// cctuip is a Co-op Cloud TUI.
package main

import (
	"errors"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"sort"
	"strings"

	"coopcloud.tech/abra/pkg/client"
	"coopcloud.tech/abra/pkg/config"
	"coopcloud.tech/abra/pkg/recipe"
	"coopcloud.tech/abra/pkg/upstream/convert"
	"coopcloud.tech/abra/pkg/upstream/stack"
	"coopcloud.tech/tagcmp"
	"github.com/charmbracelet/bubbles/key"
	"github.com/charmbracelet/bubbles/spinner"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
	"github.com/evertras/bubble-table/table"
	"golang.org/x/term"
)

// version is the cctuip version. This is overridden at build time with
// -ldflags "-X 'main.version=$(VERSION)'", see the Makefile.
var version = "v0.1.0"

// help is the cctuip CLI help output.
const help = `cctuip [options]

cctuip is a Co-op Cloud TUI.

Options:
  -h, --help       output help
  -v, --version    output version
`

// Table row, column and per-stack status keys. The same keys are used for all
// three so that they cannot drift apart.
const (
	keyDomain       = "domain"
	keyServer       = "server"
	keyRecipe       = "recipe"
	keyStatus       = "status"
	keyVersion      = "version"
	keyUpdates      = "updates"
	keyChaos        = "chaos"
	keyChaosVersion = "chaos-version"
	keyAutoUpdate   = "auto-update"
	keyApp          = "app"
)

// statusKeys are the columns rendered from the per-stack status maps, in the
// order they appear in the table.
var statusKeys = []string{
	keyStatus,
	keyVersion,
	keyUpdates,
	keyChaos,
	keyChaosVersion,
	keyAutoUpdate,
}

// unknownStatus is rendered for any value which could not be determined.
const unknownStatus = "🤷"

// maxConcurrentServers caps how many servers are queried at the same time so
// that a large fleet does not open one SSH connection per server at once.
const maxConcurrentServers = 5

// maxReportedProblems caps how many problems the error banner shows before it
// collapses the rest into a count.
const maxReportedProblems = 3

// chromeRows is the number of terminal rows reserved for the counts line, the
// error banner and the footer around the table.
const chromeRows = 10

// newFlagSet registers the cctuip flags, including their long forms, on a
// dedicated flag set so that a bad flag returns an error rather than exiting
// from inside the flag package.
func newFlagSet(helpFlag, versionFlag *bool) *flag.FlagSet {
	fs := flag.NewFlagSet("cctuip", flag.ContinueOnError)
	fs.BoolVar(helpFlag, "h", false, "output help")
	fs.BoolVar(helpFlag, "help", false, "output help")
	fs.BoolVar(versionFlag, "v", false, "output version")
	fs.BoolVar(versionFlag, "version", false, "output version")

	return fs
}

// getApps retrieves app metadata from the abra API.
func getApps() ([]config.App, error) {
	appFiles, err := config.LoadAppFiles("")
	if err != nil {
		return []config.App{}, fmt.Errorf("getApps: %s", err)
	}

	apps, err := config.GetApps(appFiles, "")
	if err != nil {
		return []config.App{}, fmt.Errorf("getApps: %s", err)
	}

	sort.Sort(config.ByName(apps))

	return apps, nil
}

// getNumServersAndRecipes totals servers and recipes.
func getNumServersAndRecipes(apps []config.App) (int, int) {
	servers := make(map[string]struct{})
	recipes := make(map[string]struct{})

	for _, app := range apps {
		servers[app.Server] = struct{}{}
		recipes[app.Recipe] = struct{}{}
	}

	return len(servers), len(recipes)
}

// errorMsg delivers errors to the UI.
type errorMsg struct{ err error }

// appsDeployStatusMsg delivers the deployment status of all apps and any
// per-server errors to the UI.
type appsDeployStatusMsg struct {
	statuses     map[string]map[string]string
	serverErrors map[string]error
	catalogueErr error
}

