agent-sdk 0.8.0

use serde::{Deserialize, Serialize};

/// The mode of extended thinking.
#[derive(Debug, Clone)]
pub enum ThinkingMode {
    /// Explicitly enabled with a token budget.
    Enabled { budget_tokens: u32 },
    /// Adaptive thinking — the model decides how much to think.
    Adaptive,
}

/// Effort level for adaptive thinking via `output_config`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum Effort {
    Low,
    Medium,
    High,
    Max,
}

/// Configuration for extended thinking.
///
/// When enabled, the model will show its reasoning process before
/// generating the final response.
#[derive(Debug, Clone)]
pub struct ThinkingConfig {
    /// Which thinking mode to use.
    pub mode: ThinkingMode,
    /// Optional effort level (sent via `output_config`).
    pub effort: Option<Effort>,
}

impl ThinkingConfig {
    /// Default budget: 10,000 tokens.
    ///
    /// This provides enough capacity for meaningful reasoning on most tasks
    /// while keeping costs reasonable. Increase for complex multi-step problems.
    pub const DEFAULT_BUDGET_TOKENS: u32 = 10_000;

    /// Minimum budget required by the Anthropic API.
    pub const MIN_BUDGET_TOKENS: u32 = 1_024;

    /// Create a config with an explicit token budget (Enabled mode).
    #[must_use]
    pub const fn new(budget_tokens: u32) -> Self {
        Self {
            mode: ThinkingMode::Enabled { budget_tokens },
            effort: None,
        }
    }

    /// Create an adaptive thinking config.
    #[must_use]
    pub const fn adaptive() -> Self {
        Self {
            mode: ThinkingMode::Adaptive,
            effort: None,
        }
    }

    /// Create an adaptive thinking config with an effort level.
    #[must_use]
    pub const fn adaptive_with_effort(effort: Effort) -> Self {
        Self {
            mode: ThinkingMode::Adaptive,
            effort: Some(effort),
        }
    }

    /// Set the effort level on an existing config.
    #[must_use]
    pub const fn with_effort(mut self, effort: Effort) -> Self {
        self.effort = Some(effort);
        self
    }
}

impl Default for ThinkingConfig {
    fn default() -> Self {
        Self::new(Self::DEFAULT_BUDGET_TOKENS)
    }
}

#[derive(Debug, Clone)]
pub struct ChatRequest {
    pub system: String,
    pub messages: Vec<Message>,
    pub tools: Option<Vec<Tool>>,
    pub max_tokens: u32,
    /// Whether `max_tokens` was explicitly configured by the caller.
    pub max_tokens_explicit: bool,
    /// Optional session identifier for provider-side prompt caching or routing.
    pub session_id: Option<String>,
    /// Optional provider-managed cached content reference.
    ///
    /// This currently maps to Gemini / Vertex AI `cachedContent` handles.
    pub cached_content: Option<String>,
    /// Optional extended thinking configuration.
    pub thinking: Option<ThinkingConfig>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Message {
    pub role: Role,
    pub content: Content,
}

impl Message {
    #[must_use]
    pub fn user(text: impl Into<String>) -> Self {
        Self {
            role: Role::User,
            content: Content::Text(text.into()),
        }
    }

    #[must_use]
    pub const fn user_with_content(blocks: Vec<ContentBlock>) -> Self {
        Self {
            role: Role::User,
            content: Content::Blocks(blocks),
        }
    }

    #[must_use]
    pub fn assistant(text: impl Into<String>) -> Self {
        Self {
            role: Role::Assistant,
            content: Content::Text(text.into()),
        }
    }

    #[must_use]
    pub fn assistant_with_tool_use(
        text: Option<String>,
        id: impl Into<String>,
        name: impl Into<String>,
        input: serde_json::Value,
    ) -> Self {
        let mut blocks = Vec::new();
        if let Some(t) = text {
            blocks.push(ContentBlock::Text { text: t });
        }
        blocks.push(ContentBlock::ToolUse {
            id: id.into(),
            name: name.into(),
            input,
            thought_signature: None,
        });
        Self {
            role: Role::Assistant,
            content: Content::Blocks(blocks),
        }
    }

    #[must_use]
    pub fn tool_result(
        tool_use_id: impl Into<String>,
        content: impl Into<String>,
        is_error: bool,
    ) -> Self {
        Self {
            role: Role::User,
            content: Content::Blocks(vec![ContentBlock::ToolResult {
                tool_use_id: tool_use_id.into(),
                content: content.into(),
                is_error: if is_error { Some(true) } else { None },
            }]),
        }
    }
}

