// Package trimmer contains the logic for the kpt fn so that it can be
// leveraged in non-kpt contexts
package trimmer

import (
	"errors"

	"sigs.k8s.io/kustomize/kyaml/yaml"
)

// Trim removes the 'status', empty/null 'metadata.creationTimestamp' and empty/null 'spec' fields
// by mutating the provided yaml.RNode pointer
func Trim(resource *yaml.RNode) error {
	return errors.Join(
		trimStatus(resource),
		trimCreationTimestamp(resource),
		trimRefreshTime(resource),
		trimEmptySpec(resource),
	)
}

// Run implements the kio.FilterFunc interface, allowing the trimmer to be
// composed into a KRM function pipeline
func (n *Trimmer) Run(input []*yaml.RNode) ([]*yaml.RNode, error) {
	for i := range input {
		err := Trim(input[i])
		if err != nil {
			return nil, err
		}
	}
	return input, nil
}

// Clears the 'status' field
func trimStatus(r *yaml.RNode) error {
	return r.PipeE(yaml.Clear("status"))
}

// trimCreationTimestamp clears the 'metadata.creationTimestamp' when it is empty or null.
func trimCreationTimestamp(r *yaml.RNode) error {
	metadata, err := r.Pipe(yaml.Lookup("metadata"))
	if yaml.IsMissingOrError(metadata, err) {
		// If the 'metadata' field is missing, the returned error will be nil
		// and this function will gracefully exit since there is nothing to trim.
		return err
	}
	creationTimestamp, err := metadata.Pipe(yaml.Lookup("creationTimestamp"))
	if yaml.IsMissingOrError(creationTimestamp, err) {
		// If the 'creationTimestamp' field is missing, the returned error will be nil
		// and this function will gracefully exit since there is nothing to trim.
		return err
	} else if yaml.IsMissingOrNull(creationTimestamp) || yaml.IsEmptyMap(creationTimestamp) {
		return metadata.PipeE(yaml.Clear("creationTimestamp"))
	}
	// The 'creationTimestamp' is kept when it is not an empty map or null.
	return nil
}

// trimRefreshTime clears the 'metadata.creationTimestamp' when it is empty or null.
func trimRefreshTime(r *yaml.RNode) error {
	metadata, err := r.Pipe(yaml.Lookup("metadata"))
	if yaml.IsMissingOrError(metadata, err) {
		// If the 'metadata' field is missing, the returned error will be nil
		// and this function will gracefully exit since there is nothing to trim.
		return err
	}
	refreshTime, err := metadata.Pipe(yaml.Lookup("refreshTime"))
	if yaml.IsMissingOrError(refreshTime, err) {
		// If the 'refreshTime' field is missing, the returned error will be nil
		// and this function will gracefully exit since there is nothing to trim.
		return err
	} else if yaml.IsMissingOrNull(refreshTime) || yaml.IsEmptyMap(refreshTime) {
		return metadata.PipeE(yaml.Clear("refreshTime"))
	}
	// The 'refreshTime' is kept when it is not an empty map or null.
	return nil
}

// trimEmptySpec remove the 'spec' field if empty
func trimEmptySpec(r *yaml.RNode) error {
	spec, err := r.Pipe(yaml.Lookup("spec"))
	if yaml.IsMissingOrError(spec, err) {
		// If the 'spec' field is missing, the returned error will be nil
		// and this function will gracefully exit since there is nothing to trim.
		return err
	} else if spec.IsNilOrEmpty() {
		return r.PipeE(yaml.Clear("spec"))
	}
	return nil
}