use rusqlite::{params, Connection, Result as SqlResult};
use std::path::Path;
use std::sync::Mutex;
use tracing::{info, warn};

/// SQLite-backed persistent state for Sol.
///
/// Stores:
/// - Conversation registry: room_id → Mistral conversation_id + token estimates
/// - Agent registry: agent_name → Mistral agent_id
///
/// ## Kubernetes mount
///
/// The database file should be on a persistent volume. Recommended setup:
///
/// ```yaml
/// # PersistentVolumeClaim (Longhorn)
/// apiVersion: v1
/// kind: PersistentVolumeClaim
/// metadata:
///   name: sol-data
///   namespace: matrix
/// spec:
///   accessModes: [ReadWriteOnce]
///   storageClassName: longhorn
///   resources:
///     requests:
///       storage: 1Gi
///
/// # Deployment volume mount
/// volumes:
///   - name: sol-data
///     persistentVolumeClaim:
///       claimName: sol-data
/// containers:
///   - name: sol
///     volumeMounts:
///       - name: sol-data
///         mountPath: /data
/// ```
///
/// Default path: `/data/sol.db` (configurable via `matrix.db_path` in sol.toml).
/// The `/data` mount also holds the Matrix SDK state store at `/data/matrix-state`.
pub struct Store {
    conn: Mutex<Connection>,
}

impl Store {
    /// Open or create the database at the given path.
    /// Creates tables if they don't exist.
    pub fn open(path: &str) -> anyhow::Result<Self> {
        // Ensure parent directory exists
        if let Some(parent) = Path::new(path).parent() {
            std::fs::create_dir_all(parent)?;
        }

        let conn = Connection::open(path)?;

        // Enable WAL mode for better concurrent read performance
        conn.execute_batch("PRAGMA journal_mode=WAL;")?;

        conn.execute_batch(
            "CREATE TABLE IF NOT EXISTS conversations (
                room_id         TEXT PRIMARY KEY,
                conversation_id TEXT NOT NULL,
                estimated_tokens INTEGER NOT NULL DEFAULT 0,
                created_at      TEXT NOT NULL DEFAULT (datetime('now'))
            );

            CREATE TABLE IF NOT EXISTS agents (
                name              TEXT PRIMARY KEY,
                agent_id          TEXT NOT NULL,
                model             TEXT NOT NULL DEFAULT '',
                instructions_hash TEXT NOT NULL DEFAULT '',
                created_at        TEXT NOT NULL DEFAULT (datetime('now'))
            );

            CREATE TABLE IF NOT EXISTS service_users (
                localpart        TEXT NOT NULL,
                service          TEXT NOT NULL,
                service_username TEXT NOT NULL,
                created_at       TEXT NOT NULL DEFAULT (datetime('now')),
                PRIMARY KEY (localpart, service)
            );

            CREATE TABLE IF NOT EXISTS code_sessions (
                session_id      TEXT PRIMARY KEY,
                user_id         TEXT NOT NULL,
                room_id         TEXT NOT NULL,
                conversation_id TEXT,
                project_path    TEXT NOT NULL,
                project_name    TEXT NOT NULL,
                model           TEXT NOT NULL,
                status          TEXT NOT NULL DEFAULT 'active',
                created_at      TEXT NOT NULL DEFAULT (datetime('now')),
                last_active     TEXT NOT NULL DEFAULT (datetime('now'))
            );

            CREATE TABLE IF NOT EXISTS research_sessions (
                session_id    TEXT PRIMARY KEY,
                room_id       TEXT NOT NULL,
                event_id      TEXT NOT NULL,
                status        TEXT NOT NULL DEFAULT 'running',
                query         TEXT NOT NULL,
                plan_json     TEXT,
                findings_json TEXT,
                depth         INTEGER NOT NULL DEFAULT 0,
                created_at    TEXT NOT NULL DEFAULT (datetime('now')),
                completed_at  TEXT
            );
",
        )?;

