package config

import (
	"errors"
	"fmt"
	"net/url"
	"path/filepath"
	"regexp"
	"strings"
	"time"

	"gitea.maximumdirect.net/eric/narratio/internal/artifactpolicy"
	"gitea.maximumdirect.net/eric/narratio/internal/pathsafe"
)

// Validate checks resolved configuration for required fields and parseable durations.
func Validate(cfg *Config) error {
	if cfg == nil {
		return fmt.Errorf("config is nil")
	}
	if cfg.Pipeline == nil {
		return fmt.Errorf("pipeline config is required")
	}
	if cfg.Campaign == nil {
		return fmt.Errorf("campaign config is required")
	}
	if cfg.Session == nil {
		return fmt.Errorf("session config is required")
	}

	if err := validatePipeline(cfg.Pipeline); err != nil {
		return fmt.Errorf("pipeline config %q invalid: %w", shortName(cfg.PipelinePath, "pipeline.yml"), err)
	}
	if err := validateCampaign(cfg.Campaign); err != nil {
		return fmt.Errorf("campaign config %q invalid: %w", shortName(cfg.CampaignPath, "campaign.yml"), err)
	}
	if err := validateSession(cfg.Session); err != nil {
		return fmt.Errorf("session config %q invalid: %w", shortName(cfg.SessionPath, "session.yml"), err)
	}
	if err := validateCrossConfig(cfg.Pipeline, cfg.Session); err != nil {
		return fmt.Errorf("pipeline/session config invalid: %w", err)
	}

	return nil
}

func validateCampaign(cfg *CampaignConfig) error {
	if cfg == nil {
		return fmt.Errorf("campaign config is required")
	}
	if CampaignID(cfg) == "" {
		return fmt.Errorf("campaign.campaign_id is required")
	}
	return nil
}

func validatePipeline(cfg *PipelineConfig) error {
	if strings.TrimSpace(cfg.Workspace.Root) == "" {
		return fmt.Errorf("pipeline.workspace.root is required")
	}
	if err := validateSecrets(cfg.Secrets); err != nil {
		return err
	}
	if err := validateStorage(cfg.Storage); err != nil {
		return err
	}
	if err := validateSpool(cfg.Spool); err != nil {
		return err
	}
	if err := validateCache(cfg.Cache); err != nil {
		return err
	}
	if err := validatePublish(cfg.Publish, cfg.Scriptorium); err != nil {
		return err
	}
	if err := validateWhisperX(cfg.WhisperX); err != nil {
		return err
	}
	if err := validateSeriatim(cfg.Seriatim); err != nil {
		return err
	}
	if err := validateAudita(cfg.Audita); err != nil {
		return err
	}
	if err := validateNormalize(cfg.Normalize); err != nil {
		return err
	}
	if err := validateTrim(cfg.Trim); err != nil {
		return err
	}
	if err := validateScriptorium(cfg.Scriptorium); err != nil {
		return err
	}
	if err := validateDuration("pipeline.notification.timeout", cfg.Notification.Timeout); err != nil {
		return err
	}

	return nil
}

func validateStorage(cfg StorageConfig) error {
	if cfg.S3 == nil {
		return nil
	}
	if strings.TrimSpace(cfg.S3.RootPrefix) == "" {
		return fmt.Errorf("pipeline.storage.s3.root_prefix must be non-empty")
	}
	if err := validateRelativeSafePath("pipeline.storage.s3.root_prefix", cfg.S3.RootPrefix); err != nil {
		return err
	}
	if cfg.S3.Endpoint != "" && strings.TrimSpace(cfg.S3.Endpoint) == "" {
		return fmt.Errorf("pipeline.storage.s3.endpoint must be non-empty when provided")
	}
	if err := validateEnvVarNameField("pipeline.storage.s3.access_key_id_env", cfg.S3.AccessKeyIDEnv); err != nil {
		return err
	}
	if err := validateEnvVarNameField("pipeline.storage.s3.secret_access_key_env", cfg.S3.SecretKeyEnv); err != nil {
		return err
	}
	return nil
}

