package engine

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

type historyCheckpointPayload struct {
	root    *document.Node
	origins map[string]Origin
}

func (builder *historyBuilder) observePreCLICheckpoint(root *document.Node, origins map[string]Origin) {
	builder.observeTypedCheckpoint(historyPhasePreCLI, root, origins, "applied retained defaults and canonical typed decoding")
}

func (builder *historyBuilder) observePostCLICheckpoint(root *document.Node, origins map[string]Origin) {
	builder.observeTypedCheckpoint(historyPhasePostCLI, root, origins, "applied the typed CLI assignment")
}

func (builder *historyBuilder) observeTypedCheckpoint(phase historyPhase, root *document.Node, origins map[string]Origin, reason string) {
	builder.requireOpen()
	if phase != historyPhasePreCLI && phase != historyPhasePostCLI {
		panic("configkit: typed checkpoint has an invalid history phase")
	}
	payload := builder.nextPayload(phase)
	checkpoint := historyCheckpointPayload{root: root, origins: cloneOriginIndex(origins)}
	switch phase {
	case historyPhasePreCLI:
		if builder.model.preCLICheckpoint != nil || payload.id != 0 {
			panic("configkit: pre-CLI checkpoint was already registered")
		}
		builder.model.preCLICheckpoint = &checkpoint
	case historyPhasePostCLI:
		if builder.model.postCLICheckpoint != nil || payload.id != 0 {
			panic("configkit: post-CLI checkpoint was already registered")
		}
		builder.model.postCLICheckpoint = &checkpoint
	}

	beforeRoot := builder.scratch
	paths := unionCLIHistoryPaths(beforeRoot, root)
	lookup := buildDocumentLookup(beforeRoot, root)
	for _, path := range paths {
		beforeNode, before := documentAtPathWithLookup(beforeRoot, path, lookup)
		afterNode, after := documentAtPathWithLookup(root, path, lookup)
		sensitive := beforeNode != nil && beforeNode.Sensitive || afterNode != nil && afterNode.Sensitive
		builder.addObservation(historyObservation{
			path: path, phase: phase, payload: payload,
			reportedPath: path, role: historyRoleInventory,
			sensitive: sensitive, attributionRef: noHistoryAttribution,
		})
		if configurationValuesEqual(beforeNode, afterNode) {
			continue
		}
		attributionRef := noHistoryAttribution
		if after {
			origin, found := origins[path.String()]
			if !found {
				origin = Origin{Layer: LayerDefault}
			}
			origin.Operation = ChangeDecoding
			attributionRef = builder.addAttribution(origin, []string{reason}, nil)
		}
		builder.addObservation(historyObservation{
			path: path, phase: phase, payload: payload,
			reportedPath: path, role: historyRoleCheckpoint,
			beforePresent: before, afterPresent: after, sensitive: sensitive,
			attributionRef: attributionRef,
		})
	}
	builder.advanceScratch(document.Clone(root))
}

func (builder *historyBuilder) observeCLIEvidence(applications []historyApplication, records []overlayRecord) {
	builder.requireOpen()
	count := max(len(applications), len(records))
	if count == 0 {
		return
	}
	index := new(mappingIndex)
	for item := 0; item < count; item++ {
		var applicationRef historyPayloadRef
		hasApplication := false
		if item < len(applications) {
			application := applications[item]
			applicationRef = builder.addCLIPayload(&application, nil)
			hasApplication = true
			walkHistoryApplication(application, func(_, effective Path, node *document.Node) {
				origin := sourceApplicationOrigin(application, node)
				attribution := builder.addAttribution(origin, nil, nil)
				builder.addObservation(historyObservation{
					path: effective, phase: historyPhaseCLI, payload: applicationRef,
					reportedPath: effective, role: historyRoleContribution,
					afterPresent: true, sensitive: node.Sensitive,
					attributionRef: attribution,
				})
			})
			applyHistoryApplication(&builder.scratch, application, index)
		}
		if item < len(records) {
			record := records[item]
			payload := builder.addCLIPayload(nil, &record)
			if hasApplication {
				owned := &builder.model.cliPayloads[payload.id]
				owned.applicationRef = applicationRef
				owned.hasApplicationRef = true
			}
			attribution := builder.addAttribution(record.change.Origin, nil, nil)
			for _, displaced := range record.displaced {
				builder.addObservation(historyObservation{
					path: displaced.path, phase: historyPhaseCLI, payload: payload,
					reportedPath: record.change.Path, role: historyRoleOperation,
					beforePresent: true, attributionRef: attribution,
				})
			}
			for _, introduced := range record.introduced {
				builder.addObservation(historyObservation{
					path: introduced.path, phase: historyPhaseCLI, payload: payload,
					reportedPath: record.change.Path, role: historyRoleOperation,
					afterPresent: true, sensitive: introduced.sensitive,
					attributionRef: attribution,
				})
			}
		}
	}
}

func (builder *historyBuilder) addCLIPayload(application *historyApplication, record *overlayRecord) historyPayloadRef {
	payload := builder.nextPayload(historyPhaseCLI)
	if payload.id != len(builder.model.cliPayloads) {
		panic("configkit: CLI payload identifiers are out of order")
	}
	owned := historySourcePayload{}
	switch {
	case application != nil:
		owned.kind = historySourceApplicationPayload
		owned.application = cloneHistoryApplications([]historyApplication{*application})[0]
	case record != nil:
		owned.kind = historySourceOverlayPayload
		owned.overlay = cloneOverlayRecords([]overlayRecord{*record})[0]
	default:
		panic("configkit: CLI payload requires an application or operation")
	}
	builder.model.cliPayloads = append(builder.model.cliPayloads, owned)
	return payload
}

func unionCLIHistoryPaths(roots ...*document.Node) []Path {
	var paths []Path
	seen := make(map[string][]Path)
	for _, root := range roots {
		if root == nil {
			continue
		}
		walkDocument(root, Path{}, func(path Path, _ *document.Node) {
			for _, existing := range seen[path.String()] {
				if sameConcreteHistoryPath(existing, path) {
					return
				}
			}
			owned := path.clone()
			paths = append(paths, owned)
			seen[path.String()] = append(seen[path.String()], owned)
		})
	}
	return paths
}