package engine

import "strings"

const (
	maxImportDepth   = 64
	maxImportSources = 1024
	maxGlobEntries   = 1_000_000
)

type importLimits struct {
	depth   int
	sources int
	bytes   int64
	nodes   int
	entries int
}

func defaultImportLimits() importLimits {
	return importLimits{
		depth: maxImportDepth, sources: maxImportSources,
		bytes: maxTotalBytes, nodes: maxDocumentNodes, entries: maxGlobEntries,
	}
}

type importRoute struct {
	canonical string
	locations []Location
	key       importNodeKey
}

type importAccounting struct {
	sources int
	bytes   int64
	nodes   int
	entries int
}

type importTraversal struct {
	access  *filesystemAccess
	request importAcquisitionRequest
	policy  *acquisitionPolicy
	state   *acquisitionState
	tier    *tierAcquisitionState

	scope        acquisitionScope
	itemScope    bool
	itemPrefix   Path
	itemFallback Path
	sources      []SourceInfo
	active       map[resourceIdentity]int
	stack        []importRoute
	importGraph  importInclusionGraph
}

func scheduleAcquisitionScopes(scope *acquisitionScope, dependencies importDependencyIndex) {
	*scope = scheduleAcquisitionScope(*scope, dependencies)
	for index := range scope.contributions {
		if pending := scope.contributions[index].pendingItem; pending != nil {
			scheduleAcquisitionScopes(pending, dependencies)
		}
	}
}

func sourceInfos(source *SourceInfo) []SourceInfo {
	if source == nil {
		return nil
	}
	return []SourceInfo{cloneSourceInfo(*source)}
}

func importDiagnostic(code Code, message string, location *Location) Diagnostic {
	return Diagnostic{Code: code, Severity: SeverityError, Message: message, Primary: cloneLocation(location)}
}

func importCycleDiagnostic(target string, location Location, cycle []importRoute) Diagnostic {
	paths := make([]string, 0, len(cycle)+1)
	related := make([]Location, 0, len(cycle))
	for _, route := range cycle {
		paths = append(paths, route.canonical)
		if len(route.locations) != 0 {
			related = append(related, route.locations[len(route.locations)-1])
		}
	}
	paths = append(paths, target)
	return Diagnostic{
		Code: CodeImportCycle, Severity: SeverityError,
		Message: "import cycle detected: " + strings.Join(paths, " -> "),
		Primary: &location, Related: related,
	}
}

func importRepeatedDiagnostic(location Location, previous, current importRoute) Diagnostic {
	related := append([]Location(nil), previous.locations...)
	if len(current.locations) > 1 {
		related = append(related, current.locations[:len(current.locations)-1]...)
	}
	return Diagnostic{
		Code: CodeImportRepeated, Severity: SeverityError,
		Message: "configuration source is included by more than one import route",
		Primary: &location, Related: related,
	}
}