//! Trajectory Store -- record and compress tool-call chains for analysis.
//!
//! Stores raw trajectory events (user requests, tool calls, LLM generations)
//! and compressed trajectory summaries. Used by the Hermes Intelligence Pipeline
//! to analyze agent behaviour patterns and improve routing over time.

use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use sqlx::SqlitePool;
use zclaw_types::{Result, ZclawError};

// ---------------------------------------------------------------------------
// Types
// ---------------------------------------------------------------------------

/// Step type in a trajectory.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum TrajectoryStepType {
    UserRequest,
    IntentClassification,
    SkillSelection,
    ToolExecution,
    LlmGeneration,
    UserFeedback,
}

impl TrajectoryStepType {
    /// Serialize to the string stored in SQLite.
    pub fn as_str(&self) -> &'static str {
        match self {
            Self::UserRequest => "user_request",
            Self::IntentClassification => "intent_classification",
            Self::SkillSelection => "skill_selection",
            Self::ToolExecution => "tool_execution",
            Self::LlmGeneration => "llm_generation",
            Self::UserFeedback => "user_feedback",
        }
    }

    /// Deserialize from the SQLite string representation.
    pub fn from_str_lossy(s: &str) -> Self {
        match s {
            "user_request" => Self::UserRequest,
            "intent_classification" => Self::IntentClassification,
            "skill_selection" => Self::SkillSelection,
            "tool_execution" => Self::ToolExecution,
            "llm_generation" => Self::LlmGeneration,
            "user_feedback" => Self::UserFeedback,
            _ => Self::UserRequest,
        }
    }
}

/// Single trajectory event.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TrajectoryEvent {
    pub id: String,
    pub session_id: String,
    pub agent_id: String,
    pub step_index: usize,
    pub step_type: TrajectoryStepType,
    /// Summarised input (max 200 chars).
    pub input_summary: String,
    /// Summarised output (max 200 chars).
    pub output_summary: String,
    pub duration_ms: u64,
    pub timestamp: DateTime<Utc>,
}

/// Satisfaction signal inferred from user feedback.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum SatisfactionSignal {
    Positive,
    Negative,
    Neutral,
}

impl SatisfactionSignal {
    pub fn as_str(&self) -> &'static str {
        match self {
            Self::Positive => "positive",
            Self::Negative => "negative",
            Self::Neutral => "neutral",
        }
    }

    pub fn from_str_lossy(s: &str) -> Option<Self> {
        match s {
            "positive" => Some(Self::Positive),
            "negative" => Some(Self::Negative),
            "neutral" => Some(Self::Neutral),
            _ => None,
        }
    }
}

/// Completion status of a compressed trajectory.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum CompletionStatus {
    Success,
    Partial,
    Failed,
    Abandoned,
}

impl CompletionStatus {
    pub fn as_str(&self) -> &'static str {
        match self {
            Self::Success => "success",
            Self::Partial => "partial",
            Self::Failed => "failed",
            Self::Abandoned => "abandoned",
        }
    }

    pub fn from_str_lossy(s: &str) -> Self {
        match s {
            "success" => Self::Success,
            "partial" => Self::Partial,
            "failed" => Self::Failed,
            "abandoned" => Self::Abandoned,
            _ => Self::Success,
        }
    }
}

/// Compressed trajectory (generated at session end).
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CompressedTrajectory {
    pub id: String,
    pub session_id: String,
    pub agent_id: String,
    pub request_type: String,
    pub tools_used: Vec<String>,
    pub outcome: CompletionStatus,
    pub total_steps: usize,
    pub total_duration_ms: u64,
    pub total_tokens: u32,
    /// Serialised JSON execution chain for analysis.
    pub execution_chain: String,
    pub satisfaction_signal: Option<SatisfactionSignal>,
    pub created_at: DateTime<Utc>,
}

// ---------------------------------------------------------------------------
// Store
// ---------------------------------------------------------------------------

/// Persistent store for trajectory events and compressed trajectories.
pub struct TrajectoryStore {
    pool: SqlitePool,
}

impl TrajectoryStore {
    /// Create a new `TrajectoryStore` backed by the given SQLite pool.
    pub fn new(pool: SqlitePool) -> Self {
        Self { pool }
    }

