package engine

import "gitea.maximumdirect.net/eric/ConfigKit/internal/document"

type sourceVersionMode uint8

const (
	sourceVersionModeDefault sourceVersionMode = iota
	sourceVersionModeIfPresent
	sourceVersionModeRequired
)

// SourceVersionModeFromFacade converts the root-owned public mode while
// keeping the engine's policy type private. Unknown values remain intact for
// pre-acquisition validation.
func SourceVersionModeFromFacade(value uint8) sourceVersionMode {
	return sourceVersionMode(value)
}

type sourceVersionRole uint8

const (
	sourceVersionMain sourceVersionRole = iota
	sourceVersionContribution
)

type sourceVersionAncestor struct {
	path Path
	kind document.Kind
}

type sourceVersionEvidence struct {
	sourceID       string
	path           Path
	resolvedPath   Path
	destination    Path
	projectedPaths []Path
	version        Version
	location       *Location
	ancestors      []sourceVersionAncestor
	absence        sourceVersionPathAbsence
	checked        bool
	redacted       bool
}

type sourceVersionState struct {
	localRule      *VersionRule
	effectiveRule  *VersionRule
	mode           sourceVersionMode
	mainProcessing *sourceVersionProcessingResult
	evidence       []*sourceVersionEvidence
	diagnostics    []Diagnostic
}

func sourceInfosWithVersionEvidence(sources []SourceInfo, evidence []*sourceVersionEvidence, secrets map[string]bool, conservative bool) []SourceInfo {
	result := cloneSourceInfos(sources)
	if len(evidence) == 0 {
		return result
	}
	sensitivity := newDiffSensitivity(secrets, nil)
	for _, item := range evidence {
		if item == nil || item.sourceID == "" {
			continue
		}
		for index := range result {
			if result[index].ID == item.sourceID {
				result[index].VersionCheck = sourceVersionCheckForEvidence(item, sensitivity, conservative)
				break
			}
		}
	}
	return result
}

func sourceVersionCheckForEvidence(evidence *sourceVersionEvidence, sensitivity *diffSensitivity, conservative bool) *SourceVersionCheck {
	path := evidence.resolvedPath
	if !path.valid() {
		path = evidence.path
	}
	version := evidence.version
	redacted := evidence.redacted
	if conservative {
		redacted = redacted || version.Text != ""
	} else if sensitivity.isSensitiveAtOrAbove(evidence.sensitivityPaths()[0].String()) {
		redacted = true
	}
	if redacted {
		version.Text = ""
	}
	return &SourceVersionCheck{
		Path: path.clone(), Version: version, Location: cloneLocation(evidence.location), Redacted: redacted,
	}
}

// sensitivityPaths preserves source-local evidence while describing its assigned
// application coordinates. Before assembly, the original mount is the fallback.
func (evidence *sourceVersionEvidence) sensitivityPaths() []Path {
	if evidence.projectedPaths != nil {
		return evidence.projectedPaths
	}
	local := evidence.resolvedPath
	if !local.valid() {
		local = evidence.path
	}
	paths := make([]Path, 0, len(evidence.ancestors)+1)
	paths = append(paths, appendDestination(evidence.destination, local))
	for _, ancestor := range evidence.ancestors {
		paths = append(paths, appendDestination(evidence.destination, ancestor.path))
	}
	return paths
}

func (state *sourceVersionState) process(root *document.Node, role sourceVersionRole, destination Path, sourceID string, placement placementMode) (sourceVersionProcessingResult, []Diagnostic) {
	if state == nil || state.mode == sourceVersionModeDefault {
		return sourceVersionProcessingResult{}, nil
	}
	projectedDestination := destination.clone()
	if placement == placementModeSequenceItem {
		projectedDestination = projectedDestination.Index(0)
	}
	result := processSourceVersion(root, state.localRule, role, projectedDestination, state.mode)
	if result.evidence != nil {
		result.evidence.sourceID = sourceID
		state.evidence = append(state.evidence, result.evidence)
	}
	var failures []Diagnostic
	for _, diagnostic := range result.diagnostics {
		if diagnostic.Severity == SeverityWarning {
			state.diagnostics = append(state.diagnostics, diagnostic)
		} else if diagnostic.Severity == SeverityError {
			failures = append(failures, diagnostic)
		}
	}
	return result, failures
}

type sourceVersionProcessingResult struct {
	payload     *document.Node
	imports     []importDeclaration
	evidence    *sourceVersionEvidence
	diagnostics []Diagnostic
}

func effectiveSourceVersionRule(local *VersionRule, destination Path, mode sourceVersionMode) *VersionRule {
	return effectiveSourceVersionRuleForPlacement(local, destination, mode, placementModeMapping)
}

func effectiveSourceVersionRuleForPlacement(local *VersionRule, destination Path, mode sourceVersionMode, placement placementMode) *VersionRule {
	if local == nil {
		return nil
	}
	if mode == sourceVersionModeDefault {
		return local
	}
	effective := *local
	prefix := destination.clone()
	if placement == placementModeSequenceItem {
		prefix = prefix.Index(0)
	}
	effective.Path = Path{
		segments: append(clonePathSegments(prefix.segments, len(local.Path.segments)), local.Path.segments...),
		invalid:  prefix.invalid || local.Path.invalid,
	}
	return &effective
}

