package engine

import "strconv"

type acquisitionPolicy struct {
	importDefaults importDefaults
	sequencePolicy sequencePolicy
	importLimits   importLimits
}

type acquisitionState struct {
	accounting   *importAccounting
	versionState *sourceVersionState
}

type tierAcquisitionState struct {
	visited   map[resourceIdentity]importRoute
	hostToken *namespaceToken
}

type inputAcquisitionRequest struct {
	input            loadInput
	role             sourceVersionRole
	directiveContext rootDirectiveContext
	protectionRule   *VersionRule
	ordinaryOverlay  string
}

type importAcquisitionRequest struct {
	input      inputAcquisitionRequest
	main       parsedSource
	processing *sourceVersionProcessingResult
}

func acquireInput(request inputAcquisitionRequest, policy acquisitionPolicy, state *acquisitionState, tier *tierAcquisitionState) (assembledInput, []Diagnostic) {
	source := request.input.source
	destination := request.input.destination
	accounting := state.accounting
	versionState := state.versionState
	sourceID := "source-" + strconv.Itoa(accounting.sources+1)
	selectedSource := source
	if source.kind == sourceSearch {
		resolved, failedSource, diagnostics := resolveSearchInput(source, sourceID, defaultDiscoveryDirectoryHelpers(), defaultDiscoveryHostProbe())
		if len(diagnostics) != 0 {
			if failedSource != nil {
				failedSource.Destination = destination.clone()
				failedSource.placementMode = request.input.placementMode
			}
			return assembledInput{source: resolved, sources: sourceInfos(failedSource), versionState: versionState, accounting: accounting}, diagnostics
		}
		selectedSource = resolved
		if request.input.filesystem != nil {
			if diagnostics := filesystemOptionDiagnostics(selectedSource, request.input.filesystem); len(diagnostics) != 0 {
				return assembledInput{source: selectedSource, versionState: versionState, accounting: accounting}, diagnostics
			}
		}
		if selectedSource.kind == sourceNone && activeOverlay(request.ordinaryOverlay) && request.input.filesystem == nil {
			return assembledInput{source: selectedSource, versionState: versionState, accounting: accounting}, []Diagnostic{optionDiagnostic(CodeOptionsInvalid, "NoSource overlays require explicit filesystem context")}
		}
	}
	limits := policy.importLimits
	parseLimits := defaultParseLimits()
	parseLimits.source.remaining = limits.bytes - accounting.bytes
	parsed, diagnostics := parseSource(selectedSource, sourceID, parseLimits)
	if parsed.source != nil {
		parsed.source.Destination = destination.clone()
		parsed.source.placementMode = request.input.placementMode
	}
	input := assembledInput{source: selectedSource, parsed: parsed, document: parsed.document, sources: sourceInfos(parsed.source), versionState: versionState, accounting: accounting}
	if len(diagnostics) != 0 {
		input.sources = sourceInfos(parsed.source)
		// Mapping value issues already identify application content. Other early
		// failures describe source syntax or access, not a placed value.
		if selectedSource.kind == sourceMapping && selectedSource.mapIssue != nil && len(destination.segments) != 0 {
			for index := range diagnostics {
				relative := diagnostics[index].Path
				segments := clonePathSegments(destination.segments, len(relative.segments))
				diagnostics[index].Path = Path{segments: append(segments, relative.segments...)}
			}
		}
		return input, diagnostics
	}
	directiveContext := request.directiveContext
	if directiveContext == 0 {
		directiveContext = rootDirectiveContextImportsOnly
	}
	if !request.input.imports && parsed.document != nil {
		var directiveDiagnostics []Diagnostic
		if directiveContext == rootDirectiveContextSource || directiveContext == rootDirectiveContextLayered {
			directiveDiagnostics = disabledRootImportDiagnostics(parsed.document)
		} else {
			directiveDiagnostics = disabledDirectiveDiagnostics(parsed.document, Path{})
		}
		if len(directiveDiagnostics) != 0 {
			return input, directiveDiagnostics
		}
	}
	request.directiveContext = directiveContext
	versionProcessing, diagnostics := processAcquiredInputVersion(parsed, request, versionState)
	if len(diagnostics) != 0 {
		return input, diagnostics
	}
	request.input.source = selectedSource
	if request.input.imports && selectedSource.kind != sourceNone {
		importRequest := importAcquisitionRequest{input: request, main: parsed, processing: versionProcessing}
		input.composition, input.sources, input.resolvedFilesystem, diagnostics = acquireImportedInput(importRequest, &policy, state, tier)
		if len(diagnostics) != 0 {
			return input, diagnostics
		}
		if input.composition != nil {
			input.acquisition = cloneAcquisitionScopes(input.composition.acquisition)
			input.document = input.composition.root
		}
	} else {
		input, diagnostics = acquireStandaloneInput(input, request, versionProcessing, policy, tier)
		if len(diagnostics) != 0 {
			return input, diagnostics
		}
	}
	return completeAcquisitionContexts(input, request, tier)
}

