value::Null => Value::Null,
        Value::String(s) => Value::String(s.clone()),
        Value::Bool(b) => Value::String(b.to_string()),
        Value::Number(n) => Value::String(n.to_string()),
        other => Value::String(other.to_string()),
    }
}

/// Build a typed error from a terminal non-success statement state.
fn statement_error(state: &str, status: Option<&StatusInfo>) -> FaucetError {
    let detail = status.and_then(|s| s.error.as_ref()).map(|e| {
        format!(
            " [{}] {}",
            e.error_code.as_deref().unwrap_or("UNKNOWN"),
            e.message.as_deref().unwrap_or("")
        )
    });
    FaucetError::Source(format!(
        "databricks: statement {state}{}",
        detail.unwrap_or_default()
    ))
}

/// Parse an HTTP response into `T`, surfacing non-2xx as a typed error with the
/// body (429/5xx/4xx transport errors; SQL errors come back as 200 + FAILED).
async fn parse_http<T: for<'de> Deserialize<'de>>(
    resp: reqwest::Response,
) -> Result<T, FaucetError> {
    let status = resp.status();
    if !status.is_success() {
        let body = resp.text().await.unwrap_or_default();
        return Err(FaucetError::Source(format!(
            "databricks: HTTP {status}: {body}"
        )));
    }
    resp.json::<T>()
        .await
        .map_err(|e| FaucetError::Source(format!("databricks: could not parse response: {e}")))
}

#[async_trait]
impl Source for DatabricksSource {
    fn config_schema(&self) -> Value {
        serde_json::to_value(faucet_core::schema_for!(DatabricksSourceConfig))
            .expect("schema serialization")
    }

    fn connector_name(&self) -> &'static str {
        "databricks"
    }

    fn dataset_uri(&self) -> String {
        format!(
            "databricks://{}/warehouses/{}",
            self.config
                .workspace_url
                .trim_start_matches("https://")
                .trim_end_matches('/'),
            self.config.warehouse_id
        )
    }

    fn state_key(&self) -> Option<String> {
        match &self.config.replication {
            DatabricksReplication::Full => None,
            DatabricksReplication::Incremental { .. } => Some(
                self.config
                    .state_key
                    .clone()
                    .unwrap_or_else(|| default_state_key(&self.config)),
            ),
        }
    }

    async fn apply_start_bookmark(&self, bookmark: Value) -> Result<(), FaucetError> {
        *self
            .start_bookmark
            .lock()
            .expect("start_bookmark mutex poisoned") = Some(bookmark);
        Ok(())
    }

    fn stream_pages<'a>(
        &'a self,
        context: &'a HashMap<String, Value>,
        _batch_size: usize,
    ) -> Pin<Box<dyn Stream<Item = Result<StreamPage, FaucetError>> + Send + 'a>> {
        Box::pin(async_stream::try_stream! {
            let auth = self.auth_header().await?;
            let incr = self.incremental_ctx();
            let resp = self.run_statement(context, incr.as_ref()).await?;

            let columns: Vec<ColumnInfo> = resp
                .manifest
                .and_then(|m| m.schema)
                .map(|s| s.columns)
                .unwrap_or_default();

            let batch = self.config.batch_size;
            let cap = if batch == 0 { 1024 } else { batch };
            let mut buffer: Vec<Value> = Vec::with_capacity(cap);
            let mut running_max: Option<Value> = None;

            // Walk chunks: the initial `result`, then follow next_chunk_internal_link.
            let mut chunk = resp.result;
            while let Some(c) = chunk {
                if let Some(data) = c.data_array {
                    for row in &data {
                        let obj = row_to_json(row, &columns);
                        // Track the running max BEFORE the client-side filter so
                        // the persisted bookmark reflects the full scan.
                        if let Some(ic) = &incr
                            && let Some(v) = obj.get(&ic.column)
                        {
                            running_max = Some(match running_max.take() {
                                Some(m) => max_value(m, v.clone()),
                                None => v.clone(),
                            });
                        }
                        buffer.push(obj);
                        if batch != 0 && buffer.len() >= batch {
                            let page = std::mem::replace(&mut buffer, Vec::with_capacity(cap));
                            let kept = apply_incr_filter(page, incr.as_ref());
                            if !kept.is_empty() {
                                yield StreamPage { records: kept, bookmark: None };
                            }
                        }
                    }
                }
                chunk = match c.next_chunk_internal_link {
                    Some(link) => Some(self.fetch_chunk(&link, &auth).await?),
                    None => None,
                };
            }

            // Final page carries the new bookmark (incremental only).
            let kept = apply_incr_filter(buffer, incr.as_ref());
            let bookmark = if incr.is_some() { running_max } else { None };
            if !kept.is_empty() || bookmark.is_some() {
                yield StreamPage { records: kept, bookmark };
            }
        })
    }

    async fn fetch_with_context(
        &self,
        context: &HashMap<String, Value>,
    ) -> Result<Vec<Value>, FaucetError> {
        use futures::StreamExt;
        let mut out = Vec::new();
        let mut s = self.stream_pages(context, self.config.batch_size);
        while let Some(page) = s.next().await {
            out.extend(page?.records);
        }
        Ok(out)
    }