// labelKey builds the Co-op Cloud label key for a stack label suffix.
func labelKey(stackName, suffix string) string {
	return fmt.Sprintf("coop-cloud.%s.%s", stackName, suffix)
}

// parseServiceStatuses folds the labels of every deployed swarm service into a
// status map per stack.
//
// Services are merged into the existing map rather than replacing it because
// most stacks run more than one service (e.g. an app alongside its database)
// and the last service read would otherwise drop the keys it does not set.
func parseServiceStatuses(all []stack.StackStatus) map[string]map[string]string {
	statuses := make(map[string]map[string]string)

	for _, result := range all {
		if result.Err != nil {
			continue
		}

		for _, service := range result.Services {
			name := service.Spec.Labels[convert.LabelNamespace]
			if name == "" {
				continue
			}

			status, ok := statuses[name]
			if !ok {
				status = map[string]string{keyStatus: "deployed"}
				statuses[name] = status
			}

			if chaos, ok := service.Spec.Labels[labelKey(name, "chaos")]; ok {
				status[keyChaos] = chaos
			}

			if chaosVersion, ok := service.Spec.Labels[labelKey(name, "chaos-version")]; ok {
				status[keyChaosVersion] = chaosVersion
			}

			if autoUpdate, ok := service.Spec.Labels[labelKey(name, "autoupdate")]; ok {
				status[keyAutoUpdate] = autoUpdate
			} else {
				status[keyAutoUpdate] = "false"
			}

			if version, ok := service.Spec.Labels[labelKey(name, "version")]; ok {
				status[keyVersion] = version
			}
		}
	}

	return statuses
}

// resolveUpdates compares each deployed version against the recipe catalogue
// and records how many newer versions are available, in place.
func resolveUpdates(
	apps []config.App,
	statuses map[string]map[string]string,
	catl recipe.RecipeCatalogue,
) {
	catalogueVersions := make(map[string][]string)

	for _, app := range apps {
		status, ok := statuses[app.StackName()]
		if !ok {
			continue
		}

		version, ok := status[keyVersion]
		if !ok {
			continue
		}

		parsedVersion, err := tagcmp.Parse(version)
		if err != nil {
			status[keyUpdates] = unknownStatus
			continue
		}

		updates, ok := catalogueVersions[app.Recipe]
		if !ok {
			updates, err = recipe.GetRecipeCatalogueVersions(app.Recipe, catl)
			if err != nil {
				status[keyUpdates] = unknownStatus
				continue
			}

			catalogueVersions[app.Recipe] = updates
		}

		var (
			newUpdates  []string
			parseFailed bool
		)

		for _, update := range updates {
			parsedUpdate, err := tagcmp.Parse(update)
			if err != nil {
				parseFailed = true
				break
			}

			if update != version && parsedUpdate.IsGreaterThan(parsedVersion) {
				newUpdates = append(newUpdates, update)
			}
		}

		switch {
		case parseFailed:
			status[keyUpdates] = unknownStatus
		case len(newUpdates) == 0:
			status[keyUpdates] = "✅"
		default:
			status[keyUpdates] = fmt.Sprintf("%v", len(newUpdates))
		}
	}
}

// hasDeployedVersion reports whether any of the apps is deployed with a known
// version, i.e. whether it is worth fetching the recipe catalogue at all.
func hasDeployedVersion(apps []config.App, statuses map[string]map[string]string) bool {
	for _, app := range apps {
		if _, ok := statuses[app.StackName()][keyVersion]; ok {
			return true
		}
	}

	return false
}

// serverResult pairs a server with the swarm services retrieved from it.
type serverResult struct {
	server string
	status stack.StackStatus
}

// serverFetcher retrieves the deployed swarm services for a single server.
type serverFetcher func(server string) stack.StackStatus

