package bot

import (
	"context"
	"strings"

	"matrix-gpt-bot/openai"

	mautrix "maunium.net/go/mautrix"
	"maunium.net/go/mautrix/event"
)

// RegisterHandler sets up the GPT message handler on the Matrix client.
func RegisterHandler(client *mautrix.Client) {
	syncer := client.Syncer.(*mautrix.DefaultSyncer)

	// Compute the bot's local name (without '@' or domain) for prefix matching
	fullID := string(client.UserID)            // e.g. "@gpt:ewnix.net"
	local := strings.SplitN(fullID, ":", 2)[0] // "@gpt"
	local = strings.TrimPrefix(local, "@")     // "gpt"

	syncer.OnEventType(event.EventMessage, func(ctx context.Context, evt *event.Event) {
		msg := evt.Content.AsMessage()
		if msg.MsgType != event.MsgText {
			return
		}

		body := msg.Body
		lcBody := strings.ToLower(body)
		var content string

		// Check for "gpt: message" prefix
		if strings.HasPrefix(lcBody, local+":") {
			content = strings.TrimSpace(body[len(local)+1:])

			// Or for full Matrix mention
		} else if strings.Contains(body, fullID) {
			content = strings.TrimSpace(strings.ReplaceAll(body, fullID, ""))
		} else {
			// Not addressed to bot
			return
		}

		// Nothing to send
		if content == "" {
			return
		}

		// Retrieve or initialize conversation history for this user
		userID := string(evt.Sender)
		history := GetHistory(userID)
		history = append(history, openai.Message{Role: "user", Content: content})

		// Ask OpenAI
		resp, err := openai.Ask(history)
		if err != nil {
			client.SendText(context.Background(), evt.RoomID, "Error talking to ChatGPT: "+err.Error())
			return
		}

		history = append(history, openai.Message{Role: "assistant", Content: resp})
		SetHistory(userID, history)

		// Send reply
		client.SendText(context.Background(), evt.RoomID, resp)
	})
}