//! SQLCipher-backed persistent storage.

use std::path::Path;
use std::sync::Mutex;

use rusqlite::{params, Connection};

use crate::storage::{StorageError, Store};

/// SQLCipher-encrypted storage backend.
pub struct SqlStore {
    conn: Mutex<Connection>,
}

impl SqlStore {
    pub fn open(path: impl AsRef<Path>, key: &str) -> Result<Self, StorageError> {
        let conn = Connection::open(path).map_err(|e| StorageError::Db(e.to_string()))?;

        if !key.is_empty() {
            conn.pragma_update(None, "key", key)
                .map_err(|e| StorageError::Db(format!("PRAGMA key failed: {e}")))?;
        }

        conn.execute_batch(
            "PRAGMA journal_mode = WAL;
             PRAGMA synchronous = NORMAL;
             PRAGMA foreign_keys = ON;",
        )
        .map_err(|e| StorageError::Db(e.to_string()))?;

        let store = Self {
            conn: Mutex::new(conn),
        };
        store.migrate()?;
        Ok(store)
    }

    fn migrate(&self) -> Result<(), StorageError> {
        let conn = self.conn.lock().unwrap();
        conn.execute_batch(
            "CREATE TABLE IF NOT EXISTS key_packages (
                id           INTEGER PRIMARY KEY AUTOINCREMENT,
                identity_key BLOB NOT NULL,
                package_data BLOB NOT NULL,
                created_at   INTEGER DEFAULT (strftime('%s','now'))
            );

            CREATE TABLE IF NOT EXISTS deliveries (
                id            INTEGER PRIMARY KEY AUTOINCREMENT,
                recipient_key BLOB NOT NULL,
                channel_id    BLOB NOT NULL DEFAULT X'',
                payload       BLOB NOT NULL,
                created_at    INTEGER DEFAULT (strftime('%s','now'))
            );

            CREATE TABLE IF NOT EXISTS hybrid_keys (
                identity_key      BLOB PRIMARY KEY,
                hybrid_public_key BLOB NOT NULL
            );

            CREATE INDEX IF NOT EXISTS idx_kp_identity
                ON key_packages(identity_key);

            CREATE INDEX IF NOT EXISTS idx_del_recipient_channel
                ON deliveries(recipient_key, channel_id);

            CREATE TABLE IF NOT EXISTS server_setup (
                id         INTEGER PRIMARY KEY CHECK (id = 1),
                setup_data BLOB NOT NULL
            );

            CREATE TABLE IF NOT EXISTS users (
                username      TEXT PRIMARY KEY,
                opaque_record BLOB NOT NULL,
                created_at    INTEGER DEFAULT (strftime('%s','now'))
            );

            CREATE TABLE IF NOT EXISTS user_identity_keys (
                username     TEXT PRIMARY KEY,
                identity_key BLOB NOT NULL
            );

            CREATE TABLE IF NOT EXISTS endpoints (
                identity_key BLOB PRIMARY KEY,
                node_addr    BLOB NOT NULL,
                updated_at   INTEGER DEFAULT (strftime('%s','now'))
            );",
        )
        .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(())
    }
}

impl Store for SqlStore {
    fn upload_key_package(
        &self,
        identity_key: &[u8],
        package: Vec<u8>,
    ) -> Result<(), StorageError> {
        let conn = self.conn.lock().unwrap();
        conn.execute(
            "INSERT INTO key_packages (identity_key, package_data) VALUES (?1, ?2)",
            params![identity_key, package],
        )
        .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(())
    }

    fn fetch_key_package(&self, identity_key: &[u8]) -> Result<Option<Vec<u8>>, StorageError> {
        let conn = self.conn.lock().unwrap();

        let mut stmt = conn
            .prepare(
                "SELECT id, package_data FROM key_packages
                 WHERE identity_key = ?1
                 ORDER BY id ASC
                 LIMIT 1",
            )
            .map_err(|e| StorageError::Db(e.to_string()))?;

        let row = stmt
            .query_row(params![identity_key], |row| {
                Ok((row.get::<_, i64>(0)?, row.get::<_, Vec<u8>>(1)?))
            })
            .optional()
            .map_err(|e| StorageError::Db(e.to_string()))?;

        match row {
            Some((id, package)) => {
                conn.execute("DELETE FROM key_packages WHERE id = ?1", params![id])
                    .map_err(|e| StorageError::Db(e.to_string()))?;
                Ok(Some(package))
            }
            None => Ok(None),
        }
    }