func validateSpool(cfg SpoolConfig) error {
	return nil
}

func validateCache(cfg CacheConfig) error {
	if cfg.S3Audio != nil && *cfg.S3Audio && strings.TrimSpace(cfg.Root) == "" {
		return fmt.Errorf("pipeline.cache.root is required when pipeline.cache.s3_audio is true")
	}
	return nil
}

func validatePublish(cfg *PublishConfig, scriptorium *ScriptoriumConfig) error {
	if cfg == nil {
		return nil
	}
	configuredOutputs := scriptoriumOutputPathMap(scriptorium)
	seenDest := map[string]struct{}{}
	for i, item := range cfg.Outputs {
		prefix := fmt.Sprintf("pipeline.publish.outputs[%d]", i)
		source := strings.TrimSpace(item.Source)
		if source == "" {
			return fmt.Errorf("%s.source is required", prefix)
		}
		if _, err := artifactpolicy.ValidatePublishSource(source, configuredOutputs); err != nil {
			return fmt.Errorf("%s.source %q is unsupported: %w", prefix, item.Source, err)
		}
		dest := strings.TrimSpace(item.Dest)
		if dest == "" {
			derivedDest, err := artifactpolicy.ResolvePublishedDestination(source, "", configuredOutputs)
			if err != nil {
				return fmt.Errorf("%s.dest is required when destination cannot be derived from %q: %w", prefix, source, err)
			}
			dest = derivedDest
			cfg.Outputs[i].Dest = derivedDest
		}
		normalizedDest, err := pathsafe.NormalizeRelativeDestination(dest)
		if err != nil {
			switch {
			case errors.Is(err, pathsafe.ErrRelativePathAbsolute):
				return fmt.Errorf("%s.dest must be a relative path", prefix)
			case errors.Is(err, pathsafe.ErrRelativePathEscape):
				return fmt.Errorf("%s.dest must not contain path traversal", prefix)
			default:
				return fmt.Errorf("%s.dest must be non-empty", prefix)
			}
		}
		if _, ok := seenDest[normalizedDest]; ok {
			return fmt.Errorf("%s.dest %q duplicates another publish output destination", prefix, dest)
		}
		seenDest[normalizedDest] = struct{}{}
	}
	locks, err := ValidatePublishLockRules(cfg.Locks, scriptorium, "pipeline.publish.locks")
	if err != nil {
		return err
	}
	cfg.Locks = locks
	return nil
}

// ValidatePublishLockRules validates and normalizes source-based publish locks.
func ValidatePublishLockRules(locks []PublishLockRule, scriptorium *ScriptoriumConfig, label string) ([]PublishLockRule, error) {
	seenLocks := map[string]struct{}{}
	out := make([]PublishLockRule, 0, len(locks))
	configuredOutputs := scriptoriumOutputPathMap(scriptorium)
	if strings.TrimSpace(label) == "" {
		label = "publish.locks"
	}
	for i, item := range locks {
		prefix := fmt.Sprintf("%s[%d]", label, i)
		source := strings.TrimSpace(item.Source)
		if source == "" {
			return nil, fmt.Errorf("%s.source is required", prefix)
		}
		if _, err := artifactpolicy.ValidatePublishSource(source, configuredOutputs); err != nil {
			return nil, fmt.Errorf("%s.source %q is unsupported: %w", prefix, item.Source, err)
		}
		if _, ok := seenLocks[source]; ok {
			return nil, fmt.Errorf("%s.source %q duplicates another publish lock source", prefix, source)
		}
		seenLocks[source] = struct{}{}
		out = append(out, PublishLockRule{
			Source: source,
			Reason: strings.TrimSpace(item.Reason),
		})
	}
	return out, nil
}

