package engine

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

type inheritanceTemplateResult struct {
	value              *document.Node
	origins            map[string]Origin
	collectionPolicies collectionPolicyScope
	policyTemplates    []collectionPolicyScope
	controls           []inheritanceControl
	transfers          []inheritanceTransfer
	replacements       []inheritanceReplacement
	operations         []inheritanceOperation
}

func combineInheritanceTemplate(
	template inheritanceExecutionTemplate,
	child preparedInheritanceChild,
	parent *preparedInheritanceParent,
	parentOrigins map[string]Origin,
	applicationPolicy sequencePolicy,
) (inheritanceTemplateResult, []Diagnostic) {
	result := inheritanceTemplateResult{}
	if child.control != nil {
		result.controls = append(result.controls, *child.control)
		result.operations = append(result.operations, inheritanceOperation{
			control: child.control, controlOrigin: child.controlOrigin,
		})
	}
	if parent == nil {
		result.value = document.Clone(child.payload)
		result.origins = child.origins
		result.collectionPolicies = cloneCollectionPolicyScopeForInheritance(child.policyTemplates)
		result.policyTemplates = []collectionPolicyScope{child.policyTemplates}
		return result, nil
	}

	mergedPolicyScope, diagnostics := mergeInheritanceCollectionPolicies(
		parent.parentPolicyScope, parent.childPolicyScope,
		template.path, parent.payload, child.payload,
		applicationPolicy, parent.replaced,
	)
	if len(diagnostics) != 0 {
		return inheritanceTemplateResult{}, diagnostics
	}
	mergedOrigins := transferredInheritanceOrigins(parentOrigins, parent.transfer.from, template.path, parent.transfer)
	mergeInheritanceOrigin(mergedOrigins, template.path, child.origins[template.path.String()])
	var sequenceContributions []sequenceHistoryContribution
	var combinationDiagnostics []Diagnostic
	mergeRecursiveMappings(parent.payload, child.payload, template.path, new(mappingIndex), recursiveMergeHooks{
		added: func(childPath Path, incoming *document.Node) {
			copyInheritanceSubtree(mergedOrigins, child.origins, incoming, childPath)
		},
		combined: func(childPath Path, _ *document.Node) {
			mergeInheritanceOrigin(mergedOrigins, childPath, child.origins[childPath.String()])
		},
		replaced: func(childPath Path, existing, incoming *document.Node) {
			result.replacements = append(result.replacements, inheritanceReplacement{
				before: existing, after: incoming,
			})
			deleteOriginSubtree(mergedOrigins, childPath, existing)
			copyInheritanceSubtree(mergedOrigins, child.origins, incoming, childPath)
		},
		merge: func(childPath Path, existing, incoming *document.Node) (*document.Node, bool) {
			resolution, _, _, active, issues := inheritanceCollectionResolution(
				childPath, parent.parentPolicyScope, parent.childPolicyScope, applicationPolicy, incoming,
			)
			if len(issues) != 0 {
				combinationDiagnostics = append(combinationDiagnostics, issues...)
				return existing, false
			}
			if !active {
				return nil, false
			}
			lowerValue := existing
			combined, problems := combineSequence(lowerValue, incoming, resolution, sequenceCombinationContext{destination: childPath})
			if len(problems) != 0 {
				combinationDiagnostics = append(combinationDiagnostics, problems...)
				return existing, false
			}
			policy := applyInheritanceSequencePolicy(
				childPath, combined, resolution, parent.parentPolicyScope, parent.childPolicyScope,
			)
			mergedPolicyScope.set(childPath, policy)
			result.replacements = append(result.replacements, applyInheritanceSequenceOrigins(
				mergedOrigins, child.origins, childPath, lowerValue, incoming, combined, resolution.operation,
			)...)
			sequenceContributions = append(sequenceContributions, sequenceHistoryContributionForCombination(
				childPath, resolution.operation, incoming, combined,
			))
			return combined.value, true
		},
	})
	preserveInheritanceIdentityFields(parent.payload, child.payload, template.identityFields)
	if len(combinationDiagnostics) != 0 {
		return inheritanceTemplateResult{}, canonicalDiagnostics(combinationDiagnostics)
	}
	if problems := validateRegisteredInheritanceSequences(parent.payload, template.path, applicationPolicy); len(problems) != 0 {
		return inheritanceTemplateResult{}, problems
	}
	parent.payload.Location = template.entry.Value.Location
	result.value = parent.payload
	result.origins = mergedOrigins
	result.collectionPolicies = inheritancePolicyScopeAtPath(mergedPolicyScope, template.path)
	result.policyTemplates = parent.effectivePolicyTemplates
	result.transfers = append(result.transfers, parent.transfer)
	result.operations = append(result.operations, inheritanceOperation{
		transfer: &parent.transfer, parent: parent.historyParent, effective: parent.payload,
		parentOrigins: parentOrigins, effectiveOrigins: mergedOrigins,
		parentPolicies:    cloneInheritancePolicyTemplates(parent.policyTemplates),
		templatePolicies:  cloneCollectionPolicyScopeForInheritance(child.policyTemplates),
		effectivePolicies: cloneInheritancePolicyTemplates(parent.effectivePolicyTemplates),
		sequences:         cloneSequenceHistoryContributions(sequenceContributions),
		identityFields:    cloneStrings(template.identityFields),
	})
	return result, nil
}