use anyhow::Result;
use chrono::{DateTime, Utc};
use rusqlite::{params, Connection};
use serde::{Deserialize, Serialize};
use std::path::Path;

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DbOAuthClient {
    pub id: i64,
    pub client_id: String,
    pub client_secret_hash: String,
    pub client_name: String,
    pub redirect_uris: String, // JSON array
    pub scopes: String,        // Space-separated
    pub grant_types: String,   // Space-separated
    pub response_types: String, // Space-separated
    pub created_at: DateTime<Utc>,
    pub updated_at: DateTime<Utc>,
    pub is_active: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DbAuthCode {
    pub id: i64,
    pub code: String,
    pub client_id: String,
    pub user_id: String,
    pub redirect_uri: String,
    pub scope: Option<String>,
    pub expires_at: DateTime<Utc>,
    pub created_at: DateTime<Utc>,
    pub is_used: bool,
    // PKCE fields
    pub code_challenge: Option<String>,
    pub code_challenge_method: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DbAccessToken {
    pub id: i64,
    pub token_id: String,
    pub client_id: String,
    pub user_id: String,
    pub scope: Option<String>,
    pub expires_at: DateTime<Utc>,
    pub created_at: DateTime<Utc>,
    pub is_revoked: bool,
    pub token_hash: String, // For revocation lookup
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DbRefreshToken {
    pub id: i64,
    pub token_id: String,
    pub access_token_id: i64,
    pub client_id: String,
    pub user_id: String,
    pub scope: Option<String>,
    pub expires_at: DateTime<Utc>,
    pub created_at: DateTime<Utc>,
    pub is_revoked: bool,
    pub token_hash: String,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DbRsaKey {
    pub id: i64,
    pub kid: String,
    pub private_key_pem: String,
    pub public_key_pem: String,
    pub created_at: DateTime<Utc>,
    pub is_current: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DbAuditLog {
    pub id: i64,
    pub event_type: String,
    pub client_id: Option<String>,
    pub user_id: Option<String>,
    pub ip_address: Option<String>,
    pub user_agent: Option<String>,
    pub details: Option<String>, // JSON
    pub created_at: DateTime<Utc>,
    pub success: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DbRateLimit {
    pub id: i64,
    pub identifier: String, // client_id or IP address
    pub endpoint: String,
    pub count: i32,
    pub window_start: DateTime<Utc>,
    pub created_at: DateTime<Utc>,
}

pub struct Database {
    conn: Connection,
}

impl Database {
    pub fn new<P: AsRef<Path>>(path: P) -> Result<Self> {
        let conn = Connection::open(path)?;
        let db = Self { conn };
        db.initialize_schema()?;
        Ok(db)
    }

    pub fn new_in_memory() -> Result<Self> {
        let conn = Connection::open_in_memory()?;
        let db = Self { conn };
        db.initialize_schema()?;
        Ok(db)
    }

    fn initialize_schema(&self) -> Result<()> {
        // OAuth Clients table
        self.conn.execute(
            "CREATE TABLE IF NOT EXISTS oauth_clients (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                client_id TEXT NOT NULL UNIQUE,
                client_secret_hash TEXT NOT NULL,
                client_name TEXT NOT NULL,
                redirect_uris TEXT NOT NULL, -- JSON array
                scopes TEXT NOT NULL, -- space-separated
                grant_types TEXT NOT NULL, -- space-separated  
                response_types TEXT NOT NULL, -- space-separated
                created_at TEXT NOT NULL,
                updated_at TEXT NOT NULL,
                is_active BOOLEAN NOT NULL DEFAULT 1
            )",
            [],
        )?;

        // Authorization Codes table
        self.conn.execute(
            "CREATE TABLE IF NOT EXISTS auth_codes (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                code TEXT NOT NULL UNIQUE,
                client_id TEXT NOT NULL,
                user_id TEXT NOT NULL,
                redirect_uri TEXT NOT NULL,
                scope TEXT,
                expires_at TEXT NOT NULL,
                created_at TEXT NOT NULL,
                is_used BOOLEAN NOT NULL DEFAULT 0,
                code_challenge TEXT,
                code_challenge_method TEXT,
                FOREIGN KEY (client_id) REFERENCES oauth_clients (client_id)
            )",
            [],
        )?;