// newServerFetcher returns a fetcher which reaches each server's docker socket
// over SSH.
func newServerFetcher() serverFetcher {
	return func(server string) stack.StackStatus {
		cl, err := client.New(server)
		if err != nil {
			return stack.StackStatus{Err: err}
		}

		return stack.GetAllDeployedServices(cl, server)
	}
}

// fetchAll queries each server concurrently, keeping at most limit requests in
// flight. Servers which cannot be reached (e.g. SSH login issues) are reported
// via serverErrors so that statuses for the remaining servers are still
// returned.
func fetchAll(
	fetcher serverFetcher,
	servers []string,
	limit int,
) ([]stack.StackStatus, map[string]error) {
	if limit < 1 {
		limit = 1
	}

	results := make(chan serverResult, len(servers))
	slots := make(chan struct{}, limit)

	for _, server := range servers {
		go func(s string) {
			slots <- struct{}{}
			defer func() { <-slots }()

			results <- serverResult{server: s, status: fetcher(s)}
		}(server)
	}

	all := make([]stack.StackStatus, 0, len(servers))
	serverErrors := make(map[string]error)

	for range servers {
		res := <-results
		if res.status.Err != nil {
			serverErrors[res.server] = res.status.Err
			continue
		}

		all = append(all, res.status)
	}

	return all, serverErrors
}

// getAppsDeployStatus retrieves apps deployment status from the servers they
// are deployed on.
func getAppsDeployStatus(m model) tea.Msg {
	apps := visibleApps(&m)

	var (
		servers []string
		seen    = make(map[string]struct{})
	)

	for _, app := range apps {
		if _, ok := seen[app.Server]; ok {
			continue
		}

		seen[app.Server] = struct{}{}
		servers = append(servers, app.Server)
	}

	all, serverErrors := fetchAll(newServerFetcher(), servers, maxConcurrentServers)
	statuses := parseServiceStatuses(all)

	// The catalogue lives behind a git fetch, so only reach for it when there
	// is a deployed version to compare it against.
	var catalogueErr error

	if hasDeployedVersion(apps, statuses) {
		catl, err := recipe.ReadRecipeCatalogue()
		if err != nil {
			catalogueErr = err
		} else {
			resolveUpdates(apps, statuses, catl)
		}
	}

	return appsDeployStatusMsg{
		statuses:     statuses,
		serverErrors: serverErrors,
		catalogueErr: catalogueErr,
	}
}

// statusOrUnknown returns a status value, falling back to 🤷.
func statusOrUnknown(status map[string]string, key string) string {
	if value := status[key]; value != "" {
		return value
	}

	return unknownStatus
}

// renderAppsDeployStatus renders the deployment statuses into the table.
func renderAppsDeployStatus(m *model, appStatuses appsDeployStatusMsg) table.Model {
	for _, row := range m.table.GetVisibleRows() {
		app, ok := row.Data[keyApp].(config.App)
		if !ok {
			continue
		}

		status := appStatuses.statuses[app.StackName()]
		for _, key := range statusKeys {
			row.Data[key] = statusOrUnknown(status, key)
		}
	}

	return m.table
}

// summariseProblems folds per-server and catalogue problems into a single
// error short enough for the one-line banner.
func summariseProblems(appStatuses appsDeployStatusMsg) error {
	var problems []string

	for server, err := range appStatuses.serverErrors {
		problems = append(problems, fmt.Sprintf("%s: %s", server, err))
	}

	if appStatuses.catalogueErr != nil {
		problems = append(problems, fmt.Sprintf("catalogue: %s", appStatuses.catalogueErr))
	}

	if len(problems) == 0 {
		return nil
	}

	sort.Strings(problems)

	if len(problems) > maxReportedProblems {
		return fmt.Errorf("%s, …and %v more",
			strings.Join(problems[:maxReportedProblems], ", "),
			len(problems)-maxReportedProblems,
		)
	}

	return errors.New(strings.Join(problems, ", "))
}

type initTableMsg struct{ table table.Model }

// newRows builds a table row per app, seeded with unknown values.
func newRows(apps []config.App) []table.Row {
	rows := make([]table.Row, 0, len(apps))

