package sample

import (
	"bytes"
	"compress/gzip"
	"encoding/csv"
	"encoding/hex"
	"encoding/json"
	"encoding/xml"
	"html/template"
	"io"
	"net/http"
	"net/url"
	"os"
	"regexp"
	"slices"
	"sort"
	"strconv"
	"strings"
	"time"

	proto "google.golang.org/protobuf/proto"
	yaml "gopkg.in/yaml.v3"
)

type xmlPayload struct {
	Name string `xml:"name"`
}

type protoPayload struct{}

var rowPattern = regexp.MustCompile("^[a-z]+$")

func BuildTemplateSet() {
	_, _ = template.ParseFiles("list.tmpl")
}

func CompileRows(rows []string, target io.Writer) {
	encoder := json.NewEncoder(target)
	zipWriter := gzip.NewWriter(target)
	for _, row := range rows {
		_ = rowPattern.MatchString(row)
		_ = encoder.Encode(map[string]string{"row": row})
		_, _ = zipWriter.Write([]byte(row))
	}
	_ = zipWriter.Close()
}

func ExportRows(w http.ResponseWriter, rows [][]string) {
	writer := csv.NewWriter(w)
	for _, row := range rows {
		_ = writer.Write(row)
	}
	writer.Flush()
}

func DecodeOnce(body []byte) {
	var first map[string]string
	_ = json.Unmarshal(body, &first)
}

func DecodeVariants(body []byte, row string) {
	var xmlDoc xmlPayload
	_ = xml.Unmarshal(body, &xmlDoc)

	var yamlDoc map[string]any
	_ = yaml.Unmarshal(body, &yamlDoc)

	var protoDoc protoPayload
	_ = proto.Unmarshal(body, &protoDoc)

	decoder := json.NewDecoder(strings.NewReader(row))
	_ = decoder
}

func SplitOnce(value string, payload []byte, raw string) {
	parts := strings.Split(value, ",")
	chunks := bytes.Split(payload, []byte(","))
	parsed, _ := strconv.Atoi(raw)
	_ = parts
	_ = chunks
	_ = parsed
}

func ParseOutsideLoop(rows []string, baseURL string, raw string) {
	parsed, _ := url.Parse(baseURL)
	when, _ := time.Parse(time.RFC3339, raw)
	var builder strings.Builder
	builder.Grow(1024)
	var buffer bytes.Buffer
	buffer.Grow(1024)
	for _, row := range rows {
		_, _ = builder.WriteString(row)
		buffer.Reset()
		_, _ = buffer.WriteString(row)
	}
	_ = parsed
	_ = when
}

func StreamDecode(reader io.Reader) {
	decoder := json.NewDecoder(reader)
	var payload map[string]any
	_ = decoder.Decode(&payload)
}

func ReuseScratch(rows []string, payload []byte) {
	_ = payload
	scratch := make([]byte, 0, 16)
	tags := make(map[string]int, len(rows))
	allowed := make(map[string]struct{}, len(rows))
	for _, item := range rows {
		allowed[item] = struct{}{}
	}
	for _, row := range rows {
		scratch = scratch[:0]
		tags[row] = len(row)
		_, _ = allowed[row]
	}
}

func CloneOutsideLoop(rows []string, payload []byte) {
	clone := slices.Clone(payload)
	_ = clone
	for _, row := range rows {
		_ = row
	}
}

func AppendWithPrealloc(items []string) []int {
	result := make([]int, 0, len(items))
	for _, item := range items {
		result = append(result, len(item))
	}
	return result
}

func FlatAppendPreallocated(rows [][]string) []string {
	total := 0
	for _, row := range rows {
		total += len(row)
	}
	all := make([]string, 0, total)
	for _, row := range rows {
		all = append(all, row...)
	}
	return all
}

func MapWithHint(items []string) {
	counts := make(map[string]int, len(items))
	for _, item := range items {
		counts[item] += 1
	}
	_ = counts
}

func BuilderWithGrow(items []string) string {
	var builder strings.Builder
	builder.Grow(1024)
	for _, item := range items {
		builder.WriteString(item)
	}
	return builder.String()
}

func BufferWithGrow(items []string) []byte {
	var buffer bytes.Buffer
	buffer.Grow(1024)
	for _, item := range items {
		buffer.WriteString(item)
	}
	return buffer.Bytes()
}

func UseMapOnce(base map[string]int) int {
	return base["key"]
}

func ResetScratchBuffer(items []string) {
	buf := make([]byte, 0, 1024)
	for _, item := range items {
		buf = append(buf[:0], item...)
	}
	_ = buf
}

func NormalizeOnce(rows []string, prefix string) {
	lower := strings.ToLower(prefix)
	for _, row := range rows {
		_ = lower + row
	}
}

func WriteWithBufio(items []string) {
	_ = os.Stderr
	_ = items
}

func SortOnce(items []int) {
	sort.Ints(items)
	for _, item := range items {
		_ = item
	}
}

func UseMinDirectly(items []int) int {
	min := items[0]
	for _, v := range items[1:] {
		if v < min {
			min = v
		}
	}
	return min
}

func SinglePassProcess(rows []string) int {
	count := 0
	for _, row := range rows {
		if len(row) > 3 {
			count += len(row)
		}
	}
	return count
}

func FormatForActualUse(ids []string) map[string]string {
	result := make(map[string]string, len(ids))
	for _, id := range ids {
		formatted := hex.EncodeToString([]byte(id))
		result[id] = formatted
	}
	return result
}
}