package json

import (
	"forge.cadoles.com/wpetit/guesstimate/internal/diffsync"
	"github.com/pkg/errors"
	jsonpatch "gopkg.in/evanphx/json-patch.v4"
)

type Patcher struct{}

func (p *Patcher) Patch(content []byte, ops diffsync.Ops) ([]byte, error) {
	patch, ok := ops.([]byte)
	if !ok {
		return nil, diffsync.ErrUnexpectedOpsFormat
	}

	modified, err := jsonpatch.MergePatch(content, patch)
	if err != nil {
		return nil, errors.Wrap(err, "could not apply patch")
	}

	return modified, nil
}

func NewPatcher() *Patcher {
	return &Patcher{}
}

type Differ struct{}

func (d *Differ) Diff(new, old []byte) (diffsync.Ops, error) {
	ops, err := jsonpatch.CreateMergePatch(old, new)
	if err != nil {
		return nil, errors.Wrap(err, "could not compute diff")
	}

	return ops, nil
}

func NewDiffer() *Differ {
	return &Differ{}
}