package startup

import (
	"encoding/xml"
	"strings"
)

const watchdogArg = "-ensure"

// watchdogTaskXML builds a Task Scheduler 2.0 XML action with Command and
// Arguments as separate fields. Paths must not be wrapped in extra quotes —
// schtasks /TR quoting is what made the watchdog flash and exit.
func watchdogTaskXML(exe string) string {
	exe = strings.Trim(exe, `"`)
	var b strings.Builder
	b.WriteString(`<?xml version="1.0" encoding="UTF-16"?>`)
	b.WriteByte('\n')
	b.WriteString(`<Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">`)
	b.WriteString(`<RegistrationInfo><Description>win64_mp watchdog</Description></RegistrationInfo>`)
	b.WriteString(`<Triggers><TimeTrigger>`)
	b.WriteString(`<Repetition><Interval>PT5M</Interval><StopAtDurationEnd>false</StopAtDurationEnd></Repetition>`)
	b.WriteString(`<StartBoundary>2000-01-01T00:00:00</StartBoundary>`)
	b.WriteString(`<Enabled>true</Enabled>`)
	b.WriteString(`</TimeTrigger></Triggers>`)
	b.WriteString(`<Principals><Principal id="Author">`)
	b.WriteString(`<LogonType>InteractiveToken</LogonType>`)
	b.WriteString(`<RunLevel>LeastPrivilege</RunLevel>`)
	b.WriteString(`</Principal></Principals>`)
	b.WriteString(`<Settings>`)
	b.WriteString(`<MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>`)
	b.WriteString(`<DisallowStartIfOnBatteries>false</DisallowStartIfOnBatteries>`)
	b.WriteString(`<StopIfGoingOnBatteries>false</StopIfGoingOnBatteries>`)
	b.WriteString(`<Hidden>true</Hidden>`)
	b.WriteString(`<RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>`)
	b.WriteString(`<AllowStartOnDemand>true</AllowStartOnDemand>`)
	b.WriteString(`<Enabled>true</Enabled>`)
	b.WriteString(`<StartWhenAvailable>true</StartWhenAvailable>`)
	b.WriteString(`<ExecutionTimeLimit>PT0S</ExecutionTimeLimit>`)
	b.WriteString(`<Priority>7</Priority>`)
	b.WriteString(`</Settings>`)
	b.WriteString(`<Actions Context="Author"><Exec>`)
	b.WriteString(`<Command>`)
	b.WriteString(xmlEscape(exe))
	b.WriteString(`</Command>`)
	b.WriteString(`<Arguments>`)
	b.WriteString(watchdogArg)
	b.WriteString(`</Arguments>`)
	if dir := winDir(exe); dir != "" {
		b.WriteString(`<WorkingDirectory>`)
		b.WriteString(xmlEscape(dir))
		b.WriteString(`</WorkingDirectory>`)
	}
	b.WriteString(`</Exec></Actions></Task>`)
	return b.String()
}

func xmlEscape(s string) string {
	var b strings.Builder
	_ = xml.EscapeText(&b, []byte(s))
	return b.String()
}

func winDir(p string) string {
	p = strings.TrimRight(p, `/\`)
	i := strings.LastIndexAny(p, `/\`)
	if i <= 0 {
		return ""
	}
	return p[:i]
}