systemprompt-ai 0.10.3

//! Typed error hierarchy for the [`systemprompt-ai`](crate) crate.
//!
//! Two error families live here:
//!
//! - [`AiError`] — the top-level public error returned by [`crate::services`].
//!   It composes provider-level failures ([`LlmProviderError`]) and
//!   repository-level failures ([`RepositoryError`]) via `#[from]`, plus common
//!   transport / parsing errors ([`reqwest::Error`], [`serde_json::Error`],
//!   [`sqlx::Error`]).
//! - [`RepositoryError`] — the persistence-layer error returned by every
//!   `*Repository` type in [`crate::repository`].
//!
//! All public service signatures use [`Result<T>`] (i.e. `Result<T, AiError>`).
//! Provider-trait signatures continue to use the boxed
//! [`systemprompt_models::errors::ProviderResult`] and bridge through
//! `AiProvider for AiService` in
//! `crate::services::core::ai_service` (the `provider_impl` submodule).

use std::time::Duration;

use thiserror::Error;
use uuid::Uuid;

use systemprompt_database::resilience::Outcome;
use systemprompt_identifiers::McpServerId;
use systemprompt_provider_contracts::LlmProviderError;

#[derive(Debug, Error)]
pub enum AiError {
    #[error("Model not specified and no default available for provider {provider}")]
    ModelNotSpecified { provider: String },

    #[error("Request metadata missing required field: {field}")]
    MissingMetadata { field: String },

    #[error("User context required for billing and audit trails")]
    MissingUserContext,

    #[error("Provider {provider} returned empty response")]
    EmptyProviderResponse { provider: String },

    #[error("Tool call schema validation failed: {reason}")]
    InvalidToolSchema { reason: String },

    #[error("Authentication required for service {service_id}")]
    AuthenticationRequired { service_id: McpServerId },

    #[error("Structured output validation failed after {retries} attempts: {details}")]
    StructuredOutputFailed { retries: usize, details: String },

    #[error("Provider {provider} error: {message}")]
    ProviderError { provider: String, message: String },

    #[error(transparent)]
    Provider(#[from] LlmProviderError),

    #[error("Serialization failed: {0}")]
    SerializationError(#[from] serde_json::Error),

    #[error("HTTP request failed: {0}")]
    Http(#[from] reqwest::Error),

    #[error("I/O error: {0}")]
    Io(#[from] std::io::Error),

    #[error("Message history cannot be serialized to JSON")]
    MessageSerializationFailed,

    #[error("Tool {tool_name} missing required field: {field}")]
    MissingToolField { tool_name: String, field: String },

    #[error("Tool description cannot be empty for tool: {tool_name}")]
    EmptyToolDescription { tool_name: String },

    #[error("No tool calls found in provider response")]
    NoToolCalls,

    #[error("Rate limit exceeded for provider {provider}: {details}")]
    RateLimit { provider: String, details: String },

    #[error("Provider {provider} returned HTTP {status}: {body}")]
    HttpStatus {
        provider: String,
        status: u16,
        retry_after: Option<Duration>,
        body: String,
    },

    #[error("Provider {provider} request timed out after {after_ms}ms")]
    Timeout { provider: String, after_ms: u64 },

    #[error("Circuit breaker open for provider {provider}; failing fast")]
    CircuitOpen { provider: String },

    #[error("Provider {provider} unavailable: concurrency limit reached")]
    DependencyUnavailable { provider: String },

    #[error("Invalid API credentials for provider {provider}")]
    AuthenticationFailed { provider: String },

    #[error("Configuration error: {0}")]
    ConfigurationError(String),

    #[error("Database operation failed: {0}")]
    DatabaseError(String),

    #[error("MCP service {service_id} not found or not configured")]
    McpServiceNotFound { service_id: McpServerId },

    #[error("MCP service {service_id} requires OAuth authentication but no token available")]
    McpAuthenticationMissing { service_id: McpServerId },

    #[error("Failed to determine service authentication requirements: {details}")]
    ServiceAuthCheckFailed { details: String },

    #[error("Storage operation failed: {0}")]
    StorageError(String),

    #[error("Invalid input: {0}")]
    InvalidInput(String),

    #[error("Regex error: {0}")]
    Regex(#[from] regex::Error),

    #[error(transparent)]
    ToolProvider(#[from] systemprompt_traits::ToolProviderError),

    #[error(transparent)]
    Secrets(#[from] systemprompt_config::SecretsBootstrapError),

    #[error("internal: {0}")]
    Internal(String),
}

#[derive(Debug, Error)]
pub enum RepositoryError {
    #[error("AI request not found: {0}")]
    NotFound(Uuid),

    #[error("Database error: {0}")]
    Database(#[from] sqlx::Error),

    #[error("Invalid data: {field} - {reason}")]
    InvalidData { field: String, reason: String },

    #[error("Database pool initialization failed: {0}")]
    PoolInitialization(String),
}

impl AiError {
    /// Build an [`AiError::HttpStatus`] from a non-success provider response,
    /// consuming the body and parsing any `Retry-After` header.
    pub async fn from_error_response(provider: &str, response: reqwest::Response) -> Self {
        let status = response.status().as_u16();
        let retry_after = parse_retry_after(response.headers());
        let body = response.text().await.unwrap_or_default();
        Self::HttpStatus {
            provider: provider.to_string(),
            status,
            retry_after,
            body,
        }
    }

    /// Classify this error for the resilience layer — which failures are worth
    /// retrying (transient) and which cannot be helped by a retry (permanent).
    #[must_use]
    pub fn classify(&self) -> Outcome {
        match self {
            Self::HttpStatus {
                status,
                retry_after,
                ..
            } => {
                if matches!(*status, 408 | 425 | 429 | 500 | 502 | 503 | 504) {
                    Outcome::Transient {
                        retry_after: *retry_after,
                    }
                } else {
                    Outcome::Permanent
                }
            },
            Self::RateLimit { .. } | Self::Timeout { .. } => {
                Outcome::Transient { retry_after: None }
            },
            Self::Http(err) if err.is_timeout() || err.is_connect() => {
                Outcome::Transient { retry_after: None }
            },
            _ => Outcome::Permanent,
        }
    }
}

/// Parse a `Retry-After` header expressed as an integer number of seconds.
fn parse_retry_after(headers: &reqwest::header::HeaderMap) -> Option<Duration> {
    headers
        .get(reqwest::header::RETRY_AFTER)?
        .to_str()
        .ok()?
        .trim()
        .parse::<u64>()
        .ok()
        .map(Duration::from_secs)
}

pub type Result<T> = std::result::Result<T, AiError>;

impl From<RepositoryError> for AiError {
    fn from(error: RepositoryError) -> Self {
        Self::DatabaseError(error.to_string())
    }
}