package service

import (
	"encoding/base64"
	"encoding/json"
	"errors"
	"strings"

	"browser.local/platform/domain"
	"browser.local/platform/repo"
	"browser.local/platform/validator"
)

const platformDistributionBuilderEndpointID = "platform-distribution-builder"

// unconfiguredDistributionBuilder stands in when no platform builder has been
// installed. It reports a platform-builder reason so an operator is not sent
// looking at run endpoint capabilities.
type unconfiguredDistributionBuilder struct{}

func (unconfiguredDistributionBuilder) Readiness() (bool, string) {
	return false, "platform builder is not configured"
}

func (unconfiguredDistributionBuilder) Build(domain.DistributionBuildInput) ([]byte, error) {
	return nil, validationError("platform builder is not configured")
}

func (svc *CoreService) configuredDistributionBuilder() DistributionBuilder {
	svc.distributionBuildMu.Lock()
	defer svc.distributionBuildMu.Unlock()
	if svc.distributionBuilder == nil {
		return unconfiguredDistributionBuilder{}
	}
	return svc.distributionBuilder
}

// distributionBuilderReadiness reports platform builder readiness. The reason
// always names the platform builder, never a run endpoint capability.
func (svc *CoreService) distributionBuilderReadiness() (bool, string) {
	builder := svc.configuredDistributionBuilder()
	ready, reason := builder.Readiness()
	if ready {
		return true, ""
	}
	reason = strings.TrimSpace(reason)
	if reason == "" {
		reason = "platform builder is unavailable"
	} else if !strings.Contains(strings.ToLower(reason), "platform builder") {
		reason = "platform builder is unavailable: " + reason
	}
	return false, reason
}

func (svc *CoreService) enqueueDistributionBuild(job domain.Job) {
	svc.distributionBuildMu.Lock()
	if _, exists := svc.distributionBuilds[job.ID]; exists {
		svc.distributionBuildMu.Unlock()
		return
	}
	svc.distributionBuilds[job.ID] = struct{}{}
	svc.distributionBuildMu.Unlock()
	go func() {
		defer func() {
			svc.distributionBuildMu.Lock()
			delete(svc.distributionBuilds, job.ID)
			svc.distributionBuildMu.Unlock()
		}()
		_ = svc.executeDistributionBuild(job)
	}()
}

// executeDistributionBuild claims the build job internally and completes it with
// the artifact produced by the platform builder. Build work is never dispatched
// to a machine-side run endpoint, so the component auth key stays on the
// platform.
func (svc *CoreService) executeDistributionBuild(job domain.Job) error {
	if job.Capability != domain.JobCapabilityDistributionBuild {
		return validationError("job is not a distribution build")
	}
	input, err := svc.platformDistributionBuildInput(job)
	if err != nil {
		return svc.failDistributionBuildJob(job, "platform builder could not assemble build input")
	}
	if err := svc.markDistributionBuildRunning(&job); err != nil {
		return err
	}
	if isTerminalJobState(job.State) {
		return nil
	}
	payload, buildErr := svc.configuredDistributionBuilder().Build(input)
	if buildErr != nil {
		return svc.failDistributionBuildJob(job, builderJobFailureMessage(buildErr))
	}
	if _, err := svc.platformDistributionBuildInput(job); err != nil {
		return svc.failDistributionBuildJob(job, "platform builder discarded output because the component key is no longer current")
	}
	if err := svc.storeDistributionBuildArtifact(input.ArtifactID, job.ID, payload); err != nil {
		return svc.failDistributionBuildJob(job, "platform builder could not record the distribution artifact")
	}
	return svc.succeedDistributionBuildJob(job, input.ArtifactID)
}

// platformDistributionBuildInput resolves the build input, including the
// component auth key, inside the platform. Unlike GetDistributionBuildInput it
// never crosses the job channel.
func (svc *CoreService) platformDistributionBuildInput(job domain.Job) (domain.DistributionBuildInput, error) {
	runDistributions, err := svc.store.RunDistributions().List(domain.RunDistributionFilter{ServerInstanceID: job.ServerInstanceID})
	if err != nil {
		return domain.DistributionBuildInput{}, err
	}
	for _, distribution := range runDistributions {
		if distribution.BuildJobID != job.ID {
			continue
		}
		key, err := svc.activeComponentKey(distribution.ServerInstanceID, domain.DistributionComponentRun, "")
		if err != nil {
			return domain.DistributionBuildInput{}, err
		}
		if key.Generation != distribution.KeyGeneration {
			return domain.DistributionBuildInput{}, validationError("run build key generation is no longer current")
		}
		plainKey, err := svc.decryptRuntimeKey(key.EncryptedKey)
		if err != nil {
			return domain.DistributionBuildInput{}, err
		}
		profileKey, workspaceSeed, err := svc.runDistributionWorkspaceSeed(distribution)
		if err != nil {
			return domain.DistributionBuildInput{}, err
		}
		return domain.DistributionBuildInput{
			JobID:            job.ID,
			ComponentKind:    domain.DistributionComponentRun,
			ServerInstanceID: distribution.ServerInstanceID,
			PluginID:         distribution.PluginID,
			RunEndpointID:    distribution.RunEndpointID,
			ProfileKey:       profileKey,
			TargetOS:         distribution.TargetOS,
			TargetArch:       distribution.TargetArch,
			TargetRelease:    distribution.ID,
			PlatformURL:      runReleasePlatformURL(),
			PackageFormat:    distribution.PackageFormat,
			ArtifactID:       distribution.ArtifactID,
			OutputFilename:   executableFilename("run", distribution.TargetOS),
			SecretRef:        distribution.SecretRef,
			KeyGeneration:    distribution.KeyGeneration,
			AuthKey:          plainKey,
			WorkspaceSeed:    workspaceSeed,
		}, nil
	}

