// file: crates/ksp-store-lib/src/settings.rs
// version: 4

const DEFAULT_CONNECT_TIMEOUT_MS: u64 = 10_000;
const DEFAULT_MAX_CONNECTIONS: u32 = 8;
const DEFAULT_MIGRATION_LOCK_TIMEOUT_MS: u64 = 10_000;
const DEFAULT_MIGRATION_TIMEOUT_MS: u64 = 30_000;
const DEFAULT_POOL_CREATE_TIMEOUT_MS: u64 = 10_000;
const DEFAULT_POOL_RECYCLE_TIMEOUT_MS: u64 = 5_000;
const DEFAULT_POOL_WAIT_TIMEOUT_MS: u64 = 5_000;
const DEFAULT_SHUTDOWN_TIMEOUT_MS: u64 = 5_000;
const MAX_CONNECTIONS: u32 = 64;
const MAX_CONNECT_TIMEOUT_MS: u64 = 60_000;
const MAX_MIGRATION_LOCK_TIMEOUT_MS: u64 = 120_000;
const MAX_MIGRATION_TIMEOUT_MS: u64 = 300_000;
const MAX_POOL_CREATE_TIMEOUT_MS: u64 = 60_000;
const MAX_POOL_RECYCLE_TIMEOUT_MS: u64 = 60_000;
const MAX_POOL_WAIT_TIMEOUT_MS: u64 = 60_000;
const MAX_SHUTDOWN_TIMEOUT_MS: u64 = 30_000;
const MIN_CONNECTIONS: u32 = 1;
const MIN_CONNECT_TIMEOUT_MS: u64 = 100;
const MIN_MIGRATION_LOCK_TIMEOUT_MS: u64 = 100;
const MIN_MIGRATION_TIMEOUT_MS: u64 = 1_000;
const MIN_POOL_CREATE_TIMEOUT_MS: u64 = 100;
const MIN_POOL_RECYCLE_TIMEOUT_MS: u64 = 100;
const MIN_POOL_WAIT_TIMEOUT_MS: u64 = 100;
const MIN_SHUTDOWN_TIMEOUT_MS: u64 = 100;

/// Backend identity understood by the common Store runtime independently from compiled Cargo features.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
#[non_exhaustive]
pub enum StoreBackendKind {
    /// Official PostgreSQL Store backend.
    Postgres,
}

impl StoreBackendKind {
    /// Returns the stable safe backend code used in diagnostics and configuration mapping.
    #[must_use]
    pub const fn code(&self) -> &'static str {
        return match self {
            Self::Postgres => "postgres",
        };
    }
}

/// TLS policy accepted by the backend-neutral PostgreSQL settings surface.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
#[non_exhaustive]
pub enum PostgresTlsMode {
    /// Connect without TLS.
    Disabled,
    /// Require TLS and verify both the certificate chain and requested server identity.
    VerifyFull,
}

/// Bounded PostgreSQL connection-pool settings owned by the Store facade.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct PostgresPoolSettings {
    connect_timeout: std::time::Duration,
    create_timeout: std::time::Duration,
    max_connections: u32,
    recycle_timeout: std::time::Duration,
    wait_timeout: std::time::Duration,
}

impl PostgresPoolSettings {
    /// Creates explicit PostgreSQL pool bounds without performing any I/O.
    #[must_use]
    pub const fn new(
        max_connections: u32,
        connect_timeout: std::time::Duration,
        wait_timeout: std::time::Duration,
        create_timeout: std::time::Duration,
        recycle_timeout: std::time::Duration,
    ) -> Self {
        return Self { connect_timeout, create_timeout, max_connections, recycle_timeout, wait_timeout };
    }

    /// Returns the timeout for establishing one physical PostgreSQL connection.
    #[must_use]
    pub const fn connect_timeout(&self) -> std::time::Duration {
        return self.connect_timeout;
    }

    /// Returns the timeout for creating one pooled PostgreSQL object.
    #[must_use]
    pub const fn create_timeout(&self) -> std::time::Duration {
        return self.create_timeout;
    }

    /// Returns the maximum number of physical PostgreSQL connections owned by the pool.
    #[must_use]
    pub const fn max_connections(&self) -> u32 {
        return self.max_connections;
    }

    /// Returns the timeout for recycling one pooled PostgreSQL object.
    #[must_use]
    pub const fn recycle_timeout(&self) -> std::time::Duration {
        return self.recycle_timeout;
    }

