package api

import (
	"context"
	"fmt"
	"net/url"
	"strings"
	"sync"
	"time"

	"github.com/ponzischeme89/memby/server/internal/store"
)

// The gateway's external services, as the console's Integrations area reads them.
//
// One catalogue in Go, the shape featureCatalogue and preferenceCatalogue already take:
// what an integration *is* — what it powers, whether it can be probed, where its switch is
// stored — belongs to the code, and only the operator's choices belong in the database.
// Adding a fifth service is an entry here plus its scheduler task, and the console page
// needs no change at all.
//
// Two decisions in here are worth stating because they look like omissions otherwise.
//
// **The switch is stored where the integration's other configuration already lives.**
// Sonarr and Radarr keep theirs in the arr integration policy, MDBList keeps its own in
// the ratings settings, and Tracearr — which had nowhere — uses the integration policy
// document. Consolidating them would mean a migration and, for the length of it, two
// documents that could disagree about whether a service was on. What the console needs is
// one reader and one writer, which is what integrationEnabled and setIntegrationEnabled
// are; which document answers is nobody else's business.
//
// **MDBList has no live probe.** Every other service here is a machine in the house and
// pinging it costs nothing. MDBList is an allowance bought by the day, and spending a
// request of it to draw a green dot on a page that polls would be the console competing
// with the televisions for the thing it is reporting on. Its health comes from its own run
// history instead, which is the honest answer and the cheaper one.
const (
	integrationSonarr   = "sonarr"
	integrationRadarr   = "radarr"
	integrationTracearr = "tracearr"
	integrationMDBList  = "mdblist"
)

// integrationDefinition is one external service.
type integrationDefinition struct {
	ID   string
	Name string
	// Summary is what the service is for, in one sentence, from Memby's point of view
	// rather than the vendor's.
	Summary string
	// Powers names the parts of Memby that stop working when this is switched off. It is
	// the "make the dependency clear rather than silently failing" half: an operator
	// turning Sonarr off is entitled to know the television calendar goes with it.
	Powers []string
	// Configured reports whether this deployment has an address and a credential for the
	// service at all. A service that is not configured has nothing to switch.
	Configured func(s *Server) bool
	// Address is the service's location, for the console to print. Never a credential —
	// the API key is part of neither the URL nor this string.
	Address func(s *Server) string
	// Enabled and SetEnabled are the operator's global switch. See the note above about
	// where each one is stored.
	Enabled    func(s *Server, ctx context.Context) bool
	SetEnabled func(s *Server, ctx context.Context, enabled bool) error
	// Probe asks the service whether it is answering. Nil where asking costs something
	// that should not be spent on a status page.
	Probe func(s *Server, ctx context.Context) error
	// Facts are the configuration lines the detail page prints. Deliberately a function
	// of the live server rather than stored text, so a page cannot describe a deployment
	// that has since been reconfigured.
	Facts func(s *Server, ctx context.Context) []integrationFact
}

// integrationFact is one label-and-value line of an integration's configuration.
type integrationFact struct {
	Label string `json:"label"`
	Value string `json:"value"`
	// Tone lets a fact carry a verdict where it has one — an unset API key is not
	// neutral. Empty is the ordinary, judgement-free case.
	Tone string `json:"tone,omitempty"`
}