	clientDistributions, err := svc.store.ClientManagerDistributions().List(domain.ClientManagerDistributionFilter{ServerInstanceID: job.ServerInstanceID})
	if err != nil {
		return domain.DistributionBuildInput{}, err
	}
	for _, distribution := range clientDistributions {
		if distribution.BuildJobID != job.ID {
			continue
		}
		key, err := svc.activeComponentKey(distribution.ServerInstanceID, domain.DistributionComponentClientManager, distribution.ProfileKey)
		if err != nil {
			return domain.DistributionBuildInput{}, err
		}
		if key.Generation != distribution.KeyGeneration {
			return domain.DistributionBuildInput{}, validationError("client-manager build key generation is no longer current")
		}
		plainKey, err := svc.decryptRuntimeKey(key.EncryptedKey)
		if err != nil {
			return domain.DistributionBuildInput{}, err
		}
		return domain.DistributionBuildInput{
			JobID:            job.ID,
			ComponentKind:    domain.DistributionComponentClientManager,
			ServerInstanceID: distribution.ServerInstanceID,
			PluginID:         distribution.PluginID,
			RunEndpointID:    job.RunEndpointID,
			ProfileKey:       distribution.ProfileKey,
			TargetOS:         distribution.TargetOS,
			TargetArch:       distribution.TargetArch,
			PlatformURL:      runReleasePlatformURL(),
			PackageFormat:    packageFormatForTarget(distribution.TargetOS),
			RepositoryURL:    distribution.RepositoryURL,
			SourceRevision:   distribution.SourceRevision,
			ArtifactID:       distribution.ArtifactID,
			OutputFilename:   clientManagerOutputName(distribution.ProfileKey, distribution.TargetOS),
			SecretRef:        distribution.SecretRef,
			KeyGeneration:    distribution.KeyGeneration,
			AuthKey:          plainKey,
		}, nil
	}
	return domain.DistributionBuildInput{}, repo.ErrNotFound
}

func (svc *CoreService) runDistributionWorkspaceSeed(distribution domain.RunDistribution) (string, string, error) {
	instance, err := svc.store.ServerInstances().Get(distribution.ServerInstanceID)
	if err != nil {
		return "", "", err
	}
	plugin, err := svc.store.GamePlugins().Get(distribution.PluginID)
	if err != nil {
		return "", "", err
	}
	seed, err := encodePluginWorkspaceSeed(plugin.LifecycleAssets)
	if err != nil {
		return "", "", err
	}
	profileKey := instance.Deployment.ProfileKey
	if binding, bindingErr := svc.runtimeBindingForServer(distribution.ServerInstanceID); bindingErr == nil {
		profileKey = binding.ProfileKey
	} else if !errors.Is(bindingErr, repo.ErrNotFound) {
		return "", "", bindingErr
	}
	return profileKey, seed, nil
}

func encodePluginWorkspaceSeed(files []domain.PluginAssetFile) (string, error) {
	if len(files) == 0 {
		return "", nil
	}
	type seedFile struct {
		Path    string `json:"path"`
		Content string `json:"content"`
		Mode    int    `json:"mode,omitempty"`
	}
	seed := make([]seedFile, len(files))
	for i, file := range files {
		seed[i] = seedFile{Path: file.Path, Content: file.Content, Mode: file.Mode}
	}
	body, err := json.Marshal(seed)
	if err != nil {
		return "", err
	}
	return base64.StdEncoding.EncodeToString(body), nil
}