    fn enqueue(
        &self,
        recipient_key: &[u8],
        channel_id: &[u8],
        payload: Vec<u8>,
    ) -> Result<(), StorageError> {
        let conn = self.conn.lock().unwrap();
        conn.execute(
            "INSERT INTO deliveries (recipient_key, channel_id, payload) VALUES (?1, ?2, ?3)",
            params![recipient_key, channel_id, payload],
        )
        .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(())
    }

    fn fetch(
        &self,
        recipient_key: &[u8],
        channel_id: &[u8],
    ) -> Result<Vec<Vec<u8>>, StorageError> {
        let conn = self.conn.lock().unwrap();

        let mut stmt = conn
            .prepare(
                "SELECT id, payload FROM deliveries
                 WHERE recipient_key = ?1 AND channel_id = ?2
                 ORDER BY id ASC",
            )
            .map_err(|e| StorageError::Db(e.to_string()))?;

        let rows: Vec<(i64, Vec<u8>)> = stmt
            .query_map(params![recipient_key, channel_id], |row| {
                Ok((row.get(0)?, row.get(1)?))
            })
            .map_err(|e| StorageError::Db(e.to_string()))?
            .collect::<Result<Vec<_>, _>>()
            .map_err(|e| StorageError::Db(e.to_string()))?;

        if !rows.is_empty() {
            let ids: Vec<i64> = rows.iter().map(|(id, _)| *id).collect();
            let placeholders: String = ids.iter().map(|_| "?").collect::<Vec<_>>().join(",");
            let sql = format!("DELETE FROM deliveries WHERE id IN ({placeholders})");
            let params: Vec<&dyn rusqlite::types::ToSql> =
                ids.iter().map(|id| id as &dyn rusqlite::types::ToSql).collect();
            conn.execute(&sql, params.as_slice())
                .map_err(|e| StorageError::Db(e.to_string()))?;
        }

        Ok(rows.into_iter().map(|(_, payload)| payload).collect())
    }

    fn fetch_limited(
        &self,
        recipient_key: &[u8],
        channel_id: &[u8],
        limit: usize,
    ) -> Result<Vec<Vec<u8>>, StorageError> {
        let conn = self.conn.lock().unwrap();

        let mut stmt = conn
            .prepare(
                "SELECT id, payload FROM deliveries
                 WHERE recipient_key = ?1 AND channel_id = ?2
                 ORDER BY id ASC
                 LIMIT ?3",
            )
            .map_err(|e| StorageError::Db(e.to_string()))?;

        let rows: Vec<(i64, Vec<u8>)> = stmt
            .query_map(params![recipient_key, channel_id, limit as i64], |row| {
                Ok((row.get(0)?, row.get(1)?))
            })
            .map_err(|e| StorageError::Db(e.to_string()))?
            .collect::<Result<Vec<_>, _>>()
            .map_err(|e| StorageError::Db(e.to_string()))?;

        if !rows.is_empty() {
            let ids: Vec<i64> = rows.iter().map(|(id, _)| *id).collect();
            let placeholders: String = ids.iter().map(|_| "?").collect::<Vec<_>>().join(",");
            let sql = format!("DELETE FROM deliveries WHERE id IN ({placeholders})");
            let params: Vec<&dyn rusqlite::types::ToSql> =
                ids.iter().map(|id| id as &dyn rusqlite::types::ToSql).collect();
            conn.execute(&sql, params.as_slice())
                .map_err(|e| StorageError::Db(e.to_string()))?;
        }

        Ok(rows.into_iter().map(|(_, payload)| payload).collect())
    }

    fn queue_depth(
        &self,
        recipient_key: &[u8],
        channel_id: &[u8],
    ) -> Result<usize, StorageError> {
        let conn = self.conn.lock().unwrap();
        let count: i64 = conn
            .query_row(
                "SELECT COUNT(*) FROM deliveries WHERE recipient_key = ?1 AND channel_id = ?2",
                params![recipient_key, channel_id],
                |row| row.get(0),
            )
            .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(count as usize)
    }

    fn gc_expired_messages(&self, max_age_secs: u64) -> Result<usize, StorageError> {
        let conn = self.conn.lock().unwrap();
        let cutoff = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap_or_default()
            .as_secs()
            .saturating_sub(max_age_secs);
        let deleted = conn
            .execute(
                "DELETE FROM deliveries WHERE created_at < ?1",
                params![cutoff as i64],
            )
            .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(deleted)
    }

    fn upload_hybrid_key(
        &self,
        identity_key: &[u8],
        hybrid_pk: Vec<u8>,
    ) -> Result<(), StorageError> {
        let conn = self.conn.lock().unwrap();
        conn.execute(
            "INSERT OR REPLACE INTO hybrid_keys (identity_key, hybrid_public_key) VALUES (?1, ?2)",
            params![identity_key, hybrid_pk],
        )
        .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(())
    }