        // Access Tokens table
        self.conn.execute(
            "CREATE TABLE IF NOT EXISTS access_tokens (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                token_id TEXT NOT NULL UNIQUE,
                client_id TEXT NOT NULL,
                user_id TEXT NOT NULL,
                scope TEXT,
                expires_at TEXT NOT NULL,
                created_at TEXT NOT NULL,
                is_revoked BOOLEAN NOT NULL DEFAULT 0,
                token_hash TEXT NOT NULL,
                FOREIGN KEY (client_id) REFERENCES oauth_clients (client_id)
            )",
            [],
        )?;

        // Refresh Tokens table
        self.conn.execute(
            "CREATE TABLE IF NOT EXISTS refresh_tokens (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                token_id TEXT NOT NULL UNIQUE,
                access_token_id INTEGER NOT NULL,
                client_id TEXT NOT NULL,
                user_id TEXT NOT NULL,
                scope TEXT,
                expires_at TEXT NOT NULL,
                created_at TEXT NOT NULL,
                is_revoked BOOLEAN NOT NULL DEFAULT 0,
                token_hash TEXT NOT NULL,
                FOREIGN KEY (client_id) REFERENCES oauth_clients (client_id),
                FOREIGN KEY (access_token_id) REFERENCES access_tokens (id)
            )",
            [],
        )?;

        // RSA Keys table
        self.conn.execute(
            "CREATE TABLE IF NOT EXISTS rsa_keys (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                kid TEXT NOT NULL UNIQUE,
                private_key_pem TEXT NOT NULL,
                public_key_pem TEXT NOT NULL,
                created_at TEXT NOT NULL,
                is_current BOOLEAN NOT NULL DEFAULT 0
            )",
            [],
        )?;

        // Audit Log table
        self.conn.execute(
            "CREATE TABLE IF NOT EXISTS audit_logs (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                event_type TEXT NOT NULL,
                client_id TEXT,
                user_id TEXT,
                ip_address TEXT,
                user_agent TEXT,
                details TEXT, -- JSON
                created_at TEXT NOT NULL,
                success BOOLEAN NOT NULL
            )",
            [],
        )?;

        // Rate Limiting table
        self.conn.execute(
            "CREATE TABLE IF NOT EXISTS rate_limits (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                identifier TEXT NOT NULL, -- client_id or IP
                endpoint TEXT NOT NULL,
                count INTEGER NOT NULL DEFAULT 1,
                window_start TEXT NOT NULL,
                created_at TEXT NOT NULL,
                UNIQUE (identifier, endpoint, window_start)
            )",
            [],
        )?;

        // Create indexes for performance
        self.conn.execute(
            "CREATE INDEX IF NOT EXISTS idx_auth_codes_client_id ON auth_codes (client_id)",
            [],
        )?;
        self.conn.execute(
            "CREATE INDEX IF NOT EXISTS idx_auth_codes_expires_at ON auth_codes (expires_at)",
            [],
        )?;
        self.conn.execute(
            "CREATE INDEX IF NOT EXISTS idx_access_tokens_client_id ON access_tokens (client_id)",
            [],
        )?;
        self.conn.execute(
            "CREATE INDEX IF NOT EXISTS idx_access_tokens_expires_at ON access_tokens (expires_at)",
            [],
        )?;
        self.conn.execute(
            "CREATE INDEX IF NOT EXISTS idx_refresh_tokens_client_id ON refresh_tokens (client_id)",
            [],
        )?;
        self.conn.execute(
            "CREATE INDEX IF NOT EXISTS idx_audit_logs_created_at ON audit_logs (created_at)",
            [],
        )?;
        self.conn.execute(
            "CREATE INDEX IF NOT EXISTS idx_rate_limits_identifier ON rate_limits (identifier, endpoint)",
            [],
        )?;

