// file: kb_lib/src/config.rs

//! JSON configuration structures and loading helpers for `kb_lib`.

/// Root application configuration loaded from `config.json`.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
pub struct Config {
    /// Application-level metadata and global behavior.
    pub app: AppConfig,
    /// Tracing and log output configuration.
    pub logging: LoggingConfig,
    /// Data directory configuration.
    pub data: DataConfig,
    /// Solana endpoint configuration.
    pub solana: SolanaConfig,
    /// Database configuration.
    pub database: DatabaseConfig,
}

impl Config {
    /// Returns the default path of the JSON configuration file.
    pub fn default_path() -> std::path::PathBuf {
        return workspace_root_dir().join("config.json");
    }

    /// Loads a configuration from a JSON file and validates it.
    pub fn load_from_path<P: AsRef<std::path::Path>>(path: P) -> Result<Self, crate::Error> {
        let path_ref = path.as_ref();
        let content_result = std::fs::read_to_string(path_ref);
        let content = match content_result {
            Ok(content) => content,
            Err(error) => {
                return Err(crate::Error::Io(format!(
                    "cannot read configuration file '{}': {error}",
                    path_ref.display()
                )));
            },
        };
        let config_result = serde_json::from_str::<Self>(&content);
        let config = match config_result {
            Ok(config) => config,
            Err(error) => {
                return Err(crate::Error::Json(format!(
                    "cannot parse configuration file '{}': {error}",
                    path_ref.display()
                )));
            },
        };
        let validation_result = config.validate();
        match validation_result {
            Ok(()) => return Ok(config),
            Err(error) => return Err(error),
        }
    }

    /// Validates the current configuration.
    pub fn validate(&self) -> Result<(), crate::Error> {
        if self.app.name.trim().is_empty() {
            return Err(crate::Error::Config("app.name must not be empty".to_string()));
        }
        if self.app.environment.trim().is_empty() {
            return Err(crate::Error::Config("app.environment must not be empty".to_string()));
        }
        if self.logging.level.trim().is_empty() {
            return Err(crate::Error::Config("logging.level must not be empty".to_string()));
        }
        if self.logging.directory.trim().is_empty() {
            return Err(crate::Error::Config("logging.directory must not be empty".to_string()));
        }
        if self.logging.file_prefix.trim().is_empty() {
            return Err(crate::Error::Config("logging.file_prefix must not be empty".to_string()));
        }
        if self.data.sqlite_path.trim().is_empty() {
            return Err(crate::Error::Config("data.sqlite_path must not be empty".to_string()));
        }
        if self.data.wallets_directory.trim().is_empty() {
            return Err(crate::Error::Config(
                "data.wallets_directory must not be empty".to_string(),
            ));
        }
        if self.logging.rotation != "daily"
            && self.logging.rotation != "hourly"
            && self.logging.rotation != "never"
        {
            return Err(crate::Error::Config(format!(
                "unsupported logging.rotation '{}'",
                self.logging.rotation
            )));
        }
        if self.logging.message_format != "full"
            && self.logging.message_format != "compact"
            && self.logging.message_format != "pretty"
            && self.logging.message_format != "json"
        {
            return Err(crate::Error::Config(format!(
                "unsupported logging.message_format '{}'",
                self.logging.message_format
            )));
        }
        if self.logging.time_format != "rfc3339"
            && self.logging.time_format != "rfc3339_millis"
            && self.logging.time_format != "none"
        {
            return Err(crate::Error::Config(format!(
                "unsupported logging.time_format '{}'",
                self.logging.time_format
            )));
        }
        let mut endpoint_names: std::vec::Vec<std::string::String> = std::vec::Vec::new();
        for endpoint in &self.solana.http_endpoints {
            let validation_result = self.validate_http_endpoint(endpoint, &mut endpoint_names);
            if let Err(error) = validation_result {
                return Err(error);
            }
        }
        for endpoint in &self.solana.ws_endpoints {
            let validation_result = self.validate_ws_endpoint(endpoint, &mut endpoint_names);
            if let Err(error) = validation_result {
                return Err(error);
            }
        }
        return Ok(());
    }

    /// Creates the basic runtime directories required by the current configuration.
    pub fn prepare_filesystem(&self) -> Result<(), crate::Error> {
        let logging_directory = self.logging.directory_path();
        let create_logs_result = std::fs::create_dir_all(&logging_directory);
        if let Err(error) = create_logs_result {
            return Err(crate::Error::Io(format!(
                "cannot create logging directory '{}': {error}",
                logging_directory.display()
            )));
        }
        let wallets_directory = self.data.wallets_directory_path();
        let create_wallets_result = std::fs::create_dir_all(&wallets_directory);
        if let Err(error) = create_wallets_result {
            return Err(crate::Error::Io(format!(
                "cannot create wallets directory '{}': {error}",
                wallets_directory.display()
            )));
        }
        let sqlite_path = self.database.sqlite.path_buf();
        let sqlite_parent_option = sqlite_path.parent();
        if let Some(sqlite_parent) = sqlite_parent_option {
            if !sqlite_parent.as_os_str().is_empty() {
                let create_db_parent_result = std::fs::create_dir_all(sqlite_parent);
                if let Err(error) = create_db_parent_result {
                    return Err(crate::Error::Io(format!(
                        "cannot create database parent directory '{}': {error}",
                        sqlite_parent.display()
                    )));
                }
            }
        }
        return Ok(());
    }