	for _, app := range apps {
		rows = append(rows, table.NewRow(table.RowData{
			keyDomain:       app.Domain,
			keyServer:       app.Server,
			keyRecipe:       app.Recipe,
			keyStatus:       unknownStatus,
			keyVersion:      unknownStatus,
			keyUpdates:      unknownStatus,
			keyChaos:        unknownStatus,
			keyChaosVersion: unknownStatus,
			keyAutoUpdate:   unknownStatus,
			keyApp:          app,
		}))
	}

	return rows
}

// pageSize returns how many table rows fit in the given terminal height.
// bubble-table mis-paginates on a non-positive page size and silently renders
// no rows at all, so the result is always at least one row.
func pageSize(height int) int {
	size := height - chromeRows
	if size < 1 {
		return 1
	}

	return size
}

// newTable builds the apps table sized for the given terminal dimensions.
func newTable(rows []table.Row, width, height int) table.Model {
	colStyle := lipgloss.NewStyle().Align(lipgloss.Left)

	columns := []table.Column{
		table.NewFlexColumn(keyDomain, "Domain", 2).WithFiltered(true).WithStyle(colStyle),
		table.NewFlexColumn(keyServer, "Server", 1).WithFiltered(true).WithStyle(colStyle),
		table.NewFlexColumn(keyRecipe, "Recipe", 1).WithFiltered(true).WithStyle(colStyle),
		table.NewFlexColumn(keyStatus, "Status", 1).WithStyle(colStyle),
		table.NewFlexColumn(keyVersion, "Version", 2).WithStyle(colStyle),
		table.NewFlexColumn(keyUpdates, "Updates", 2).WithStyle(colStyle),
		table.NewFlexColumn(keyChaos, "Chaos", 1).WithStyle(colStyle),
		table.NewFlexColumn(keyChaosVersion, "Chaos version", 2).WithStyle(colStyle),
		table.NewFlexColumn(keyAutoUpdate, "Auto-update", 1).WithStyle(colStyle),
	}

	keymap := table.DefaultKeyMap()
	keymap.Filter = key.NewBinding(key.WithKeys("/", "f"))
	keymap.PageDown = key.NewBinding(key.WithKeys("right", "l", "pgdown", "ctrl+d"))
	keymap.PageUp = key.NewBinding(key.WithKeys("left", "h", "pgup", "ctrl+u"))

	return table.
		New(columns).
		Filtered(true).
		Focused(true).
		WithPageSize(pageSize(height)).
		WithRows(rows).
		WithTargetWidth(width).
		WithKeyMap(keymap)
}

// initTable loads the table layout from local-first data sources (~/.abra).
func initTable(m model) tea.Msg {
	width, height, err := term.GetSize(0)
	if err != nil {
		return errorMsg{err}
	}

	return initTableMsg{table: newTable(newRows(m.apps), width, height)}
}

// model is the TUI application state.
type model struct {
	apps []config.App

	numApps    int
	numServers int
	numRecipes int

	numFilteredApps    int
	numFilteredServers int
	numFilteredRecipes int

	table         table.Model
	spinner       spinner.Model
	pollingStatus bool

	err error
}

// visibleApps retrieves all apps currently visible in the table.
func visibleApps(m *model) []config.App {
	var apps []config.App

	for _, row := range m.table.GetVisibleRows() {
		app, ok := row.Data[keyApp].(config.App)
		if !ok {
			continue
		}

		apps = append(apps, app)
	}

	return apps
}

// updateCount updates the apps/servers/recipes count.
func (m *model) updateCount() {
	if m.table.GetIsFilterActive() {
		apps := visibleApps(m)
		m.numFilteredApps = len(apps)
		m.numFilteredServers, m.numFilteredRecipes = getNumServersAndRecipes(apps)
	} else {
		m.numFilteredApps = m.numApps
		m.numFilteredServers = m.numServers
		m.numFilteredRecipes = m.numRecipes
	}
}

