package configkit

// Layer identifies the precedence layer responsible for a configuration value.
type Layer string

const (
	LayerDefault    Layer = "default"
	LayerBase       Layer = "base"
	LayerProfile    Layer = "profile"
	LayerCLI        Layer = "cli"
	LayerResolution Layer = "resolution"
)

// ChangeKind identifies an application resolution operation. The zero value is
// used for input and default origins.
type ChangeKind string

const (
	ChangeDerivedDefault ChangeKind = "derived_default"
	ChangeNormalization  ChangeKind = "normalization"
)

// Severity classifies a diagnostic.
type Severity string

const (
	SeverityError   Severity = "error"
	SeverityWarning Severity = "warning"
)

// Code is a stable, machine-readable diagnostic classification.
type Code string

const (
	CodeSourceInvalid       Code = "source.invalid"
	CodeSourceMissing       Code = "source.missing"
	CodeSourcePermission    Code = "source.permission"
	CodeSourceRead          Code = "source.read"
	CodeSourceNotRegular    Code = "source.not_regular"
	CodeSourceLimitExceeded Code = "source.limit_exceeded"
	CodeSourceReaderUsed    Code = "source.reader_used"

	CodeYAMLInvalid           Code = "yaml.invalid"
	CodeYAMLEmpty             Code = "yaml.empty"
	CodeYAMLMultipleDocuments Code = "yaml.multiple_documents"
	CodeYAMLRootType          Code = "yaml.root_type"
	CodeYAMLDuplicateKey      Code = "yaml.duplicate_key"
	CodeYAMLTag               Code = "yaml.tag"
	CodeYAMLAnchor            Code = "yaml.anchor"
	CodeYAMLAlias             Code = "yaml.alias"
	CodeYAMLMergeKey          Code = "yaml.merge_key"
	CodeYAMLScalar            Code = "yaml.scalar"
	CodeYAMLDepthLimit        Code = "yaml.depth_limit"
	CodeYAMLNodeLimit         Code = "yaml.node_limit"

	CodeSchemaRoot            Code = "schema.root"
	CodeSchemaUnsupportedType Code = "schema.unsupported_type"
	CodeSchemaAmbiguousField  Code = "schema.ambiguous_field"
	CodeSchemaTag             Code = "schema.tag"
	CodeSchemaTextCodec       Code = "schema.text_codec"
	CodeSchemaInline          Code = "schema.inline"
	CodeSchemaCycle           Code = "schema.cycle"
	CodeSchemaProjectionLimit Code = "schema.projection_limit"
	CodeSchemaCodec           Code = "schema.codec"
	CodeSchemaNonFinite       Code = "schema.non_finite"
	CodeSchemaDynamicType     Code = "schema.dynamic_type"

	CodeDecodeType         Code = "decode.type"
	CodeDecodeNull         Code = "decode.null"
	CodeDecodeRange        Code = "decode.range"
	CodeDecodeDuration     Code = "decode.duration"
	CodeDecodeText         Code = "decode.text"
	CodeDecodeUnknownField Code = "decode.unknown_field"
	CodeDecodeArrayLength  Code = "decode.array_length"
)

// Location identifies a position in a configuration source. Zero line and column
// values mean that coordinates are unavailable or synthetic.
type Location struct {
	SourceID string
	Line     int
	Column   int
}

// SourceInfo describes a source discovered during a load. Path is a canonical
// local path when one exists. ImportedFrom identifies the declaration that
// included this source.
type SourceInfo struct {
	ID           string
	Label        string
	Path         string
	Layer        Layer
	ImportedFrom *Location
}

// Diagnostic is a safe structured problem report. Message and source labels must
// never contain configuration values or other secrets.
type Diagnostic struct {
	Code     Code
	Severity Severity
	Path     Path
	Message  string
	Primary  *Location
	Related  []Location
}

// Origin describes where an effective definition came from. Multiple locations
// represent a composite origin.
type Origin struct {
	Layer     Layer
	Locations []Location
	Operation ChangeKind
}

// FieldInfo describes an effective configuration path.
type FieldInfo struct {
	Explicit bool
	Null     bool
	Origin   Origin
}

// Change describes a definition or application-resolution operation. Historical
// values are intentionally not exposed by this record.
type Change struct {
	Path         Path
	Origin       Origin
	Previous     []Origin
	Reasons      []string
	Dependencies []Path
}

func cloneLocation(location *Location) *Location {
	if location == nil {
		return nil
	}
	cloned := *location
	return &cloned
}

func cloneLocations(locations []Location) []Location {
	if locations == nil {
		return nil
	}
	return append([]Location(nil), locations...)
}

func cloneSourceInfo(source SourceInfo) SourceInfo {
	source.ImportedFrom = cloneLocation(source.ImportedFrom)
	return source
}

func cloneSourceInfos(sources []SourceInfo) []SourceInfo {
	if sources == nil {
		return nil
	}
	cloned := make([]SourceInfo, len(sources))
	for i, source := range sources {
		cloned[i] = cloneSourceInfo(source)
	}
	return cloned
}

func cloneOrigin(origin Origin) Origin {
	origin.Locations = cloneLocations(origin.Locations)
	return origin
}

func cloneFieldInfo(info FieldInfo) FieldInfo {
	info.Origin = cloneOrigin(info.Origin)
	return info
}

func cloneChange(change Change) Change {
	change.Path = change.Path.clone()
	change.Origin = cloneOrigin(change.Origin)
	if change.Previous != nil {
		previous := make([]Origin, len(change.Previous))
		for i, origin := range change.Previous {
			previous[i] = cloneOrigin(origin)
		}
		change.Previous = previous
	}
	change.Reasons = append([]string(nil), change.Reasons...)
	if change.Dependencies != nil {
		dependencies := make([]Path, len(change.Dependencies))
		for i, path := range change.Dependencies {
			dependencies[i] = path.clone()
		}
		change.Dependencies = dependencies
	}
	return change
}

func cloneDiagnostic(diagnostic Diagnostic) Diagnostic {
	diagnostic.Path = diagnostic.Path.clone()
	diagnostic.Primary = cloneLocation(diagnostic.Primary)
	diagnostic.Related = cloneLocations(diagnostic.Related)
	return diagnostic
}

func cloneDiagnostics(diagnostics []Diagnostic) []Diagnostic {
	if diagnostics == nil {
		return nil
	}
	cloned := make([]Diagnostic, len(diagnostics))
	for i, diagnostic := range diagnostics {
		cloned[i] = cloneDiagnostic(diagnostic)
	}
	return cloned
}