    async fn check(
        &self,
        ctx: &faucet_core::check::CheckContext,
    ) -> Result<faucet_core::check::CheckReport, FaucetError> {
        use faucet_core::check::{CheckReport, Probe};
        let started = std::time::Instant::now();
        // Non-scanning probe: run `SELECT 1` on the warehouse.
        let auth = match self.auth_header().await {
            Ok(a) => a,
            Err(e) => {
                return Ok(CheckReport::single(Probe::fail(
                    "auth",
                    started.elapsed(),
                    e.to_string(),
                )));
            }
        };
        let body = json!({
            "statement": "SELECT 1",
            "warehouse_id": self.config.warehouse_id,
            "wait_timeout": "50s",
            "disposition": "INLINE",
            "format": "JSON_ARRAY",
        });
        let fut = self
            .client
            .post(self.statements_url())
            .header("Authorization", &auth)
            .header("Content-Type", "application/json")
            .json(&body)
            .send();
        let probe = match tokio::time::timeout(ctx.timeout, fut).await {
            Ok(Ok(r)) if r.status().is_success() => Probe::pass("warehouse", started.elapsed()),
            Ok(Ok(r)) => Probe::fail_hint(
                "warehouse",
                started.elapsed(),
                format!("databricks probe returned HTTP {}", r.status()),
                "Verify workspace_url, warehouse_id, and token permissions (CAN USE).",
            ),
            Ok(Err(e)) => Probe::fail_hint(
                "warehouse",
                started.elapsed(),
                format!("databricks probe request failed: {e}"),
                "Verify workspace_url and network reachability.",
            ),
            Err(_) => Probe::fail_hint(
                "warehouse",
                started.elapsed(),
                format!("databricks probe timed out after {:?}", ctx.timeout),
                "Check warehouse availability and network reachability.",
            ),
        };
        Ok(CheckReport::single(probe))
    }
}

/// Apply the client-side incremental filter to a page (no-op for full runs).
fn apply_incr_filter(page: Vec<Value>, incr: Option<&IncrementalCtx>) -> Vec<Value> {
    match incr {
        Some(ic) => filter_incremental(page, &ic.column, &ic.start),
        None => page,
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::config::{DatabricksAuth, DatabricksParam};

    fn cfg() -> DatabricksSourceConfig {
        DatabricksSourceConfig {
            workspace_url: "https://x.cloud.databricks.com".into(),
            warehouse_id: "wh1".into(),
            sql: "SELECT * FROM t WHERE ts > ${bookmark}".into(),
            auth: AuthSpec::Inline(DatabricksAuth::Pat {
                token: "tok".into(),
            }),
            catalog: Some("main".into()),
            schema: Some("s".into()),
            parameters: vec![DatabricksParam {
                name: "min".into(),
                value: json!(10),
                param_type: Some("INT".into()),
            }],
            wait_timeout_secs: 50,
            poll_interval_secs: 1,
            batch_size: 1000,
            replication: DatabricksReplication::Incremental {
                column: "ts".into(),
                initial_value: json!("2026-01-01"),
            },
            state_key: None,
        }
    }

    fn source(c: DatabricksSourceConfig) -> DatabricksSource {
        DatabricksSource::new(c).unwrap()
    }

    #[test]
    fn body_has_required_fields_and_params() {
        let s = source(cfg());
        let incr = s.incremental_ctx();
        let body = s.build_body(&HashMap::new(), incr.as_ref());
        assert_eq!(body["warehouse_id"], json!("wh1"));
        assert_eq!(body["catalog"], json!("main"));
        assert_eq!(body["disposition"], json!("INLINE"));
        assert_eq!(body["format"], json!("JSON_ARRAY"));
        assert_eq!(body["wait_timeout"], json!("50s"));
        // ${bookmark} rewritten to the named param marker.
        assert!(
            body["statement"]
                .as_str()
                .unwrap()
                .contains(":_faucet_bookmark")
        );
        assert!(!body["statement"].as_str().unwrap().contains("${bookmark}"));
        let params = body["parameters"].as_array().unwrap();
        // static `min` (typed) + the bookmark param.
        assert!(
            params
                .iter()
                .any(|p| p["name"] == json!("min") && p["type"] == json!("INT"))
        );
        let bm = params
            .iter()
            .find(|p| p["name"] == json!("_faucet_bookmark"))
            .unwrap();
        assert_eq!(bm["value"], json!("2026-01-01"));
    }

    #[test]
    fn full_mode_has_no_state_key_or_bookmark_param() {
        let mut c = cfg();
        c.replication = DatabricksReplication::Full;
        c.sql = "SELECT 1".into();
        let s = source(c);
        assert!(s.state_key().is_none());
        let body = s.build_body(&HashMap::new(), None);
        assert!(
            body.get("parameters").is_none()
                || body["parameters"]
                    .as_array()
                    .unwrap()
                    .iter()
                    .all(|p| p["name"] != json!("_faucet_bookmark"))
        );
    }

    #[test]
    fn incremental_state_key_derived_and_stable() {
        let s = source(cfg());
        let k1 = s.state_key().unwrap();
        let k2 = source(cfg()).state_key().unwrap();
        assert_eq!(k1, k2);
        assert!(k1.starts_with("databricks:"));
    }

    #[tokio::test]
    async fn explicit_state_key_wins() {
        let mut c = cfg();
        c.state_key = Some("my-key".into());
        let s = source(c);
        assert_eq!(s.state_key().as_deref(), Some("my-key"));
        // apply_start_bookmark overrides initial_value in the incr ctx.
        s.apply_start_bookmark(json!("2026-06-01")).await.unwrap();
        assert_eq!(s.incremental_ctx().unwrap().start, json!("2026-06-01"));
    }

    #[test]
    fn value_to_param_string_stringifies() {
        assert_eq!(value_to_param_string(&json!(5)), json!("5"));
        assert_eq!(value_to_param_string(&json!(true)), json!("true"));
        assert_eq!(value_to_param_string(&json!("x")), json!("x"));
        assert_eq!(value_to_param_string(&Value::Null), Value::Null);
    }

    #[test]
    fn dataset_uri_redacts_scheme() {
        let s = source(cfg());
        assert_eq!(
            s.dataset_uri(),
            "databricks://x.cloud.databricks.com/warehouses/wh1"
        );
    }
}