// MergePublishLockRules returns the union of static and remote locks. Static
// locks win when both sources contain the same lock.
func MergePublishLockRules(staticLocks, remoteLocks []PublishLockRule) []PublishLockRule {
	out := make([]PublishLockRule, 0, len(staticLocks)+len(remoteLocks))
	seen := map[string]struct{}{}
	for _, item := range staticLocks {
		source := strings.TrimSpace(item.Source)
		if source == "" {
			continue
		}
		out = append(out, PublishLockRule{Source: source, Reason: strings.TrimSpace(item.Reason)})
		seen[source] = struct{}{}
	}
	for _, item := range remoteLocks {
		source := strings.TrimSpace(item.Source)
		if source == "" {
			continue
		}
		if _, ok := seen[source]; ok {
			continue
		}
		out = append(out, PublishLockRule{Source: source, Reason: strings.TrimSpace(item.Reason)})
		seen[source] = struct{}{}
	}
	return out
}

func scriptoriumOutputPathMap(scriptorium *ScriptoriumConfig) map[string]string {
	out := map[string]string{}
	if scriptorium == nil || len(scriptorium.Artifacts) == 0 {
		return out
	}
	for key, artifactCfg := range scriptorium.Artifacts {
		out[strings.TrimSpace(key)] = strings.TrimSpace(artifactCfg.OutputPath)
	}
	return out
}

func validateSecrets(cfg *SecretsConfig) error {
	if cfg == nil {
		return nil
	}
	if strings.TrimSpace(cfg.EnvDir) == "" {
		return fmt.Errorf("pipeline.secrets.env_dir must be non-empty when pipeline.secrets is configured")
	}
	return nil
}

func validateNormalize(cfg *NormalizeConfig) error {
	if cfg == nil {
		return nil
	}
	if strings.TrimSpace(cfg.OutputPath) == "" {
		return fmt.Errorf("pipeline.normalize.output_path must be non-empty")
	}
	if err := validateSeriatimOutputSchema("pipeline.normalize.output_schema", cfg.OutputSchema); err != nil {
		return err
	}
	return nil
}

func validateTrim(cfg *TrimConfig) error {
	if cfg == nil {
		return nil
	}
	if !cfg.Enabled {
		return nil
	}

	if strings.TrimSpace(cfg.OutputPath) == "" {
		return fmt.Errorf("pipeline.trim.output_path is required when pipeline.trim.enabled is true")
	}
	if strings.TrimSpace(cfg.Bounds.PromptID) == "" {
		return fmt.Errorf("pipeline.trim.bounds.prompt_id is required when pipeline.trim.enabled is true")
	}
	if strings.TrimSpace(cfg.Bounds.TranscriptInputName) == "" {
		return fmt.Errorf("pipeline.trim.bounds.transcript_input_name is required when pipeline.trim.enabled is true")
	}
	if strings.TrimSpace(cfg.Bounds.OutputPath) == "" {
		return fmt.Errorf("pipeline.trim.bounds.output_path is required when pipeline.trim.enabled is true")
	}
	if err := validateDuration("pipeline.trim.bounds.timeout", cfg.Bounds.Timeout); err != nil {
		return err
	}
	if cfg.Bounds.RenderDebug && strings.TrimSpace(cfg.Bounds.RenderOutputPath) == "" {
		return fmt.Errorf("pipeline.trim.bounds.render_output_path is required when pipeline.trim.bounds.render_debug is true")
	}