// Init initialises a new model. All I/O happens here and the results are fed
// into the UI for further updates and rendering.
func (m model) Init() tea.Cmd {
	return tea.Batch(
		func() tea.Msg { return initTable(m) },
		m.spinner.Tick,
	)
}

// Update handles updates to the TUI via I/O and the user.
func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmds []tea.Cmd
	var cmd tea.Cmd

	m.table, cmd = m.table.Update(msg)
	cmds = append(cmds, cmd)

	m.spinner, cmd = m.spinner.Update(msg)
	cmds = append(cmds, cmd)

	switch msg := msg.(type) {
	case tea.KeyMsg:
		if m.err != nil {
			m.err = nil
		}

		m.updateCount()

		// While the fuzzy filter has focus every keypress belongs to it.
		if m.table.GetIsFilterInputFocused() {
			break
		}

		switch msg.String() {
		case "q":
			return m, tea.Quit
		case "s":
			if !m.pollingStatus {
				m.pollingStatus = true
				cmds = append(cmds, func() tea.Msg { return getAppsDeployStatus(m) })
			}
		}
	case initTableMsg:
		m.table = msg.table
	case appsDeployStatusMsg:
		m.pollingStatus = false
		m.table = renderAppsDeployStatus(&m, msg)

		if err := summariseProblems(msg); err != nil {
			m.err = err
		}
	case tea.WindowSizeMsg:
		m.table = m.table.WithTargetWidth(msg.Width)
		m.table = m.table.WithPageSize(pageSize(msg.Height))
	case errorMsg:
		m.pollingStatus = false
		m.err = msg.err
	}

	return m, tea.Batch(cmds...)
}

// View renders the UI.
func (m model) View() string {
	body := strings.Builder{}

	body.WriteString(fmt.Sprintf(
		"Servers: %v, Apps: %v, Recipes: %v\n",
		m.numFilteredServers, m.numFilteredApps, m.numFilteredRecipes,
	))

	body.WriteString(m.table.View() + "\n")

	if m.err != nil {
		body.WriteString(fmt.Sprintf("⚠ %v\n", m.err))
	}

	body.WriteString(fmt.Sprintf("cctuip %s", version))

	if m.pollingStatus {
		body.WriteString(fmt.Sprintf(" %s querying app status...", m.spinner.View()))
	}

	return body.String()
}

// main is the command-line entrypoint.
func main() {
	var helpFlag bool
	var versionFlag bool

	fs := newFlagSet(&helpFlag, &versionFlag)
	// The flag package prints its own error and usage text, but we want to
	// report problems against cctuip's help instead.
	fs.SetOutput(io.Discard)

	if err := fs.Parse(os.Args[1:]); err != nil {
		fmt.Fprintf(os.Stderr, "cctuip: %s\n\n%s", err, help)
		os.Exit(2)
	}

	if helpFlag {
		fmt.Print(help)
		os.Exit(0)
	}

	if versionFlag {
		fmt.Println(version)
		os.Exit(0)
	}

	apps, err := getApps()
	if err != nil {
		log.Fatal(err)
	}

	numServers, numRecipes := getNumServersAndRecipes(apps)

	s := spinner.New()
	s.Spinner = spinner.Dot
	s.Style = lipgloss.NewStyle().Foreground(lipgloss.Color("205"))

	numApps := len(apps)
	m := model{
		apps:               apps,
		numApps:            numApps,
		numServers:         numServers,
		numRecipes:         numRecipes,
		numFilteredApps:    numApps,
		numFilteredServers: numServers,
		numFilteredRecipes: numRecipes,
		spinner:            s,
	}

	p := tea.NewProgram(m, tea.WithAltScreen())
	if _, err := p.Run(); err != nil {
		log.Fatalf("oops, cctuip exploded: %s", err)
	}
}