    /// Finds one HTTP endpoint by its logical name.
    pub fn find_http_endpoint(
        &self,
        endpoint_name: &str,
    ) -> std::option::Option<&HttpEndpointConfig> {
        return self
            .solana
            .http_endpoints
            .iter()
            .find(|endpoint| return endpoint.name == endpoint_name);
    }

    /// Returns a named WebSocket endpoint by reference.
    pub fn find_ws_endpoint(&self, endpoint_name: &str) -> std::option::Option<&WsEndpointConfig> {
        return self
            .solana
            .ws_endpoints
            .iter()
            .find(|endpoint| return endpoint.name == endpoint_name);
    }

    fn validate_http_endpoint(
        &self,
        endpoint: &HttpEndpointConfig,
        endpoint_names: &mut std::vec::Vec<std::string::String>,
    ) -> Result<(), crate::Error> {
        if endpoint.name.trim().is_empty() {
            return Err(crate::Error::Config("http endpoint name must not be empty".to_string()));
        }
        if endpoint_names.iter().any(|name| return name == &endpoint.name) {
            return Err(crate::Error::Config(format!(
                "duplicated endpoint name '{}'",
                endpoint.name
            )));
        }
        if !endpoint.url.starts_with("http://") && !endpoint.url.starts_with("https://") {
            return Err(crate::Error::Config(format!(
                "http endpoint '{}' must start with http:// or https://",
                endpoint.name
            )));
        }
        if endpoint.requests_per_second == 0 {
            return Err(crate::Error::Config(format!(
                "http endpoint '{}' requests_per_second must be > 0",
                endpoint.name
            )));
        }
        if endpoint.burst_capacity == 0 {
            return Err(crate::Error::Config(format!(
                "http endpoint '{}' burst_capacity must be > 0",
                endpoint.name
            )));
        }
        if endpoint.connect_timeout_ms == 0 {
            return Err(crate::Error::Config(format!(
                "http endpoint '{}' connect_timeout_ms must be > 0",
                endpoint.name
            )));
        }
        if endpoint.request_timeout_ms == 0 {
            return Err(crate::Error::Config(format!(
                "http endpoint '{}' request_timeout_ms must be > 0",
                endpoint.name
            )));
        }
        endpoint_names.push(endpoint.name.clone());
        return Ok(());
    }

    fn validate_ws_endpoint(
        &self,
        endpoint: &WsEndpointConfig,
        endpoint_names: &mut std::vec::Vec<std::string::String>,
    ) -> Result<(), crate::Error> {
        if endpoint.name.trim().is_empty() {
            return Err(crate::Error::Config("ws endpoint name must not be empty".to_string()));
        }
        if endpoint_names.iter().any(|name| return name == &endpoint.name) {
            return Err(crate::Error::Config(format!(
                "duplicated endpoint name '{}'",
                endpoint.name
            )));
        }
        if !endpoint.url.starts_with("ws://") && !endpoint.url.starts_with("wss://") {
            return Err(crate::Error::Config(format!(
                "ws endpoint '{}' must start with ws:// or wss://",
                endpoint.name
            )));
        }
        if endpoint.max_subscriptions == 0 {
            return Err(crate::Error::Config(format!(
                "ws endpoint '{}' max_subscriptions must be > 0",
                endpoint.name
            )));
        }
        if endpoint.connect_timeout_ms == 0 {
            return Err(crate::Error::Config(format!(
                "ws endpoint '{}' connect_timeout_ms must be > 0",
                endpoint.name
            )));
        }
        if endpoint.request_timeout_ms == 0 {
            return Err(crate::Error::Config(format!(
                "ws endpoint '{}' request_timeout_ms must be > 0",
                endpoint.name
            )));
        }
        if endpoint.unsubscribe_timeout_ms == 0 {
            return Err(crate::Error::Config(format!(
                "ws endpoint '{}' unsubscribe_timeout_ms must be > 0",
                endpoint.name
            )));
        }
        if endpoint.write_channel_capacity == 0 {
            return Err(crate::Error::Config(format!(
                "ws endpoint '{}' write_channel_capacity must be > 0",
                endpoint.name
            )));
        }
        if endpoint.event_channel_capacity == 0 {
            return Err(crate::Error::Config(format!(
                "ws endpoint '{}' event_channel_capacity must be > 0",
                endpoint.name
            )));
        }
        endpoint_names.push(endpoint.name.clone());
        return Ok(());
    }
}