func acquireStandaloneInput(input assembledInput, request inputAcquisitionRequest, processing *sourceVersionProcessingResult, policy acquisitionPolicy, tier *tierAcquisitionState) (assembledInput, []Diagnostic) {
	parsed := input.parsed
	input.sources = sourceInfos(parsed.source)
	if processing != nil {
		input.document = processing.payload
	}
	if request.input.filesystem != nil && (input.source.kind == sourceNone || !activeOverlay(request.ordinaryOverlay)) {
		resolved, diagnostic := validateFilesystemContext(input.source, request.input.filesystem, parsed, tier.hostToken)
		if diagnostic != nil {
			return input, []Diagnostic{*diagnostic}
		}
		input.resolvedFilesystem = &resolved
	}
	if request.input.imports || input.document == nil {
		return input, nil
	}

	limits := policy.importLimits
	placement := request.input.destination
	documentLimits := defaultParseLimits().document
	_, placed, err := placeDocumentWithMode(input.document, placement, request.input.placementMode, input.document.Location, documentLimits.Depth, documentLimits.Nodes)
	if err != nil {
		return input, []Diagnostic{sourceDiagnostic(CodeSourceLimitExceeded, parsed.source.ID, "configuration exceeds the source depth or node limit after destination placement")}
	}
	localPayload := input.document
	input.document = placed
	identity := importKeyForMainSource(parsed.source)
	var sequenceDeclarations []sequenceDeclarationSpec
	if processing != nil {
		sequenceDeclarations = cloneSequenceDeclarations(processing.sequences)
	}
	input.acquisition = []acquisitionScope{{
		owner:       identity,
		destination: placement.clone(),
		contributions: []acquiredContribution{{
			source: cloneSourceInfo(*parsed.source), payload: localPayload,
			identity: identity, role: importRoleMain, scopeOwner: identity,
			document: placed, destination: placement.clone(), processing: processing,
			sequenceDeclarations: sequenceDeclarations,
		}},
	}}
	rawNodes := countInputNodes(parsed.document)
	placementNodes := destinationWrapperNodeCountForMode(placement, request.input.placementMode)
	accounting := input.accounting
	if accounting.sources+1 > limits.sources || accounting.bytes+parsed.bytes > limits.bytes || accounting.nodes+rawNodes+placementNodes > limits.nodes {
		return input, []Diagnostic{sourceDiagnostic(CodeSourceLimitExceeded, parsed.source.ID, "configuration exceeds the aggregate input limit")}
	}
	if diagnostic := registerAcquiredSource(input.source, request.input.filesystem, parsed.source, tier.visited, tier.hostToken); diagnostic != nil {
		return input, []Diagnostic{*diagnostic}
	}
	accounting.sources++
	accounting.bytes += parsed.bytes
	accounting.nodes += rawNodes + placementNodes
	return input, nil
}