// storeDistributionBuildArtifact records the built package under job ownership
// so the existing ArtifactOwnerKindJob scope assertions keep guarding it.
func (svc *CoreService) storeDistributionBuildArtifact(artifactID string, jobID string, payload []byte) error {
	if strings.TrimSpace(artifactID) == "" {
		return validationError("distribution build artifact id is required")
	}
	if len(payload) == 0 {
		return validationError("distribution build produced no package bytes")
	}
	stamp := svc.now()
	svc.artifactMu.Lock()
	defer svc.artifactMu.Unlock()

	artifact, err := svc.store.Artifacts().Get(artifactID)
	if err != nil && !errors.Is(err, repo.ErrNotFound) {
		return err
	}
	create := errors.Is(err, repo.ErrNotFound)
	if create {
		artifact = domain.Artifact{ID: artifactID, OwnerKind: domain.ArtifactOwnerKindJob, OwnerID: jobID, CreatedAt: stamp}
	}
	if artifact.OwnerKind != domain.ArtifactOwnerKindJob || artifact.OwnerID != jobID {
		return validationError("distribution build artifact is outside the job scope")
	}
	artifact.SizeBytes = int64(len(payload))
	artifact.Checksum = validator.BytesChecksum(payload)
	artifact.State = domain.ArtifactStateAvailable
	artifact.UpdatedAt = stamp
	if err := validator.ValidateArtifact(artifact); err != nil {
		return err
	}
	if err := svc.artifactStore.PutPayload(artifact.ID, payload); err != nil {
		return err
	}
	if create {
		if err := svc.store.Artifacts().Create(artifact); err != nil {
			return err
		}
	} else if err := svc.store.Artifacts().Update(artifact); err != nil {
		return err
	}
	svc.artifactPayloads[artifact.ID] = domain.CopyBytes(payload)
	return nil
}

func (svc *CoreService) markDistributionBuildRunning(job *domain.Job) error {
	stamp := svc.now()
	svc.jobMu.Lock()
	defer svc.jobMu.Unlock()

	current, err := svc.store.Jobs().Get(job.ID)
	if err != nil {
		return err
	}
	if isTerminalJobState(current.State) {
		*job = current
		return nil
	}
	current.State = domain.JobStateRunning
	current.Attempt = maxInt(current.Attempt, 1)
	current.Progress = domain.JobProgress{Percent: 5, Phase: current.Progress.Phase, Message: "platform builder started"}
	current.UpdatedAt = stamp
	if err := svc.updateScheduledJob(current); err != nil {
		return err
	}
	if err := svc.projectDistributionBuildProgress(current, stamp); err != nil {
		return err
	}
	*job = current
	return nil
}

func (svc *CoreService) succeedDistributionBuildJob(job domain.Job, artifactID string) error {
	stamp := svc.now()
	svc.jobMu.Lock()
	current, err := svc.store.Jobs().Get(job.ID)
	if err != nil {
		svc.jobMu.Unlock()
		return err
	}
	if isTerminalJobState(current.State) {
		if current.State == domain.JobStateSucceeded && current.ResultRef == "artifact://"+artifactID {
			svc.jobMu.Unlock()
			return nil
		}
		svc.jobMu.Unlock()
		_ = svc.expireDistributionArtifact(artifactID)
		return nil
	}
	current.State = domain.JobStateSucceeded
	current.ResultRef = "artifact://" + artifactID
	current.Progress = domain.JobProgress{Percent: 100, Phase: current.Progress.Phase, Message: "platform builder completed"}
	current.LeaseTokenHash = ""
	current.TerminalAt = stamp
	current.TerminalFingerprint = "platform-builder:succeeded:" + artifactID
	current.UpdatedAt = stamp
	if err := svc.updateScheduledJob(current); err != nil {
		svc.jobMu.Unlock()
		return err
	}
	svc.jobMu.Unlock()
	return svc.projectDistributionBuildResult(current, stamp)
}

func (svc *CoreService) failDistributionBuildJob(job domain.Job, reason string) error {
	stamp := svc.now()
	if strings.TrimSpace(reason) == "" {
		reason = "platform builder failed"
	}
	svc.jobMu.Lock()
	current, err := svc.store.Jobs().Get(job.ID)
	if err != nil {
		svc.jobMu.Unlock()
		return err
	}
	if isTerminalJobState(current.State) {
		svc.jobMu.Unlock()
		return nil
	}
	current.State = domain.JobStateFailed
	current.Progress = domain.JobProgress{Percent: current.Progress.Percent, Phase: current.Progress.Phase, Message: reason}
	current.LeaseTokenHash = ""
	current.TerminalAt = stamp
	current.TerminalFingerprint = "platform-builder:failed:" + reason
	current.UpdatedAt = stamp
	if err := svc.updateScheduledJob(current); err != nil {
		svc.jobMu.Unlock()
		return err
	}
	svc.jobMu.Unlock()
	if err := svc.projectDistributionBuildResult(current, stamp); err != nil && !errors.Is(err, repo.ErrNotFound) {
		return err
	}
	return validationError(reason)
}