package web

import (
	"bufio"
	"encoding/json"
	"fmt"
	"html/template"
	"io"
	"log"
	"mime/multipart"
	"net/http"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"github.com/go-echarts/go-echarts/v2/charts"
	"github.com/go-echarts/go-echarts/v2/opts"
)

func loadTemplates(name string) (*template.Template, error) {

	funcs := template.FuncMap{
		"safeHTML": func(s string) interface{} { return template.HTML(s) },
	}

	templates, err := loadTemplatesFromDir("internal/web/templates")
	if err != nil {
		log.Printf("Error loading templates: %v", err)
		return nil, err
	}

	return template.New(name).Funcs(funcs).ParseFiles(templates...)
}

func ConvertAndSort[K comparable](data map[K]int, limit int) []CommandStat {
	var result []CommandStat
	for key, count := range data {
		result = append(result, CommandStat{
			Command: fmt.Sprintf("%v", key),
			Count:   count,
		})
	}

	sort.Slice(result, func(i, j int) bool {
		return result[i].Count > result[j].Count
	})
	if len(result) > limit {
		result = result[:limit]
	}

	return result
}

func parseHistoryFile(file http.File) (map[string]int, error) {
	commandCounts := make(map[string]int)
	scanner := bufio.NewScanner(file)

	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}

		command := strings.Fields(line)[0]
		commandCounts[command]++
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}
	return commandCounts, nil
}

func generateTopCommands(commandCounts map[string]int, topN int) []CommandStat {
	stats := make([]CommandStat, 0, len(commandCounts))
	for cmd, count := range commandCounts {
		stats = append(stats, CommandStat{Command: cmd, Count: count})
	}

	sort.Slice(stats, func(i, j int) bool {
		return stats[i].Count > stats[j].Count
	})

	if topN < len(stats) {
		stats = stats[:topN]
	}
	return stats
}

func createBarChart(stats []CommandStat) *charts.Bar {
	bar := charts.NewBar()
	bar.SetGlobalOptions(
		charts.WithTitleOpts(opts.Title{
			Title:    "Top Commands",
			Subtitle: "Most used commands",
		}),
		charts.WithXAxisOpts(opts.XAxis{
			AxisLabel: &opts.AxisLabel{
				Show:     opts.Bool(true),
				Interval: "0",
				Rotate:   45,
			},
		}),
		charts.WithLegendOpts(opts.Legend{
			TextStyle: &opts.TextStyle{
				Color: "#888",
			},
		}),
	)

	commands := make([]string, len(stats))
	counts := make([]int, len(stats))
	for i, stat := range stats {
		commands[i] = stat.Command
		counts[i] = stat.Count
	}

	bar.SetXAxis(commands).
		AddSeries("Frequency", generateBarItems(counts))

	return bar
}

func generateBarItems(data []int) []opts.BarData {
	items := make([]opts.BarData, len(data))
	for i, v := range data {
		items[i] = opts.BarData{Value: v}
	}
	return items
}

func saveResults(uniqueID string, stats map[string]interface{}) {
	filename := "results/" + uniqueID + ".json"
	file, err := os.Create(filename)
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()
	json.NewEncoder(file).Encode(stats)
}

func loadResults(uniqueID string) (map[string]interface{}, error) {
	filename := "results/" + uniqueID + ".json"
	file, err := os.Open(filename)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	var stats map[string]interface{}
	err = json.NewDecoder(file).Decode(&stats)
	return stats, err
}

func loadTemplatesFromDir(dir string) ([]string, error) {
	var templates []string

	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !info.IsDir() && filepath.Ext(path) == ".html" {
			templates = append(templates, path)
		}
		return nil
	})

	return templates, err
}

func isTextFileAndSizeOk(file multipart.File, size int64) (bool, error) {
	if size > 1*1024*1024 {
		return false, fmt.Errorf("File size exceeds 1MB")
	}

	buffer := make([]byte, 512)
	_, err := file.Read(buffer)
	if err != nil && err != io.EOF {
		return false, fmt.Errorf("Error reading file: %v", err)
	}

	mimeType := http.DetectContentType(buffer)

	if !strings.HasPrefix(mimeType, "text/") {
		return false, fmt.Errorf("File is not a text file (mimetype: %s)", mimeType)
	}

	_, err = file.Seek(0, 0)
	if err != nil {
		return false, fmt.Errorf("Error seeking file: %v", err)
	}

	return true, nil
}