package main

import (
	"encoding/base64"
	"encoding/json"
	"fmt"
	"github.com/joho/godotenv"
	"net/http"
	"os"
	"os/exec"
	"strings"
)

var (
	registryName     string
	registryURL      string
	registryUsername string
	registryPassword string
)

func main() {
	// Load .env file
	err := godotenv.Load()
	if err != nil {
		fmt.Println("Error loading .env file:", err)
		return
	}

	// Read values from environment
	registryName = os.Getenv("REGISTRY_NAME")
	if registryName == "" {
		fmt.Println("REGISTRY_NAME not found in .env")
		return
	}

	registryURL = "https://" + registryName
	registryUsername = os.Getenv("REGISTRY_USERNAME")
	registryPassword = os.Getenv("REGISTRY_PASSWORD")
	if registryUsername == "" || registryPassword == "" {
		fmt.Println("REGISTRY_USERNAME or REGISTRY_PASSWORD not found in .env")
		return
	}

	if len(os.Args) < 2 {
		fmt.Println("Invalid command. Usage: registry [images|tags|rm|push|tag] <args>")
		return
	}

	switch os.Args[1] {
	case "images":
		registryImages()
	case "tags":
		if len(os.Args) < 3 {
			fmt.Println("Error: Please provide an image name.")
			return
		}
		registryTags(os.Args[2])
	case "rm":
		if len(os.Args) < 3 {
			fmt.Println("Error: Please provide an image name and optionally a tag (e.g., my-image or my-image:latest).")
			return
		}
		registryRm(os.Args[2])
	case "push":
		if len(os.Args) < 3 {
			fmt.Println("Error: Please provide an image name to push.")
			return
		}
		registryPush(os.Args[2])
	case "tag":
		if len(os.Args) < 4 {
			fmt.Println("Error: Please provide both source and target image names.")
			return
		}
		registryTag(os.Args[2], os.Args[3])
	default:
		fmt.Println("Invalid command. Usage: registry [images|tags|rm|push|tag] <args>")
	}
}

func registryImages() {
	type catalog struct {
		Repositories []string `json:"repositories"`
	}

	resp, err := http.Get(registryURL + "/v2/_catalog")
	if err != nil {
		fmt.Println("Error fetching images:", err)
		return
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusNotFound {
		fmt.Println("No images found in the registry.")
		return
	}

	var cat catalog
	if err := json.NewDecoder(resp.Body).Decode(&cat); err != nil {
		fmt.Println("Error decoding response:", err)
		return
	}

	if len(cat.Repositories) == 0 {
		fmt.Println("No images found in the registry.")
	} else {
		for _, img := range cat.Repositories {
			fmt.Println(img)
		}
	}
}

func registryTags(imageName string) {
	type tagList struct {
		Tags []string `json:"tags"`
	}

	resp, err := http.Get(fmt.Sprintf("%s/v2/%s/tags/list", registryURL, imageName))
	if err != nil {
		fmt.Println("Error fetching tags:", err)
		return
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusNotFound {
		fmt.Printf("Error: Image '%s' not found in the registry.\n", imageName)
		return
	}

	var tl tagList
	if err := json.NewDecoder(resp.Body).Decode(&tl); err != nil {
		fmt.Println("Error decoding response:", err)
		return
	}

	if len(tl.Tags) == 0 {
		fmt.Printf("No tags found for image: %s\n", imageName)
	} else {
		for _, tag := range tl.Tags {
			fmt.Println(tag)
		}
	}
}

func registryRm(imageArg string) {
	parts := strings.SplitN(imageArg, ":", 2)
	imageName := parts[0]
	tag := ""
	if len(parts) > 1 {
		tag = parts[1]
	}

	if tag == "" {
		deleteImageByName(imageName)
	} else {
		deleteImageByTag(imageName, tag)
	}
}

func deleteImageByName(imageName string) {
	type tagList struct {
		Tags []string `json:"tags"`
	}

	resp, err := http.Get(fmt.Sprintf("%s/v2/%s/tags/list", registryURL, imageName))
	if err != nil {
		fmt.Println("Error fetching tags:", err)
		return
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusNotFound {
		fmt.Printf("Error: Image '%s' not found in the registry.\n", imageName)
		return
	}

	var tl tagList
	if err := json.NewDecoder(resp.Body).Decode(&tl); err != nil {
		fmt.Println("Error decoding response:", err)
		return
	}

	for _, tag := range tl.Tags {
		deleteImageByTag(imageName, tag)
	}
}

func deleteImageByTag(imageName, tag string) {
	client := &http.Client{}

	req, err := http.NewRequest("HEAD", fmt.Sprintf("%s/v2/%s/manifests/%s", registryURL, imageName, tag), nil)
	if err != nil {
		fmt.Println("Error creating request:", err)
		return
	}
	req.Header.Set("Accept", "application/vnd.docker.distribution.manifest.v2+json")

	resp, err := client.Do(req)
	if err != nil {
		fmt.Println("Error fetching manifest:", err)
		return
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusNotFound {
		fmt.Printf("Error: Image '%s:%s' not found in the registry.\n", imageName, tag)
		return
	}

	digest := resp.Header.Get("Docker-Content-Digest")

	req, err = http.NewRequest("DELETE", fmt.Sprintf("%s/v2/%s/manifests/%s", registryURL, imageName, digest), nil)
	if err != nil {
		fmt.Println("Error creating delete request:", err)
		return
	}

	// Join username and password for Basic Auth
	registryCredentials := registryUsername + ":" + registryPassword
	req.Header.Set("Authorization", "Basic "+base64.StdEncoding.EncodeToString([]byte(registryCredentials)))

	resp, err = client.Do(req)
	if err != nil {
		fmt.Println("Error deleting image:", err)
		return
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusAccepted {
		fmt.Printf("Deleted image: %s:%s\n", imageName, tag)
	} else {
		fmt.Printf("Failed to delete image: %s:%s (status code: %d)\n", imageName, tag, resp.StatusCode)
	}
}

func registryPush(imageName string) {
	if !strings.HasPrefix(imageName, registryName) {
		imageName = registryName + "/" + imageName
	}

	cmd := exec.Command("docker", "push", imageName)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		fmt.Println("Error pushing image:", err)
	}
}

func registryTag(sourceImage, targetImage string) {
	if !strings.HasPrefix(targetImage, registryName) {
		targetImage = registryName + "/" + targetImage
	}

	cmd := exec.Command("docker", "tag", sourceImage, targetImage)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		fmt.Println("Error tagging image:", err)
	}
}