package main

import (
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"text/template"

	"git.site.quack-lab.dev/dave/cylogger"
	"github.com/BurntSushi/toml"
	"github.com/sergi/go-diff/diffmatchpatch"
)

type ServiceConfig struct {
	Domains  []string `toml:"domains"`
	Backend  string   `toml:"backend"`
	IPRange  string   `toml:"ip_range"`
}

type FileConfig struct {
	Services []ServiceConfig `toml:"services"`
}

type Config struct {
	IPRanges map[string]string `toml:"ip_ranges"`
	Files    map[string]FileConfig `toml:"files"`
}

// Template for generating Caddy configuration
const caddyTemplate = `{{- range $service := .Services -}}
{{ join $service.Domains " " }} {
    @lan {
        remote_ip {{ $service.IPRange }}
    }
    handle @lan {
        reverse_proxy {{ $service.Backend }}
    }
    handle {
        respond "Njet Molotoff" 403
    }
}
{{ end }}`

// Global variables
var (
	dryRun   = flag.Bool("dry-run", false, "Show what would be done without making changes")
	force    = flag.Bool("force", false, "Force apply changes")
	delete   = flag.Bool("d", false, "Delete files not in TOML config")
	tomlFile = flag.String("config", "services.toml", "Path to TOML configuration file")
)

func main() {
	flag.Parse()
	cylogger.InitFlag() // Automatically reads -loglevel flag

	logger := cylogger.Default.WithPrefix(fmt.Sprintf("config=%s", *tomlFile))
	logger.Info("Starting Caddy configuration sync")
	logger.Debug("Flags: dry-run=%v, force=%v, delete=%v", *dryRun, *force, *delete)

	if *delete {
		logger.Warning("Delete mode enabled - will remove files not in TOML")
	}

	if *dryRun {
		logger.Info("Dry-run mode enabled - no changes will be made")
	}

	// Parse TOML configuration
	logger.Debug("Loading configuration from TOML")
	config, err := loadConfig(*tomlFile)
	if err != nil {
		logger.Error("Failed to load configuration: %v", err)
		os.Exit(1)
	}
	logger.Debug("Successfully loaded configuration")

	// Validate configuration
	logger.Debug("Validating configuration")
	if err := validateConfig(config); err != nil {
		logger.Error("Configuration validation failed: %v", err)
		os.Exit(1)
	}
	logger.Debug("Configuration validation passed")

	// Perform synchronization
	logger.Debug("Starting synchronization")
	if err := syncConfigs(config); err != nil {
		logger.Error("Synchronization failed: %v", err)
		os.Exit(1)
	}

	logger.Info("Caddy configuration sync completed successfully")
}

func loadConfig(filename string) (*Config, error) {
	logger := cylogger.Default.WithPrefix(fmt.Sprintf("file=%s", filename))
	logger.Debug("Loading TOML configuration")

	var config Config

	_, err := toml.DecodeFile(filename, &config)
	if err != nil {
		return nil, fmt.Errorf("failed to decode TOML: %w", err)
	}

	logger.Trace("Loaded %d IP ranges and %d files", len(config.IPRanges), len(config.Files))
	return &config, nil
}

func validateConfig(config *Config) error {
	// Validate IP ranges are defined
	for filename, fileConfig := range config.Files {
		for i, service := range fileConfig.Services {
			if service.IPRange == "" {
				return fmt.Errorf("service %d in file %s has no IP range specified", i+1, filename)
			}

			if _, exists := config.IPRanges[service.IPRange]; !exists {
				return fmt.Errorf("IP range '%s' not defined for service %d in file %s", service.IPRange, i+1, filename)
			}

			if len(service.Domains) == 0 {
				return fmt.Errorf("service %d in file %s has no domains specified", i+1, filename)
			}

			if service.Backend == "" {
				return fmt.Errorf("service %d in file %s has no backend specified", i+1, filename)
			}
		}
	}

	return nil
}

func syncConfigs(config *Config) error {
	// Get current directory
	currentDir, err := os.Getwd()
	if err != nil {
		return fmt.Errorf("failed to get current directory: %w", err)
	}
	logger := cylogger.Default.WithPrefix(fmt.Sprintf("dir=%s", currentDir))

	// Get existing .caddy files
	logger.Debug("Scanning for existing .caddy files")
	existingFiles, err := getExistingCaddyFiles(currentDir)
	if err != nil {
		return fmt.Errorf("failed to get existing .caddy files: %w", err)
	}
	logger.Debug("Found %d existing .caddy files", len(existingFiles))

	// Track which files we've processed
	processedFiles := make(map[string]bool)
	var created, updated, unchanged int

	// Process each file in configuration
	logger.Debug("Processing %d configured files", len(config.Files))
	for filename, fileConfig := range config.Files {
		caddyFilename := filename + ".caddy"
		processedFiles[caddyFilename] = true
		fileLogger := logger.WithPrefix(fmt.Sprintf("file=%s", caddyFilename))
		fileLogger.Trace("Processing")

		// Generate expected content
		expectedContent, err := generateCaddyContent(fileConfig, config.IPRanges)
		if err != nil {
			return fmt.Errorf("failed to generate content for %s: %w", caddyFilename, err)
		}