        Ok(())
    }

    // OAuth Client operations
    pub fn create_oauth_client(&self, client: &DbOAuthClient) -> Result<i64> {
        let mut stmt = self.conn.prepare(
            "INSERT INTO oauth_clients 
             (client_id, client_secret_hash, client_name, redirect_uris, scopes, 
              grant_types, response_types, created_at, updated_at, is_active)
             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10)"
        )?;

        let id = stmt.insert(params![
            client.client_id,
            client.client_secret_hash,
            client.client_name,
            client.redirect_uris,
            client.scopes,
            client.grant_types,
            client.response_types,
            client.created_at.to_rfc3339(),
            client.updated_at.to_rfc3339(),
            client.is_active
        ])?;

        Ok(id)
    }

    pub fn get_oauth_client(&self, client_id: &str) -> Result<Option<DbOAuthClient>> {
        let mut stmt = self.conn.prepare(
            "SELECT id, client_id, client_secret_hash, client_name, redirect_uris, 
                    scopes, grant_types, response_types, created_at, updated_at, is_active
             FROM oauth_clients WHERE client_id = ?1 AND is_active = 1"
        )?;

        let client = stmt.query_row([client_id], |row| {
            Ok(DbOAuthClient {
                id: row.get(0)?,
                client_id: row.get(1)?,
                client_secret_hash: row.get(2)?,
                client_name: row.get(3)?,
                redirect_uris: row.get(4)?,
                scopes: row.get(5)?,
                grant_types: row.get(6)?,
                response_types: row.get(7)?,
                created_at: DateTime::parse_from_rfc3339(&row.get::<_, String>(8)?)
                    .map_err(|_| rusqlite::Error::InvalidColumnType(8, "created_at".to_string(), rusqlite::types::Type::Text))?
                    .with_timezone(&Utc),
                updated_at: DateTime::parse_from_rfc3339(&row.get::<_, String>(9)?)
                    .map_err(|_| rusqlite::Error::InvalidColumnType(9, "updated_at".to_string(), rusqlite::types::Type::Text))?
                    .with_timezone(&Utc),
                is_active: row.get(10)?,
            })
        });

        match client {
            Ok(client) => Ok(Some(client)),
            Err(rusqlite::Error::QueryReturnedNoRows) => Ok(None),
            Err(e) => Err(e.into()),
        }
    }

    // Authorization Code operations
    pub fn create_auth_code(&self, auth_code: &DbAuthCode) -> Result<i64> {
        let mut stmt = self.conn.prepare(
            "INSERT INTO auth_codes 
             (code, client_id, user_id, redirect_uri, scope, expires_at, created_at, 
              is_used, code_challenge, code_challenge_method)
             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10)"
        )?;

        let id = stmt.insert(params![
            auth_code.code,
            auth_code.client_id,
            auth_code.user_id,
            auth_code.redirect_uri,
            auth_code.scope,
            auth_code.expires_at.to_rfc3339(),
            auth_code.created_at.to_rfc3339(),
            auth_code.is_used,
            auth_code.code_challenge,
            auth_code.code_challenge_method
        ])?;

        Ok(id)
    }

    pub fn get_auth_code(&self, code: &str) -> Result<Option<DbAuthCode>> {
        let mut stmt = self.conn.prepare(
            "SELECT id, code, client_id, user_id, redirect_uri, scope, expires_at, 
                    created_at, is_used, code_challenge, code_challenge_method
             FROM auth_codes WHERE code = ?1"
        )?;

