package main

import (
	"bytes"
	"fmt"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"text/template"
)

const nginxTemplate = `server {
    listen {{.ListenPort}};
    listen [::]:{{.ListenPort}};
    
    # Replace with your actual domain(s)
    server_name {{.MonitoringHost}};
    
    # Document root for static files
    root {{.LocalDirectory}};
    
    location = / {
        try_files /index.html =404;
        
        add_header Content-Type "text/html; charset=utf-8";
        add_header Access-Control-Allow-Origin "*";
    }
    
    # Checkpoint endpoint - no caching
    location = /checkpoint {
        try_files /checkpoint =404;
        
        add_header Content-Type "text/plain; charset=utf-8";
        add_header Access-Control-Allow-Origin "*";
        add_header Cache-Control "no-store";
    }
    
    # Log info endpoint
    location = /log.v3.json {
        try_files /log.v3.json =404;
        
        add_header Content-Type "application/json";
        add_header Access-Control-Allow-Origin "*";
        add_header Cache-Control "public, max-age=3600, immutable";
    }
    
    # Issuer certificate endpoint - long cache
    location ~ ^/issuer/(.+)$ {
        try_files /issuer/$1 =404;
        
        add_header Content-Type "application/pkix-cert";
        add_header Access-Control-Allow-Origin "*";
        add_header Cache-Control "public, max-age=604800, immutable";
    }
    
    # Tile data endpoint - long cache, may have gzip
    location ~ ^/tile/(.+)$ {
        try_files /tile/$1 =404;
        
        add_header Content-Type "application/octet-stream";
        add_header Access-Control-Allow-Origin "*";
        add_header Cache-Control "public, max-age=604800, immutable";
        
        # Gzip encoding for .gz files
        location ~ \.gz$ {
            add_header Content-Encoding "gzip";
        }
    }
}
`

// NginxTemplateData contains the data needed to generate nginx configuration files
type NginxTemplateData struct {
	MonitoringHost string
	LocalDirectory string
	ListenPort     string
}

func generateNginx(yamlFile string, wantDiff bool, allowWrite bool, useColor bool) {
	config := loadConfig(yamlFile)

	// Extract port from first listen address
	listenPort := "8080" // fallback default
	if len(config.Listen) > 0 {
		port := extractPort(config.Listen[0])
		if port != "" {
			listenPort = port
		}
	}

	for _, log := range config.Logs {
		// Extract hostname from monitoring prefix
		hostname, err := extractHostname(log.MonitoringPrefix)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failed to extract hostname from %s: %v\n", log.MonitoringPrefix, err)
			continue
		}

		// Create template data
		data := NginxTemplateData{
			MonitoringHost: hostname,
			LocalDirectory: log.LocalDirectory,
			ListenPort:     listenPort,
		}

		// Parse and execute template
		tmpl, err := template.New("nginx").Parse(nginxTemplate)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failed to parse nginx template: %v\n", err)
			continue
		}

		// Generate output filename using only hostname part
		outputFilename := fmt.Sprintf("%s.conf", hostname)
		outputPath := filepath.Join(log.LocalDirectory, outputFilename)

		// Execute template to buffer
		var buf bytes.Buffer
		err = tmpl.Execute(&buf, data)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failed to execute nginx template for %s: %v\n", outputPath, err)
			continue
		}

		// Write file with status
		err = writeFileWithStatus(outputPath, buf.Bytes(), wantDiff, allowWrite, useColor)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failed to write nginx config file %s: %v\n", outputPath, err)
			continue
		}
	}
}

func extractPort(listenAddr string) string {
	// Handle common listen address formats:
	// ":8080" -> "8080"
	// "localhost:8080" -> "8080"
	// "[::]:8080" -> "8080"

	if strings.HasPrefix(listenAddr, ":") {
		return listenAddr[1:] // Remove the leading ":"
	}

	// For addresses with host:port format
	if strings.Contains(listenAddr, ":") {
		parts := strings.Split(listenAddr, ":")
		return parts[len(parts)-1] // Return the last part (port)
	}

	return ""
}

func extractHostname(urlStr string) (string, error) {
	parsedURL, err := url.Parse(urlStr)
	if err != nil {
		return "", err
	}

	return parsedURL.Host, nil
}