        // Migration: add instructions_hash column to agents table if missing
        let has_hash: bool = conn
            .prepare("SELECT instructions_hash FROM agents LIMIT 0")
            .is_ok();
        if !has_hash {
            conn.execute_batch(
                "ALTER TABLE agents ADD COLUMN instructions_hash TEXT NOT NULL DEFAULT '';"
            )?;
            info!("Migrated agents table: added instructions_hash column");
        }

        info!(path, "Opened Sol state database");
        Ok(Self {
            conn: Mutex::new(conn),
        })
    }

    /// Open an in-memory database (for tests).
    pub fn open_memory() -> anyhow::Result<Self> {
        Self::open(":memory:")
    }

    // =========================================================================
    // Conversations
    // =========================================================================

    /// Get the conversation_id for a room, if one exists.
    pub fn get_conversation(&self, room_id: &str) -> Option<(String, u32)> {
        let conn = self.conn.lock().unwrap();
        conn.query_row(
            "SELECT conversation_id, estimated_tokens FROM conversations WHERE room_id = ?1",
            params![room_id],
            |row| Ok((row.get::<_, String>(0)?, row.get::<_, u32>(1)?)),
        )
        .ok()
    }

    /// Store or update a conversation mapping.
    pub fn upsert_conversation(
        &self,
        room_id: &str,
        conversation_id: &str,
        estimated_tokens: u32,
    ) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "INSERT INTO conversations (room_id, conversation_id, estimated_tokens)
             VALUES (?1, ?2, ?3)
             ON CONFLICT(room_id) DO UPDATE SET
                conversation_id = excluded.conversation_id,
                estimated_tokens = excluded.estimated_tokens",
            params![room_id, conversation_id, estimated_tokens],
        ) {
            warn!("Failed to upsert conversation: {e}");
        }
    }

    /// Update token estimate for a conversation.
    pub fn update_tokens(&self, room_id: &str, estimated_tokens: u32) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "UPDATE conversations SET estimated_tokens = ?1 WHERE room_id = ?2",
            params![estimated_tokens, room_id],
        ) {
            warn!("Failed to update token estimate: {e}");
        }
    }

    /// Remove all conversation mappings (e.g., after agent recreation).
    pub fn delete_all_conversations(&self) -> usize {
        let conn = self.conn.lock().unwrap();
        conn.execute("DELETE FROM conversations", []).unwrap_or(0)
    }

    /// Remove a conversation mapping (e.g., after compaction).
    pub fn delete_conversation(&self, room_id: &str) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "DELETE FROM conversations WHERE room_id = ?1",
            params![room_id],
        ) {
            warn!("Failed to delete conversation: {e}");
        }
    }

    /// Load all conversation mappings (for startup recovery).
    pub fn load_all_conversations(&self) -> Vec<(String, String, u32)> {
        let conn = self.conn.lock().unwrap();
        let mut stmt = match conn.prepare(
            "SELECT room_id, conversation_id, estimated_tokens FROM conversations",
        ) {
            Ok(s) => s,
            Err(_) => return Vec::new(),
        };

        stmt.query_map([], |row| {
            Ok((
                row.get::<_, String>(0)?,
                row.get::<_, String>(1)?,
                row.get::<_, u32>(2)?,
            ))
        })
        .ok()
        .map(|rows| rows.filter_map(|r| r.ok()).collect())
        .unwrap_or_default()
    }

    // =========================================================================
    // Agents
    // =========================================================================

    /// Get the agent_id and instructions hash for a named agent.
    pub fn get_agent(&self, name: &str) -> Option<(String, String)> {
        let conn = self.conn.lock().unwrap();
        conn.query_row(
            "SELECT agent_id, instructions_hash FROM agents WHERE name = ?1",
            params![name],
            |row| Ok((row.get::<_, String>(0)?, row.get::<_, String>(1)?)),
        )
        .ok()
    }

