package session

import (
	"ollie/agent"
	"ollie/backend"
	"os"
	"strings"
)

func LoadAgentConfig(agentsDir, name string, open func(string) (*os.File, error)) *agent.AgentConfig {
	if open == nil {
		open = os.Open
	}
	path := agent.AgentConfigPath(agentsDir, name)
	f, err := open(path)
	if err != nil {
		return nil
	}
	defer f.Close()
	cfg, _ := agent.Load(f)
	return cfg
}

// FormatEvent converts an agent Event to bytes for appending to a chat log.
// Streaming roles (assistant, reasoning) return only the content chunk;
// the caller (startEventLog) is responsible for writing the [role] header.
func FormatEvent(ev agent.Event) []byte {
	switch ev.Role {
	case "user":
		return []byte("[user]\n" + ev.Content + "\n")
	case "assistant":
		return []byte(ev.Content)
	case "reasoning":
		return []byte(ev.Content)
	case "call":
		args := squashWhitespace(ev.Content)
		return []byte("[call:" + ev.Name + "]\n" + args + "\n")
	case "tool":
		return []byte("[tool:" + ev.Name + "]\n" + strings.TrimRight(ev.Content, "\n") + "\n")
	case "error":
		return []byte("[error]\n" + ev.Content + "\n")
	case "info":
		return []byte("[info]\n" + ev.Content)
	case "retry":
		return []byte("[retry]\n" + ev.Content + "s\n")
	case "stalled":
		return []byte("[stalled]\n")
	case "maxsteps":
		return []byte("[maxsteps]\n" + ev.Content + "\n")
	default:
		return nil
	}
}

func squashWhitespace(s string) string {
	return strings.Join(strings.Fields(s), " ")
}

// replayMessagesToLog renders the tail of a persisted message list into the
// session's chat log so that restored sessions show recent history.
func replayMessagesToLog(sess *Session, messages []backend.Message) {
	const maxReplay = 20
	start := len(messages) - maxReplay
	if start < 0 {
		start = 0
	}
	// Skip system messages at the start of the replay window.
	for start < len(messages) && messages[start].Role == "system" {
		start++
	}
	for _, m := range messages[start:] {
		switch m.Role {
		case "system":
			// skip
		case "user":
			sess.AppendLog([]byte("[user]\n" + m.Content + "\n"))
		case "assistant":
			header := "[assistant]"
			if m.ID != "" {
				header = "[assistant:" + m.ID + "]"
			}
			sess.AppendLog([]byte(header + "\n"))
			if m.Content != "" {
				sess.AppendLog([]byte(m.Content + "\n"))
			}
			for _, tc := range m.ToolCalls {
				args := squashWhitespace(string(tc.Arguments))
				sess.AppendLog([]byte("[call:" + tc.Name + "]\n" + args + "\n"))
			}
		case "tool":
			sess.AppendLog([]byte("[tool]\n" + strings.TrimRight(m.Content, "\n") + "\n"))
		}
	}
}