    fn fetch_hybrid_key(&self, identity_key: &[u8]) -> Result<Option<Vec<u8>>, StorageError> {
        let conn = self.conn.lock().unwrap();
        let mut stmt = conn
            .prepare("SELECT hybrid_public_key FROM hybrid_keys WHERE identity_key = ?1")
            .map_err(|e| StorageError::Db(e.to_string()))?;

        stmt.query_row(params![identity_key], |row| row.get(0))
            .optional()
            .map_err(|e| StorageError::Db(e.to_string()))
    }

    fn store_server_setup(&self, setup: Vec<u8>) -> Result<(), StorageError> {
        let conn = self.conn.lock().unwrap();
        conn.execute(
            "INSERT OR REPLACE INTO server_setup (id, setup_data) VALUES (1, ?1)",
            params![setup],
        )
        .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(())
    }

    fn get_server_setup(&self) -> Result<Option<Vec<u8>>, StorageError> {
        let conn = self.conn.lock().unwrap();
        let mut stmt = conn
            .prepare("SELECT setup_data FROM server_setup WHERE id = 1")
            .map_err(|e| StorageError::Db(e.to_string()))?;

        stmt.query_row([], |row| row.get(0))
            .optional()
            .map_err(|e| StorageError::Db(e.to_string()))
    }

    fn store_user_record(&self, username: &str, record: Vec<u8>) -> Result<(), StorageError> {
        let conn = self.conn.lock().unwrap();
        conn.execute(
            "INSERT OR REPLACE INTO users (username, opaque_record) VALUES (?1, ?2)",
            params![username, record],
        )
        .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(())
    }

    fn get_user_record(&self, username: &str) -> Result<Option<Vec<u8>>, StorageError> {
        let conn = self.conn.lock().unwrap();
        let mut stmt = conn
            .prepare("SELECT opaque_record FROM users WHERE username = ?1")
            .map_err(|e| StorageError::Db(e.to_string()))?;

        stmt.query_row(params![username], |row| row.get(0))
            .optional()
            .map_err(|e| StorageError::Db(e.to_string()))
    }

    fn has_user_record(&self, username: &str) -> Result<bool, StorageError> {
        let conn = self.conn.lock().unwrap();
        let exists: bool = conn
            .query_row(
                "SELECT EXISTS(SELECT 1 FROM users WHERE username = ?1)",
                params![username],
                |row| row.get(0),
            )
            .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(exists)
    }

    fn store_user_identity_key(
        &self,
        username: &str,
        identity_key: Vec<u8>,
    ) -> Result<(), StorageError> {
        let conn = self.conn.lock().unwrap();
        conn.execute(
            "INSERT OR REPLACE INTO user_identity_keys (username, identity_key) VALUES (?1, ?2)",
            params![username, identity_key],
        )
        .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(())
    }

    fn get_user_identity_key(&self, username: &str) -> Result<Option<Vec<u8>>, StorageError> {
        let conn = self.conn.lock().unwrap();
        let mut stmt = conn
            .prepare("SELECT identity_key FROM user_identity_keys WHERE username = ?1")
            .map_err(|e| StorageError::Db(e.to_string()))?;

        stmt.query_row(params![username], |row| row.get(0))
            .optional()
            .map_err(|e| StorageError::Db(e.to_string()))
    }

    fn publish_endpoint(
        &self,
        identity_key: &[u8],
        node_addr: Vec<u8>,
    ) -> Result<(), StorageError> {
        let conn = self.conn.lock().unwrap();
        conn.execute(
            "INSERT OR REPLACE INTO endpoints (identity_key, node_addr) VALUES (?1, ?2)",
            params![identity_key, node_addr],
        )
        .map_err(|e| StorageError::Db(e.to_string()))?;
        Ok(())
    }

    fn resolve_endpoint(&self, identity_key: &[u8]) -> Result<Option<Vec<u8>>, StorageError> {
        let conn = self.conn.lock().unwrap();
        let mut stmt = conn
            .prepare("SELECT node_addr FROM endpoints WHERE identity_key = ?1")
            .map_err(|e| StorageError::Db(e.to_string()))?;

        stmt.query_row(params![identity_key], |row| row.get(0))
            .optional()
            .map_err(|e| StorageError::Db(e.to_string()))
    }
}