func completeAcquisitionContexts(input assembledInput, request inputAcquisitionRequest, tier *tierAcquisitionState) (assembledInput, []Diagnostic) {
	if activeOverlay(request.ordinaryOverlay) && !request.input.imports {
		return input, nil
	}
	if input.resolvedFilesystem == nil && len(input.sources) != 0 && (input.source.kind == sourceFile || request.input.filesystem != nil || nativeContext(input.source, request.input.filesystem)) {
		resolved, diagnostic := resolveFilesystemContext(input.source, request.input.filesystem, input.parsed, tier.hostToken)
		if diagnostic != nil {
			return input, []Diagnostic{*diagnostic}
		}
		input.resolvedFilesystem = &resolved
	}
	contexts, diagnostic := contextsForResolvedSources(input.resolvedFilesystem, input.sources)
	if diagnostic != nil {
		return input, []Diagnostic{*diagnostic}
	}
	input.contexts = contexts
	return input, nil
}

func processAcquiredInputVersion(parsed parsedSource, request inputAcquisitionRequest, state *sourceVersionState) (*sourceVersionProcessingResult, []Diagnostic) {
	sourceID := ""
	if parsed.source != nil {
		sourceID = parsed.source.ID
	}

	var result sourceVersionProcessingResult
	hasResult := false
	updateMainProcessing := false
	switch request.directiveContext {
	case rootDirectiveContextSource:
		if state != nil {
			processed, diagnostics := state.processWithDirectiveContext(
				parsed.document, request.role, request.input.destination, sourceID,
				request.input.placementMode, request.directiveContext,
			)
			if len(diagnostics) != 0 {
				return nil, diagnostics
			}
			result = processed
			updateMainProcessing = request.role == sourceVersionMain
		} else {
			result = processSourceVersionWithDirectiveContext(
				parsed.document, request.protectionRule, request.role,
				request.input.destination, sourceVersionModeDefault, request.directiveContext,
			)
			if len(result.diagnostics) != 0 {
				return nil, result.diagnostics
			}
		}
		hasResult = true
	case rootDirectiveContextLayered:
		extracted, diagnostics := extractRootDirectives(parsed.document, request.directiveContext)
		if len(diagnostics) != 0 {
			return nil, diagnostics
		}
		result = sourceVersionProcessingResult{
			payload: extracted.body, imports: extracted.imports, sequences: extracted.sequences,
			directiveContext: request.directiveContext,
		}
		hasResult = true
		if state != nil && state.mode != sourceVersionModeDefault {
			processed, diagnostics := state.process(
				extracted.body, request.role, request.input.destination,
				sourceID, request.input.placementMode,
			)
			if len(diagnostics) != 0 {
				return nil, diagnostics
			}
			processed.imports = extracted.imports
			processed.sequences = append(cloneSequenceDeclarations(extracted.sequences), processed.sequences...)
			processed.directiveContext = request.directiveContext
			result = processed
			updateMainProcessing = request.role == sourceVersionMain
		}
	default:
		if state != nil && state.mode != sourceVersionModeDefault {
			processed, diagnostics := state.process(
				parsed.document, request.role, request.input.destination,
				sourceID, request.input.placementMode,
			)
			if len(diagnostics) != 0 {
				return nil, diagnostics
			}
			result = processed
			hasResult = true
			updateMainProcessing = request.role == sourceVersionMain
		}
	}
	if !hasResult {
		return nil, nil
	}
	if updateMainProcessing {
		completed := result
		state.mainProcessing = &completed
	}
	return &result, nil
}

func registerAcquiredSource(source Source, context *FilesystemContext, info *SourceInfo, visited map[resourceIdentity]importRoute, hostToken *namespaceToken) *Diagnostic {
	if visited == nil || info == nil || info.Path == "" {
		return nil
	}
	identity := resourceIdentity{namespace: hostToken, path: info.Path}
	if source.kind == sourceFilesystem {
		identity.namespace = source.namespace.token
	} else if context != nil && context.FS != nil {
		identity.namespace = context.FS.namespace.token
	}
	if previous, repeated := visited[identity]; repeated {
		value := importRepeatedDiagnostic(Location{SourceID: info.ID}, previous, importRoute{})
		return &value
	}
	visited[identity] = importRoute{canonical: info.Path}
	return nil
}