package webassets

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

	"github.com/grafana/grafana/pkg/api/dtos"
	"github.com/grafana/grafana/pkg/setting"
)

type ManifestInfo struct {
	FilePath  string `json:"src,omitempty"`
	Integrity string `json:"integrity,omitempty"`

	// The known entrypoints
	App   *EntryPointInfo `json:"app,omitempty"`
	Dark  *EntryPointInfo `json:"dark,omitempty"`
	Light *EntryPointInfo `json:"light,omitempty"`
}

type EntryPointInfo struct {
	Assets struct {
		JS  []string `json:"js,omitempty"`
		CSS []string `json:"css,omitempty"`
	} `json:"assets,omitempty"`
}

var entryPointAssetsCache *dtos.EntryPointAssets = nil

func GetWebAssets(cfg *setting.Cfg) (*dtos.EntryPointAssets, error) {
	if cfg.Env != setting.Dev && entryPointAssetsCache != nil {
		return entryPointAssetsCache, nil
	}

	result, err := readWebAssets(filepath.Join(cfg.StaticRootPath, "build", "assets-manifest.json"))
	entryPointAssetsCache = result

	return entryPointAssetsCache, err
}

func readWebAssets(manifestpath string) (*dtos.EntryPointAssets, error) {
	//nolint:gosec
	bytes, err := os.ReadFile(manifestpath)
	if err != nil {
		return nil, fmt.Errorf("failed to load assets-manifest.json %w", err)
	}

	manifest := map[string]ManifestInfo{}
	err = json.Unmarshal(bytes, &manifest)
	if err != nil {
		return nil, fmt.Errorf("failed to read assets-manifest.json %w", err)
	}

	integrity := make(map[string]string, 100)
	for _, v := range manifest {
		if v.Integrity != "" && v.FilePath != "" {
			integrity[v.FilePath] = v.Integrity
		}
	}

	entryPoints, ok := manifest["entrypoints"]
	if !ok {
		return nil, fmt.Errorf("could not find entrypoints in asssets-manifest")
	}

	if entryPoints.App == nil || len(entryPoints.App.Assets.JS) == 0 {
		return nil, fmt.Errorf("missing app entry")
	}
	if entryPoints.Dark == nil || len(entryPoints.Dark.Assets.CSS) == 0 {
		return nil, fmt.Errorf("missing dark entry")
	}
	if entryPoints.Light == nil || len(entryPoints.Light.Assets.CSS) == 0 {
		return nil, fmt.Errorf("missing light entry")
	}

	entryPointJSAssets := make([]dtos.EntryPointAsset, 0)
	for _, entry := range entryPoints.App.Assets.JS {
		entryPointJSAssets = append(entryPointJSAssets, dtos.EntryPointAsset{
			FilePath:  entry,
			Integrity: integrity[entry],
		})
	}

	return &dtos.EntryPointAssets{
		JSFiles:  entryPointJSAssets,
		CSSDark:  entryPoints.Dark.Assets.CSS[0],
		CSSLight: entryPoints.Light.Assets.CSS[0],
	}, nil
}