        let auth_code = stmt.query_row([code], |row| {
            Ok(DbAuthCode {
                id: row.get(0)?,
                code: row.get(1)?,
                client_id: row.get(2)?,
                user_id: row.get(3)?,
                redirect_uri: row.get(4)?,
                scope: row.get(5)?,
                expires_at: DateTime::parse_from_rfc3339(&row.get::<_, String>(6)?)
                    .map_err(|_| rusqlite::Error::InvalidColumnType(6, "expires_at".to_string(), rusqlite::types::Type::Text))?
                    .with_timezone(&Utc),
                created_at: DateTime::parse_from_rfc3339(&row.get::<_, String>(7)?)
                    .map_err(|_| rusqlite::Error::InvalidColumnType(7, "created_at".to_string(), rusqlite::types::Type::Text))?
                    .with_timezone(&Utc),
                is_used: row.get(8)?,
                code_challenge: row.get(9)?,
                code_challenge_method: row.get(10)?,
            })
        });

        match auth_code {
            Ok(code) => Ok(Some(code)),
            Err(rusqlite::Error::QueryReturnedNoRows) => Ok(None),
            Err(e) => Err(e.into()),
        }
    }

    pub fn mark_auth_code_used(&self, code: &str) -> Result<()> {
        self.conn.execute(
            "UPDATE auth_codes SET is_used = 1 WHERE code = ?1",
            [code],
        )?;
        Ok(())
    }

    // Access Token operations
    pub fn create_access_token(&self, token: &DbAccessToken) -> Result<i64> {
        let mut stmt = self.conn.prepare(
            "INSERT INTO access_tokens 
             (token_id, client_id, user_id, scope, expires_at, created_at, is_revoked, token_hash)
             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)"
        )?;

        let id = stmt.insert(params![
            token.token_id,
            token.client_id,
            token.user_id,
            token.scope,
            token.expires_at.to_rfc3339(),
            token.created_at.to_rfc3339(),
            token.is_revoked,
            token.token_hash
        ])?;

        Ok(id)
    }

    pub fn get_access_token(&self, token_hash: &str) -> Result<Option<DbAccessToken>> {
        let mut stmt = self.conn.prepare(
            "SELECT id, token_id, client_id, user_id, scope, expires_at, created_at, is_revoked, token_hash
             FROM access_tokens WHERE token_hash = ?1"
        )?;

        let token = stmt.query_row([token_hash], |row| {
            Ok(DbAccessToken {
                id: row.get(0)?,
                token_id: row.get(1)?,
                client_id: row.get(2)?,
                user_id: row.get(3)?,
                scope: row.get(4)?,
                expires_at: DateTime::parse_from_rfc3339(&row.get::<_, String>(5)?)
                    .map_err(|_| rusqlite::Error::InvalidColumnType(5, "expires_at".to_string(), rusqlite::types::Type::Text))?
                    .with_timezone(&Utc),
                created_at: DateTime::parse_from_rfc3339(&row.get::<_, String>(6)?)
                    .map_err(|_| rusqlite::Error::InvalidColumnType(6, "created_at".to_string(), rusqlite::types::Type::Text))?
                    .with_timezone(&Utc),
                is_revoked: row.get(7)?,
                token_hash: row.get(8)?,
            })
        });

        match token {
            Ok(token) => Ok(Some(token)),
            Err(rusqlite::Error::QueryReturnedNoRows) => Ok(None),
            Err(e) => Err(e.into()),
        }
    }

    pub fn revoke_access_token(&self, token_hash: &str) -> Result<()> {
        self.conn.execute(
            "UPDATE access_tokens SET is_revoked = 1 WHERE token_hash = ?1",
            [token_hash],
        )?;
        Ok(())
    }

    // RSA Key operations
    pub fn create_rsa_key(&self, key: &DbRsaKey) -> Result<i64> {
        let mut stmt = self.conn.prepare(
            "INSERT INTO rsa_keys (kid, private_key_pem, public_key_pem, created_at, is_current)
             VALUES (?1, ?2, ?3, ?4, ?5)"
        )?;

        let id = stmt.insert(params![
            key.kid,
            key.private_key_pem,
            key.public_key_pem,
            key.created_at.to_rfc3339(),
            key.is_current
        ])?;