/// Convenience extension for `rusqlite::OptionalExtension`.
trait OptionalExt<T> {
    fn optional(self) -> Result<Option<T>, rusqlite::Error>;
}

impl<T> OptionalExt<T> for Result<T, rusqlite::Error> {
    fn optional(self) -> Result<Option<T>, rusqlite::Error> {
        match self {
            Ok(v) => Ok(Some(v)),
            Err(rusqlite::Error::QueryReturnedNoRows) => Ok(None),
            Err(e) => Err(e),
        }
    }
}

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

    fn open_in_memory() -> SqlStore {
        SqlStore::open(":memory:", "").unwrap()
    }

    #[test]
    fn key_package_fifo() {
        let store = open_in_memory();
        let mut identity = [0u8; 32];
        identity[..31].copy_from_slice(b"alice_identity_key__32bytes_lon");

        store
            .upload_key_package(&identity, b"kp1".to_vec())
            .unwrap();
        store
            .upload_key_package(&identity, b"kp2".to_vec())
            .unwrap();

        assert_eq!(
            store.fetch_key_package(&identity).unwrap(),
            Some(b"kp1".to_vec())
        );
        assert_eq!(
            store.fetch_key_package(&identity).unwrap(),
            Some(b"kp2".to_vec())
        );
        assert_eq!(store.fetch_key_package(&identity).unwrap(), None);
    }

    #[test]
    fn delivery_round_trip() {
        let store = open_in_memory();
        let rk = [1u8; 32];
        let ch = b"channel-1";

        store.enqueue(&rk, ch, b"msg1".to_vec()).unwrap();
        store.enqueue(&rk, ch, b"msg2".to_vec()).unwrap();

        let msgs = store.fetch(&rk, ch).unwrap();
        assert_eq!(msgs, vec![b"msg1".to_vec(), b"msg2".to_vec()]);

        assert!(store.fetch(&rk, ch).unwrap().is_empty());
    }

    #[test]
    fn fetch_limited_partial_drain() {
        let store = open_in_memory();
        let rk = [5u8; 32];
        let ch = b"ch";

        store.enqueue(&rk, ch, b"a".to_vec()).unwrap();
        store.enqueue(&rk, ch, b"b".to_vec()).unwrap();
        store.enqueue(&rk, ch, b"c".to_vec()).unwrap();

        let msgs = store.fetch_limited(&rk, ch, 2).unwrap();
        assert_eq!(msgs, vec![b"a".to_vec(), b"b".to_vec()]);

        let remaining = store.fetch(&rk, ch).unwrap();
        assert_eq!(remaining, vec![b"c".to_vec()]);
    }

    #[test]
    fn queue_depth_count() {
        let store = open_in_memory();
        let rk = [6u8; 32];
        let ch = b"ch";

        assert_eq!(store.queue_depth(&rk, ch).unwrap(), 0);
        store.enqueue(&rk, ch, b"x".to_vec()).unwrap();
        store.enqueue(&rk, ch, b"y".to_vec()).unwrap();
        assert_eq!(store.queue_depth(&rk, ch).unwrap(), 2);
    }

    #[test]
    fn has_user_record_check() {
        let store = open_in_memory();
        assert!(!store.has_user_record("alice").unwrap());
        store.store_user_record("alice", b"record".to_vec()).unwrap();
        assert!(store.has_user_record("alice").unwrap());
        assert!(!store.has_user_record("bob").unwrap());
    }

    #[test]
    fn user_identity_key_round_trip() {
        let store = open_in_memory();
        assert!(store.get_user_identity_key("alice").unwrap().is_none());
        store.store_user_identity_key("alice", vec![1u8; 32]).unwrap();
        assert_eq!(store.get_user_identity_key("alice").unwrap(), Some(vec![1u8; 32]));
    }

    #[test]
    fn hybrid_key_round_trip() {
        let store = open_in_memory();
        let ik = [2u8; 32];
        let pk = b"hybrid_public_key_data".to_vec();

        store.upload_hybrid_key(&ik, pk.clone()).unwrap();
        assert_eq!(store.fetch_hybrid_key(&ik).unwrap(), Some(pk));
    }

    #[test]
    fn separate_channels_isolated() {
        let store = open_in_memory();
        let rk = [4u8; 32];

        store.enqueue(&rk, b"ch-a", b"a1".to_vec()).unwrap();
        store.enqueue(&rk, b"ch-b", b"b1".to_vec()).unwrap();

        let a_msgs = store.fetch(&rk, b"ch-a").unwrap();
        assert_eq!(a_msgs, vec![b"a1".to_vec()]);

        let b_msgs = store.fetch(&rk, b"ch-b").unwrap();
        assert_eq!(b_msgs, vec![b"b1".to_vec()]);
    }
}