package main

import (
	"fmt"
	"net/url"
	"time"
)

type TracePlugin struct{}

func (p TracePlugin) Name() string { return "trace" }
func (p TracePlugin) ShortHelp() string { return "Time an HTTP request" }
func (p TracePlugin) DetailedHelp() string {
	return "trace <url>\n\nTimes an HTTP/HTTPS request to the given URL and reports DNS lookup, connect, TLS negotiation, time to first byte, and time to last byte.\n\nExample:\n  trace https://example.com"
}
func (p TracePlugin) Execute(msg BotMessage, args string) string {
	uri, err := url.Parse(args)
	if err != nil || (uri.Scheme != "http" && uri.Scheme != "https") {
		return "That doesn't look like a valid URL for me to call"
	}

	response, err := timeRequest(msg.User.Name, uri)
	if err != nil {
		return "Failed to time the request"
	}
	return response
}

func timeRequest(username string, uri *url.URL) (string, error) {
	trace, err := TraceRequest(uri)
	if err != nil {
		return "", err
	}

	result := fmt.Sprintf("Hi %s! I've checked %s for you, and here's what I found:<br><br>\n", username, uri)
	result += formatDuration("DNS lookup", trace.DNSStart, trace.DNSDone)
	result += formatDuration("Connect", trace.ConnectStart, trace.ConnectDone)
	result += formatDuration("TLS negotiation", trace.TLSStart, trace.TLSDone)
	result += formatDuration("Sending headers", trace.ConnectionReady(), trace.WroteHeaders)
	result += formatDuration("Time to first byte", trace.WroteHeaders, trace.FirstByte)
	result += formatDuration("Time to last byte", trace.WroteHeaders, trace.AllDone)

	return result, nil
}

func formatDuration(label string, start, end time.Time) string {
	dur := end.Sub(start).String()
	if start.IsZero() || end.IsZero() {
		dur = "n/a"
	}
	return fmt.Sprintf("%s: <strong>%s</strong><br>\n", label, dur)
}