        Ok(id)
    }

    pub fn get_current_rsa_key(&self) -> Result<Option<DbRsaKey>> {
        let mut stmt = self.conn.prepare(
            "SELECT id, kid, private_key_pem, public_key_pem, created_at, is_current
             FROM rsa_keys WHERE is_current = 1 ORDER BY created_at DESC LIMIT 1"
        )?;

        let key = stmt.query_row([], |row| {
            Ok(DbRsaKey {
                id: row.get(0)?,
                kid: row.get(1)?,
                private_key_pem: row.get(2)?,
                public_key_pem: row.get(3)?,
                created_at: DateTime::parse_from_rfc3339(&row.get::<_, String>(4)?)
                    .map_err(|_| rusqlite::Error::InvalidColumnType(4, "created_at".to_string(), rusqlite::types::Type::Text))?
                    .with_timezone(&Utc),
                is_current: row.get(5)?,
            })
        });

        match key {
            Ok(key) => Ok(Some(key)),
            Err(rusqlite::Error::QueryReturnedNoRows) => Ok(None),
            Err(e) => Err(e.into()),
        }
    }

    pub fn get_all_rsa_keys(&self) -> Result<Vec<DbRsaKey>> {
        let mut stmt = self.conn.prepare(
            "SELECT id, kid, private_key_pem, public_key_pem, created_at, is_current
             FROM rsa_keys ORDER BY created_at DESC"
        )?;

        let keys = stmt.query_map([], |row| {
            Ok(DbRsaKey {
                id: row.get(0)?,
                kid: row.get(1)?,
                private_key_pem: row.get(2)?,
                public_key_pem: row.get(3)?,
                created_at: DateTime::parse_from_rfc3339(&row.get::<_, String>(4)?)
                    .map_err(|_| rusqlite::Error::InvalidColumnType(4, "created_at".to_string(), rusqlite::types::Type::Text))?
                    .with_timezone(&Utc),
                is_current: row.get(5)?,
            })
        })?;

        let mut result = Vec::new();
        for key in keys {
            result.push(key?);
        }
        Ok(result)
    }

    pub fn set_current_rsa_key(&self, kid: &str) -> Result<()> {
        // First, unset all current keys
        self.conn.execute("UPDATE rsa_keys SET is_current = 0", [])?;
        
        // Then set the specified key as current
        self.conn.execute(
            "UPDATE rsa_keys SET is_current = 1 WHERE kid = ?1",
            [kid],
        )?;
        
        Ok(())
    }

    // Audit Log operations
    pub fn create_audit_log(&self, log: &DbAuditLog) -> Result<i64> {
        let mut stmt = self.conn.prepare(
            "INSERT INTO audit_logs 
             (event_type, client_id, user_id, ip_address, user_agent, details, created_at, success)
             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)"
        )?;

        let id = stmt.insert(params![
            log.event_type,
            log.client_id,
            log.user_id,
            log.ip_address,
            log.user_agent,
            log.details,
            log.created_at.to_rfc3339(),
            log.success
        ])?;

        Ok(id)
    }

    // Rate Limiting operations
    pub fn increment_rate_limit(&self, identifier: &str, endpoint: &str, window_minutes: i32) -> Result<i32> {
        let now = Utc::now();
        let window_start = now - chrono::Duration::minutes(window_minutes as i64);

        // Try to increment existing counter in current window
        let affected = self.conn.execute(
            "UPDATE rate_limits SET count = count + 1 
             WHERE identifier = ?1 AND endpoint = ?2 AND window_start >= ?3",
            params![identifier, endpoint, window_start.to_rfc3339()],
        )?;

        if affected == 0 {
            // No existing record, create new one
            self.conn.execute(
                "INSERT OR REPLACE INTO rate_limits (identifier, endpoint, count, window_start, created_at)
                 VALUES (?1, ?2, 1, ?3, ?4)",
                params![identifier, endpoint, now.to_rfc3339(), now.to_rfc3339()],
            )?;
            Ok(1)
        } else {
            // Return current count
            let count: i32 = self.conn.query_row(
                "SELECT count FROM rate_limits 
                 WHERE identifier = ?1 AND endpoint = ?2 AND window_start >= ?3",
                params![identifier, endpoint, window_start.to_rfc3339()],
                |row| row.get(0),
            )?;
            Ok(count)
        }
    }

