package reference

import (
	"embed"
	"encoding/json"
	"errors"
	"os"
	"path/filepath"
	"strings"
)

//go:embed data/*.json
var bundled embed.FS

var ErrNotFound = errors.New("reference data not found")

type Service struct {
	overrideRoot string
}

func NewService(overrideRoot string) *Service {
	return &Service{overrideRoot: strings.TrimSpace(overrideRoot)}
}

func (s *Service) Read(kind string) (map[string]any, error) {
	name, ok := fileName(kind)
	if !ok {
		return nil, ErrNotFound
	}
	var data []byte
	var err error
	if s.overrideRoot != "" {
		data, err = os.ReadFile(filepath.Join(s.overrideRoot, "reference-data", name))
		if err != nil && !errors.Is(err, os.ErrNotExist) {
			return nil, err
		}
	}
	if len(data) == 0 {
		data, err = bundled.ReadFile("data/" + name)
		if err != nil {
			return nil, err
		}
	}
	var payload map[string]any
	if err := json.Unmarshal(data, &payload); err != nil {
		return nil, err
	}
	if payload["schemaVersion"] == nil || payload["items"] == nil {
		return nil, errors.New("reference data schema is invalid")
	}
	return payload, nil
}

func (s *Service) Descriptors() map[string]any {
	return map[string]any{
		"cpu": map[string]any{
			"url":             "/api/client/reference-data/cpu",
			"bundledFallback": true,
		},
		"gpu": map[string]any{
			"url":             "/api/client/reference-data/gpu",
			"bundledFallback": true,
		},
	}
}

func fileName(kind string) (string, bool) {
	switch strings.ToLower(strings.TrimSpace(kind)) {
	case "cpu", "cpu-ranking":
		return "cpu-ranking.json", true
	case "gpu", "gpu-ranking":
		return "gpu-ranking.json", true
	default:
		return "", false
	}
}