package localstate

import (
	"encoding/json"
	"os"
	"path/filepath"

	"github.com/docker/docker/pkg/ioutils"
	"github.com/pkg/errors"
)

const (
	refsDir  = "refs"
	groupDir = "__group__"
)

type State struct {
	// Target is the name of the invoked target (default if empty)
	Target string
	// LocalPath is the absolute path to the context
	LocalPath string
	// DockerfilePath is the absolute path to the Dockerfile
	DockerfilePath string
	// GroupRef is the ref of the state group that this ref belongs to
	GroupRef string `json:",omitempty"`
}

type StateGroup struct {
	// Definition is the raw representation of the group (bake definition)
	Definition []byte
	// Targets are the targets invoked
	Targets []string `json:",omitempty"`
	// Inputs are the user inputs (bake overrides)
	Inputs []string `json:",omitempty"`
	// Refs are used to track all the refs that belong to the same group
	Refs []string
}

type LocalState struct {
	root string
}

func New(root string) (*LocalState, error) {
	if root == "" {
		return nil, errors.Errorf("root dir empty")
	}
	if err := os.MkdirAll(filepath.Join(root, refsDir), 0700); err != nil {
		return nil, err
	}
	return &LocalState{
		root: root,
	}, nil
}

func (ls *LocalState) ReadRef(builderName, nodeName, id string) (*State, error) {
	if err := ls.validate(builderName, nodeName, id); err != nil {
		return nil, err
	}
	dt, err := os.ReadFile(filepath.Join(ls.root, refsDir, builderName, nodeName, id))
	if err != nil {
		return nil, err
	}
	var st State
	if err := json.Unmarshal(dt, &st); err != nil {
		return nil, err
	}
	return &st, nil
}

func (ls *LocalState) SaveRef(builderName, nodeName, id string, st State) error {
	if err := ls.validate(builderName, nodeName, id); err != nil {
		return err
	}
	refDir := filepath.Join(ls.root, refsDir, builderName, nodeName)
	if err := os.MkdirAll(refDir, 0700); err != nil {
		return err
	}
	dt, err := json.Marshal(st)
	if err != nil {
		return err
	}
	return ioutils.AtomicWriteFile(filepath.Join(refDir, id), dt, 0600)
}

func (ls *LocalState) ReadGroup(id string) (*StateGroup, error) {
	dt, err := os.ReadFile(filepath.Join(ls.root, refsDir, groupDir, id))
	if err != nil {
		return nil, err
	}
	var stg StateGroup
	if err := json.Unmarshal(dt, &stg); err != nil {
		return nil, err
	}
	return &stg, nil
}

func (ls *LocalState) SaveGroup(id string, stg StateGroup) error {
	refDir := filepath.Join(ls.root, refsDir, groupDir)
	if err := os.MkdirAll(refDir, 0700); err != nil {
		return err
	}
	dt, err := json.Marshal(stg)
	if err != nil {
		return err
	}
	return ioutils.AtomicWriteFile(filepath.Join(refDir, id), dt, 0600)
}

func (ls *LocalState) RemoveBuilder(builderName string) error {
	if builderName == "" {
		return errors.Errorf("builder name empty")
	}
	return os.RemoveAll(filepath.Join(ls.root, refsDir, builderName))
}

func (ls *LocalState) RemoveBuilderNode(builderName string, nodeName string) error {
	if builderName == "" {
		return errors.Errorf("builder name empty")
	}
	if nodeName == "" {
		return errors.Errorf("node name empty")
	}
	return os.RemoveAll(filepath.Join(ls.root, refsDir, builderName, nodeName))
}

func (ls *LocalState) validate(builderName, nodeName, id string) error {
	if builderName == "" {
		return errors.Errorf("builder name empty")
	}
	if nodeName == "" {
		return errors.Errorf("node name empty")
	}
	if id == "" {
		return errors.Errorf("ref ID empty")
	}
	return nil
}