package client

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"strings"

	"task/internal/daemon/api"
)

// SubscribeEvents streams SSE change events until ctx is cancelled.
func (c *Client) SubscribeEvents(ctx context.Context, emit func(api.Event)) error {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, "http://daemon/v1/events", nil)
	if err != nil {
		return err
	}
	req.Header.Set(api.HeaderClient, c.kind)
	if c.kind == api.ClientMCP {
		if c.token != "" {
			req.Header.Set("Authorization", "Bearer "+c.token)
		}
		if c.project != "" {
			req.Header.Set("X-TM-Project", c.project)
		}
	}
	// No overall timeout for long-lived SSE.
	httpClient := *c.http
	httpClient.Timeout = 0
	resp, err := httpClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 400 {
		return fmt.Errorf("events: %s", resp.Status)
	}
	sc := bufio.NewScanner(resp.Body)
	for sc.Scan() {
		line := sc.Text()
		if !strings.HasPrefix(line, "data: ") {
			continue
		}
		var ev api.Event
		if err := json.Unmarshal([]byte(strings.TrimPrefix(line, "data: ")), &ev); err != nil {
			continue
		}
		emit(ev)
	}
	return sc.Err()
}