// Package catalogue provides ways of interacting with recipe catalogues which
// are JSON data structures which contain meta information about recipes (e.g.
// what versions of the Nextcloud recipe are available?).
package catalogue

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"path"
	"strings"
	"time"

	"coopcloud.tech/abra/config"
	"coopcloud.tech/abra/web"
	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
)

// RecipeCatalogueURL is the only current recipe catalogue available.
const RecipeCatalogueURL = "https://apps.coopcloud.tech"

// image represents a recipe container image.
type image struct {
	Image  string `json:"image"`
	Rating string `json:"rating"`
	Source string `json:"source"`
	URL    string `json:"url"`
}

// features represent what top-level features a recipe supports (e.g. does this
// recipe support backups?).
type features struct {
	Backups     string `json:"backups"`
	Email       string `json:"email"`
	Healthcheck string `json:"healthcheck"`
	Image       image  `json:"image"`
	Status      int    `json:"status"`
	Tests       string `json:"tests"`
}

// tag represents a git tag.
type tag = string

// service represents a service within a recipe.
type service = string

// serviceMeta represents meta info associated with a service.
type serviceMeta struct {
	Digest string `json:"digest"`
	Image  string `json:"image"`
	Tag    string `json:"tag"`
}

// Recipe represents a recipe in the abra catalogue
type Recipe struct {
	Category      string                          `json:"category"`
	DefaultBranch string                          `json:"default_branch"`
	Description   string                          `json:"description"`
	Features      features                        `json:"features"`
	Icon          string                          `json:"icon"`
	Name          string                          `json:"name"`
	Repository    string                          `json:"repository"`
	Versions      map[tag]map[service]serviceMeta `json:"versions"`
	Website       string                          `json:"website"`
}

// EnsureExists checks whether a recipe has been cloned locally or not.
func (r Recipe) EnsureExists() error {
	recipeDir := path.Join(config.ABRA_DIR, "apps", strings.ToLower(r.Name))

	if _, err := os.Stat(recipeDir); os.IsNotExist(err) {
		url := fmt.Sprintf("%s/%s.git", config.REPOS_BASE_URL, r.Name)
		_, err := git.PlainClone(recipeDir, false, &git.CloneOptions{URL: url, Tags: git.AllTags})
		if err != nil {
			return err
		}
	}

	return nil
}

// EnsureVersion checks whether a specific version exists for a recipe.
func (r Recipe) EnsureVersion(version string) error {
	recipeDir := path.Join(config.ABRA_DIR, "apps", strings.ToLower(r.Name))

	repo, err := git.PlainOpen(recipeDir)
	if err != nil {
		return err
	}

	tags, err := repo.Tags()
	if err != nil {
		return nil
	}

	var tagRef plumbing.ReferenceName
	if err := tags.ForEach(func(ref *plumbing.Reference) (err error) {
		if ref.Name().Short() == version {
			tagRef = ref.Name()
		}
		return nil
	}); err != nil {
		return err
	}

	if tagRef.String() == "" {
		return fmt.Errorf("%s is not available?", version)
	}

	worktree, err := repo.Worktree()
	if err != nil {
		return err
	}

	opts := &git.CheckoutOptions{Branch: tagRef, Keep: true}
	if err := worktree.Checkout(opts); err != nil {
		return err
	}

	return nil
}

// LatestVersion returns the latest version of a recipe.
func (r Recipe) LatestVersion() string {
	var latestVersion string
	for tag := range r.Versions {
		// apps.json versions are sorted so the last key is latest
		latestVersion = tag
	}
	return latestVersion
}

// Name represents a recipe name.
type Name = string

// RecipeCatalogue represents the entire recipe catalogue.
type RecipeCatalogue map[Name]Recipe

// Flatten converts AppCatalogue to slice
func (r RecipeCatalogue) Flatten() []Recipe {
	recipes := make([]Recipe, 0, len(r))
	for name := range r {
		recipes = append(recipes, r[name])
	}
	return recipes
}

// ByRecipeName sorts recipes by name.
type ByRecipeName []Recipe

func (r ByRecipeName) Len() int      { return len(r) }
func (r ByRecipeName) Swap(i, j int) { r[i], r[j] = r[j], r[i] }
func (r ByRecipeName) Less(i, j int) bool {
	return strings.ToLower(r[i].Name) < strings.ToLower(r[j].Name)
}

// recipeCatalogueFSIsLatest checks whether the recipe catalogue stored locally
// is up to date.
func recipeCatalogueFSIsLatest() (bool, error) {
	httpClient := &http.Client{Timeout: web.Timeout}
	res, err := httpClient.Head(RecipeCatalogueURL)
	if err != nil {
		return false, err
	}

	lastModified := res.Header["Last-Modified"][0]
	parsed, err := time.Parse(time.RFC1123, lastModified)
	if err != nil {
		return false, err
	}
	info, err := os.Stat(config.APPS_JSON)
	if err != nil {
		if os.IsNotExist(err) {
			return false, nil
		}
		return false, err
	}

	localModifiedTime := info.ModTime().Unix()
	remoteModifiedTime := parsed.Unix()

	if localModifiedTime < remoteModifiedTime {
		return false, nil
	}

	return true, nil
}

// ReadRecipeCatalogue reads the recipe catalogue.
func ReadRecipeCatalogue() (RecipeCatalogue, error) {
	recipes := make(RecipeCatalogue)

	recipeFSIsLatest, err := recipeCatalogueFSIsLatest()
	if err != nil {
		return nil, err
	}

	if !recipeFSIsLatest {
		if err := readRecipeCatalogueWeb(&recipes); err != nil {
			return nil, err
		}
		return recipes, nil
	}

	if err := readRecipeCatalogueFS(&recipes); err != nil {
		return nil, err
	}

	return recipes, nil
}

// readRecipeCatalogueFS reads the catalogue from the file system.
func readRecipeCatalogueFS(target interface{}) error {
	recipesJSONFS, err := ioutil.ReadFile(config.APPS_JSON)
	if err != nil {
		return err
	}
	if err := json.Unmarshal(recipesJSONFS, &target); err != nil {
		return err
	}
	return nil
}

// readRecipeCatalogueWeb reads the catalogue from the web.
func readRecipeCatalogueWeb(target interface{}) error {
	if err := web.ReadJSON(RecipeCatalogueURL, &target); err != nil {
		return err
	}

	recipesJSON, err := json.MarshalIndent(target, "", "    ")
	if err != nil {
		return err
	}

	if err := ioutil.WriteFile(config.APPS_JSON, recipesJSON, 0644); err != nil {
		return err
	}

	return nil
}

// VersionsOfService lists the version of a service.
func VersionsOfService(recipe, serviceName string) ([]string, error) {
	catalogue, err := ReadRecipeCatalogue()
	if err != nil {
		return nil, err
	}

	rec, ok := catalogue[recipe]
	if !ok {
		return nil, fmt.Errorf("recipe '%s' does not exist?", recipe)
	}

	versions := []string{}
	alreadySeen := make(map[string]bool)
	for version := range rec.Versions {
		appVersion := rec.Versions[version][serviceName].Tag
		if _, ok := alreadySeen[appVersion]; !ok {
			alreadySeen[appVersion] = true
			versions = append(versions, appVersion)
		}
	}

	return versions, nil
}