type sourceVersionPathAbsence uint8

const (
	sourceVersionPathPresent sourceVersionPathAbsence = iota
	sourceVersionPathInvalid
	sourceVersionMemberMissing
	sourceVersionIndexUnavailable
	sourceVersionPathObstructed
)

type sourceVersionPath struct {
	node         *document.Node
	present      bool
	absence      sourceVersionPathAbsence
	nearest      document.Location
	resolvedPath Path
	ancestors    []sourceVersionAncestor
}

func processSourceVersion(root *document.Node, rule *VersionRule, role sourceVersionRole, destination Path, mode sourceVersionMode) sourceVersionProcessingResult {
	if role != sourceVersionMain && role != sourceVersionContribution {
		return sourceVersionProcessingResult{diagnostics: []Diagnostic{sourceVersionOptionsDiagnostic("source role is invalid")}}
	}
	if mode != sourceVersionModeDefault && mode != sourceVersionModeIfPresent && mode != sourceVersionModeRequired {
		return sourceVersionProcessingResult{diagnostics: []Diagnostic{sourceVersionOptionsDiagnostic("source-version mode is invalid")}}
	}
	if mode != sourceVersionModeDefault && (rule == nil || rule.Check == nil || !rule.Path.valid()) {
		return sourceVersionProcessingResult{diagnostics: []Diagnostic{sourceVersionOptionsDiagnostic("source-version checking requires a valid version rule and checker")}}
	}
	if root == nil {
		if role == sourceVersionMain && mode != sourceVersionModeDefault {
			return sourceVersionProcessingResult{diagnostics: canonicalDiagnostics(reportVersion(rule, Version{}, nil))}
		}
		return sourceVersionProcessingResult{}
	}

	payload, imports, diagnostics := splitImportDirectives(root)
	if len(diagnostics) != 0 {
		return sourceVersionProcessingResult{diagnostics: diagnostics}
	}
	result := sourceVersionProcessingResult{payload: payload, imports: imports}
	if mode == sourceVersionModeDefault {
		return result
	}

	resolved := resolveSourceVersionPath(root, rule.Path)
	evidence := &sourceVersionEvidence{
		path: rule.Path.clone(), resolvedPath: resolved.resolvedPath,
		destination: destination.clone(), ancestors: resolved.ancestors,
		absence: resolved.absence,
	}
	location := resolved.nearest
	if resolved.present {
		location = resolved.node.Location
	}
	if locationKnown(location) {
		public := publicLocation(location)
		evidence.location = &public
	}
	result.evidence = evidence

	interpreted := interpretVersion(rule, root)
	evidence.version = interpreted.version
	if resolved.present && sourceVersionControlOverlap(root, evidence.resolvedPath) {
		evidence.redactText()
		result.payload = nil
		result.diagnostics = []Diagnostic{sourceVersionOverlapDiagnostic(rule, evidence)}
		return result
	}
	if hasErrors(interpreted.diagnostics) {
		evidence.redactText()
		result.payload = nil
		result.diagnostics = canonicalDiagnostics(interpreted.diagnostics)
		return result
	}
	if !interpreted.version.Present {
		if mode == sourceVersionModeRequired {
			evidence.redactText()
			result.payload = nil
			result.diagnostics = []Diagnostic{sourceVersionMissingDiagnostic(rule, evidence)}
			return result
		}
		if role == sourceVersionContribution {
			return result
		}
	}

	evidence.checked = true
	result.diagnostics = canonicalDiagnostics(reportVersion(rule, interpreted.version, root))
	if hasErrors(result.diagnostics) {
		evidence.redactText()
		result.payload = nil
		return result
	}
	if role == sourceVersionContribution && interpreted.version.Present {
		if !removeSourceVersionNode(result.payload, evidence.resolvedPath) {
			evidence.redactText()
			result.payload = nil
			result.diagnostics = []Diagnostic{sourceVersionOptionsDiagnostic("selected source version could not be removed from its owned payload")}
			return result
		}
	}
	return result
}

func sourceVersionOptionsDiagnostic(message string) Diagnostic {
	return Diagnostic{Code: CodeOptionsInvalid, Severity: SeverityError, Message: message}
}

func sourceVersionMissingDiagnostic(rule *VersionRule, evidence *sourceVersionEvidence) Diagnostic {
	return Diagnostic{
		Code: CodeVersionError, Severity: SeverityError, Path: rule.Path.clone(),
		Message: "required schema version is missing", Primary: cloneLocation(evidence.location),
	}
}

func sourceVersionOverlapDiagnostic(rule *VersionRule, evidence *sourceVersionEvidence) Diagnostic {
	return Diagnostic{
		Code: CodeVersionError, Severity: SeverityError, Path: rule.Path.clone(),
		Message: "schema version path overlaps a structural directive", Primary: cloneLocation(evidence.location),
	}
}

