package main

import (
	"bufio"
	"crypto/md5"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"time"
)

type ContainerInfo struct {
	ID       string
	Name     string
	CName    string
	Interval string
	Ignores  []string
}

var notifiedChanges = struct {
	sync.RWMutex
	changes map[string]string
}{changes: make(map[string]string)}

var apiAddress string

func init() {
	apiAddress = os.Getenv("API_ADDRESS")
	if apiAddress == "" {
		apiAddress = "http://localhost:8080"
	}
}

func main() {
	// Check if GLITCHTIP_DSN environment variable is set
	glitchtipDSN := os.Getenv("GLITCHTIP_DSN")
	if glitchtipDSN == "" {
		log.Fatal("GLITCHTIP_DSN environment variable is not set")
	}

	log.Println("Starting Oculus...")

	// Ensure the diffs directory exists
	err := ensureDiffsDirectory()
	if err != nil {
		log.Fatalf("Error creating diffs directory: %v", err)
	}

	for {
		containers, err := fetchContainers()
		if err != nil {
			log.Printf("Error fetching containers: %v", err)
			time.Sleep(1 * time.Minute)
			continue
		}

		var wg sync.WaitGroup
		for _, container := range containers {
			wg.Add(1)
			go func(container ContainerInfo) {
				defer wg.Done()
				checkAndNotify(container)
			}(container)
		}
		wg.Wait()

		cleanupHashes(containers)

		// Sleep for 1 minute before checking for new containers again
		time.Sleep(1 * time.Minute)
	}
}

func fetchContainers() ([]ContainerInfo, error) {
	resp, err := http.Get(fmt.Sprintf("%s/containers", apiAddress))
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("error fetching containers: %s", resp.Status)
	}

	var containers []ContainerInfo
	if err := json.NewDecoder(resp.Body).Decode(&containers); err != nil {
		return nil, err
	}

	return containers, nil
}

func fetchDiffOutput(containerID string) (string, error) {
	resp, err := http.Get(fmt.Sprintf("%s/diff?id=%s", apiAddress, containerID))
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("error fetching diff: %s", resp.Status)
	}

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return "", err
	}

	return string(body), nil
}

func checkAndNotify(container ContainerInfo) {
	diffOutput, err := fetchDiffOutput(container.ID)
	if err != nil {
		log.Printf("Error getting diffs for container %s (%s): %v", container.Name, container.ID, err)
		return
	}

	filteredOutput, err := filterDiffOutput(diffOutput, container.CName, container.Ignores)
	if err != nil {
		log.Printf("Error filtering diffs for container %s (%s): %v", container.Name, container.ID, err)
		return
	}
	log.Printf("Filtered diff output for container %s: %s", container.Name, filteredOutput)

	if filteredOutput != "" {
		diffHash := fmt.Sprintf("%x", md5.Sum([]byte(filteredOutput)))
		log.Printf("Diff hash for container %s: %s", container.Name, diffHash)

		notifiedChanges.RLock()
		lastNotifiedHash, notified := notifiedChanges.changes[container.ID]
		notifiedChanges.RUnlock()

		if !notified || lastNotifiedHash != diffHash {
			filename := filepath.Join("diffs", fmt.Sprintf("%s.diff", container.CName))
			err := writeToFile(filename, filteredOutput)
			if err != nil {
				log.Printf("Error writing diff to file: %v", err)
				return
			}

			err = sendNotification(filteredOutput)
			if err != nil {
				log.Printf("Error sending notification for container %s: %v", container.ID, err)
			} else {
				notifiedChanges.Lock()
				notifiedChanges.changes[container.ID] = diffHash
				notifiedChanges.Unlock()
				log.Printf("Notification sent and hash updated for container: %s (%s)", container.Name, container.ID)
			}
		} else {
			log.Printf("No new changes detected for container: %s (%s)", container.Name, container.ID)
		}
	} else {
		log.Printf("No significant changes detected for container: %s (%s)", container.Name, container.ID)
	}
}

func filterDiffOutput(diffOutput, cname string, ignores []string) (string, error) {
	filename := filepath.Join("diffs", fmt.Sprintf("%s.diff", cname))

	// Write the diff output to the file
	err := ioutil.WriteFile(filename, []byte(diffOutput), 0644)
	if err != nil {
		return "", fmt.Errorf("error writing diff to file: %s", err)
	}

	// Read and filter the diff output
	var filteredLines []string
	file, err := os.Open(filename)
	if err != nil {
		return "", fmt.Errorf("error opening diff file: %s", err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()
		ignore := false
		for _, pattern := range ignores {
			match, err := filepath.Match(pattern, line)
			if err != nil {
				return "", fmt.Errorf("error matching pattern: %s", err)
			}
			if match {
				ignore = true
				break
			}
		}
		if !ignore {
			filteredLines = append(filteredLines, line)
		}
	}

	if err := scanner.Err(); err != nil {
		return "", fmt.Errorf("error reading diff file: %s", err)
	}

	filteredOutput := strings.Join(filteredLines, "\n")
	err = ioutil.WriteFile(filename, []byte(filteredOutput), 0644)
	if err != nil {
		return "", fmt.Errorf("error writing filtered diff to file: %s", err)
	}

	return filteredOutput, nil
}

func writeToFile(filename, content string) error {
	file, err := os.Create(filename)
	if err != nil {
		return err
	}
	defer file.Close()

	_, err = file.WriteString(content)
	return err
}

func sendNotification(content string) error {
	cmd := exec.Command("go-glitch")
	cmd.Stdin = strings.NewReader(content)
	output, err := cmd.CombinedOutput()
	if err != nil {
		log.Printf("go-glitch output: %s", output)
		return err
	}
	return nil
}

func ensureDiffsDirectory() error {
	return os.MkdirAll("./diffs", os.ModePerm)
}

func cleanupHashes(containers []ContainerInfo) {
	notifiedChanges.Lock()
	defer notifiedChanges.Unlock()

	activeContainers := make(map[string]bool)
	for _, container := range containers {
		activeContainers[container.ID] = true
	}

	for id := range notifiedChanges.changes {
		if !activeContainers[id] {
			delete(notifiedChanges.changes, id)
		}
	}
}