//! Session models shared by protocol-aware download workflows.

#![forbid(unsafe_code)]

use crate::{
    auth::AuthCredentialModel,
    http::{Cookie, HttpHeader, ProxyConfig, RetryStrategy, TlsConfig},
};

/// Coarse lifecycle state for a transport session.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum SessionState {
    /// Session exists but has not started work.
    Idle,
    /// Session is establishing a connection.
    Connecting,
    /// Session is actively transferring data.
    Active,
    /// Session is paused.
    Paused,
    /// Session completed successfully.
    Completed,
    /// Session ended with a failure.
    Failed,
}

/// Scope at which a session model applies.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum SessionScope {
    /// Global client-wide scope.
    Global,
    /// Protocol-family scope.
    Protocol,
    /// Single transfer scope.
    Transfer,
}

/// Operational limits attached to a session.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct SessionLimits {
    /// Maximum simultaneous connections.
    pub max_connections: u16,
    /// Maximum parallel downloads across the session.
    pub max_parallel_downloads: u16,
    /// Delay before reconnecting after a failure, in milliseconds.
    pub reconnect_delay_ms: u64,
}

/// Preferred protocol ordering within a session.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SessionTransportPreference {
    /// Protocol identifier string.
    pub protocol: String,
    /// Smaller numbers indicate higher preference.
    pub priority: u8,
    /// Whether this protocol is enabled.
    pub enabled: bool,
}

/// End-user session configuration and live state.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SessionModel {
    /// Stable session identifier.
    pub session_id: String,
    /// Current lifecycle state.
    pub state: SessionState,
    /// Scope for this session.
    pub scope: SessionScope,
    /// Optional user-agent string.
    pub user_agent: Option<String>,
    /// Default headers applied to requests.
    pub headers: Vec<HttpHeader>,
    /// Persisted or injected cookies.
    pub cookies: Vec<Cookie>,
    /// Optional authentication material.
    pub auth: Option<AuthCredentialModel>,
    /// Optional proxy configuration.
    pub proxy: Option<ProxyConfig>,
    /// Optional TLS configuration.
    pub tls: Option<TlsConfig>,
    /// Retry behavior for requests in the session.
    pub retry: RetryStrategy,
    /// Operational session limits.
    pub limits: SessionLimits,
    /// Ordered transport preferences.
    pub preferred_transports: Vec<SessionTransportPreference>,
}

/// Remote server descriptor associated with a session.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct ServerModel {
    /// Human-readable server name.
    pub name: String,
    /// Host name or IP address.
    pub host: String,
    /// Listen port.
    pub port: u16,
    /// Whether TLS is enabled.
    pub tls_enabled: bool,
}

/// Client descriptor that can be associated with server sessions.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct ClientModel {
    /// Stable client identifier.
    pub client_id: String,
    /// Preferred session id when one exists.
    pub preferred_session: Option<String>,
    /// Optional server currently associated with the client.
    pub server: Option<ServerModel>,
}

/// Collection of sessions known for a given server.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct ServerSessionModel {
    /// Server whose sessions are being reported.
    pub server: ServerModel,
    /// Sessions currently associated with the server.
    pub sessions: Vec<SessionModel>,
}