    /// Create the required tables. Idempotent -- safe to call on startup.
    pub async fn initialize_schema(&self) -> Result<()> {
        sqlx::query(
            r#"
            CREATE TABLE IF NOT EXISTS trajectory_events (
                id TEXT PRIMARY KEY,
                session_id TEXT NOT NULL,
                agent_id TEXT NOT NULL,
                step_index INTEGER NOT NULL,
                step_type TEXT NOT NULL,
                input_summary TEXT,
                output_summary TEXT,
                duration_ms INTEGER DEFAULT 0,
                timestamp TEXT NOT NULL
            );
            CREATE INDEX IF NOT EXISTS idx_trajectory_session ON trajectory_events(session_id);
            "#,
        )
        .execute(&self.pool)
        .await
        .map_err(|e| ZclawError::StorageError(e.to_string()))?;

        sqlx::query(
            r#"
            CREATE TABLE IF NOT EXISTS compressed_trajectories (
                id TEXT PRIMARY KEY,
                session_id TEXT NOT NULL,
                agent_id TEXT NOT NULL,
                request_type TEXT NOT NULL,
                tools_used TEXT,
                outcome TEXT NOT NULL,
                total_steps INTEGER DEFAULT 0,
                total_duration_ms INTEGER DEFAULT 0,
                total_tokens INTEGER DEFAULT 0,
                execution_chain TEXT NOT NULL,
                satisfaction_signal TEXT,
                created_at TEXT NOT NULL
            );
            CREATE INDEX IF NOT EXISTS idx_ct_request_type ON compressed_trajectories(request_type);
            CREATE INDEX IF NOT EXISTS idx_ct_outcome ON compressed_trajectories(outcome);
            "#,
        )
        .execute(&self.pool)
        .await
        .map_err(|e| ZclawError::StorageError(e.to_string()))?;

        Ok(())
    }

    /// Insert a raw trajectory event.
    pub async fn insert_event(&self, event: &TrajectoryEvent) -> Result<()> {
        sqlx::query(
            r#"
            INSERT INTO trajectory_events
                (id, session_id, agent_id, step_index, step_type,
                 input_summary, output_summary, duration_ms, timestamp)
            VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
            "#,
        )
        .bind(&event.id)
        .bind(&event.session_id)
        .bind(&event.agent_id)
        .bind(event.step_index as i64)
        .bind(event.step_type.as_str())
        .bind(&event.input_summary)
        .bind(&event.output_summary)
        .bind(event.duration_ms as i64)
        .bind(event.timestamp.to_rfc3339())
        .execute(&self.pool)
        .await
        .map_err(|e| {
            tracing::warn!("[TrajectoryStore] insert_event failed: {}", e);
            ZclawError::StorageError(e.to_string())
        })?;

        Ok(())
    }

    /// Retrieve all raw events for a session, ordered by step_index.
    pub async fn get_events_by_session(&self, session_id: &str) -> Result<Vec<TrajectoryEvent>> {
        let rows = sqlx::query_as::<_, (String, String, String, i64, String, Option<String>, Option<String>, Option<i64>, String)>(
            r#"
            SELECT id, session_id, agent_id, step_index, step_type,
                   input_summary, output_summary, duration_ms, timestamp
            FROM trajectory_events
            WHERE session_id = ?
            ORDER BY step_index ASC
            "#,
        )
        .bind(session_id)
        .fetch_all(&self.pool)
        .await
        .map_err(|e| ZclawError::StorageError(e.to_string()))?;

        let mut events = Vec::with_capacity(rows.len());
        for (id, sid, aid, step_idx, stype, input_s, output_s, dur_ms, ts) in rows {
            let timestamp = DateTime::parse_from_rfc3339(&ts)
                .map(|dt| dt.with_timezone(&Utc))
                .unwrap_or_else(|_| Utc::now());

            events.push(TrajectoryEvent {
                id,
                session_id: sid,
                agent_id: aid,
                step_index: step_idx as usize,
                step_type: TrajectoryStepType::from_str_lossy(&stype),
                input_summary: input_s.unwrap_or_default(),
                output_summary: output_s.unwrap_or_default(),
                duration_ms: dur_ms.unwrap_or(0) as u64,
                timestamp,
            });
        }

        Ok(events)
    }

    /// Insert a compressed trajectory.
    pub async fn insert_compressed(&self, trajectory: &CompressedTrajectory) -> Result<()> {
        let tools_json = serde_json::to_string(&trajectory.tools_used)
            .map_err(|e| ZclawError::StorageError(e.to_string()))?;

        sqlx::query(
            r#"
            INSERT INTO compressed_trajectories
                (id, session_id, agent_id, request_type, tools_used,
                 outcome, total_steps, total_duration_ms, total_tokens,
                 execution_chain, satisfaction_signal, created_at)
            VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
            "#,
        )
        .bind(&trajectory.id)
        .bind(&trajectory.session_id)
        .bind(&trajectory.agent_id)
        .bind(&trajectory.request_type)
        .bind(&tools_json)
        .bind(trajectory.outcome.as_str())
        .bind(trajectory.total_steps as i64)
        .bind(trajectory.total_duration_ms as i64)
        .bind(trajectory.total_tokens as i64)
        .bind(&trajectory.execution_chain)
        .bind(trajectory.satisfaction_signal.map(|s| s.as_str()))
        .bind(trajectory.created_at.to_rfc3339())
        .execute(&self.pool)
        .await
        .map_err(|e| {
            tracing::warn!("[TrajectoryStore] insert_compressed failed: {}", e);
            ZclawError::StorageError(e.to_string())
        })?;