    /// Store or update an agent mapping (with instructions hash for staleness detection).
    pub fn upsert_agent(&self, name: &str, agent_id: &str, model: &str, instructions_hash: &str) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "INSERT INTO agents (name, agent_id, model, instructions_hash)
             VALUES (?1, ?2, ?3, ?4)
             ON CONFLICT(name) DO UPDATE SET
                agent_id = excluded.agent_id,
                model = excluded.model,
                instructions_hash = excluded.instructions_hash",
            params![name, agent_id, model, instructions_hash],
        ) {
            warn!("Failed to upsert agent: {e}");
        }
    }

    /// Remove an agent mapping.
    pub fn delete_agent(&self, name: &str) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute("DELETE FROM agents WHERE name = ?1", params![name]) {
            warn!("Failed to delete agent: {e}");
        }
    }

    // =========================================================================
    // Code Sessions (sunbeam code)
    // =========================================================================

    /// Find an active code session for a user + project.
    pub fn find_code_session(
        &self,
        user_id: &str,
        project_name: &str,
    ) -> Option<(String, String, String)> {
        let conn = self.conn.lock().unwrap();
        conn.query_row(
            "SELECT session_id, room_id, conversation_id FROM code_sessions
             WHERE user_id = ?1 AND project_name = ?2 AND status = 'active'
             ORDER BY last_active DESC LIMIT 1",
            params![user_id, project_name],
            |row| Ok((
                row.get::<_, String>(0)?,
                row.get::<_, String>(1)?,
                row.get::<_, String>(2)?,
            )),
        )
        .ok()
    }

    /// Create a new code session.
    pub fn create_code_session(
        &self,
        session_id: &str,
        user_id: &str,
        room_id: &str,
        project_path: &str,
        project_name: &str,
        model: &str,
    ) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "INSERT INTO code_sessions (session_id, user_id, room_id, project_path, project_name, model)
             VALUES (?1, ?2, ?3, ?4, ?5, ?6)",
            params![session_id, user_id, room_id, project_path, project_name, model],
        ) {
            warn!("Failed to create code session: {e}");
        }
    }

    /// Update the conversation_id for a code session.
    pub fn set_code_session_conversation(
        &self,
        session_id: &str,
        conversation_id: &str,
    ) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "UPDATE code_sessions SET conversation_id = ?1, last_active = datetime('now')
             WHERE session_id = ?2",
            params![conversation_id, session_id],
        ) {
            warn!("Failed to update code session conversation: {e}");
        }
    }

    /// Touch the last_active timestamp.
    pub fn touch_code_session(&self, session_id: &str) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "UPDATE code_sessions SET last_active = datetime('now') WHERE session_id = ?1",
            params![session_id],
        ) {
            warn!("Failed to touch code session: {e}");
        }
    }

    /// End a code session.
    pub fn end_code_session(&self, session_id: &str) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "UPDATE code_sessions SET status = 'ended' WHERE session_id = ?1",
            params![session_id],
        ) {
            warn!("Failed to end code session: {e}");
        }
    }

    /// Check if a room is a code session room.
    pub fn is_code_room(&self, room_id: &str) -> bool {
        let conn = self.conn.lock().unwrap();
        conn.query_row(
            "SELECT 1 FROM code_sessions WHERE room_id = ?1 AND status = 'active' LIMIT 1",
            params![room_id],
            |_| Ok(()),
        )
        .is_ok()
    }

    /// Get project context for a code room.
    pub fn get_code_room_context(
        &self,
        room_id: &str,
    ) -> Option<(String, String, String)> {
        let conn = self.conn.lock().unwrap();
        conn.query_row(
            "SELECT project_name, project_path, model FROM code_sessions
             WHERE room_id = ?1 AND status = 'active'
             ORDER BY last_active DESC LIMIT 1",
            params![room_id],
            |row| Ok((
                row.get::<_, String>(0)?,
                row.get::<_, String>(1)?,
                row.get::<_, String>(2)?,
            )),
        )
        .ok()
    }

    // =========================================================================
    // Service Users (OIDC → service username mapping)
    // =========================================================================