	return nil
}

func validateWhisperX(cfg WhisperXConfig) error {
	if strings.TrimSpace(cfg.TranscribeURL) == "" {
		return fmt.Errorf("pipeline.whisperx.transcribe_url is required")
	}
	u, err := url.Parse(cfg.TranscribeURL)
	if err != nil || u.Scheme == "" || u.Host == "" {
		if err != nil {
			return fmt.Errorf("pipeline.whisperx.transcribe_url must be a valid URL: %w", err)
		}
		return fmt.Errorf("pipeline.whisperx.transcribe_url must be a valid URL")
	}
	if err := validateDuration("pipeline.whisperx.timeout", cfg.Timeout); err != nil {
		return err
	}
	if err := validateDuration("pipeline.whisperx.retry_delay", cfg.RetryDelay); err != nil {
		return err
	}
	if cfg.Retries == nil {
		return fmt.Errorf("pipeline.whisperx.retries must be set (defaults should populate this)")
	}
	if *cfg.Retries < 0 {
		return fmt.Errorf("pipeline.whisperx.retries must be >= 0")
	}
	if cfg.Concurrency == nil {
		return fmt.Errorf("pipeline.whisperx.concurrency must be set (defaults should populate this)")
	}
	if *cfg.Concurrency <= 0 {
		return fmt.Errorf("pipeline.whisperx.concurrency must be > 0")
	}
	return nil
}

func validateSeriatim(cfg SeriatimConfig) error {
	if strings.TrimSpace(cfg.Binary) == "" {
		return fmt.Errorf("pipeline.seriatim.binary is required")
	}
	if err := validateDuration("pipeline.seriatim.timeout", cfg.Timeout); err != nil {
		return err
	}
	if err := validateSeriatimOutputSchema("pipeline.seriatim.output_schema", cfg.OutputSchema); err != nil {
		return err
	}

	if cfg.CoalesceGap == nil {
		return fmt.Errorf("pipeline.seriatim.coalesce_gap must be set (defaults should populate this)")
	}
	if *cfg.CoalesceGap < 0 {
		return fmt.Errorf("pipeline.seriatim.coalesce_gap must be >= 0")
	}

	for _, item := range []struct {
		name  string
		value *float64
	}{
		{name: "pipeline.seriatim.env.overlap_word_run_gap", value: cfg.Env.OverlapWordRunGap},
		{name: "pipeline.seriatim.env.overlap_word_run_reorder_window", value: cfg.Env.OverlapWordRunReorderWindow},
		{name: "pipeline.seriatim.env.backchannel_max_duration", value: cfg.Env.BackchannelMaxDuration},
		{name: "pipeline.seriatim.env.filler_max_duration", value: cfg.Env.FillerMaxDuration},
	} {
		if item.value != nil && *item.value <= 0 {
			return fmt.Errorf("%s must be > 0 when provided", item.name)
		}
	}

	return nil
}

func validateSeriatimOutputSchema(field, value string) error {
	switch strings.TrimSpace(value) {
	case "seriatim-minimal", "seriatim-intermediate", "seriatim-full":
		return nil
	default:
		return fmt.Errorf("%s must be one of: seriatim-minimal, seriatim-intermediate, seriatim-full", field)
	}
}

