package cmd

import (
	"fmt"
	"net"
	"os"
	"path/filepath"
	"sort"
	"time"

	"github.com/mr0xb/nxstats/internal/geo"
	"github.com/mr0xb/nxstats/internal/parser"
	"github.com/mr0xb/nxstats/internal/report"
	"github.com/spf13/cobra"
)

var (
	flagDir        string
	flagOutput     string
	flagAccessLog  string
	flagErrorLog   string
	flagNoGzip     bool
	flagGeoIP      string
	flagSplitByDay bool
)

var rootCmd = &cobra.Command{
	Use:   "nxstats",
	Short: "Nginx log parser and HTML report generator",
	Long: `nxstats parses nginx access and error logs (including gzip-compressed
rotated logs) and generates a rich cyberpunk-themed HTML report with
charts, searchable tables, and optional GeoIP2 hit maps.`,
	RunE: runE,
}

func init() {
	rootCmd.Flags().StringVarP(&flagDir, "dir", "d", "/var/log/nginx", "Directory to scan for nginx logs")
	rootCmd.Flags().StringVarP(&flagOutput, "output", "o", "report.html", "Output HTML file path")
	rootCmd.Flags().StringVarP(&flagAccessLog, "access-log", "a", "", "Specific access log file (skips dir scan for access logs)")
	rootCmd.Flags().StringVarP(&flagErrorLog, "error-log", "e", "", "Specific error log file (skips dir scan for error logs)")
	rootCmd.Flags().BoolVar(&flagNoGzip, "no-gzip", false, "Skip .gz compressed rotated logs")
	rootCmd.Flags().StringVar(&flagGeoIP, "geoip", "", "Path to MaxMind GeoLite2-City.mmdb (enables map)")
	rootCmd.Flags().BoolVar(&flagSplitByDay, "split-by-day", false, "Write one HTML report per calendar day plus an index page")
}

// Execute runs the root command.
func Execute() {
	if err := rootCmd.Execute(); err != nil {
		os.Exit(1)
	}
}

func runE(cmd *cobra.Command, args []string) error {
	accessFiles, errorFiles, err := resolveLogFiles()
	if err != nil {
		return err
	}

	fmt.Fprintf(os.Stderr, "nxstats: reading %d access file(s), %d error file(s)\n",
		len(accessFiles), len(errorFiles))

	accessEntries, err := parser.ReadAccessEntries(accessFiles)
	if err != nil {
		return fmt.Errorf("read access logs: %w", err)
	}
	errorEntries, err := parser.ReadErrorEntries(errorFiles)
	if err != nil {
		return fmt.Errorf("read error logs: %w", err)
	}

	fmt.Fprintf(os.Stderr, "nxstats: %d access entries, %d error entries\n",
		len(accessEntries), len(errorEntries))

	gl, err := geo.NewGeoLookup(flagGeoIP)
	if err != nil {
		return fmt.Errorf("geoip: %w", err)
	}
	defer gl.Close()

	// Build global IP→GeoPoint map (one lookup per unique IP, reused per day).
	geoPoints := buildGeoPoints(gl, accessEntries)

	if flagSplitByDay {
		return runSplitByDay(accessEntries, errorEntries, geoPoints)
	}

	// ── Single-report path ─────────────────────────────────────────────────
	data := report.ReportData{
		GeneratedAt:   time.Now(),
		AccessEntries: accessEntries,
		ErrorEntries:  errorEntries,
	}
	report.ComputeStats(&data)

	if gl.IsEnabled() {
		pts := geoPointsSlice(geoPoints)
		data.GeoLocations = pts
		fmt.Fprintf(os.Stderr, "nxstats: resolved %d geo locations\n", len(pts))
	}

	html, err := report.GenerateHTML(data)
	if err != nil {
		return fmt.Errorf("generate html: %w", err)
	}
	if err := os.WriteFile(flagOutput, []byte(html), 0644); err != nil {
		return fmt.Errorf("write output %q: %w", flagOutput, err)
	}
	fmt.Fprintf(os.Stderr, "nxstats: report written to %s\n", flagOutput)
	return nil
}

// resolveLogFiles returns the access and error file lists, honouring --access-log,
// --error-log, and --dir flags.
func resolveLogFiles() (accessFiles, errorFiles []string, err error) {
	includeGzip := !flagNoGzip

	if flagAccessLog != "" {
		accessFiles = []string{flagAccessLog}
	} else {
		accessFiles, _, err = parser.ScanDirectory(flagDir, includeGzip)
		if err != nil {
			return nil, nil, fmt.Errorf("scan dir %q: %w", flagDir, err)
		}
	}

	if flagErrorLog != "" {
		errorFiles = []string{flagErrorLog}
	} else {
		_, errorFiles, err = parser.ScanDirectory(flagDir, includeGzip)
		if err != nil {
			return nil, nil, fmt.Errorf("scan dir %q: %w", flagDir, err)
		}
	}
	return accessFiles, errorFiles, nil
}