    /// Get the service-specific username for a Matrix localpart.
    pub fn get_service_user(&self, localpart: &str, service: &str) -> Option<String> {
        let conn = self.conn.lock().unwrap();
        conn.query_row(
            "SELECT service_username FROM service_users WHERE localpart = ?1 AND service = ?2",
            params![localpart, service],
            |row| row.get(0),
        )
        .ok()
    }

    /// Store or update a service user mapping.
    pub fn upsert_service_user(&self, localpart: &str, service: &str, service_username: &str) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "INSERT INTO service_users (localpart, service, service_username)
             VALUES (?1, ?2, ?3)
             ON CONFLICT(localpart, service) DO UPDATE SET
                service_username = excluded.service_username",
            params![localpart, service, service_username],
        ) {
            warn!("Failed to upsert service user: {e}");
        }
    }

    /// Remove a service user mapping.
    pub fn delete_service_user(&self, localpart: &str, service: &str) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "DELETE FROM service_users WHERE localpart = ?1 AND service = ?2",
            params![localpart, service],
        ) {
            warn!("Failed to delete service user: {e}");
        }
    }

    // =========================================================================
    // Research Sessions
    // =========================================================================

    /// Create a new research session.
    pub fn create_research_session(
        &self,
        session_id: &str,
        room_id: &str,
        event_id: &str,
        query: &str,
        plan_json: &str,
    ) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "INSERT INTO research_sessions (session_id, room_id, event_id, query, plan_json, findings_json)
             VALUES (?1, ?2, ?3, ?4, ?5, '[]')",
            params![session_id, room_id, event_id, query, plan_json],
        ) {
            warn!("Failed to create research session: {e}");
        }
    }

    /// Append a finding to a research session.
    pub fn append_research_finding(&self, session_id: &str, finding_json: &str) {
        let conn = self.conn.lock().unwrap();
        // Append to the JSON array
        if let Err(e) = conn.execute(
            "UPDATE research_sessions
             SET findings_json = json_insert(findings_json, '$[#]', json(?1))
             WHERE session_id = ?2",
            params![finding_json, session_id],
        ) {
            warn!("Failed to append research finding: {e}");
        }
    }

    /// Mark a research session as complete.
    pub fn complete_research_session(&self, session_id: &str) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "UPDATE research_sessions SET status = 'complete', completed_at = datetime('now')
             WHERE session_id = ?1",
            params![session_id],
        ) {
            warn!("Failed to complete research session: {e}");
        }
    }

    /// Mark a research session as failed.
    pub fn fail_research_session(&self, session_id: &str) {
        let conn = self.conn.lock().unwrap();
        if let Err(e) = conn.execute(
            "UPDATE research_sessions SET status = 'failed', completed_at = datetime('now')
             WHERE session_id = ?1",
            params![session_id],
        ) {
            warn!("Failed to mark research session failed: {e}");
        }
    }

    /// Load all running research sessions (for crash recovery on startup).
    pub fn load_running_research_sessions(&self) -> Vec<(String, String, String, String)> {
        let conn = self.conn.lock().unwrap();
        let mut stmt = match conn.prepare(
            "SELECT session_id, room_id, query, findings_json
             FROM research_sessions WHERE status = 'running'",
        ) {
            Ok(s) => s,
            Err(_) => return Vec::new(),
        };

        stmt.query_map([], |row| {
            Ok((
                row.get::<_, String>(0)?,
                row.get::<_, String>(1)?,
                row.get::<_, String>(2)?,
                row.get::<_, String>(3)?,
            ))
        })
        .ok()
        .map(|rows| rows.filter_map(|r| r.ok()).collect())
        .unwrap_or_default()
    }

    /// Load all agent mappings (for startup recovery).
    pub fn load_all_agents(&self) -> Vec<(String, String)> {
        let conn = self.conn.lock().unwrap();
        let mut stmt = match conn.prepare("SELECT name, agent_id FROM agents") {
            Ok(s) => s,
            Err(_) => return Vec::new(),
        };

        stmt.query_map([], |row| {
            Ok((row.get::<_, String>(0)?, row.get::<_, String>(1)?))
        })
        .ok()
        .map(|rows| rows.filter_map(|r| r.ok()).collect())
        .unwrap_or_default()
    }
}