		// Check if file exists and compare content
		existingContent, exists := existingFiles[caddyFilename]

		if !exists {
			// File doesn't exist, create it
			fileLogger.Info("Creating new file")
			created++
			if !*dryRun {
				if err := writeFile(caddyFilename, expectedContent); err != nil {
					return fmt.Errorf("failed to create file %s: %w", caddyFilename, err)
				}
			}
		} else if normalizeContent(existingContent) != normalizeContent(expectedContent) {
			// File exists but content differs
			fileLogger.Warning("File content differs, updating")
			updated++

			// Show detailed diff of what's changing
			generateAndLogDiff(fileLogger, caddyFilename, existingContent, expectedContent)

			if !*dryRun {
				if err := writeFile(caddyFilename, expectedContent); err != nil {
					return fmt.Errorf("failed to update file %s: %w", caddyFilename, err)
				}
			}
		} else {
			// File exists and content matches
			fileLogger.Debug("File content matches, no action needed")
			unchanged++
		}
	}

	// Handle orphaned files (files that exist but are not in config)
	var orphanedCount int
	for filename := range existingFiles {
		if !processedFiles[filename] {
			orphanedCount++
			orphanLogger := logger.WithPrefix(fmt.Sprintf("orphan=%s", filename))
			if *delete {
				orphanLogger.Warning("Deleting orphaned file")
				if !*dryRun {
					if err := os.Remove(filename); err != nil {
						return fmt.Errorf("failed to delete file %s: %w", filename, err)
					}
				}
			} else {
				orphanLogger.Warning("Found orphaned file not in configuration (use -d to delete)")
			}
		}
	}

	logger.Debug("Sync summary: created=%d, updated=%d, unchanged=%d, orphaned=%d",
		created, updated, unchanged, orphanedCount)
	return nil
}

func generateCaddyContent(fileConfig FileConfig, ipRanges map[string]string) (string, error) {
	logger := cylogger.Default.WithPrefix(fmt.Sprintf("template services=%d", len(fileConfig.Services)))
	logger.Debug("Generating Caddy content")

	// Create template data with resolved IP ranges
	templateData := struct {
		Services []ServiceConfig
	}{
		Services: make([]ServiceConfig, len(fileConfig.Services)),
	}

	// Resolve IP ranges for each service
	for i, service := range fileConfig.Services {
		logger.Trace("Resolving service %d: domains=%v, backend=%s, ip_range=%s",
			i, service.Domains, service.Backend, service.IPRange)

		templateData.Services[i] = ServiceConfig{
			Domains:  service.Domains,
			Backend:  service.Backend,
			IPRange:  ipRanges[service.IPRange],
		}
	}

	// Create template with join function
	funcMap := template.FuncMap{
		"join": strings.Join,
	}

	tmpl, err := template.New("caddy").Funcs(funcMap).Parse(caddyTemplate)
	if err != nil {
		return "", fmt.Errorf("failed to parse template: %w", err)
	}

	var result strings.Builder
	if err := tmpl.Execute(&result, templateData); err != nil {
		return "", fmt.Errorf("failed to execute template: %w", err)
	}

	content := result.String()
	logger.Trace("Generated content:\n%s", content)
	return content, nil
}

func getExistingCaddyFiles(dir string) (map[string]string, error) {
	logger := cylogger.Default.WithPrefix(fmt.Sprintf("scanner dir=%s", dir))
	logger.Debug("Scanning directory for .caddy files")

	files := make(map[string]string)

	entries, err := os.ReadDir(dir)
	if err != nil {
		return nil, fmt.Errorf("failed to read directory: %w", err)
	}

	for _, entry := range entries {
		if !entry.IsDir() && strings.HasSuffix(entry.Name(), ".caddy") {
			// Skip services.toml and other non-caddy files
			if entry.Name() == "services.toml" {
				continue
			}

			logger.Trace("Found .caddy file: %s", entry.Name())
			content, err := os.ReadFile(filepath.Join(dir, entry.Name()))
			if err != nil {
				return nil, fmt.Errorf("failed to read file %s: %w", entry.Name(), err)
			}
			files[entry.Name()] = string(content)
		}
	}

	logger.Debug("Scanned %d files, found %d .caddy files", len(entries), len(files))
	return files, nil
}

func writeFile(filename, content string) error {
	return os.WriteFile(filename, []byte(content), 0644)
}

func generateAndLogDiff(logger *cylogger.Logger, filename, existingContent, expectedContent string) {
	logger.Info("Changes needed for %s:", filename)

	// ANSI color codes
	const (
		ColorRed     = "\033[31m"
		ColorGreen   = "\033[32m"
		ColorReset   = "\033[0m"
	)

	dmp := diffmatchpatch.New()
	diffs := dmp.DiffMain(existingContent, expectedContent, false)

	// Use the library's built-in pretty diff formatting
	prettyDiff := dmp.DiffPrettyText(diffs)

	// Print the pretty diff with colors
	lines := strings.Split(prettyDiff, "\n")
	for _, line := range lines {
		if line == "" {
			continue
		}

		if strings.HasPrefix(line, "+") {
			fmt.Printf("%s%s%s\n", ColorGreen, line, ColorReset)
		} else if strings.HasPrefix(line, "-") {
			fmt.Printf("%s%s%s\n", ColorRed, line, ColorReset)
		} else {
			fmt.Printf("%s\n", line)
		}
	}
}

func normalizeContent(content string) string {
	// Normalize content for comparison by trimming whitespace and standardizing line endings
	lines := strings.Split(content, "\n")
	var normalizedLines []string

	for _, line := range lines {
		normalizedLines = append(normalizedLines, strings.TrimSpace(line))
	}

	return strings.Join(normalizedLines, "\n")
}