package main

import (
	"strings"
	"time"
)

const IdleThreshold = 60 * time.Second

// DetectState determines the session state from the last JSONL messages.
// The now parameter enables deterministic testing of the idle threshold.
func DetectState(messages []JSONLMessage, now time.Time) SessionState {
	if len(messages) == 0 {
		return Unknown
	}

	last := messages[len(messages)-1]

	// Check idle threshold first
	if ts, err := time.Parse(time.RFC3339, last.Timestamp); err == nil {
		if now.Sub(ts) > IdleThreshold {
			return Idle
		}
	}

	if last.Type == "assistant" && last.Message != nil {
		switch last.Message.StopReason {
		case "end_turn":
			return NeedsInput
		case "tool_use":
			for _, block := range last.Message.Content {
				if block.Type == "tool_use" && block.Name == "AskUserQuestion" {
					return NeedsInput
				}
			}
			return Working
		}
	}

	if last.Type == "progress" {
		return Working
	}

	if last.Type == "user" && last.Message != nil {
		for _, block := range last.Message.Content {
			if block.Type == "tool_result" {
				return Working
			}
		}
	}

	return Unknown
}

// ExtractPreview finds the last assistant text content and returns the first
// 3 lines, truncated to 200 characters.
func ExtractPreview(messages []JSONLMessage) string {
	for i := len(messages) - 1; i >= 0; i-- {
		msg := messages[i]
		if msg.Type != "assistant" || msg.Message == nil {
			continue
		}
		for _, block := range msg.Message.Content {
			if block.Type == "text" && block.Text != "" {
				return truncatePreview(block.Text)
			}
		}
	}
	return ""
}

func truncatePreview(text string) string {
	lines := strings.SplitN(text, "\n", 4)
	if len(lines) > 3 {
		lines = lines[:3]
	}
	result := strings.Join(lines, "\n")

	if len(result) > 200 {
		result = result[:200] + "..."
	}
	return result
}