package app

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"strings"
	"time"

	"sub2api-cn-relay-manager/internal/host/sub2api"
	"sub2api-cn-relay-manager/internal/pack"
	"sub2api-cn-relay-manager/internal/provision"
	"sub2api-cn-relay-manager/internal/reconcile"
	"sub2api-cn-relay-manager/internal/store/sqlite"
	"sub2api-cn-relay-manager/internal/worker"
)

const sqliteTimestampLayout = "2006-01-02 15:04:05"

func runReconcileBackgroundScheduler(ctx context.Context, sqliteDSN string, interval time.Duration) {
	if interval <= 0 {
		return
	}
	worker.NewRunner(
		[]worker.Job{reconcileSweepJob{sqliteDSN: sqliteDSN, interval: interval}},
		interval,
		log.Printf,
	).Start(ctx)
}

type reconcileSweepJob struct {
	sqliteDSN string
	interval  time.Duration
}

func (j reconcileSweepJob) Name() string {
	return "reconcile background scheduler"
}

func (j reconcileSweepJob) Run(ctx context.Context) error {
	store, err := sqlite.Open(ctx, j.sqliteDSN)
	if err != nil {
		return err
	}
	defer store.Close()
	return runReconcileBackgroundSweep(ctx, store, j.interval, time.Now())
}

func runReconcileBackgroundSweep(ctx context.Context, store *sqlite.DB, interval time.Duration, now time.Time) error {
	if store == nil {
		return fmt.Errorf("store is required")
	}
	candidates, err := store.ImportBatches().ListLatestReconcilable(ctx)
	if err != nil {
		return err
	}

	var errs []error
	for _, batch := range candidates {
		if ctx.Err() != nil {
			return ctx.Err()
		}
		lastRun, err := latestReconcileRunForBatch(ctx, store, batch.ProviderID, batch.HostID)
		if err != nil {
			errs = append(errs, fmt.Errorf("load latest reconcile run for batch %d: %w", batch.ID, err))
			continue
		}
		if !reconcileRunDue(now, lastRun, interval) {
			continue
		}
		if err := runReconcileCandidate(ctx, store, batch); err != nil {
			errs = append(errs, fmt.Errorf("run reconcile for batch %d: %w", batch.ID, err))
		}
	}
	return errors.Join(errs...)
}

func latestReconcileRunForBatch(ctx context.Context, store *sqlite.DB, providerID, hostID int64) (*sqlite.ReconcileRun, error) {
	runs, err := store.ReconcileRuns().GetByProviderIDAndHostID(ctx, providerID, hostID)
	if err != nil {
		return nil, err
	}
	if len(runs) == 0 {
		return nil, nil
	}
	return &runs[0], nil
}

func reconcileRunDue(now time.Time, run *sqlite.ReconcileRun, interval time.Duration) bool {
	if run == nil || interval <= 0 {
		return true
	}
	lastRunAt, err := time.ParseInLocation(sqliteTimestampLayout, strings.TrimSpace(run.CreatedAt), time.UTC)
	if err != nil {
		return true
	}
	return now.Sub(lastRunAt) >= interval
}

func runReconcileCandidate(ctx context.Context, store *sqlite.DB, batch sqlite.ImportBatch) error {
	hostRow, err := store.Hosts().GetByID(ctx, batch.HostID)
	if err != nil {
		return err
	}
	packRow, err := store.Packs().GetByID(ctx, batch.PackID)
	if err != nil {
		return err
	}
	providerRow, err := store.Providers().GetByID(ctx, batch.ProviderID)
	if err != nil {
		return err
	}
	accessClosures, err := store.AccessClosures().GetByBatchID(ctx, batch.ID)
	if err != nil {
		return err
	}
	accessProbeAPIKey, err := reconcileProbeAPIKey(ctx, store, hostRow, batch, accessClosures)
	if err != nil {
		return err
	}

	loadedPack, err := storedLoadedPack(packRow)
	if err != nil {
		return err
	}
	providerManifest, err := storedProviderManifest(providerRow)
	if err != nil {
		return err
	}

	client, err := newSub2APIClient(hostRow.BaseURL, authFromStoredHost(hostRow))
	if err != nil {
		return err
	}
	_, err = reconcile.NewService(store, client).Reconcile(ctx, reconcile.Request{
		HostID:            hostRow.HostID,
		HostBaseURL:       hostRow.BaseURL,
		AccessProbeAPIKey: accessProbeAPIKey,
		Pack:              loadedPack,
		Provider:          providerManifest,
	})
	return err
}

