package web

import (
	"strings"
	"time"

	"github.com/shcizo/package-updater/internal/imageref"
	"github.com/shcizo/package-updater/internal/master/jobs"
	"github.com/shcizo/package-updater/internal/master/model"
	"github.com/shcizo/package-updater/internal/master/poller"
	"github.com/shcizo/package-updater/internal/protocol"
)

type serviceGroup struct {
	Title    string
	Services []serviceRow
}

// serviceRow is a service as shown in the overview table.
type serviceRow struct {
	model.Service
	AutoBlocked string // why the service cannot be set to auto; "" when it can
}

// groupServices groups machine-bound services per agent and Swarm services
// in one group, keeping the store's order (machines first, Swarm last).
// autoBlocked is called for every service and returns the reason it cannot be
// set to auto, or "" when it can.
func groupServices(services []model.Service, autoBlocked func(model.Service) string) []serviceGroup {
	var groups []serviceGroup
	index := map[string]int{}
	for _, s := range services {
		title := s.AgentName
		if s.Kind == protocol.KindSwarm {
			title = "Swarm"
		} else if title == "" {
			title = "Unknown agent"
		}
		i, ok := index[title]
		if !ok {
			i = len(groups)
			index[title] = i
			groups = append(groups, serviceGroup{Title: title})
		}
		groups[i].Services = append(groups[i].Services, serviceRow{Service: s, AutoBlocked: autoBlocked(s)})
	}
	return groups
}

// shortRef shortens a digest in an image reference to 12 hex characters.
func shortRef(ref string) string {
	r := imageref.Parse(ref)
	if hex, ok := strings.CutPrefix(r.Digest, "sha256:"); ok && len(hex) > 12 {
		r.Digest = "sha256:" + hex[:12] + "…"
	}
	return r.String()
}

// followsNoTag says the service's image reference has a digest but no tag,
// so there is no tag to poll or update.
func followsNoTag(svc model.Service) bool {
	return jobs.FollowedRef(svc.ActualRef) == ""
}

// versionRow is an image version as shown on the service page.
type versionRow struct {
	model.ImageVersion
	Running bool // the service runs exactly this digest
}

// versionRows marks the version the service runs now, by digest.
func versionRows(versions []model.ImageVersion, actualDigest string) []versionRow {
	rows := make([]versionRow, len(versions))
	for i, v := range versions {
		rows[i] = versionRow{ImageVersion: v, Running: v.Digest != "" && v.Digest == actualDigest}
	}
	return rows
}

// pollingStatus is the text of the "Polling" row on the service page and
// whether it is a registry error.
func pollingStatus(svc model.Service, interval time.Duration) (text string, failed bool) {
	switch {
	case poller.SkipReason(svc) != "":
		return "not polled: " + poller.SkipReason(svc), false
	case svc.LastPollError != "":
		return "last check failed: " + svc.LastPollError, true
	}
	return "every " + shortDuration(interval), false
}

// shortDuration formats d without trailing zero units: "6h", "1h30m", "90s".
func shortDuration(d time.Duration) string {
	s := d.String()
	if strings.HasSuffix(s, "m0s") {
		s = s[:len(s)-2]
	}
	if strings.HasSuffix(s, "h0m") {
		s = s[:len(s)-2]
	}
	return s
}

type agentRow struct {
	model.Agent
	Online bool
}

// jobDuration is how long a job ran, or has been running; "" before it starts.
func jobDuration(j model.Job) string {
	if j.StartedAt == nil {
		return ""
	}
	end := time.Now()
	if j.FinishedAt != nil {
		end = *j.FinishedAt
	}
	return end.Sub(*j.StartedAt).Round(time.Second).String()
}