        Ok(())
    }

    /// Retrieve the compressed trajectory for a session, if any.
    pub async fn get_compressed_by_session(&self, session_id: &str) -> Result<Option<CompressedTrajectory>> {
        let row = sqlx::query_as::<_, (
            String, String, String, String, Option<String>,
            String, i64, i64, i64, String, Option<String>, String,
        )>(
            r#"
            SELECT id, session_id, agent_id, request_type, tools_used,
                   outcome, total_steps, total_duration_ms, total_tokens,
                   execution_chain, satisfaction_signal, created_at
            FROM compressed_trajectories
            WHERE session_id = ?
            "#,
        )
        .bind(session_id)
        .fetch_optional(&self.pool)
        .await
        .map_err(|e| ZclawError::StorageError(e.to_string()))?;

        match row {
            Some((id, sid, aid, req_type, tools_json, outcome_str, steps, dur_ms, tokens, chain, sat, created)) => {
                let tools_used: Vec<String> = tools_json
                    .as_deref()
                    .and_then(|j| serde_json::from_str(j).ok())
                    .unwrap_or_default();

                let timestamp = DateTime::parse_from_rfc3339(&created)
                    .map(|dt| dt.with_timezone(&Utc))
                    .unwrap_or_else(|_| Utc::now());

                Ok(Some(CompressedTrajectory {
                    id,
                    session_id: sid,
                    agent_id: aid,
                    request_type: req_type,
                    tools_used,
                    outcome: CompletionStatus::from_str_lossy(&outcome_str),
                    total_steps: steps as usize,
                    total_duration_ms: dur_ms as u64,
                    total_tokens: tokens as u32,
                    execution_chain: chain,
                    satisfaction_signal: sat.as_deref().and_then(SatisfactionSignal::from_str_lossy),
                    created_at: timestamp,
                }))
            }
            None => Ok(None),
        }
    }

    /// Delete raw trajectory events older than `days` days. Returns count deleted.
    pub async fn delete_events_older_than(&self, days: i64) -> Result<u64> {
        let result = sqlx::query(
            r#"
            DELETE FROM trajectory_events
            WHERE timestamp < datetime('now', ?)
            "#,
        )
        .bind(format!("-{} days", days))
        .execute(&self.pool)
        .await
        .map_err(|e| {
            tracing::warn!("[TrajectoryStore] delete_events_older_than failed: {}", e);
            ZclawError::StorageError(e.to_string())
        })?;

        Ok(result.rows_affected())
    }

    /// Delete compressed trajectories older than `days` days. Returns count deleted.
    pub async fn delete_compressed_older_than(&self, days: i64) -> Result<u64> {
        let result = sqlx::query(
            r#"
            DELETE FROM compressed_trajectories
            WHERE created_at < datetime('now', ?)
            "#,
        )
        .bind(format!("-{} days", days))
        .execute(&self.pool)
        .await
        .map_err(|e| {
            tracing::warn!("[TrajectoryStore] delete_compressed_older_than failed: {}", e);
            ZclawError::StorageError(e.to_string())
        })?;

        Ok(result.rows_affected())
    }
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

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

    async fn test_store() -> TrajectoryStore {
        let pool = SqlitePool::connect("sqlite::memory:")
            .await
            .expect("in-memory pool");
        let store = TrajectoryStore::new(pool);
        store.initialize_schema().await.expect("schema init");
        store
    }

    fn sample_event(index: usize) -> TrajectoryEvent {
        TrajectoryEvent {
            id: format!("evt-{}", index),
            session_id: "sess-1".to_string(),
            agent_id: "agent-1".to_string(),
            step_index: index,
            step_type: TrajectoryStepType::ToolExecution,
            input_summary: "search query".to_string(),
            output_summary: "3 results found".to_string(),
            duration_ms: 150,
            timestamp: Utc::now(),
        }
    }