func validateAudita(cfg AuditaConfig) error {
	if strings.TrimSpace(cfg.Binary) == "" {
		return fmt.Errorf("pipeline.audita.binary is required")
	}
	if err := validateDuration("pipeline.audita.timeout", cfg.Timeout); err != nil {
		return err
	}
	for i, m := range cfg.Modules {
		module := strings.TrimSpace(m)
		if module == "" {
			return fmt.Errorf("pipeline.audita.modules[%d] must be non-empty", i)
		}
		switch module {
		case "glossary", "homophones", "spoken_word", "grammar":
		default:
			return fmt.Errorf("pipeline.audita.modules[%d] must be one of: glossary, homophones, spoken_word, grammar", i)
		}
	}
	if strings.TrimSpace(cfg.BaseURL) != "" {
		u, err := url.Parse(cfg.BaseURL)
		if err != nil || u.Scheme == "" || u.Host == "" {
			if err != nil {
				return fmt.Errorf("pipeline.audita.base_url must be a valid URL: %w", err)
			}
			return fmt.Errorf("pipeline.audita.base_url must be a valid URL")
		}
	}
	if cfg.TotalLLMConcurrency != nil && *cfg.TotalLLMConcurrency <= 0 {
		return fmt.Errorf("pipeline.audita.total_llm_concurrency must be > 0")
	}
	if cfg.ProposalLLMConcurrency != nil && *cfg.ProposalLLMConcurrency <= 0 {
		return fmt.Errorf("pipeline.audita.proposal_llm_concurrency must be > 0")
	}
	if cfg.ValidationLLMConcurrency != nil && *cfg.ValidationLLMConcurrency <= 0 {
		return fmt.Errorf("pipeline.audita.validation_llm_concurrency must be > 0")
	}
	if strings.TrimSpace(cfg.TranscriptDescription) == "" && cfg.TranscriptDescription != "" {
		return fmt.Errorf("pipeline.audita.transcript_description must be non-empty when provided")
	}
	if strings.TrimSpace(cfg.ConfigPath) == "" && cfg.ConfigPath != "" {
		return fmt.Errorf("pipeline.audita.config_path must be non-empty when provided")
	}
	switch strings.TrimSpace(cfg.OutputSchema) {
	case "", "bare-segments", "audita-v1":
	default:
		return fmt.Errorf("pipeline.audita.output_schema must be one of: bare-segments, audita-v1")
	}
	switch strings.TrimSpace(cfg.WorkDirRetention) {
	case "", "always", "auto", "never":
	default:
		return fmt.Errorf("pipeline.audita.work_dir_retention must be one of: always, auto, never")
	}
	return nil
}

func validateScriptorium(cfg *ScriptoriumConfig) error {
	if cfg == nil {
		return nil
	}
	if strings.TrimSpace(cfg.Binary) == "" {
		return fmt.Errorf("pipeline.scriptorium.binary is required when pipeline.scriptorium is configured")
	}
	if cfg.ConfigPath != "" && strings.TrimSpace(cfg.ConfigPath) == "" {
		return fmt.Errorf("pipeline.scriptorium.config_path must be non-empty when provided")
	}
	if err := validateDuration("pipeline.scriptorium.timeout", cfg.Timeout); err != nil {
		return err
	}

	configuredArtifacts := make(map[string]struct{}, len(cfg.Artifacts))
	referencedArtifacts := make(map[string]struct{})
	for artifactName := range cfg.Artifacts {
		if !scriptoriumArtifactKeyRE.MatchString(strings.TrimSpace(artifactName)) {
			return fmt.Errorf("pipeline.scriptorium.artifacts keys must match ^[a-z][a-z0-9_]*$")
		}
		configuredArtifacts[artifactName] = struct{}{}
	}

	for artifactName, artifactCfg := range cfg.Artifacts {
		if artifactCfg.Enabled && strings.TrimSpace(artifactCfg.PromptID) == "" {
			return fmt.Errorf("pipeline.scriptorium.artifacts.%s.prompt_id is required when enabled", artifactName)
		}
		if artifactCfg.Enabled && strings.TrimSpace(artifactCfg.OutputPath) == "" {
			return fmt.Errorf("pipeline.scriptorium.artifacts.%s.output_path is required when enabled", artifactName)
		}
		if strings.TrimSpace(artifactCfg.OutputPath) != "" {
			pathField := "pipeline.scriptorium.artifacts." + artifactName + ".output_path"
			if err := validateRelativeSafePath(pathField, artifactCfg.OutputPath); err != nil {
				return err
			}
			if err := validatePathWithinRoot(pathField, artifactCfg.OutputPath, DefaultScriptoriumArtifactOutputRoot); err != nil {
				return err
			}
		}
		if err := validateDuration("pipeline.scriptorium.artifacts."+artifactName+".timeout", artifactCfg.Timeout); err != nil {
			return err
		}