func integrationCatalogue() []integrationDefinition {
	return []integrationDefinition{
		{
			ID:      integrationSonarr,
			Name:    "Sonarr",
			Summary: "Follows television: what has been imported, what is still to air, and which shows have ended.",
			Powers: []string{
				"The television calendar and the launcher's airing-soon row",
				"Series requests from a television",
				"Cancellation and returning-show notifications",
				"Import announcements for newly downloaded episodes",
			},
			Configured: func(s *Server) bool { return s.sonarr != nil },
			Address:    func(s *Server) string { return serviceAddress(s.cfg.SonarrURL) },
			Enabled: func(s *Server, ctx context.Context) bool {
				policy, err := s.store.ArrIntegrationPolicy(ctx)
				if err != nil {
					return false
				}
				return policy.SonarrEnabled
			},
			SetEnabled: func(s *Server, ctx context.Context, enabled bool) error {
				policy, err := s.store.ArrIntegrationPolicy(ctx)
				if err != nil {
					policy = store.DefaultArrIntegrationPolicy()
				}
				policy.SonarrEnabled = enabled
				return s.store.SetArrIntegrationPolicy(ctx, policy)
			},
			Probe: func(s *Server, ctx context.Context) error {
				// Quality profiles rather than the series list: it is a handful of rows on
				// any household, where the catalogue is thousands and would make the
				// health check the most expensive thing on the page.
				_, err := s.sonarr.QualityProfiles(ctx)
				return err
			},
			Facts: func(s *Server, ctx context.Context) []integrationFact {
				return []integrationFact{
					{Label: "Address", Value: serviceAddress(s.cfg.SonarrURL)},
					{Label: "API key", Value: credentialState(s.cfg.SonarrAPIKey),
						Tone: credentialTone(s.cfg.SonarrAPIKey)},
					{Label: "Import webhook", Value: credentialState(s.cfg.SonarrWebhookToken),
						Tone: credentialTone(s.cfg.SonarrWebhookToken)},
				}
			},
		},
		{
			ID:      integrationRadarr,
			Name:    "Radarr",
			Summary: "Follows films: what the household holds, what is on the way, and when a release becomes watchable.",
			Powers: []string{
				"The launcher's upcoming releases row and the Radarr-only film pages",
				"Film requests from a television",
				"Digital release dates, which the home hero is ranked by",
				"Import announcements for newly downloaded films",
			},
			Configured: func(s *Server) bool { return s.radarr != nil },
			Address:    func(s *Server) string { return serviceAddress(s.cfg.RadarrURL) },
			Enabled: func(s *Server, ctx context.Context) bool {
				policy, err := s.store.ArrIntegrationPolicy(ctx)
				if err != nil {
					return false
				}
				return policy.RadarrEnabled
			},
			SetEnabled: func(s *Server, ctx context.Context, enabled bool) error {
				policy, err := s.store.ArrIntegrationPolicy(ctx)
				if err != nil {
					policy = store.DefaultArrIntegrationPolicy()
				}
				policy.RadarrEnabled = enabled
				return s.store.SetArrIntegrationPolicy(ctx, policy)
			},
			Probe: func(s *Server, ctx context.Context) error {
				_, err := s.radarr.QualityProfiles(ctx)
				return err
			},
			Facts: func(s *Server, ctx context.Context) []integrationFact {
				return []integrationFact{
					{Label: "Address", Value: serviceAddress(s.cfg.RadarrURL)},
					{Label: "API key", Value: credentialState(s.cfg.RadarrAPIKey),
						Tone: credentialTone(s.cfg.RadarrAPIKey)},
					{Label: "Import webhook", Value: credentialState(s.cfg.RadarrWebhookToken),
						Tone: credentialTone(s.cfg.RadarrWebhookToken)},
				}
			},
		},
		{
			ID:      integrationTracearr,
			Name:    "Tracearr",
			Summary: "The household's real watch history, which is what personalised rows and watch-time summaries are built from.",
			Powers: []string{
				"For You rows and the recommendation profiles behind them",
				"Weekly and monthly watch-time summaries",
				"Watch time on the console's user pages",
			},
			Configured: func(s *Server) bool { return s.forYou != nil },
			Address:    func(s *Server) string { return serviceAddress(s.cfg.TracearrURL) },
			Enabled: func(s *Server, ctx context.Context) bool {
				policy, err := s.store.IntegrationPolicy(ctx)
				if err != nil {
					return false
				}
				return policy.Enabled(integrationTracearr)
			},
			SetEnabled: func(s *Server, ctx context.Context, enabled bool) error {
				return s.store.SetIntegrationEnabled(ctx, integrationTracearr, enabled)
			},
			Probe: func(s *Server, ctx context.Context) error { return s.forYou.Ping(ctx) },
			Facts: func(s *Server, ctx context.Context) []integrationFact {
				facts := []integrationFact{
					{Label: "Address", Value: serviceAddress(s.cfg.TracearrURL)},
					{Label: "API key", Value: credentialState(s.cfg.TracearrAPIKey),
						Tone: credentialTone(s.cfg.TracearrAPIKey)},
				}
				if s.cfg.TracearrServerID != "" {
					facts = append(facts,
						integrationFact{Label: "Server", Value: s.cfg.TracearrServerID})
				}
				if state, err := s.store.TracearrImportState(ctx); err == nil {
					facts = append(facts, integrationFact{
						Label: "Last full import", Value: importStamp(state.LastFullAt),
					}, integrationFact{
						Label: "Last incremental import", Value: importStamp(state.LastIncrementalAt),
					})
				}
				return facts
			},
		},
		{
			ID:      integrationMDBList,
			Name:    "MDBList",
			Summary: "External review scores. Bought by the day, so a title is fetched once and kept.",
			Powers: []string{
				"The ratings strip on detail pages and cards",
				"Score weighting in the home hero's ranking",
			},
			Configured: func(s *Server) bool { return s.mdblist != nil },
			Address:    func(s *Server) string { return "mdblist.com" },
			Enabled: func(s *Server, ctx context.Context) bool {
				settings, err := s.store.MDBListSettings(ctx)
				if err != nil {
					return false
				}
				return settings.Enabled
			},
			SetEnabled: func(s *Server, ctx context.Context, enabled bool) error {
				settings, err := s.store.MDBListSettings(ctx)
				if err != nil {
					settings = store.DefaultMDBListSettings()
				}
				settings.Enabled = enabled
				if err := s.store.SetMDBListSettings(ctx, settings); err != nil {
					return err
				}
				// The ratings path caches this document for thirty seconds; without this
				// the switch appears not to have worked for half a minute.
				s.forgetMDBListSettings()
				return nil
			},
			// Deliberately no probe. See the note at the top of this file.
			Facts: func(s *Server, ctx context.Context) []integrationFact {
				settings, err := s.store.MDBListSettings(ctx)
				if err != nil {
					settings = store.DefaultMDBListSettings()
				}
				facts := []integrationFact{
					{Label: "API key", Value: credentialState(settings.APIKey),
						Tone: credentialTone(settings.APIKey)},
					{Label: "Sources shown", Value: fmt.Sprint(len(settings.Sources))},
				}
				total, stale, statsErr := s.store.MediaRatingsStats(
					ctx, time.Now().Add(-ratingsRefreshInterval))
				if statsErr == nil {
					facts = append(facts,
						integrationFact{Label: "Titles stored", Value: fmt.Sprint(total)},
						integrationFact{Label: "Due to be re-checked", Value: fmt.Sprint(stale)})
				}
				return facts
			},
		},
	}
}