    #[tokio::test]
    async fn test_insert_and_get_events() {
        let store = test_store().await;

        let e1 = sample_event(0);
        let e2 = TrajectoryEvent {
            id: "evt-1".to_string(),
            step_index: 1,
            step_type: TrajectoryStepType::LlmGeneration,
            ..sample_event(0)
        };

        store.insert_event(&e1).await.unwrap();
        store.insert_event(&e2).await.unwrap();

        let events = store.get_events_by_session("sess-1").await.unwrap();
        assert_eq!(events.len(), 2);
        assert_eq!(events[0].step_index, 0);
        assert_eq!(events[1].step_index, 1);
        assert_eq!(events[0].step_type, TrajectoryStepType::ToolExecution);
        assert_eq!(events[1].step_type, TrajectoryStepType::LlmGeneration);
    }

    #[tokio::test]
    async fn test_get_events_empty_session() {
        let store = test_store().await;
        let events = store.get_events_by_session("nonexistent").await.unwrap();
        assert!(events.is_empty());
    }

    #[tokio::test]
    async fn test_insert_and_get_compressed() {
        let store = test_store().await;

        let ct = CompressedTrajectory {
            id: "ct-1".to_string(),
            session_id: "sess-1".to_string(),
            agent_id: "agent-1".to_string(),
            request_type: "data_query".to_string(),
            tools_used: vec!["search".to_string(), "calculate".to_string()],
            outcome: CompletionStatus::Success,
            total_steps: 5,
            total_duration_ms: 1200,
            total_tokens: 350,
            execution_chain: r#"[{"step":0,"type":"tool_execution"}]"#.to_string(),
            satisfaction_signal: Some(SatisfactionSignal::Positive),
            created_at: Utc::now(),
        };

        store.insert_compressed(&ct).await.unwrap();

        let loaded = store.get_compressed_by_session("sess-1").await.unwrap();
        assert!(loaded.is_some());

        let loaded = loaded.unwrap();
        assert_eq!(loaded.id, "ct-1");
        assert_eq!(loaded.request_type, "data_query");
        assert_eq!(loaded.tools_used.len(), 2);
        assert_eq!(loaded.outcome, CompletionStatus::Success);
        assert_eq!(loaded.satisfaction_signal, Some(SatisfactionSignal::Positive));
    }

    #[tokio::test]
    async fn test_get_compressed_nonexistent() {
        let store = test_store().await;
        let result = store.get_compressed_by_session("nonexistent").await.unwrap();
        assert!(result.is_none());
    }

    #[tokio::test]
    async fn test_step_type_roundtrip() {
        let all_types = [
            TrajectoryStepType::UserRequest,
            TrajectoryStepType::IntentClassification,
            TrajectoryStepType::SkillSelection,
            TrajectoryStepType::ToolExecution,
            TrajectoryStepType::LlmGeneration,
            TrajectoryStepType::UserFeedback,
        ];

        for st in all_types {
            assert_eq!(TrajectoryStepType::from_str_lossy(st.as_str()), st);
        }
    }

    #[tokio::test]
    async fn test_satisfaction_signal_roundtrip() {
        let signals = [SatisfactionSignal::Positive, SatisfactionSignal::Negative, SatisfactionSignal::Neutral];
        for sig in signals {
            assert_eq!(SatisfactionSignal::from_str_lossy(sig.as_str()), Some(sig));
        }
        assert_eq!(SatisfactionSignal::from_str_lossy("bogus"), None);
    }

    #[tokio::test]
    async fn test_completion_status_roundtrip() {
        let statuses = [CompletionStatus::Success, CompletionStatus::Partial, CompletionStatus::Failed, CompletionStatus::Abandoned];
        for s in statuses {
            assert_eq!(CompletionStatus::from_str_lossy(s.as_str()), s);
        }
    }

    #[tokio::test]
    async fn test_delete_events_older_than() {
        let store = test_store().await;

        // Insert an event with a timestamp far in the past
        let old_event = TrajectoryEvent {
            id: "old-evt".to_string(),
            timestamp: Utc::now() - chrono::Duration::days(100),
            ..sample_event(0)
        };
        store.insert_event(&old_event).await.unwrap();

        // Insert a recent event
        let recent_event = TrajectoryEvent {
            id: "recent-evt".to_string(),
            step_index: 1,
            ..sample_event(0)
        };
        store.insert_event(&recent_event).await.unwrap();

        let deleted = store.delete_events_older_than(30).await.unwrap();
        assert_eq!(deleted, 1);

        let remaining = store.get_events_by_session("sess-1").await.unwrap();
        assert_eq!(remaining.len(), 1);
        assert_eq!(remaining[0].id, "recent-evt");
    }
}