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

    #[test]
    fn test_open_memory_db() {
        let store = Store::open_memory().unwrap();
        assert!(store.load_all_conversations().is_empty());
        assert!(store.load_all_agents().is_empty());
    }

    #[test]
    fn test_conversation_crud() {
        let store = Store::open_memory().unwrap();

        // Insert
        store.upsert_conversation("!room:x", "conv_abc", 100);
        let (conv_id, tokens) = store.get_conversation("!room:x").unwrap();
        assert_eq!(conv_id, "conv_abc");
        assert_eq!(tokens, 100);

        // Update tokens
        store.update_tokens("!room:x", 500);
        let (_, tokens) = store.get_conversation("!room:x").unwrap();
        assert_eq!(tokens, 500);

        // Upsert (replace conversation_id)
        store.upsert_conversation("!room:x", "conv_def", 0);
        let (conv_id, tokens) = store.get_conversation("!room:x").unwrap();
        assert_eq!(conv_id, "conv_def");
        assert_eq!(tokens, 0);

        // Delete
        store.delete_conversation("!room:x");
        assert!(store.get_conversation("!room:x").is_none());
    }

    #[test]
    fn test_agent_crud() {
        let store = Store::open_memory().unwrap();

        store.upsert_agent("sol-orchestrator", "ag_123", "mistral-medium-latest", "hash1");
        let (id, hash) = store.get_agent("sol-orchestrator").unwrap();
        assert_eq!(id, "ag_123");
        assert_eq!(hash, "hash1");

        // Update
        store.upsert_agent("sol-orchestrator", "ag_456", "mistral-medium-latest", "hash2");
        let (id, hash) = store.get_agent("sol-orchestrator").unwrap();
        assert_eq!(id, "ag_456");
        assert_eq!(hash, "hash2");

        // Delete
        store.delete_agent("sol-orchestrator");
        assert!(store.get_agent("sol-orchestrator").is_none());
    }

    #[test]
    fn test_load_all_conversations() {
        let store = Store::open_memory().unwrap();
        store.upsert_conversation("!a:x", "conv_1", 10);
        store.upsert_conversation("!b:x", "conv_2", 20);
        store.upsert_conversation("!c:x", "conv_3", 30);

        let all = store.load_all_conversations();
        assert_eq!(all.len(), 3);
    }

    #[test]
    fn test_load_all_agents() {
        let store = Store::open_memory().unwrap();
        store.upsert_agent("orch", "ag_1", "medium", "h1");
        store.upsert_agent("obs", "ag_2", "medium", "h2");

        let all = store.load_all_agents();
        assert_eq!(all.len(), 2);
    }

    #[test]
    fn test_nonexistent_keys_return_none() {
        let store = Store::open_memory().unwrap();
        assert!(store.get_conversation("!nope:x").is_none());
        assert!(store.get_agent("nope").is_none());
    }

    #[test]
    fn test_service_user_crud() {
        let store = Store::open_memory().unwrap();

        // Insert
        store.upsert_service_user("sienna", "gitea", "siennav");
        assert_eq!(
            store.get_service_user("sienna", "gitea").unwrap(),
            "siennav"
        );

        // Update
        store.upsert_service_user("sienna", "gitea", "sienna");
        assert_eq!(
            store.get_service_user("sienna", "gitea").unwrap(),
            "sienna"
        );

        // Different service
        store.upsert_service_user("sienna", "grafana", "sienna-g");
        assert_eq!(
            store.get_service_user("sienna", "grafana").unwrap(),
            "sienna-g"
        );

        // Delete
        store.delete_service_user("sienna", "gitea");
        assert!(store.get_service_user("sienna", "gitea").is_none());
        // Other service unaffected
        assert!(store.get_service_user("sienna", "grafana").is_some());
    }

