package main

// The after-upgrade check (novox/hq ADR 0508 §4), written to the run as its last step: the .pacnew and .pacsave
// files the transaction left, the distribution's news since the node's previous upgrade, the units failed now
// that were not failed in the record, and whether a restart is needed (the running kernel is no longer the one
// its package installed). It passes when the transaction succeeded and no unit newly failed (and, with the
// second part, every DKMS module is built); the rest is said and does not stop the round. The mesh restarts no
// machine (ADR 0477 §5).

import (
	"sort"
	"strings"
	"time"
)

// AfterCheck is the after-upgrade check of a run whose transaction ended, against the record taken before it
// (nil when there is none: every unit failed now is then said as newly failed).
func (u *Upgrades) AfterCheck(run Run, rec *Record) Check {
	c := Check{Pacnew: []string{}, Pacsave: []string{}, News: []NewsTitle{}, Mapped: []Mapped{}, NewlyFailed: []string{}, Unbuilt: []DKMSBuild{}}
	succeeded := transactionSucceeded(run)
	var started time.Time
	for _, s := range run.Steps {
		if s.Step == StepStarted {
			started = s.At
		}
	}
	if !started.IsZero() {
		if b := u.transactionBlock(run.Kind, started); b != nil {
			c.Pacnew = append(c.Pacnew, b.Pacnew...)
			c.Pacsave = append(c.Pacsave, b.Pacsave...)
		}
	}
	c.News, c.NewsError = u.newsSince(u.previousUpgrade(run))
	healthy := true
	if failed, err := u.Machine.FailedUnits(); err != nil {
		healthy = false
		c.NewlyFailed = append(c.NewlyFailed, "(the failed units could not be read: "+err.Error()+")")
	} else {
		before := map[string]bool{}
		if rec != nil {
			for _, f := range rec.FailedUnits {
				before[f] = true
			}
		}
		for _, f := range failed {
			if !before[f] {
				c.NewlyFailed = append(c.NewlyFailed, f)
			}
		}
	}
	c.RunningKernel, c.InstalledKernel, c.RestartNeeded = u.restartNeeded()
	c.Passed = succeeded && healthy && len(c.NewlyFailed) == 0
	u.afterCheckII(&c)
	return c
}

// previousUpgrade is when the node's upgrade before this run started: its previous run with a transaction.
func (u *Upgrades) previousUpgrade(run Run) time.Time {
	runs, err := u.ownRuns()
	if err != nil {
		return time.Time{}
	}
	var last time.Time
	for _, r := range runs {
		if r.Run.Run >= run.Run || r.Kind != RunUpgrade {
			continue
		}
		for _, s := range r.Steps {
			if s.Step == StepStarted && s.At.After(last) {
				last = s.At
			}
		}
	}
	return last
}

// newsSince is the distribution's news published after a time, titles only; or why it could not be read.
func (u *Upgrades) newsSince(since time.Time) ([]NewsTitle, string) {
	body, err := fetch(NewsFeed)
	if err != nil {
		return []NewsTitle{}, err.Error()
	}
	items, err := ParseNews(body, since)
	if err != nil {
		return []NewsTitle{}, "the feed could not be read: " + err.Error()
	}
	titles := []NewsTitle{}
	for _, it := range items {
		titles = append(titles, NewsTitle{Title: it.Title, Link: it.Link, Published: it.Published})
	}
	return titles, ""
}

// kernelTag is a release's flavour, its letters alone: `7.2.8-arch1-2` is arch, `6.18.54-2-lts` is lts.
func kernelTag(release string) string {
	return strings.Map(func(r rune) rune {
		if r >= 'a' && r <= 'z' {
			return r
		}
		return -1
	}, release)
}

// installedKernels are the releases the installed kernel packages install, sorted.
func (m *Machine) installedKernels() ([]string, error) {
	out, err := m.Out("pacman", "-Qq")
	if err != nil {
		return nil, err
	}
	var releases []string
	for _, name := range lines(out) {
		name = strings.TrimSpace(name)
		if name != "linux" && !strings.HasPrefix(name, "linux-") {
			continue
		}
		release, kernel, err := m.kernelRelease(name)
		if err != nil {
			return nil, err
		}
		if kernel {
			releases = append(releases, release)
		}
	}
	sort.Strings(releases)
	return releases, nil
}

// restartNeeded compares the running kernel with what its package installs now: when no installed kernel is the
// running one, the one of its flavour is what a restart would boot.
func (u *Upgrades) restartNeeded() (running, installed string, needed bool) {
	raw, err := u.Machine.ReadFile(OSRelease)
	if err != nil {
		return "(the running kernel could not be read: " + err.Error() + ")", "", false
	}
	running = strings.TrimSpace(string(raw))
	kernels, err := u.Machine.installedKernels()
	if err != nil {
		return running, "(the installed kernels could not be read: " + err.Error() + ")", false
	}
	for _, k := range kernels {
		if k == running {
			return running, k, false
		}
	}
	for _, k := range kernels {
		if kernelTag(k) == kernelTag(running) {
			return running, k, true
		}
	}
	return running, "", true
}