#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
#[serde(rename_all = "lowercase")]
pub enum Role {
    User,
    Assistant,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(untagged)]
pub enum Content {
    Text(String),
    Blocks(Vec<ContentBlock>),
}

impl Content {
    #[must_use]
    pub fn first_text(&self) -> Option<&str> {
        match self {
            Self::Text(s) => Some(s),
            Self::Blocks(blocks) => blocks.iter().find_map(|b| match b {
                ContentBlock::Text { text } => Some(text.as_str()),
                _ => None,
            }),
        }
    }
}

/// Source data for image and document content blocks.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ContentSource {
    pub media_type: String,
    pub data: String,
}

impl ContentSource {
    #[must_use]
    pub fn new(media_type: impl Into<String>, data: impl Into<String>) -> Self {
        Self {
            media_type: media_type.into(),
            data: data.into(),
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type")]
pub enum ContentBlock {
    #[serde(rename = "text")]
    Text { text: String },

    #[serde(rename = "thinking")]
    Thinking {
        thinking: String,
        /// Opaque signature for round-tripping thinking blocks back to the API.
        #[serde(skip_serializing_if = "Option::is_none")]
        signature: Option<String>,
    },

    #[serde(rename = "redacted_thinking")]
    RedactedThinking { data: String },

    #[serde(rename = "tool_use")]
    ToolUse {
        id: String,
        name: String,
        input: serde_json::Value,
        /// Gemini thought signature for preserving reasoning context.
        /// Required for Gemini 3 models when sending function calls back.
        #[serde(skip_serializing_if = "Option::is_none")]
        thought_signature: Option<String>,
    },

    #[serde(rename = "tool_result")]
    ToolResult {
        tool_use_id: String,
        content: String,
        #[serde(skip_serializing_if = "Option::is_none")]
        is_error: Option<bool>,
    },

    #[serde(rename = "image")]
    Image { source: ContentSource },

    #[serde(rename = "document")]
    Document { source: ContentSource },
}

#[derive(Debug, Clone, Serialize)]
pub struct Tool {
    pub name: String,
    pub description: String,
    pub input_schema: serde_json::Value,
}

#[derive(Debug, Clone)]
pub struct ChatResponse {
    pub id: String,
    pub content: Vec<ContentBlock>,
    pub model: String,
    pub stop_reason: Option<StopReason>,
    pub usage: Usage,
}

impl ChatResponse {
    #[must_use]
    pub fn first_text(&self) -> Option<&str> {
        self.content.iter().find_map(|b| match b {
            ContentBlock::Text { text } => Some(text.as_str()),
            _ => None,
        })
    }

    #[must_use]
    pub fn first_thinking(&self) -> Option<&str> {
        self.content.iter().find_map(|b| match b {
            ContentBlock::Thinking { thinking, .. } => Some(thinking.as_str()),
            _ => None,
        })
    }

    pub fn tool_uses(&self) -> impl Iterator<Item = (&str, &str, &serde_json::Value)> {
        self.content.iter().filter_map(|b| match b {
            ContentBlock::ToolUse {
                id, name, input, ..
            } => Some((id.as_str(), name.as_str(), input)),
            _ => None,
        })
    }

    #[must_use]
    pub fn has_tool_use(&self) -> bool {
        self.content
            .iter()
            .any(|b| matches!(b, ContentBlock::ToolUse { .. }))
    }
}

#[derive(Debug, Clone, Copy, Deserialize, PartialEq, Eq)]
#[serde(rename_all = "snake_case")]
pub enum StopReason {
    EndTurn,
    ToolUse,
    MaxTokens,
    StopSequence,
    Refusal,
    ModelContextWindowExceeded,
}

#[derive(Debug, Clone, Deserialize)]
pub struct Usage {
    /// Total input tokens reported by the provider.
    pub input_tokens: u32,
    pub output_tokens: u32,
    /// Portion of `input_tokens` billed at a cached-input rate, when reported.
    #[serde(default)]
    pub cached_input_tokens: u32,
}

#[derive(Debug)]
pub enum ChatOutcome {
    Success(ChatResponse),
    RateLimited,
    InvalidRequest(String),
    ServerError(String),
}