func integrationDefinitionFor(id string) (integrationDefinition, bool) {
	for _, definition := range integrationCatalogue() {
		if definition.ID == id {
			return definition, true
		}
	}
	return integrationDefinition{}, false
}

// integrationEnabled is the single reader of an integration's global switch.
//
// It answers false for a service this deployment has not configured, which is what every
// caller means by the question: "may I use Sonarr" and "is Sonarr switched on" are only
// different questions to somebody looking at the console.
func (s *Server) integrationEnabled(ctx context.Context, id string) bool {
	definition, ok := integrationDefinitionFor(id)
	if !ok || s.store == nil || !definition.Configured(s) {
		return false
	}
	return definition.Enabled(s, ctx)
}

// integrationSuppressed reports that the operator has explicitly switched a service off.
//
// Deliberately not the negation of integrationEnabled, which is also false for a service
// this deployment never configured. The difference matters at the import webhooks: a
// household can perfectly well point Sonarr's notification at Memby without giving Memby
// Sonarr's API key, and reading "no API credentials" as "the operator turned this off"
// would silently stop recording their imports.
func (s *Server) integrationSuppressed(ctx context.Context, id string) bool {
	definition, ok := integrationDefinitionFor(id)
	if !ok || s.store == nil {
		return false
	}
	return !definition.Enabled(s, ctx)
}