    #[test]
    fn test_delete_all_conversations() {
        let store = Store::open_memory().unwrap();
        store.upsert_conversation("!a:x", "conv_1", 10);
        store.upsert_conversation("!b:x", "conv_2", 20);
        store.upsert_conversation("!c:x", "conv_3", 30);

        let deleted = store.delete_all_conversations();
        assert_eq!(deleted, 3);
        assert!(store.load_all_conversations().is_empty());

        // DB still works after bulk delete
        store.upsert_conversation("!d:x", "conv_4", 0);
        assert_eq!(store.load_all_conversations().len(), 1);
    }

    #[test]
    fn test_nonexistent_service_user() {
        let store = Store::open_memory().unwrap();
        assert!(store.get_service_user("nobody", "gitea").is_none());
    }

    // ── Research session tests ──────────────────────────────────────────

    #[test]
    fn test_research_session_lifecycle() {
        let store = Store::open_memory().unwrap();

        // Create
        store.create_research_session("sess-1", "!room:x", "$event1", "investigate SBBB", "[]");
        let running = store.load_running_research_sessions();
        assert_eq!(running.len(), 1);
        assert_eq!(running[0].0, "sess-1");
        assert_eq!(running[0].2, "investigate SBBB");
    }

    #[test]
    fn test_research_session_append_finding() {
        let store = Store::open_memory().unwrap();
        store.create_research_session("sess-2", "!room:x", "$event2", "test", "[]");

        store.append_research_finding("sess-2", r#"{"focus":"repo","findings":"found 3 files"}"#);
        store.append_research_finding("sess-2", r#"{"focus":"archive","findings":"12 messages"}"#);

        let running = store.load_running_research_sessions();
        assert_eq!(running.len(), 1);
        // findings_json should be a JSON array with 2 entries
        let findings: serde_json::Value = serde_json::from_str(&running[0].3).unwrap();
        assert_eq!(findings.as_array().unwrap().len(), 2);
    }

    #[test]
    fn test_research_session_complete() {
        let store = Store::open_memory().unwrap();
        store.create_research_session("sess-3", "!room:x", "$event3", "test", "[]");

        store.complete_research_session("sess-3");

        // Should no longer appear in running sessions
        let running = store.load_running_research_sessions();
        assert!(running.is_empty());
    }

    #[test]
    fn test_research_session_fail() {
        let store = Store::open_memory().unwrap();
        store.create_research_session("sess-4", "!room:x", "$event4", "test", "[]");

        store.fail_research_session("sess-4");

        let running = store.load_running_research_sessions();
        assert!(running.is_empty());
    }

    #[test]
    fn test_hung_session_cleanup_on_startup() {
        let store = Store::open_memory().unwrap();

        // Simulate 2 hung sessions + 1 completed
        store.create_research_session("hung-1", "!room:a", "$e1", "query A", "[]");
        store.create_research_session("hung-2", "!room:b", "$e2", "query B", "[]");
        store.create_research_session("done-1", "!room:c", "$e3", "query C", "[]");
        store.complete_research_session("done-1");

        // Only the 2 hung sessions should be returned
        let hung = store.load_running_research_sessions();
        assert_eq!(hung.len(), 2);

        // Clean them up (simulates startup logic)
        for (session_id, _, _, _) in &hung {
            store.fail_research_session(session_id);
        }

        // Now none should be running
        assert!(store.load_running_research_sessions().is_empty());
    }

    #[test]
    fn test_research_session_partial_findings_survive_failure() {
        let store = Store::open_memory().unwrap();
        store.create_research_session("sess-5", "!room:x", "$e5", "deep dive", "[]");

        // Agent 1 completes, agent 2 hasn't yet
        store.append_research_finding("sess-5", r#"{"focus":"agent1","findings":"found stuff"}"#);

        // Crash! Mark as failed
        store.fail_research_session("sess-5");

        // Findings should still be queryable even though session failed
        // (would need a get_session method to verify, but the key point is
        // append_research_finding persists incrementally)
    }
}