    // Cleanup operations
    pub fn cleanup_expired_codes(&self) -> Result<usize> {
        let now = Utc::now();
        let affected = self.conn.execute(
            "DELETE FROM auth_codes WHERE expires_at < ?1",
            [now.to_rfc3339()],
        )?;
        Ok(affected)
    }

    pub fn cleanup_expired_tokens(&self) -> Result<usize> {
        let now = Utc::now();
        let affected = self.conn.execute(
            "DELETE FROM access_tokens WHERE expires_at < ?1 AND is_revoked = 1",
            [now.to_rfc3339()],
        )?;
        Ok(affected)
    }

    pub fn cleanup_old_audit_logs(&self, days: i32) -> Result<usize> {
        let cutoff = Utc::now() - chrono::Duration::days(days as i64);
        let affected = self.conn.execute(
            "DELETE FROM audit_logs WHERE created_at < ?1",
            [cutoff.to_rfc3339()],
        )?;
        Ok(affected)
    }
}

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

    #[test]
    fn test_database_creation() {
        let _db = Database::new_in_memory().expect("Failed to create database");
        assert!(true); // If we got here, database was created successfully
    }

    #[test]
    fn test_oauth_client_operations() {
        let db = Database::new_in_memory().expect("Failed to create database");
        
        let client = DbOAuthClient {
            id: 0,
            client_id: "test_client".to_string(),
            client_secret_hash: "hash123".to_string(),
            client_name: "Test Client".to_string(),
            redirect_uris: "[\"http://localhost:3000/callback\"]".to_string(),
            scopes: "openid profile".to_string(),
            grant_types: "authorization_code".to_string(),
            response_types: "code".to_string(),
            created_at: Utc::now(),
            updated_at: Utc::now(),
            is_active: true,
        };

        let id = db.create_oauth_client(&client).expect("Failed to create client");
        assert!(id > 0);

        let retrieved = db.get_oauth_client("test_client").expect("Failed to get client");
        assert!(retrieved.is_some());
        assert_eq!(retrieved.unwrap().client_name, "Test Client");
    }

    #[test]
    fn test_auth_code_operations() {
        let db = Database::new_in_memory().expect("Failed to create database");

        // First create a client (required for foreign key constraint)
        let client = DbOAuthClient {
            id: 0,
            client_id: "test_client".to_string(),
            client_secret_hash: "hash123".to_string(),
            client_name: "Test Client".to_string(),
            redirect_uris: "[\"http://localhost:3000/callback\"]".to_string(),
            scopes: "openid profile".to_string(),
            grant_types: "authorization_code".to_string(),
            response_types: "code".to_string(),
            created_at: Utc::now(),
            updated_at: Utc::now(),
            is_active: true,
        };
        db.create_oauth_client(&client).expect("Failed to create client");

        let auth_code = DbAuthCode {
            id: 0,
            code: "test_code_123".to_string(),
            client_id: "test_client".to_string(),
            user_id: "test_user".to_string(),
            redirect_uri: "http://localhost:3000/callback".to_string(),
            scope: Some("openid".to_string()),
            expires_at: Utc::now() + chrono::Duration::minutes(10),
            created_at: Utc::now(),
            is_used: false,
            code_challenge: Some("challenge123".to_string()),
            code_challenge_method: Some("S256".to_string()),
        };

        let id = db.create_auth_code(&auth_code).expect("Failed to create auth code");
        assert!(id > 0);

        let retrieved = db.get_auth_code("test_code_123").expect("Failed to get auth code");
        assert!(retrieved.is_some());
        let code = retrieved.unwrap();
        assert_eq!(code.client_id, "test_client");
        assert_eq!(code.is_used, false);

        db.mark_auth_code_used("test_code_123").expect("Failed to mark code as used");
        let updated = db.get_auth_code("test_code_123").expect("Failed to get auth code");
        assert_eq!(updated.unwrap().is_used, true);
    }
}