// TracearrEnabled is the Tracearr switch, exported for the pieces of the gateway that are
// built outside this package and still have to honour it — today the recommendation
// engine, which calls Tracearr on the rebuild path.
func (s *Server) TracearrEnabled(ctx context.Context) bool {
	return s.integrationEnabled(ctx, integrationTracearr)
}

// serviceAddress is a service's location with anything credential-shaped removed.
//
// An *arr address is ordinarily a bare host and port, but nothing stops an operator
// putting one behind basic auth, and a console that printed the URL verbatim would put
// that password on a page. Scheme, host and path only.
func serviceAddress(raw string) string {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return ""
	}
	parsed, err := url.Parse(raw)
	if err != nil || parsed.Host == "" {
		return raw
	}
	parsed.User = nil
	parsed.RawQuery = ""
	parsed.Fragment = ""
	return strings.TrimSuffix(parsed.String(), "/")
}

// credentialState says whether a credential is set and never what it is. The console has
// no use for the value and every reason not to hold it — the stance the MDBList key and
// the OpenSubtitles login already take.
func credentialState(value string) string {
	if strings.TrimSpace(value) == "" {
		return "not set"
	}
	return "saved"
}

func credentialTone(value string) string {
	if strings.TrimSpace(value) == "" {
		return "warn"
	}
	return "ok"
}

func importStamp(at *time.Time) string {
	if at == nil {
		return "never"
	}
	return at.UTC().Format(time.RFC3339)
}

// --- health -----------------------------------------------------------------------

// integrationProbeInterval is how often the health task asks each service whether it is
// answering. Five minutes is chosen against what a probe is worth rather than against what
// it costs: a service that has just gone away is news, and being up to five minutes late
// with it is invisible next to the hourly jobs that would otherwise be the first thing to
// notice. It is also the reason the console does not probe on page load — every open tab
// would be its own request against somebody's Sonarr.
const integrationProbeInterval = 5 * time.Minute

// integrationHealth is what the last probe found.
type integrationHealth struct {
	Reachable bool      `json:"reachable"`
	CheckedAt time.Time `json:"checkedAt"`
	Error     string    `json:"error,omitempty"`
	// LatencyMS is how long the service took to answer, which is the difference between
	// "working" and "working, and it is why the launcher is slow".
	LatencyMS int64 `json:"latencyMs"`
}

type integrationHealthCache struct {
	mu     sync.RWMutex
	states map[string]integrationHealth
}

func (c *integrationHealthCache) get(id string) (integrationHealth, bool) {
	c.mu.RLock()
	defer c.mu.RUnlock()
	state, ok := c.states[id]
	return state, ok
}

func (c *integrationHealthCache) set(id string, state integrationHealth) {
	c.mu.Lock()
	defer c.mu.Unlock()
	if c.states == nil {
		c.states = map[string]integrationHealth{}
	}
	c.states[id] = state
}

func (c *integrationHealthCache) forget(id string) {
	c.mu.Lock()
	defer c.mu.Unlock()
	delete(c.states, id)
}

// probeIntegration asks one service whether it is answering and records what it found.
//
// It is also what the console's Test button calls, which is deliberate: a test that took a
// different path from the scheduled probe could report a service as working while the page
// beside it stayed red.
func (s *Server) probeIntegration(
	ctx context.Context, definition integrationDefinition,
) integrationHealth {
	if definition.Probe == nil || !definition.Configured(s) {
		return integrationHealth{}
	}
	probeCtx, cancel := context.WithTimeout(ctx, 20*time.Second)
	defer cancel()
	started := time.Now()
	err := definition.Probe(s, probeCtx)
	state := integrationHealth{
		CheckedAt: time.Now().UTC(),
		LatencyMS: time.Since(started).Milliseconds(),
		Reachable: err == nil,
	}
	if err != nil {
		state.Error = err.Error()
	}
	s.integrationHealth.set(definition.ID, state)
	return state
}