//! Handlers for query audit trail endpoints.

use axum::{
    extract::{Path, Query as AxumQuery, State},
    Json,
};
use tracing::instrument;

use crate::{
    dto::{AuditQueryParams, QueryAuditListResponse, QueryAuditResponse},
    error::{ApiError, Result},
    hex as hex_utils,
    state::AppState,
};

use stemedb_storage::{AuditStore, GenericAuditStore};

/// List recent query audits with optional filters.
///
/// Returns a paginated list of query audit records. Use the `agent_id` and
/// time range filters to narrow down results for incident investigation.
///
/// # Query Parameters
///
/// - `agent_id` (optional): Filter by agent public key (hex-encoded, 32 bytes)
/// - `subject` (optional): Filter by subject (case-insensitive substring match)
/// - `predicate` (optional): Filter by predicate (case-insensitive substring match)
/// - `from` (optional): Start of time range (Unix timestamp)
/// - `to` (optional): End of time range (Unix timestamp)
/// - `limit` (optional): Maximum number of results (default: 100)
#[utoipa::path(
    get,
    path = "/v1/audit/queries",
    params(AuditQueryParams),
    responses(
        (status = 200, description = "List of query audits", body = QueryAuditListResponse),
        (status = 400, description = "Invalid request", body = crate::dto::ErrorResponse),
        (status = 500, description = "Internal server error", body = crate::dto::ErrorResponse)
    ),
    tag = "audit"
)]
#[instrument(skip(state), fields(
    agent_id = ?params.agent_id,
    subject = ?params.subject,
    predicate = ?params.predicate,
    from = ?params.from,
    to = ?params.to,
    limit = params.limit
))]
pub async fn list_audits(
    State(state): State<AppState>,
    AxumQuery(params): AxumQuery<AuditQueryParams>,
) -> Result<Json<QueryAuditListResponse>> {
    let start = std::time::Instant::now();
    metrics::counter!("stemedb_http_requests_total", "method" => "GET", "path" => "/v1/audit/queries").increment(1);

    let audit_store = GenericAuditStore::new(state.store.clone());

    // Fetch a larger set to allow for subject/predicate filtering
    // (storage layer doesn't have an index by subject/predicate)
    let fetch_limit = if params.subject.is_some() || params.predicate.is_some() {
        params.limit * 10 // Fetch more to compensate for filtering
    } else {
        params.limit
    };

    let mut audits = if let Some(agent_id_hex) = &params.agent_id {
        // Filter by agent with limit pushed down to storage layer
        let agent_id = hex_utils::decode_agent_id(agent_id_hex)?;
        let from = params.from.unwrap_or(0);
        let to = params.to;
        audit_store.get_audits_for_agent(&agent_id, from, to, fetch_limit).await?
    } else {
        // List recent (limit already applied in storage layer)
        audit_store.list_recent_audits(fetch_limit).await?
    };

    // Apply time range filter if not already filtered by agent
    if params.agent_id.is_none() {
        if let Some(from_ts) = params.from {
            audits.retain(|a| a.timestamp >= from_ts);
        }
        if let Some(to_ts) = params.to {
            audits.retain(|a| a.timestamp <= to_ts);
        }
    }

    // Apply subject filter (case-insensitive substring match)
    if let Some(ref subject_filter) = params.subject {
        let filter_lower = subject_filter.to_lowercase();
        audits.retain(|a| {
            a.params
                .subject
                .as_ref()
                .map(|s| s.to_lowercase().contains(&filter_lower))
                .unwrap_or(false)
        });
    }

    // Apply predicate filter (case-insensitive substring match)
    if let Some(ref predicate_filter) = params.predicate {
        let filter_lower = predicate_filter.to_lowercase();
        audits.retain(|a| {
            a.params
                .predicate
                .as_ref()
                .map(|p| p.to_lowercase().contains(&filter_lower))
                .unwrap_or(false)
        });
    }

    // Apply final limit
    audits.truncate(params.limit);
    let total_count = audits.len();

    // Convert to response DTOs
    let audit_responses: Vec<QueryAuditResponse> =
        audits.into_iter().map(QueryAuditResponse::from).collect();

    // Track request duration (success case)
    metrics::histogram!("stemedb_http_request_duration_seconds",
        "method" => "GET",
        "path" => "/v1/audit/queries",
        "status" => "200"
    )
    .record(start.elapsed().as_secs_f64());

    Ok(Json(QueryAuditListResponse { audits: audit_responses, total_count }))
}

/// Get a specific query audit by ID.
///
/// Returns the full audit record including all contributing assertions
/// that influenced the query result.
#[utoipa::path(
    get,
    path = "/v1/audit/query/{id}",
    params(
        ("id" = String, Path, description = "Query ID (hex-encoded, 32 bytes)")
    ),
    responses(
        (status = 200, description = "Query audit details", body = QueryAuditResponse),
        (status = 400, description = "Invalid query ID", body = crate::dto::ErrorResponse),
        (status = 404, description = "Audit not found", body = crate::dto::ErrorResponse),
        (status = 500, description = "Internal server error", body = crate::dto::ErrorResponse)
    ),
    tag = "audit"
)]
#[instrument(skip(state), fields(query_id = %id))]
pub async fn get_audit(
    State(state): State<AppState>,
    Path(id): Path<String>,
) -> Result<Json<QueryAuditResponse>> {
    let start = std::time::Instant::now();
    metrics::counter!("stemedb_http_requests_total", "method" => "GET", "path" => "/v1/audit/query/{id}").increment(1);

    let query_id = hex_utils::decode_hash_32(&id)?;
    let audit_store = GenericAuditStore::new(state.store.clone());

    match audit_store.get_audit(&query_id).await? {
        Some(audit) => {
            // Track request duration (success case)
            metrics::histogram!("stemedb_http_request_duration_seconds",
                "method" => "GET",
                "path" => "/v1/audit/query/{id}",
                "status" => "200"
            )
            .record(start.elapsed().as_secs_f64());

            Ok(Json(QueryAuditResponse::from(audit)))
        }
        None => Err(ApiError::NotFound(format!("Query audit not found: {}", id))),
    }
}