// 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"
	"strings"
	"time"

	"coopcloud.tech/abra/pkg/config"
	"coopcloud.tech/abra/pkg/recipe"
	"coopcloud.tech/abra/pkg/web"
	"github.com/sirupsen/logrus"
)

// 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"`
}

// RecipeMeta represents metadata for a recipe in the abra catalogue.
type RecipeMeta 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"`
}

// LatestVersion returns the latest version of a recipe.
func (r RecipeMeta) LatestVersion() string {
	var version string

	// apps.json versions are sorted so the last key is latest
	latest := r.Versions[len(r.Versions)-1]

	for tag := range latest {
		version = tag
	}

	logrus.Debugf("choosing '%s' as latest version of '%s'", version, r.Name)

	return version
}

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

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

// Flatten converts AppCatalogue to slice
func (r RecipeCatalogue) Flatten() []RecipeMeta {
	recipes := make([]RecipeMeta, 0, len(r))

	for name := range r {
		recipes = append(recipes, r[name])
	}

	return recipes
}

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

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) {
			logrus.Debugf("no recipe catalogue found in file system cache")
			return false, nil
		}
		return false, err
	}

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

	if localModifiedTime < remoteModifiedTime {
		logrus.Debug("file system cached recipe catalogue is out-of-date")
		return false, nil
	}

	logrus.Debug("file system cached recipe catalogue is up-to-date")

	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 {
		logrus.Debugf("reading recipe catalogue from web to get latest")
		if err := readRecipeCatalogueWeb(&recipes); err != nil {
			return nil, err
		}
		return recipes, nil
	}

	logrus.Debugf("reading recipe catalogue from file system cache to get latest")
	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
	}

	logrus.Debugf("read recipe catalogue from file system cache in '%s'", config.APPS_JSON)

	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
	}

	logrus.Debugf("read recipe catalogue from web at '%s'", RecipeCatalogueURL)

	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 _, serviceVersion := range rec.Versions {
		for tag := range serviceVersion {
			if _, ok := alreadySeen[tag]; !ok {
				alreadySeen[tag] = true
				versions = append(versions, tag)
			}
		}
	}

	logrus.Debugf("detected versions '%s' for '%s'", strings.Join(versions, ", "), recipe)

	return versions, nil
}

// GetRecipeMeta retrieves the recipe metadata from the recipe catalogue.
func GetRecipeMeta(recipeName string) (RecipeMeta, error) {
	catl, err := ReadRecipeCatalogue()
	if err != nil {
		return RecipeMeta{}, err
	}

	recipeMeta, ok := catl[recipeName]
	if !ok {
		err := fmt.Errorf("recipe '%s' does not exist?", recipeName)
		return RecipeMeta{}, err
	}

	if err := recipe.EnsureExists(recipeName); err != nil {
		return RecipeMeta{}, err
	}

	logrus.Debugf("recipe metadata retrieved for '%s'", recipeName)

	return recipeMeta, nil
}