/// Generic application settings.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
pub struct AppConfig {
    /// Human-readable application name.
    pub name: std::string::String,
    /// Current environment name such as `development` or `production`.
    pub environment: std::string::String,
    /// Default reconnection preference used by future UI settings.
    pub auto_reconnect_default: bool,
}

/// Logging and tracing configuration.
///
/// In version `0.0.2`, the project actively uses:
/// `level`, `console_enabled`, `console_ansi`, `file_enabled`,
/// `directory`, `file_prefix`, and `rotation`.
///
/// The fields `message_format` and `time_format` are already stored in the
/// configuration so that the format policy is stabilized early, even though
/// their handling will be refined in later versions.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
pub struct LoggingConfig {
    /// Global default log level.
    pub level: std::string::String,
    /// Enables console logging.
    pub console_enabled: bool,
    /// Enables ANSI colors on console output.
    pub console_ansi: bool,
    /// Enables file logging.
    pub file_enabled: bool,
    /// Directory where log files are stored.
    pub directory: std::string::String,
    /// Prefix used for log file names.
    pub file_prefix: std::string::String,
    /// File rotation strategy such as `daily`, `hourly`, or `never`.
    pub rotation: std::string::String,
    /// Preferred message formatting preset.
    pub message_format: std::string::String,
    /// Preferred time formatting preset.
    pub time_format: std::string::String,
    /// Per-target log level overrides.
    pub target_filters: std::collections::BTreeMap<std::string::String, std::string::String>,
}

impl LoggingConfig {
    /// Returns the resolved logging directory path.
    pub fn directory_path(&self) -> std::path::PathBuf {
        return resolve_workspace_relative_path(&self.directory);
    }
}

/// Local data paths used by the application.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
pub struct DataConfig {
    /// SQLite database path.
    pub sqlite_path: std::string::String,
    /// Directory storing Solana wallets and related material in future versions.
    pub wallets_directory: std::string::String,
}

impl DataConfig {
    /// Returns the resolved SQLite database path.
    pub fn sqlite_path_buf(&self) -> std::path::PathBuf {
        return resolve_workspace_relative_path(&self.sqlite_path);
    }

    /// Returns the resolved wallets directory path.
    pub fn wallets_directory_path(&self) -> std::path::PathBuf {
        return resolve_workspace_relative_path(&self.wallets_directory);
    }
}

/// Solana transport configuration.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
pub struct SolanaConfig {
    /// Named HTTP endpoints.
    pub http_endpoints: std::vec::Vec<HttpEndpointConfig>,
    /// Named WebSocket endpoints.
    pub ws_endpoints: std::vec::Vec<WsEndpointConfig>,
}

/// HTTP endpoint configuration.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct HttpEndpointConfig {
    /// Logical endpoint name.
    pub name: std::string::String,
    /// Whether this endpoint is enabled.
    pub enabled: bool,
    /// Provider name.
    pub provider: std::string::String,
    /// Base HTTP URL.
    pub url: std::string::String,
    /// Optional environment variable name containing an API key.
    pub api_key_env_var: std::option::Option<std::string::String>,
    /// Allowed roles for this endpoint.
    pub roles: std::vec::Vec<std::string::String>,
    /// Requests per second allowed by the local limiter for general RPC methods.
    pub requests_per_second: u32,
    /// Maximum local burst capacity for general RPC methods.
    pub burst_capacity: u32,
    /// Optional requests per second override for `sendTransaction`-class methods.
    pub send_transaction_requests_per_second: std::option::Option<u32>,
    /// Optional burst override for `sendTransaction`-class methods.
    pub send_transaction_burst_capacity: std::option::Option<u32>,
    /// Optional requests per second override for heavy read methods.
    pub heavy_requests_per_second: std::option::Option<u32>,
    /// Optional burst override for heavy read methods.
    pub heavy_burst_capacity: std::option::Option<u32>,
    /// Connect timeout in milliseconds.
    pub connect_timeout_ms: u64,
    /// Total request timeout in milliseconds.
    pub request_timeout_ms: u64,
    /// Maximum idle pooled connections per host.
    pub max_idle_connections_per_host: usize,
    /// Automatic pause duration after an HTTP 429 response, in milliseconds.
    pub pause_after_http_429_ms: std::option::Option<u64>,
    /// Maximum number of concurrent in-flight HTTP requests for this endpoint.
    pub max_concurrent_requests_per_endpoint: usize,
}