func (evidence *sourceVersionEvidence) redactText() {
	if evidence == nil {
		return
	}
	evidence.version.Text = ""
	evidence.redacted = true
}

func resolveSourceVersionPath(root *document.Node, path Path) sourceVersionPath {
	// Refine only segments whose container shape is known, keeping the full
	// requested suffix when lookup stops before the declaration.
	resolved := sourceVersionPath{absence: sourceVersionPathInvalid, resolvedPath: path.clone()}
	if root == nil || !path.valid() {
		return resolved
	}
	current := root
	resolved.nearest = current.Location
	resolved.ancestors = append(resolved.ancestors, sourceVersionAncestor{kind: current.Kind})
	for position, segment := range path.segments {
		switch current.Kind {
		case document.Mapping:
			if segment.kind == pathSegmentIndex {
				resolved.absence = sourceVersionPathObstructed
				return resolved
			}
			resolved.resolvedPath.segments[position] = pathSegment{kind: pathSegmentKey, key: segment.key}
			found := false
			for _, entry := range current.Mapping {
				if entry.Key == segment.key {
					current = entry.Value
					found = true
					break
				}
			}
			if !found {
				resolved.absence = sourceVersionMemberMissing
				return resolved
			}
		case document.Sequence:
			index, ok := schemaIndex(segment)
			if !ok {
				resolved.absence = sourceVersionIndexUnavailable
				return resolved
			}
			resolved.resolvedPath.segments[position] = pathSegment{kind: pathSegmentIndex, index: index}
			if index >= len(current.Sequence) {
				resolved.absence = sourceVersionIndexUnavailable
				return resolved
			}
			current = current.Sequence[index]
		default:
			resolved.absence = sourceVersionPathObstructed
			return resolved
		}
		resolved.nearest = current.Location
		resolved.ancestors = append(resolved.ancestors, sourceVersionAncestor{
			path: Path{segments: clonePathSegments(resolved.resolvedPath.segments[:position+1], 0)}, kind: current.Kind,
		})
	}
	resolved.node = current
	resolved.present = true
	resolved.absence = sourceVersionPathPresent
	return resolved
}

func sourceVersionControlOverlap(root *document.Node, path Path) bool {
	if root == nil || !path.valid() {
		return false
	}
	if root.Kind == document.Mapping {
		for _, entry := range root.Mapping {
			if entry.Key == directiveKey && pathHasPrefix(path, Keys(directiveKey)) {
				return true
			}
		}
	}
	return sourceVersionInheritanceOverlap(root, Path{}, path)
}

func sourceVersionInheritanceOverlap(node *document.Node, current, path Path) bool {
	if node == nil {
		return false
	}
	if node.Kind == document.Mapping {
		if _, found := inheritanceDirective(node); found {
			controlPath := current.Key(inheritanceKey)
			if pathHasPrefix(path, controlPath) {
				return true
			}
		}
		for _, entry := range node.Mapping {
			if entry.Key == inheritanceKey {
				continue
			}
			if sourceVersionInheritanceOverlap(entry.Value, current.Key(entry.Key), path) {
				return true
			}
		}
	} else if node.Kind == document.Sequence {
		for index, child := range node.Sequence {
			if sourceVersionInheritanceOverlap(child, current.Index(index), path) {
				return true
			}
		}
	}
	return false
}

func pathHasPrefix(path, prefix Path) bool {
	if !path.valid() || !prefix.valid() || len(prefix.segments) > len(path.segments) {
		return false
	}
	for index, segment := range prefix.segments {
		candidate := path.segments[index]
		if candidate.kind != segment.kind || candidate.key != segment.key || candidate.index != segment.index {
			return false
		}
	}
	return true
}

func removeSourceVersionNode(root *document.Node, path Path) bool {
	if root == nil || !path.valid() || len(path.segments) == 0 {
		return false
	}
	current := root
	for _, segment := range path.segments[:len(path.segments)-1] {
		switch current.Kind {
		case document.Mapping:
			if segment.kind == pathSegmentIndex {
				return false
			}
			found := false
			for _, entry := range current.Mapping {
				if entry.Key == segment.key {
					current = entry.Value
					found = true
					break
				}
			}
			if !found {
				return false
			}
		case document.Sequence:
			index, ok := schemaIndex(segment)
			if !ok || index >= len(current.Sequence) {
				return false
			}
			current = current.Sequence[index]
		default:
			return false
		}
	}
	last := path.segments[len(path.segments)-1]
	switch current.Kind {
	case document.Mapping:
		if last.kind == pathSegmentIndex {
			return false
		}
		for index, entry := range current.Mapping {
			if entry.Key == last.key {
				current.Mapping = append(current.Mapping[:index], current.Mapping[index+1:]...)
				return true
			}
		}
	case document.Sequence:
		index, ok := schemaIndex(last)
		if !ok || index >= len(current.Sequence) {
			return false
		}
		current.Sequence = append(current.Sequence[:index], current.Sequence[index+1:]...)
		return true
	}
	return false
}