    /// Returns the maximum time one acquisition can wait for pool capacity.
    #[must_use]
    pub const fn wait_timeout(&self) -> std::time::Duration {
        return self.wait_timeout;
    }

    /// Validates all pool bounds without opening a connection.
    pub fn validate(&self) -> ksp_store_api::Result<()> {
        if self.max_connections < MIN_CONNECTIONS || self.max_connections > MAX_CONNECTIONS {
            return std::result::Result::Err(
                ksp_store_api::Error::new(crate::ERROR_CODE_SETTINGS_INVALID, "PostgreSQL pool connection bound is invalid")
                    .with_context("field", "postgres.pool.max_connections")
                    .with_context("minimum", MIN_CONNECTIONS.to_string())
                    .with_context("maximum", MAX_CONNECTIONS.to_string()),
            );
        }
        let connect_validation = validate_duration("postgres.pool.connect_timeout", self.connect_timeout, MIN_CONNECT_TIMEOUT_MS, MAX_CONNECT_TIMEOUT_MS);
        if let std::result::Result::Err(error) = connect_validation {
            return std::result::Result::Err(error);
        }
        let wait_validation = validate_duration("postgres.pool.wait_timeout", self.wait_timeout, MIN_POOL_WAIT_TIMEOUT_MS, MAX_POOL_WAIT_TIMEOUT_MS);
        if let std::result::Result::Err(error) = wait_validation {
            return std::result::Result::Err(error);
        }
        let create_validation = validate_duration("postgres.pool.create_timeout", self.create_timeout, MIN_POOL_CREATE_TIMEOUT_MS, MAX_POOL_CREATE_TIMEOUT_MS);
        if let std::result::Result::Err(error) = create_validation {
            return std::result::Result::Err(error);
        }
        let recycle_validation =
            validate_duration("postgres.pool.recycle_timeout", self.recycle_timeout, MIN_POOL_RECYCLE_TIMEOUT_MS, MAX_POOL_RECYCLE_TIMEOUT_MS);
        if let std::result::Result::Err(error) = recycle_validation {
            return std::result::Result::Err(error);
        }
        return std::result::Result::Ok(());
    }
}

impl std::default::Default for PostgresPoolSettings {
    fn default() -> Self {
        return Self::new(
            DEFAULT_MAX_CONNECTIONS,
            std::time::Duration::from_millis(DEFAULT_CONNECT_TIMEOUT_MS),
            std::time::Duration::from_millis(DEFAULT_POOL_WAIT_TIMEOUT_MS),
            std::time::Duration::from_millis(DEFAULT_POOL_CREATE_TIMEOUT_MS),
            std::time::Duration::from_millis(DEFAULT_POOL_RECYCLE_TIMEOUT_MS),
        );
    }
}

/// Bounded PostgreSQL bootstrap settings owned by the Store facade.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct PostgresBootstrapSettings {
    migration_lock_timeout: std::time::Duration,
    migration_timeout: std::time::Duration,
    schema_autocreate: bool,
    schema_autoupdate: bool,
}

impl PostgresBootstrapSettings {
    /// Creates bootstrap settings using the legacy single migration switch for source compatibility.
    ///
    /// The supplied value is mapped to both schema auto-creation and schema auto-update. New code should prefer
    /// [`Self::with_schema_policy`] when these policies need to differ.
    #[must_use]
    pub const fn new(auto_migrate: bool, migration_timeout: std::time::Duration, migration_lock_timeout: std::time::Duration) -> Self {
        return Self::with_schema_policy(auto_migrate, auto_migrate, migration_timeout, migration_lock_timeout);
    }

    /// Creates explicit schema creation/update policy and migration deadlines.
    #[must_use]
    pub const fn with_schema_policy(
        schema_autocreate: bool,
        schema_autoupdate: bool,
        migration_timeout: std::time::Duration,
        migration_lock_timeout: std::time::Duration,
    ) -> Self {
        return Self { migration_lock_timeout, migration_timeout, schema_autocreate, schema_autoupdate };
    }

    /// Returns the legacy pending-migration switch, mapped to the schema auto-update policy.
    #[must_use]
    pub const fn auto_migrate(&self) -> bool {
        return self.schema_autoupdate;
    }

    /// Returns whether an absent KSP-managed schema may be created or adopted during Store opening.
    #[must_use]
    pub const fn schema_autocreate(&self) -> bool {
        return self.schema_autocreate;
    }

