session

type Compactor struct {
	Store          Store
	Summarize      SummarizeFn
	Threshold      int  // trigger when MessageCount >= this
	KeepLast       int  // messages to retain
	ExtractFacts   bool // true = parse "- " bullets as facts
	MultiPart      bool // split large histories before summarizing
	MultiPartMin   int  // minimum messages for multi-part split (default: 10)
	MaxTokensGuard int  // skip messages with len(Content)/4 > this
}

type Fact struct {
	Content     string    `json:"content"`
	ExtractedAt time.Time `json:"extracted_at"`
}

type FileStore struct {
	*InMemoryStore
	// contains filtered or unexported fields
}

type FunctionCall struct {
	Name      string `json:"name"`
	Arguments string `json:"arguments"`
}

type InMemoryStore struct {
	// contains filtered or unexported fields
}

type Message struct {
	Role       string     `json:"role"`
	Content    string     `json:"content"`
	ToolCallID string     `json:"tool_call_id,omitempty"`
	ToolCalls  []ToolCall `json:"tool_calls,omitempty"`

	// ChatTime is the message timestamp in RFC3339-UTC format.
	// Use go-kit/llm.FormatChatTime(time.Time) to produce a value
	// that round-trips cleanly across kitllm, MemDB, and this store.
	ChatTime string `json:"chat_time,omitempty"`

	// MessageID is a stable per-message identifier (MemDB dedup key).
	MessageID string `json:"message_id,omitempty"`

	// Name is an optional speaker label (OpenAI-native; MemDB-honoured).
	Name string `json:"name,omitempty"`
}

type Options struct {
	TTL            time.Duration // 0 = no expiry
	MaxMessages    int           // 0 = unlimited
	MaxContentSize int           // truncate message content beyond this byte length; 0 = unlimited
	MaxFacts       int           // rotate oldest facts when exceeded; 0 = unlimited
}

type Session struct {
	Key      string    `json:"key"`
	Messages []Message `json:"messages"`
	Summary  string    `json:"summary,omitempty"`
	Facts    []Fact    `json:"facts,omitempty"`
	Created  time.Time `json:"created"`
	Updated  time.Time `json:"updated"`
}

type Store interface {
	// GetOrCreate returns an existing session or creates a new one.
	GetOrCreate(key string) *Session

	// AddMessage appends a message to the session's history.
	AddMessage(key string, msg Message)

	// UpdateLastMessage replaces the content of the most recent message.
	// Useful for streaming LLM responses: buffer chunks into the last message.
	UpdateLastMessage(key string, content string)

	// GetHistory returns an ordered copy of the session's messages.
	GetHistory(key string) []Message

	// GetSummary returns the compaction summary for a session.
	GetSummary(key string) string

	// SetSummary stores a compaction summary.
	SetSummary(key, summary string)

	// GetFacts returns a copy of extracted facts.
	GetFacts(key string) []Fact

	// AddFacts appends new facts to a session.
	AddFacts(key string, facts []Fact)

	// MessageCount returns the number of messages in a session.
	MessageCount(key string) int

	// CompactMessages extracts the oldest messages, keeping keepLast.
	// Returns the extracted messages without modifying the caller's view.
	CompactMessages(key string, keepLast int) []Message

	// TruncateHistory removes the oldest messages, keeping keepLast.
	TruncateHistory(key string, keepLast int)

	// Clear resets a session's messages, summary, and facts.
	Clear(key string)

	// Delete removes a session entirely.
	Delete(key string) error

	// Save persists a session to the backend's storage.
	Save(key string) error

	// ListStale returns session keys where Updated is older than maxAge.
	ListStale(maxAge time.Duration) []string
}

type SummarizeFn func(ctx context.Context, prompt string) (string, error)

type ToolCall struct {
	ID       string        `json:"id"`
	Name     string        `json:"name,omitempty"`
	Args     string        `json:"arguments,omitempty"`
	Function *FunctionCall `json:"function,omitempty"`
}