impl HttpEndpointConfig {
    /// Returns the resolved URL, replacing an `${ENV_VAR}` placeholder when
    /// `api_key_env_var` is configured.
    pub fn resolved_url(&self) -> Result<std::string::String, crate::Error> {
        let env_var_name_option = self.api_key_env_var.as_ref();
        let env_var_name = match env_var_name_option {
            Some(env_var_name) => env_var_name,
            None => {
                return Ok(self.url.clone());
            },
        };
        let api_key_result = std::env::var(env_var_name);
        let api_key = match api_key_result {
            Ok(api_key) => api_key,
            Err(error) => {
                return Err(crate::Error::Config(format!(
                    "cannot resolve api key env var '{}' for http endpoint '{}': {}",
                    env_var_name, self.name, error
                )));
            },
        };
        let placeholder = format!("${{{}}}", env_var_name);
        if self.url.contains(&placeholder) {
            return Ok(self.url.replace(&placeholder, &api_key));
        }
        return Ok(self.url.clone());
    }
}

/// WebSocket endpoint configuration.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
pub struct WsEndpointConfig {
    /// Stable internal endpoint name used by the application.
    pub name: std::string::String,
    /// Enables or disables the endpoint.
    pub enabled: bool,
    /// Provider name such as `solana-public`, `helius`, or `custom`.
    pub provider: std::string::String,
    /// Base WebSocket RPC URL.
    pub url: std::string::String,
    /// Optional environment variable name used to resolve an API key later.
    pub api_key_env_var: std::option::Option<std::string::String>,
    /// Logical roles assigned to this endpoint.
    pub roles: std::vec::Vec<std::string::String>,
    /// Maximum number of subscriptions allowed on this endpoint.
    pub max_subscriptions: u32,
    /// WebSocket connect timeout in milliseconds.
    pub connect_timeout_ms: u64,
    /// Timeout for request/response round-trips in milliseconds.
    pub request_timeout_ms: u64,
    /// Timeout used during unsubscribe on disconnect in milliseconds.
    pub unsubscribe_timeout_ms: u64,
    /// Capacity of the future outgoing write channel.
    pub write_channel_capacity: usize,
    /// Capacity of the future event channel.
    pub event_channel_capacity: usize,
    /// Enables future automatic reconnection behavior.
    pub auto_reconnect: bool,
}

impl WsEndpointConfig {
    /// Returns the resolved endpoint URL.
    pub fn resolved_url(&self) -> Result<std::string::String, crate::Error> {
        return resolve_endpoint_url(&self.url, &self.api_key_env_var);
    }
}

/// SQLite configuration.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SqliteDatabaseConfig {
    /// SQLite database path.
    pub path: std::string::String,
    /// Whether the file should be created if missing.
    pub create_if_missing: bool,
    /// SQLite busy timeout in milliseconds.
    pub busy_timeout_ms: u64,
    /// Maximum pool connections.
    pub max_connections: u32,
    /// Whether the schema should be initialized automatically at startup.
    pub auto_initialize_schema: bool,
    /// Whether WAL journal mode should be enabled.
    pub use_wal: bool,
}

impl SqliteDatabaseConfig {
    /// Returns the resolved SQLite database path.
    pub fn path_buf(&self) -> std::path::PathBuf {
        return resolve_workspace_relative_path(&self.path);
    }
}

/// Database configuration.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct DatabaseConfig {
    /// Whether the database layer is enabled.
    pub enabled: bool,
    /// Selected backend.
    pub backend: crate::DatabaseBackend,
    /// SQLite-specific configuration.
    pub sqlite: SqliteDatabaseConfig,
}

fn workspace_root_dir() -> std::path::PathBuf {
    let manifest_dir = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"));
    match manifest_dir.parent() {
        Some(parent) => return parent.to_path_buf(),
        None => return manifest_dir,
    }
}

fn resolve_workspace_relative_path<P: AsRef<std::path::Path>>(path: P) -> std::path::PathBuf {
    let input_path = std::path::PathBuf::from(path.as_ref());
    if input_path.is_absolute() {
        return input_path;
    }
    return workspace_root_dir().join(input_path);
}

fn resolve_endpoint_url(
    url: &str,
    api_key_env_var: &std::option::Option<std::string::String>,
) -> Result<std::string::String, crate::Error> {
    let env_var_name_option = api_key_env_var.as_deref();
    let env_var_name = match env_var_name_option {
        Some(env_var_name) => env_var_name,
        None => {
            return Ok(url.to_string());
        },
    };
    let placeholder = format!("${{{env_var_name}}}");
    if !url.contains(&placeholder) {
        return Ok(url.to_string());
    }
    let env_value_result = std::env::var(env_var_name);
    let env_value = match env_value_result {
        Ok(env_value) => env_value,
        Err(error) => {
            return Err(crate::Error::Config(format!(
                "environment variable '{}' is required to resolve endpoint url '{}': {error}",
                env_var_name, url
            )));
        },
    };
    return Ok(url.replace(&placeholder, &env_value));
}