package engine

func normalizeInput(input loadInput, ordinaryOverlay string) (loadInput, []Diagnostic) {
	var diagnostics []Diagnostic
	if input.placementMode != placementModeMapping && input.placementMode != placementModeSequenceItem {
		diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "input placement mode is invalid"))
	}
	if normalized, err := normalizeDestination(input.destination); err != nil {
		diagnostics = append(diagnostics, invalidDestinationDiagnostic(input.destination))
	} else {
		input.destination = normalized
	}
	if input.placementMode == placementModeSequenceItem && len(input.destination.segments) == 0 {
		diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "sequence-item placement requires a nonempty destination"))
	}
	if input.filesystem != nil {
		diagnostics = append(diagnostics, filesystemOptionDiagnostics(input.source, input.filesystem)...)
	}
	if input.source.kind == sourceSearch {
		for _, issue := range input.source.searchIssues {
			diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, issue))
		}
		if input.source.search == nil {
			diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "configuration search is invalid"))
		} else {
			diagnostics = append(diagnostics, validateSearch(*input.source.search, input.source.searchApp)...)
		}
	}
	if input.source.kind == sourceNone && activeOverlay(ordinaryOverlay) && input.filesystem == nil {
		diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "NoSource overlays require explicit filesystem context"))
	}
	if input.filesystem == nil && (input.source.kind == sourceBytes || input.source.kind == sourceReader || input.source.kind == sourceMapping) && (input.imports || activeOverlay(ordinaryOverlay)) {
		diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "synthetic-source imports or overlays require filesystem context"))
	}
	return input, canonicalDiagnostics(diagnostics)
}

func loadSettings[T any](defaults importDefaults, definition Definition[T], mode sourceVersionMode) (importDefaults, sequencePolicy, []Diagnostic) {
	defaults = snapshotImportDefaults(defaults)
	var diagnostics []Diagnostic
	diagnostics = append(diagnostics, validateImportDefaults(defaults)...)
	diagnostics = append(diagnostics, sourceVersionOptionDiagnostics(definition, mode)...)
	policy, policyDiagnostics := compileSequenceIdentityPolicy(definition.sequenceIdentityRegistrations)
	diagnostics = append(diagnostics, policyDiagnostics...)
	return defaults, policy, canonicalDiagnostics(diagnostics)
}

func sourceVersionOptionDiagnostics[T any](definition Definition[T], mode sourceVersionMode) []Diagnostic {
	var diagnostics []Diagnostic
	if definition.Version != nil {
		if !definition.Version.Path.valid() {
			diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "schema-version path is invalid"))
		}
		if definition.Version.Check == nil {
			diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "schema-version rule requires a checker"))
		}
	}
	if mode != sourceVersionModeDefault && mode != sourceVersionModeIfPresent && mode != sourceVersionModeRequired {
		diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "source-version mode is invalid"))
	} else if mode != sourceVersionModeDefault && (definition.Version == nil || !definition.Version.Path.valid() || definition.Version.Check == nil) {
		diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "source-version checking requires a valid version rule and checker"))
	}
	return diagnostics
}

func overlayOptionDiagnostics(name string) []Diagnostic {
	if validOverlayName(name) {
		return nil
	}
	return []Diagnostic{optionDiagnostic(CodeOptionsInvalid, "overlay name must contain only ASCII letters, digits, underscore, or hyphen")}
}

func optionDiagnostic(code Code, message string) Diagnostic {
	return Diagnostic{Code: code, Severity: SeverityError, Message: message}
}