// buildGeoPoints runs GeoIP lookups for all unique IPs in accessEntries and
// returns a map of ip string → report.GeoPoint. Returns an empty map when
// GeoIP is disabled.
func buildGeoPoints(gl *geo.GeoLookup, accessEntries []parser.AccessEntry) map[string]report.GeoPoint {
	result := make(map[string]report.GeoPoint)
	if !gl.IsEnabled() {
		return result
	}
	for _, e := range accessEntries {
		if _, seen := result[e.RemoteAddr]; seen {
			continue
		}
		ip := net.ParseIP(e.RemoteAddr)
		if ip == nil {
			continue
		}
		pt := gl.Lookup(ip)
		if pt == nil {
			continue
		}
		result[e.RemoteAddr] = report.GeoPoint{
			IP:          pt.IP,
			Lat:         pt.Lat,
			Lon:         pt.Lon,
			Country:     pt.Country,
			CountryCode: pt.CountryCode,
		}
	}
	return result
}

// geoPointsSlice converts the geo map to a slice for a single-report run,
// tallying the request count for each IP from a pre-built count map.
func geoPointsSlice(geoPoints map[string]report.GeoPoint) []report.GeoPoint {
	pts := make([]report.GeoPoint, 0, len(geoPoints))
	for _, p := range geoPoints {
		pts = append(pts, p)
	}
	return pts
}

// runSplitByDay groups entries by calendar day, writes one HTML file per day,
// then writes the index page to flagOutput.
func runSplitByDay(
	accessEntries []parser.AccessEntry,
	errorEntries []parser.ErrorEntry,
	geoPoints map[string]report.GeoPoint,
) error {
	indexBase := filepath.Base(flagOutput)

	days := report.GroupByDay(flagOutput, accessEntries, errorEntries, geoPoints)
	if len(days) == 0 {
		fmt.Fprintln(os.Stderr, "nxstats: no entries found, writing empty index")
	}

	// Write per-day reports (oldest → newest)
	for i := range days {
		days[i].Data.IndexFile = indexBase
		days[i].Data.DayTitle = days[i].Date.Format("2006-01-02")

		// Per-day geo: set Count from this day's access entries
		if len(geoPoints) > 0 {
			countByIP := make(map[string]int)
			for _, e := range days[i].Data.AccessEntries {
				countByIP[e.RemoteAddr]++
			}
			updated := make([]report.GeoPoint, len(days[i].Data.GeoLocations))
			for j, g := range days[i].Data.GeoLocations {
				g.Count = countByIP[g.IP]
				updated[j] = g
			}
			days[i].Data.GeoLocations = updated
		}

		html, err := report.GenerateHTML(days[i].Data)
		if err != nil {
			return fmt.Errorf("generate html for %s: %w", days[i].Filename, err)
		}
		dailyPath := filepath.Join(filepath.Dir(flagOutput), days[i].Filename)
		if err := os.WriteFile(dailyPath, []byte(html), 0644); err != nil {
			return fmt.Errorf("write %q: %w", dailyPath, err)
		}
		fmt.Fprintf(os.Stderr, "nxstats: wrote %s\n", dailyPath)
	}

	// Build IndexData (days newest first in the table)
	idx := buildIndexData(accessEntries, days)

	indexHTML, err := report.GenerateIndexHTML(idx)
	if err != nil {
		return fmt.Errorf("generate index html: %w", err)
	}
	if err := os.WriteFile(flagOutput, []byte(indexHTML), 0644); err != nil {
		return fmt.Errorf("write index %q: %w", flagOutput, err)
	}
	fmt.Fprintf(os.Stderr, "nxstats: index written to %s (%d daily report(s))\n",
		flagOutput, len(days))
	return nil
}

// buildIndexData assembles the IndexData from all daily reports. Days are
// returned newest-first in the table. Unique IPs are counted across all
// access entries (not summed per day) to avoid double-counting.
func buildIndexData(allAccess []parser.AccessEntry, days []report.DayReport) report.IndexData {
	// Reverse a copy for newest-first display
	summaries := make([]report.DaySummary, len(days))
	for i, d := range days {
		summaries[len(days)-1-i] = report.DaySummary{
			Date:       d.Date,
			Filename:   d.Filename,
			Requests:   d.Data.TotalRequests,
			UniqueIPs:  d.Data.UniqueIPs,
			TotalBytes: d.Data.TotalBytes,
			ErrorRate:  d.Data.ErrorRate,
		}
	}

	// Sort summaries newest first (they were built from oldest-first days)
	sort.Slice(summaries, func(i, j int) bool {
		return summaries[i].Date.After(summaries[j].Date)
	})

	var totalReqs int
	var totalBytes int64
	var totalErrors int
	for _, d := range days {
		totalReqs += d.Data.TotalRequests
		totalBytes += d.Data.TotalBytes
		for status, count := range d.Data.StatusCounts {
			if status >= 500 {
				totalErrors += count
			}
		}
	}

	// Unique IPs across all days (union, not sum)
	ipSet := make(map[string]struct{}, len(allAccess))
	for _, e := range allAccess {
		ipSet[e.RemoteAddr] = struct{}{}
	}

	var errorRate float64
	if totalReqs > 0 {
		errorRate = float64(totalErrors) / float64(totalReqs) * 100.0
	}

	return report.IndexData{
		GeneratedAt:      time.Now(),
		Days:             summaries,
		TotalRequests:    totalReqs,
		TotalUniqueIPs:   len(ipSet),
		TotalBytes:       totalBytes,
		OverallErrorRate: errorRate,
	}
}