		depSet := make(map[string]struct{}, len(artifactCfg.DependsOn))
		for i, depName := range artifactCfg.DependsOn {
			trimmedDep := strings.TrimSpace(depName)
			field := fmt.Sprintf("pipeline.scriptorium.artifacts.%s.depends_on[%d]", artifactName, i)
			if trimmedDep == "" {
				return fmt.Errorf("%s must be non-empty", field)
			}
			if _, ok := configuredArtifacts[trimmedDep]; !ok {
				return fmt.Errorf("%s %q is not a configured artifact key", field, depName)
			}
			if trimmedDep == artifactName {
				return fmt.Errorf("pipeline.scriptorium.artifacts.%s.depends_on must not include itself", artifactName)
			}
			depSet[trimmedDep] = struct{}{}
			referencedArtifacts[trimmedDep] = struct{}{}
		}

		for inputName, inputCfg := range artifactCfg.Inputs {
			trimmedInputName := strings.TrimSpace(inputName)
			if trimmedInputName == "" {
				return fmt.Errorf("pipeline.scriptorium.artifacts.%s.inputs keys must be non-empty", artifactName)
			}
			source := strings.TrimSpace(inputCfg.Source)
			if source == "" {
				return fmt.Errorf("pipeline.scriptorium.artifacts.%s.inputs.%s.source is required", artifactName, inputName)
			}

			referencedArtifact, err := validateScriptoriumInputSource(artifactName, inputName, source, configuredArtifacts)
			if err != nil {
				return err
			}
			if referencedArtifact != "" {
				if _, ok := depSet[referencedArtifact]; !ok {
					return fmt.Errorf(
						"pipeline.scriptorium.artifacts.%s.inputs.%s.source %q requires depends_on entry %q",
						artifactName,
						inputName,
						source,
						referencedArtifact,
					)
				}
				referencedArtifacts[referencedArtifact] = struct{}{}
			}
		}
		for varName, varValue := range artifactCfg.Vars {
			if strings.TrimSpace(varName) == "" {
				return fmt.Errorf("pipeline.scriptorium.artifacts.%s.vars keys must be non-empty", artifactName)
			}
			switch varValue.(type) {
			case bool, string:
			default:
				return fmt.Errorf("pipeline.scriptorium.artifacts.%s.vars.%s must be a string or boolean", artifactName, varName)
			}
		}
	}

	for artifactName := range referencedArtifacts {
		artifactCfg := cfg.Artifacts[artifactName]
		if strings.TrimSpace(artifactCfg.OutputPath) == "" {
			return fmt.Errorf("pipeline.scriptorium.artifacts.%s.output_path is required when artifact is referenced", artifactName)
		}
	}

	if err := validateEnabledArtifactDependencyCycles(cfg.Artifacts); err != nil {
		return err
	}

	return nil
}

func validateSession(cfg *SessionConfig) error {
	if err := validateSessionIdentifier("session.session_id", cfg.SessionID, true); err != nil {
		return err
	}
	if err := validateSessionIdentifier("session.previous_session_id", cfg.PreviousSessionID, false); err != nil {
		return err
	}
	if strings.TrimSpace(cfg.PreviousSessionID) != "" && strings.TrimSpace(cfg.PreviousSessionID) == strings.TrimSpace(cfg.SessionID) {
		return fmt.Errorf("session.previous_session_id must not equal session.session_id")
	}
	if strings.TrimSpace(cfg.Campaign) == "" {
		return fmt.Errorf("session.campaign is required")
	}

	if strings.TrimSpace(cfg.Inputs.SpeakersFile) == "" {
		return fmt.Errorf("session.inputs.speakers_file is required")
	}
	if strings.TrimSpace(cfg.Inputs.AutocorrectFile) == "" {
		return fmt.Errorf("session.inputs.autocorrect_file is required")
	}
	if strings.TrimSpace(cfg.Inputs.GlossaryFile) == "" {
		return fmt.Errorf("session.inputs.glossary_file is required")
	}