    /// Returns whether pending migrations and safe additive schema repairs may be applied during Store opening.
    #[must_use]
    pub const fn schema_autoupdate(&self) -> bool {
        return self.schema_autoupdate;
    }

    /// Returns the bounded wait allowed for the private PostgreSQL migration lock.
    #[must_use]
    pub const fn migration_lock_timeout(&self) -> std::time::Duration {
        return self.migration_lock_timeout;
    }

    /// Returns the bounded duration allowed for one migration/bootstrap run.
    #[must_use]
    pub const fn migration_timeout(&self) -> std::time::Duration {
        return self.migration_timeout;
    }

    /// Validates bootstrap and migration deadlines without contacting PostgreSQL.
    pub fn validate(&self) -> ksp_store_api::Result<()> {
        let migration_validation =
            validate_duration("postgres.bootstrap.migration_timeout", self.migration_timeout, MIN_MIGRATION_TIMEOUT_MS, MAX_MIGRATION_TIMEOUT_MS);
        if let std::result::Result::Err(error) = migration_validation {
            return std::result::Result::Err(error);
        }
        let lock_validation = validate_duration(
            "postgres.bootstrap.migration_lock_timeout",
            self.migration_lock_timeout,
            MIN_MIGRATION_LOCK_TIMEOUT_MS,
            MAX_MIGRATION_LOCK_TIMEOUT_MS,
        );
        if let std::result::Result::Err(error) = lock_validation {
            return std::result::Result::Err(error);
        }
        return std::result::Result::Ok(());
    }
}

impl std::default::Default for PostgresBootstrapSettings {
    fn default() -> Self {
        return Self::with_schema_policy(
            true,
            true,
            std::time::Duration::from_millis(DEFAULT_MIGRATION_TIMEOUT_MS),
            std::time::Duration::from_millis(DEFAULT_MIGRATION_LOCK_TIMEOUT_MS),
        );
    }
}

/// PostgreSQL settings owned by the Store facade and independent from Config or backend implementation types.
pub struct PostgresStoreSettings {
    bootstrap: PostgresBootstrapSettings,
    connection_uri: std::string::String,
    pool: PostgresPoolSettings,
    tls_mode: PostgresTlsMode,
}

impl PostgresStoreSettings {
    /// Creates PostgreSQL Store settings from an explicitly supplied sensitive connection URI and typed runtime bounds.
    #[must_use]
    pub fn new(
        connection_uri: impl std::convert::Into<std::string::String>,
        pool: PostgresPoolSettings,
        tls_mode: PostgresTlsMode,
        bootstrap: PostgresBootstrapSettings,
    ) -> Self {
        return Self { bootstrap, connection_uri: connection_uri.into(), pool, tls_mode };
    }

    /// Returns the PostgreSQL bootstrap settings without exposing the sensitive connection URI.
    #[must_use]
    pub const fn bootstrap(&self) -> PostgresBootstrapSettings {
        return self.bootstrap;
    }

    /// Returns the sensitive PostgreSQL connection URI only to the compiled backend bridge.
    #[cfg(feature = "postgres")]
    #[must_use]
    pub(crate) fn connection_uri(&self) -> &str {
        return self.connection_uri.as_str();
    }

    /// Returns the PostgreSQL pool settings without exposing the sensitive connection URI.
    #[must_use]
    pub const fn pool(&self) -> PostgresPoolSettings {
        return self.pool;
    }

    /// Returns the selected PostgreSQL TLS policy without exposing the sensitive connection URI.
    #[must_use]
    pub const fn tls_mode(&self) -> PostgresTlsMode {
        return self.tls_mode;
    }

    /// Validates backend-neutral PostgreSQL settings without parsing the URI or performing I/O.
    pub fn validate(&self) -> ksp_store_api::Result<()> {
        if self.connection_uri.is_empty() {
            return std::result::Result::Err(
                ksp_store_api::Error::new(crate::ERROR_CODE_SETTINGS_INVALID, "PostgreSQL connection URI is required")
                    .with_context("field", "postgres.connection_uri"),
            );
        }
        let pool_validation = self.pool.validate();
        if let std::result::Result::Err(error) = pool_validation {
            return std::result::Result::Err(error);
        }
        let bootstrap_validation = self.bootstrap.validate();
        if let std::result::Result::Err(error) = bootstrap_validation {
            return std::result::Result::Err(error);
        }
        return std::result::Result::Ok(());
    }
}

impl std::fmt::Debug for PostgresStoreSettings {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        return formatter
            .debug_struct("PostgresStoreSettings")
            .field("connection_uri", &"<redacted>")
            .field("pool", &self.pool)
            .field("tls_mode", &self.tls_mode)
            .field("bootstrap", &self.bootstrap)
            .finish();
    }
}