func reconcileProbeAPIKey(ctx context.Context, store *sqlite.DB, hostRow sqlite.Host, batch sqlite.ImportBatch, accessClosures []sqlite.AccessClosureRecord) (string, error) {
	if len(accessClosures) == 0 {
		return "", fmt.Errorf("access closure not found for batch %d", batch.ID)
	}
	latestClosure := accessClosures[len(accessClosures)-1]
	switch strings.TrimSpace(latestClosure.ClosureType) {
	case provision.AccessModeSelfService:
		details := parseAccessClosureDetails(latestClosure.DetailsJSON)
		apiKey, _ := details["access_api_key"].(string)
		if strings.TrimSpace(apiKey) == "" {
			apiKey, _ = details["probe_api_key"].(string)
		}
		if strings.TrimSpace(apiKey) == "" {
			return "", fmt.Errorf("self_service access closure missing probe api key")
		}
		return strings.TrimSpace(apiKey), nil
	case provision.AccessModeSubscription:
		details := parseAccessClosureDetails(latestClosure.DetailsJSON)
		subscriptionUsers := parseJSONStringArray(details["subscription_users"])
		if len(subscriptionUsers) == 0 {
			return "", fmt.Errorf("subscription access closure missing subscription_users")
		}
		subscriptionDays := parseJSONInt(details["subscription_days"])
		groupID, err := resolveManagedResourceHostIDByBatch(ctx, store, batch.ID, "group")
		if err != nil {
			return "", err
		}
		client, err := newSub2APIClient(hostRow.BaseURL, authFromStoredHost(hostRow))
		if err != nil {
			return "", err
		}
		accessRef, err := client.EnsureSubscriptionAccess(ctx, sub2api.EnsureSubscriptionAccessRequest{
			UserSelector: subscriptionUsers[0],
			GroupID:      groupID,
		})
		if err != nil {
			return "", err
		}
		userID := strings.TrimSpace(accessRef.UserID)
		if userID == "" {
			userID = subscriptionUsers[0]
		}
		if subscriptionDays > 0 {
			if _, err := client.AssignSubscription(ctx, sub2api.AssignSubscriptionRequest{
				UserID:       userID,
				GroupID:      groupID,
				DurationDays: subscriptionDays,
			}); err != nil {
				return "", err
			}
		}
		if strings.TrimSpace(accessRef.APIKey) == "" {
			return "", fmt.Errorf("subscription access api key is empty")
		}
		return strings.TrimSpace(accessRef.APIKey), nil
	default:
		return "", fmt.Errorf("unsupported access closure type %q", latestClosure.ClosureType)
	}
}

func parseAccessClosureDetails(raw string) map[string]any {
	payload := map[string]any{}
	if err := json.Unmarshal([]byte(strings.TrimSpace(raw)), &payload); err != nil {
		return map[string]any{}
	}
	return payload
}

func parseJSONStringArray(raw any) []string {
	values, ok := raw.([]any)
	if !ok {
		return nil
	}
	result := make([]string, 0, len(values))
	for _, value := range values {
		text, ok := value.(string)
		if !ok {
			continue
		}
		if trimmed := strings.TrimSpace(text); trimmed != "" {
			result = append(result, trimmed)
		}
	}
	return result
}

func parseJSONInt(raw any) int {
	switch value := raw.(type) {
	case float64:
		return int(value)
	case int:
		return value
	default:
		return 0
	}
}

func storedLoadedPack(packRow sqlite.Pack) (pack.LoadedPack, error) {
	manifest := pack.Manifest{}
	if trimmed := strings.TrimSpace(packRow.ManifestJSON); trimmed != "" && trimmed != "{}" {
		if err := json.Unmarshal([]byte(trimmed), &manifest); err != nil {
			return pack.LoadedPack{}, fmt.Errorf("decode stored pack manifest: %w", err)
		}
	}
	if strings.TrimSpace(manifest.PackID) == "" {
		manifest.PackID = strings.TrimSpace(packRow.PackID)
	}
	if strings.TrimSpace(manifest.Version) == "" {
		manifest.Version = strings.TrimSpace(packRow.Version)
	}
	if strings.TrimSpace(manifest.Vendor) == "" {
		manifest.Vendor = strings.TrimSpace(packRow.Vendor)
	}
	if strings.TrimSpace(manifest.TargetHost) == "" {
		manifest.TargetHost = strings.TrimSpace(packRow.TargetHost)
	}
	if strings.TrimSpace(manifest.MinHostVersion) == "" {
		manifest.MinHostVersion = strings.TrimSpace(packRow.MinHostVersion)
	}
	if strings.TrimSpace(manifest.MaxHostVersion) == "" {
		manifest.MaxHostVersion = strings.TrimSpace(packRow.MaxHostVersion)
	}
	return pack.LoadedPack{Manifest: manifest, Checksum: strings.TrimSpace(packRow.Checksum)}, nil
}

func storedProviderManifest(providerRow sqlite.Provider) (pack.ProviderManifest, error) {
	provider := pack.ProviderManifest{}
	if trimmed := strings.TrimSpace(providerRow.ManifestJSON); trimmed != "" && trimmed != "{}" {
		if err := json.Unmarshal([]byte(trimmed), &provider); err != nil {
			return pack.ProviderManifest{}, fmt.Errorf("decode stored provider manifest: %w", err)
		}
	}
	if strings.TrimSpace(provider.ProviderID) == "" {
		provider.ProviderID = strings.TrimSpace(providerRow.ProviderID)
	}
	if strings.TrimSpace(provider.DisplayName) == "" {
		provider.DisplayName = strings.TrimSpace(providerRow.DisplayName)
	}
	if strings.TrimSpace(provider.BaseURL) == "" {
		provider.BaseURL = strings.TrimSpace(providerRow.BaseURL)
	}
	if strings.TrimSpace(provider.Platform) == "" {
		provider.Platform = strings.TrimSpace(providerRow.Platform)
	}
	if strings.TrimSpace(provider.AccountType) == "" {
		provider.AccountType = strings.TrimSpace(providerRow.AccountType)
	}
	if strings.TrimSpace(provider.SmokeTestModel) == "" {
		provider.SmokeTestModel = strings.TrimSpace(providerRow.SmokeTestModel)
	}
	return provider, nil
}

func resolveManagedResourceHostIDByBatch(ctx context.Context, store *sqlite.DB, batchID int64, resourceType string) (string, error) {
	resources, err := store.ManagedResources().GetByBatchID(ctx, batchID)
	if err != nil {
		return "", err
	}
	resourceType = strings.TrimSpace(resourceType)
	for _, resource := range resources {
		if strings.TrimSpace(resource.ResourceType) == resourceType && strings.TrimSpace(resource.HostResourceID) != "" {
			return strings.TrimSpace(resource.HostResourceID), nil
		}
	}
	return "", fmt.Errorf("managed resource %q not found for batch %d", resourceType, batchID)
}