	hasAudioDir := strings.TrimSpace(cfg.Inputs.AudioDir) != ""
	hasAudioFiles := len(cfg.Inputs.AudioFiles) > 0
	hasAudioS3 := cfg.Inputs.AudioS3 != nil
	if hasAudioS3 {
		if strings.TrimSpace(cfg.Inputs.AudioS3.Prefix) == "" {
			return fmt.Errorf("session.inputs.audio_s3.prefix is required when session.inputs.audio_s3 is configured")
		}
		if err := validateRelativeSafePath("session.inputs.audio_s3.prefix", cfg.Inputs.AudioS3.Prefix); err != nil {
			return err
		}
	}
	if hasAudioS3 && (hasAudioDir || hasAudioFiles) {
		return fmt.Errorf("session.inputs.audio_dir/audio_files and session.inputs.audio_s3 are mutually exclusive")
	}
	if !hasAudioDir && !hasAudioFiles && !hasAudioS3 {
		return fmt.Errorf("session.inputs requires audio_dir, at least one audio_files entry, or audio_s3")
	}

	return nil
}

func validateSessionIdentifier(fieldName, value string, required bool) error {
	if strings.TrimSpace(value) == "" {
		if required {
			return fmt.Errorf("%s is required", fieldName)
		}
		return nil
	}
	return nil
}

func validateCrossConfig(pipeline *PipelineConfig, session *SessionConfig) error {
	if pipeline == nil || session == nil {
		return nil
	}
	if pipeline.Storage.S3 == nil {
		return nil
	}

	audioS3Enabled := session.Inputs.AudioS3 != nil
	publishUploadEnabled := publishUploadConfiguredForS3(pipeline)
	if (audioS3Enabled || publishUploadEnabled) && strings.TrimSpace(pipeline.Storage.S3.Bucket) == "" {
		return fmt.Errorf("pipeline.storage.s3.bucket is required when S3 session audio or publish upload is enabled")
	}
	return nil
}

func publishUploadConfiguredForS3(pipeline *PipelineConfig) bool {
	if pipeline == nil || pipeline.Publish == nil {
		return false
	}
	if !strings.EqualFold(strings.TrimSpace(pipeline.Storage.Backend), "s3") {
		return false
	}
	enabled := true
	if pipeline.Publish.Enabled != nil {
		enabled = *pipeline.Publish.Enabled
	}
	upload := true
	if pipeline.Publish.UploadRun != nil {
		upload = *pipeline.Publish.UploadRun
	}
	return enabled && upload
}

var windowsAbsPathRE = regexp.MustCompile(`^[A-Za-z]:[\\/].*`)
var envVarNameRE = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*$`)
var scriptoriumArtifactKeyRE = regexp.MustCompile(`^[a-z][a-z0-9_]*$`)

func validateScriptoriumInputSource(artifactName, inputName, source string, configuredArtifacts map[string]struct{}) (string, error) {
	trimmedSource := strings.TrimSpace(source)
	descriptor, err := artifactpolicy.DescribeScriptoriumInputSource(trimmedSource)
	if err != nil {
		if errors.Is(err, artifactpolicy.ErrInvalidPreviousSessionSource) {
			return "", fmt.Errorf(
				"pipeline.scriptorium.artifacts.%s.inputs.%s.source %q must reference configured artifact key matching ^[a-z][a-z0-9_]*$",
				artifactName,
				inputName,
				source,
			)
		}
		return "", fmt.Errorf(
			"pipeline.scriptorium.artifacts.%s.inputs.%s.source %q is unsupported",
			artifactName,
			inputName,
			source,
		)
	}
	if err := artifactpolicy.ValidateInputConfiguredReference(descriptor, configuredArtifacts); err != nil {
		var unknownConfigured *artifactpolicy.UnknownConfiguredArtifactError
		if errors.As(err, &unknownConfigured) {
			return "", fmt.Errorf(
				"pipeline.scriptorium.artifacts.%s.inputs.%s.source %q references unknown artifact %q",
				artifactName,
				inputName,
				source,
				unknownConfigured.ConfiguredKey,
			)
		}
		return "", fmt.Errorf(
			"pipeline.scriptorium.artifacts.%s.inputs.%s.source %q is unsupported",
			artifactName,
			inputName,
			source,
		)
	}
	if descriptor.Source.Kind == artifactpolicy.SourceKindConfiguredArtifact {
		return descriptor.Source.ConfiguredKey, nil
	}
	return "", nil
}