/// Backend-specific settings selected through the common Store facade.
#[derive(Debug)]
#[non_exhaustive]
pub enum StoreBackendSettings {
    /// Settings for the known PostgreSQL backend, whether or not its Cargo feature is compiled.
    Postgres(PostgresStoreSettings),
}

impl StoreBackendSettings {
    /// Returns the stable backend identity represented by these settings.
    #[must_use]
    pub const fn kind(&self) -> StoreBackendKind {
        return match self {
            Self::Postgres(_) => StoreBackendKind::Postgres,
        };
    }

    /// Validates backend-specific settings without performing I/O.
    pub fn validate(&self) -> ksp_store_api::Result<()> {
        return match self {
            Self::Postgres(settings) => settings.validate(),
        };
    }
}

/// Complete backend-neutral settings consumed by the common Store runtime facade.
#[derive(Debug)]
pub struct StoreSettings {
    backend: StoreBackendSettings,
    network: ksp_store_api::RawNetworkId,
    shutdown_timeout: std::time::Duration,
}

impl StoreSettings {
    /// Creates complete Store runtime settings for one explicit logical network, backend and shutdown bound.
    #[must_use]
    pub fn new(network: ksp_store_api::RawNetworkId, backend: StoreBackendSettings, shutdown_timeout: std::time::Duration) -> Self {
        return Self { backend, network, shutdown_timeout };
    }

    /// Returns the selected backend settings.
    #[must_use]
    pub const fn backend(&self) -> &StoreBackendSettings {
        return &self.backend;
    }

    /// Returns the selected stable backend identity.
    #[must_use]
    pub const fn backend_kind(&self) -> StoreBackendKind {
        return self.backend.kind();
    }

    /// Returns the single logical network bound to this Store instance.
    #[must_use]
    pub const fn network(&self) -> &ksp_store_api::RawNetworkId {
        return &self.network;
    }

    /// Returns the maximum duration allowed for explicit Store shutdown.
    #[must_use]
    pub const fn shutdown_timeout(&self) -> std::time::Duration {
        return self.shutdown_timeout;
    }

    /// Validates all backend-neutral Store settings before any backend I/O can start.
    pub fn validate(&self) -> ksp_store_api::Result<()> {
        let shutdown_validation = validate_duration("shutdown_timeout", self.shutdown_timeout, MIN_SHUTDOWN_TIMEOUT_MS, MAX_SHUTDOWN_TIMEOUT_MS);
        if let std::result::Result::Err(error) = shutdown_validation {
            return std::result::Result::Err(error);
        }
        let backend_validation = self.backend.validate();
        if let std::result::Result::Err(error) = backend_validation {
            return std::result::Result::Err(error);
        }
        return std::result::Result::Ok(());
    }
}

impl StoreSettings {
    /// Creates settings using the common default shutdown bound while keeping network and backend construction explicit.
    #[must_use]
    pub fn with_default_shutdown(network: ksp_store_api::RawNetworkId, backend: StoreBackendSettings) -> Self {
        return Self::new(network, backend, std::time::Duration::from_millis(DEFAULT_SHUTDOWN_TIMEOUT_MS));
    }
}

fn validate_duration(field: &'static str, value: std::time::Duration, minimum_ms: u64, maximum_ms: u64) -> ksp_store_api::Result<()> {
    let minimum = std::time::Duration::from_millis(minimum_ms);
    let maximum = std::time::Duration::from_millis(maximum_ms);
    if value < minimum || value > maximum {
        return std::result::Result::Err(
            ksp_store_api::Error::new(crate::ERROR_CODE_SETTINGS_INVALID, "Store runtime duration is outside the supported resource bound")
                .with_context("field", field)
                .with_context("minimum_ms", minimum_ms.to_string())
                .with_context("maximum_ms", maximum_ms.to_string()),
        );
    }
    return std::result::Result::Ok(());
}

#[cfg(test)]
#[path = "../unit_tests/settings.rs"]
mod tests;