func validateEnvVarNameField(fieldName, value string) error {
	trimmed := strings.TrimSpace(value)
	if trimmed == "" {
		return fmt.Errorf("%s must be non-empty", fieldName)
	}
	if !envVarNameRE.MatchString(trimmed) {
		return fmt.Errorf("%s must be a valid environment variable name", fieldName)
	}
	return nil
}

func validateRelativeSafePath(fieldName, value string) error {
	trimmed := strings.TrimSpace(value)
	if trimmed == "" {
		return fmt.Errorf("%s must be non-empty", fieldName)
	}
	if filepath.IsAbs(trimmed) || strings.HasPrefix(trimmed, "/") || strings.HasPrefix(trimmed, "\\") || windowsAbsPathRE.MatchString(trimmed) {
		return fmt.Errorf("%s must be a relative path", fieldName)
	}

	normalized := strings.ReplaceAll(trimmed, "\\", "/")
	for _, segment := range strings.Split(normalized, "/") {
		if segment == ".." {
			return fmt.Errorf("%s must not contain path traversal", fieldName)
		}
	}
	return nil
}

func validatePathWithinRoot(fieldName, value, root string) error {
	normalizedValue := filepath.ToSlash(filepath.Clean(strings.TrimSpace(value)))
	normalizedRoot := filepath.ToSlash(filepath.Clean(strings.TrimSpace(root)))
	if normalizedValue == normalizedRoot {
		return nil
	}
	if strings.HasPrefix(normalizedValue, normalizedRoot+"/") {
		return nil
	}
	return fmt.Errorf("%s must be under %s/", fieldName, normalizedRoot)
}

func validateEnabledArtifactDependencyCycles(artifacts map[string]ScriptoriumArtifactConfig) error {
	if len(artifacts) == 0 {
		return nil
	}

	enabled := make(map[string]struct{}, len(artifacts))
	graph := make(map[string][]string, len(artifacts))
	for name, cfg := range artifacts {
		if !cfg.Enabled {
			continue
		}
		enabled[name] = struct{}{}
	}
	for name, cfg := range artifacts {
		if !cfg.Enabled {
			continue
		}
		for _, dep := range cfg.DependsOn {
			trimmedDep := strings.TrimSpace(dep)
			if _, ok := enabled[trimmedDep]; ok {
				graph[name] = append(graph[name], trimmedDep)
			}
		}
	}

	visiting := make(map[string]bool, len(enabled))
	visited := make(map[string]bool, len(enabled))

	var visit func(node string) error
	visit = func(node string) error {
		if visiting[node] {
			return fmt.Errorf("pipeline.scriptorium.artifacts enabled dependencies must not contain cycles")
		}
		if visited[node] {
			return nil
		}
		visiting[node] = true
		for _, dep := range graph[node] {
			if err := visit(dep); err != nil {
				return err
			}
		}
		visiting[node] = false
		visited[node] = true
		return nil
	}

	for node := range enabled {
		if err := visit(node); err != nil {
			return err
		}
	}
	return nil
}

func validateDuration(fieldName, value string) error {
	trimmed := strings.TrimSpace(value)
	if trimmed == "" {
		return nil
	}

	if _, err := time.ParseDuration(trimmed); err != nil {
		return fmt.Errorf("%s must be a valid duration: %w", fieldName, err)
	}

	return nil
}